CFturbo En

© CFturbo Software & Engineering GmbH

CFturbo8

User manual for CFturbo8 software

CFturbo8Introduction

This manual describes the usage of the software CFturbo8and corresponds to the online help with regards to content.

All rights reserved. No parts of this work may be reproduced in any form or by any means - graphic, electronic, ormechanical, including photocopying, recording, taping, or information storage and retrieval systems - without thewritten permission of the publisher.

Products that are referred to in this document may be either trademarks and/or registered trademarks of therespective owners. The publisher and the author make no claim to these trademarks.

While every precaution has been taken in the preparation of this document, the publisher and the author assume noresponsibility for errors or omissions, or for damages resulting from the use of information contained in thisdocument or from the use of programs and source code that may accompany it. In no event shall the publisher andthe author be liable for any loss of profit or any other commercial damage caused or alleged to have been causeddirectly or indirectly by this document.

© CFturbo Software & Engineering GmbH, 2010

3Contents


Table of Contents

Part I CFturbo 8 7

Part II General 9

................................................................................................................................... 91 Licensing

........................................................................................................................... 11Request license

........................................................................................................................... 12Activate license

........................................................................................................................... 13Select license

........................................................................................................................... 14Show license information ................................................................................................................................... 152 Batch mode

........................................................................................................................... 18Parameters for impellers

........................................................................................................................... 19Parameters for volutes ................................................................................................................................... 203 Preferences - General

................................................................................................................................... 214 Preferences - Export

................................................................................................................................... 225 Approximation functions

................................................................................................................................... 266 Comparing different designs

................................................................................................................................... 297 Remove design steps

................................................................................................................................... 308 Graphical dialogs

Part III Main window 33

................................................................................................................................... 331 Create new design

................................................................................................................................... 342 Open/ Save design

................................................................................................................................... 343 Project

................................................................................................................................... 374 3D Model

........................................................................................................................... 42Problems when generating surfaces/solids ................................................................................................................................... 445 Help

................................................................................................................................... 446 Data export

........................................................................................................................... 49Autodesk AutoCAD

........................................................................................................................... 51Autodesk Inventor

........................................................................................................................... 53Catia (Dassault Systèmes)

........................................................................................................................... 53Numeca AutoGrid5

........................................................................................................................... 55Pro/ENGINEER (PTC)

........................................................................................................................... 65Ansys ICEM CFD ................................................................................................................................... 677 Data export limitations

................................................................................................................................... 678 CAE-Startup

Part IV Impeller 74

................................................................................................................................... 741 Main dimensions

........................................................................................................................... 74Pump / Ventilator .................................................................................................................... 75Design point.................................................................................................................... 77Parameters

CFturbo84


.................................................................................................................... 81Dimensions

........................................................................................................................... 85Compressor / Turbine .................................................................................................................... 85General.................................................................................................................... 86Compressor

............................................................................................................. 87Design point

............................................................................................................. 90Parameters

............................................................................................................. 93Dimensions.................................................................................................................... 96Turbine

............................................................................................................. 97Design point

............................................................................................................. 99Parameters............................................................................................................. 102Dimensions

........................................................................................................................... 105Shaft/Hub

........................................................................................................................... 106Full impeller ................................................................................................................................... 1072 Meridional section

........................................................................................................................... 107Meridional contour .................................................................................................................... 110Bezier-mode

............................................................................................................. 113Converting Polyline / Bezier.................................................................................................................... 114Simple-mode

........................................................................................................................... 116Meridional flow ................................................................................................................................... 1173 Blade properties

........................................................................................................................... 118Blade setup .................................................................................................................... 121Radial element blade

........................................................................................................................... 122Blade angles .................................................................................................................... 124Inlet triangle.................................................................................................................... 126Outlet triangle

............................................................................................................. 128Decreased output by PFLEIDERER

............................................................................................................. 129Outflow coefficient by WIESNER................................................................................................................................... 1304 Blade design

........................................................................................................................... 130Mean line .................................................................................................................... 131Freeform blades, 2D blades, Radial element blades.................................................................................................................... 133Circular blades, Straight blades.................................................................................................................... 134Blade Information.................................................................................................................... 137Blade lean angle

........................................................................................................................... 138Blade profile .................................................................................................................... 141Converting Polyline / Bezier

........................................................................................................................... 142Blade edge .................................................................................................................... 145Edge position

................................................................................................................................... 1465 Performance Estimation

................................................................................................................................... 1506 CFD Setup

Part V Volute 153

................................................................................................................................... 1531 Inlet definition

........................................................................................................................... 154Impeller

........................................................................................................................... 156Diffuser

........................................................................................................................... 157Volute ................................................................................................................................... 1582 Cross Section

........................................................................................................................... 161Bezier cross section

........................................................................................................................... 162Internal cross sections ................................................................................................................................... 1623 Spiral development areas

........................................................................................................................... 164Design rule

........................................................................................................................... 166Cut-water

5Contents


................................................................................................................................... 1664 Diffuser

Part VI Appendix 172

................................................................................................................................... 1721 References

................................................................................................................................... 1732 Contact addresses

................................................................................................................................... 1743 License agreement

Index 180

Part

I

7CFturbo 8


1 CFturbo 8

CFturbo is made to design interactively radial and mixed-flowturbomachinery: pumps, ventilators, compressors, turbines. The software iseasy to use and does enable quick generation and variation of impeller andvolute geometries. Several models can be displayed, compared andmodified simultaneously.

It contains numerous approximation functions that may be customized bythe user in order to implement user specific knowledge into the CFturbo-based design process. In spite of the creation of semiautomatic proposals, fundamental experiences in turbomachinery design are helpful but notnecessary. An experienced turbomachinery design engineer should be ableto design new high-quality impellers and volutes more easily and quickly.

Integration of geometry data into the CAE environment is easily possible bydirect interfaces to various CAD- and CFD-systems.

Please read the License agreement before using the program.Information about activating license you can read in chapter Licensing .

Contact persons you can find under Contact addresses , actualinformation on the CFturbo website.

Copyright © 2009, CFturbo Software & Engineering GmbH.

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http://www.cfturbo.com

http://www.cfturbo.com

Part

II

9General


2 General

2.1 Licensing

Edit | Licensing

A valid license is necessary to run CFturbo on your computer.Menu item Licensing enables license handling in a wizard style.

REQUEST new license by e-mail ACTIVATE new license by License Transfer File SELECT existing license SHOW current license information

If the license of a software module has expired, you can reactivate the program by entering a newlicense.A hint with remaining days appears on startup screen 20 days before expiration of the license. Thenumber of days for this hint can be specified in "Edit | Preferences | General ".

Steps for licensing

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10 CFturbo8


At the first start of CFturbo there is no running licenseavailable. You have to either

a) REQUEST a license and ACTIVATE it later likedescribed below

or

b) SELECT a running network license .

For license request you have to select the license type first: Local Computer License ORNetwork Server License.

Local Computer License

Step Notes

1. Start CFturbo - you see the "License Wizard" dialog(or open menu Edit | Licensing).

2. Request Local Computer License and send licenserequest to [email protected]

REQUEST

3. Activate license using the "Licence Transfer" file (*.lic-trf) recieved from CFturbo sales team

ACTIVATE

4. Show license information to check modules anddates

SHOW

Network Server License(NOT available for trial license)

Step Notes

1. Start CFturbo - you see the "License Wizard" dialog(or open menu Edit | Licensing).

2. Request Network Server License and send licenserequest to [email protected]

REQUEST

3. Activate license using the "Licence Transfer" file (*.lic-trf) recieved from CFturbo sales team

ACTIVATE

4. Show license information to check modules anddates

SHOW

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mailto:[email protected]

mailto:[email protected]

11General


2.1.1 Request license

For license request you have to select the license type first: Local Computer License ORNetwork Server License.

For booth license types you have to specify: - requested software modules - name of your company - start date of the license

The Session Code and the Checksum are calculated automatically and ensure the singular usageof provided license information.

Details of the 2 license types: see below

After input of all necessary information you can - use the Send E-mail button to prepare a message with your default E-mail client if possible (E-mail will NOT be transmitted automatically!) OR - use the Copy to Clipboard button if you want to create the E-mail message manually and pastethe information (send the E-mail to [email protected])


The so-called Machine ID is calculated byCFturbo considering hardware and operatingsystem information to link the license to thelocal computer.


12 CFturbo8


You have to select the License directoryfirst. The directory has to be a shared folderor a directory within a shared folder.

Please note: All CFturbo users need read and writeaccess rights for this directory.DFS shares (Distributed File System)are not supported.

After selecting the directory CFturbo copiesthe license file automatically to this networklocation.

The Machine ID is calculated automatically.

Select the correct MAC address from the list if there’s more than one network interface on theserver sharing this path.If no MAC address is available please check, that you are not using a DFS share and the MACaddress of the server can be resolved using 'nbtstat -a <servername>', otherwise contact technicalsupport.

Finally you have to specify the desired/ordered number of users that can use the software in parallel.

2.1.2 Activate license

Please note: License activation is possible with administrator rights only.

For License activation a "Licence Transfer" file (*.lic-trf) is necessary, which you can get on request via E-mail.11

13General


The Session Code is calculatedautomatically and may not be changed sincethe license request .

After selecting the License Transfer File thelicense activation can be started by pressingthe Activate! button.

2.1.3 Select license

Please note: License selection is possible with administrator right only.

Selecting license is possible if you already have a valid license on your computer or in your localnetwork.For license selection you have to specify the license type first: Local Computer License ORNetwork Server License.

The license file can be selected by pressing the Apply License File button.


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14 CFturbo8


The location of the license file ("cfturbo8.lic") is fixed to the directory

c:\documents and settings\all users\application data\cfturbo


You have to select the License file("cfturbo8.lic") location in your local network.

2.1.4 Show license information

Current license information are displayed here.

The company name is for information only.The license mode can be "Local (Nodelocked)" or "Network", whereas for a network license thenumber of possible users and the number of active users is displayed.

15General


Path is the license file location.

Normally Flags should not exist.If necessary the last Error message of license checking is displayed.

2.2 Batch mode

CFturbo can be executed in Batch mode to change designs without any screen display and userinteraction. This is essential for using CFturbo with optimization software.

Syntax:cfturbo.exe -batch <batch file>

All batch commands have to be defined in a file (<batch file>).

Batch file

Structur:InputFile=<full filename>[OutputFile=<full filename>][ExportFile=<full filename>][Parameter=<variable>:<value[%]>[:value[%]][…]][...]

InputFile and OutputFile are CFturbo files (*.cft).The export format is detected from the file extension of ExportFile (see Data export ).All parameters are in SI-units or in %(‘%’-sign).Exception: angles in °InputFile is necessary, all others are optional.

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16 CFturbo8


More than 1 parameter-line is possible.Parameter can containa) 1 value, e.g. d2:0.15

b) several values separated by ‘:’, e.g. for blade angles on several sections Beta2:23:24:25

(number of values must match with number of sections)c) Point values for Bezier-curves as ‘Index:x-value:y-value’, e.g. Hub:0:0.03:0.025

(missing x- or y-coordinate results in unchanged coordinate, e.g. Hub:0:0.03:)

Lines starting with ‘#’ are comments.

Example:

# Example CFturbo batch fileInputFile=c:\daten\Software\CFturbo\Examples\batch\MixedflowPump.cftOutputFile=c:\daten\Software\CFturbo\Examples\batch\MixedflowPump1.cftExportFile=c:\daten\Software\CFturbo\Examples\batch\MixedflowPump1.tinParameter=d2:0.291Parameter=b2:90%Parameter=Beta2:0.4538:0.4363:0.4189

A log-file <batchfile>.log is created in the directory of <batch file>:

>>> bilbao.cftDirectory: c:\daten\mitarbeiter\kreuzfeld\Eigene Dateien\Batch file created: bilbao.batchStart CFturbo... CFturbo 8.1 - 04.06.2009 Batch mode started Time: 04.06.2009 20:07:32 File: c:\daten\mitarbeiter\kreuzfeld\Eigene Dateien\bilbao.batch Reading batch file: c:\daten\mitarbeiter\kreuzfeld\Eigene Dateien\bilbao.batch Open input file: c:\daten\mitarbeiter\kreuzfeld\Eigene Dateien\bilbao.cft Update design ... Hints available: Blade properties The deviation (slip) between blade and flow Delta > 20°.This can be causedby overloading the impeller.Please try to increase the impeller diameter,decrease required energy transmission or increase number of blades. Batch mode terminated. (00:265 sec)CFturbo terminated normally...

Parameters for impellers Parameters for volutes

Example for parametric modified design

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17General


18 CFturbo8


2.2.1 Parameters for impellers

Name Description Unit

Main dimensions

dN Hub diameter dN m

dS Suction diameter dS m

d1 Inlet diameter (leading edge) d1 m

b1 Inlet width (leading edge) b1 m

d2 Impeller diameter d2 m

b2 Impeller outlet width b2 m

nBl Number of blades nBl -

Meridional contour

19General


Name Description Unit

Hub Hub Bezier points (Index):m:m

Shroud Shroud Bezier points (Index):m:m

LEHub Leading edge position on hub (0…1) -

LEShroud Leading edge position on shroud (0…1) -

LEHubSpl Splitter leading edge position on hub (0…1) -

LEShroudSpl Splitter leading edge position on shroud (0…1) -

Blade properties

ProfCt Number of blade profiles -

Beta1 Blade angles at leading edge β1 °:°:°…

Beta2 Blade angles at trailing edge β2 °:°:°…

Beta1Spl Splitter blade angles at leading edge β1,Spl °:°:°…

Beta2Spl Splitter blade angles at trailing edge β2,Spl °:°:°…

Mean lines

dPhi Wrap angle ∆ °:°:°…

dPhiSplSplitter trailing edge position (tangential) betweenneighboring main blades

%:%:...

Phi0 Leading edge angle 0 °:°:°…

Phi0Spl Splitter leading edge position (tangential) %:%:...

MLBeta1 Bezier point position on β1 line -:-:...

MLBeta2 Bezier point position on β2 line -:-:...

2.2.2 Parameters for volutes

Name Description Einheit

Inlet definition

d2 Impeller diameter d2 m

b2 Impeller outlet width b2 m

20 CFturbo8


Name Description Einheit

d4 Spiral inlet diameter d4 m

b4 Spiral inlet width b4 m

2.3 Preferences - General

Edit | Preferences | General

Menu item Preferences - General is used for global options of the program.

On tab sheet Units you can select physical units to be used in thedialogs. Following units are available:

Head: m, ftgeom. length: mm, in, m

Flow rate: m3/h, m3/s, ft3/h, gpm, gps

Density: kg/m3, lb/ft3

Stress: MPa, PSIPressure: MPa, PSI, bar, PaPower: kW, hpMassflow: kg/s, lb/s

You can simultaneously change all units to SI or US system bypressing the buttons above.

On tab sheet Other you can adjust the language of online help.The standard is English.

Furthermore you can specify the number of days for licenseexpiration warning at startup.

21General


2.4 Preferences - Export

Edit | Preferences | Export

On dialog Preferences - Export you can specify how many data points are to be used for the 3Dmodel and for the point based export formats.

The number of points can be selected separately in each case for all geometry parts. The availableoptions depend on active design module:

Impeller

Meridian: hub/ shroudBlade: mean line, pressure/ suction side, leading/trailing edge

Volute

Spiral: cross sections, points per cross sectionDiffuser: cross sectionsCutwater: cross sections

22 CFturbo8


3 different global pre-settings can be selected.

Furthermore, you can specify length unit for exporting geometry. Please select the appropriate unitswhen importing data to the chosen CAE software.

2.5 Approximation functions

Edit | Approximation functions

CFturbo uses many approximation functions. These functions are based on published measurementdata that facilitate the forecast of optimal or accessible values.

In this dialog the approximation functions are graphically displayed and can be individuallycustomized. Functions for the following physical quantity are available:

ImpellerVolumetric efficiency

V

Tip clearance efficiency T

Side friction efficiency S

Mechanical efficiency m

Width number b2/d

2

Flow angle inflow 0A

Flow angle outflow 3

Radial/mixed-flow pump impeller

23General


Hydraulic efficiency h

Work coefficient Intake coefficient Number of blades zWrap angle

u

Meridional deceleration cm3

/cmS

Inclination angle hub H

Inclination angle shroud S

Inclination angle trailing edge Blade thickness leading edge s

1

Blade thickness trailing edge s2

Blade thickness max. smax

Radial/mixed-flow ventilator impellerHydraulic efficiency

h

Work coefficient Diameter coefficient

Radial/mixed-flow compressor impellerWork coefficient Lokal flow coefficient Total flow coefficient

t

Meridional flow coefficient m

Width number b2/d

2

Rel. deceleration ratio w2/w

1


/cm1


/cmS


/cmS

Radial/mixed-flow turbine rotorWork coefficient Meridional flow coefficient

m

Tangential force coefficient ct

Coefficient ratio cr


/cm1

Wrap angle u


/cmS

VoluteCut-water diameter ratio d

4/d

2

Cut-water width ratio b4/b

2

Stepanoff constant ks

On the left at File location, the name of the file is shown that contains all data of the functions. Ingeneral this file is called Functions.cftfu, and is located in the installation directory of CFturbo.

24 CFturbo8


Modifications to functions are saved automatically if you leave the dialog window by pressing the OK-button. In case the user has no write permissions one could choose a different directory to save thefile. Renaming files is possible by using the Save as-function. By clicking the Open-button apreviously saved functions file can be opened.

The user must first select the Machine type and the variable in the Physical variable panel.CFturbo’s internal function is displayed in the diagram if corresponding check box is active. Onpanel Function you can add any functions. Selected function is displayed in the diagram in additionto CFturbo internal function. Function with active check box is used by CFturbo for calculations. If nofunction has active checkbox or no additional function is defined at all, then the CFturbo internalfunction is used.

In panel Points you can edit curve points of selected function. You can add new points at the end ofthe table – the points are automatically sorted by x values. To remove a point you have to deleteeither x or y value.

These 3 buttons are enabling the user to import points from file (one point per line)or export points to file or to clear the table.

On panel Test you can test the active function. Saving of values is possible by clicking OK-button.

2 special features are existing:

Functions depending on 2 variablesFunctions can depend on 2 variables whereas one serves as parameter. Separate curves exist foreach particular parameter value that are used to calculate function values. These parameter curvescan be added in the Parameter panel. The parameter value is displayed on endpoint of curve in thediagram.

25General


Following functions with 2 variables exist:

Function depends on curve parameter

hydraulic efficiency h

specific speed nq flow rate Q

mechanical efficiency m flow rate Q revolutions n

tip clearance efficiency T

specific speed nq

area ratio AR

Range definitionSome parameters have a recommended range, which means an area that is defined by a higher anda lower limit. The definition of the 2 parameter curves can be done as written above.

26 CFturbo8


2.6 Comparing different designs

Edit | Reference designs

This functionality can be used for simultaneous display of various designs to compare each otherand for purposeful modification.

27General


Using the Add-button any reference design (*.CFT- files) can be added. Each design has its owncolor and line width (panel Options). On panel Hint some information about the selected design isprovided.With the Remove-button selected reference design can be deleted from list.However reference design may be deactivated by the check box at the beginning of the line.

Reference geometries are displayed in the dialogs with selected color and line width. Numericalvalues appear as small hints on input fields when mouse is moved over it.

28 CFturbo8


Down to the right in the dialog windows you could completely switch offthe display of reference geometries and start a dialog for newconfiguration.

Reference geometry is displayed as 3D modeladditionally.

All reference geometries are arranged in the modelltree in the region "Imports" beginning with "REF",whereas the single parts can be configured like thenormal geometry.

29General


2.7 Remove design steps

Edit | Remove design steps

If you make any design changes on the design all initial design steps based upon this status areautomatically adapted (automatic update). This is done to prevent repeating the same design steps(parametric model).

However, if you would like to start with an automatic generated CFturbo primary design, certaindesign steps can be removed manually. Then CFturbo continues with new primary design data. Forthat purpose you have to select the appropriate design step to be removed and then press the OK-button.

30 CFturbo8


2.8 Graphical dialogs

All graphical representations are made in diagrams that are automatically scaled according todisplayed objects. All diagrams have a popup menu (right click on empty diagram area) with basicfunctions. Alternatively you can use the buttons on the left side of the diagram:

Zoom window by mouseFit viewLens magnificationCopy to clipboardSave as WMF, BMP or JPGPrintAdd any polyline from file (x,y points) to compare different curves or to visualize componentsMeasure distanceConfigure diagram

31General


If the mouse cursor is moved over a graphical object (e.g. polyline, Bezier point) then this ishighlighted by color or by increased line width. Right mouse click is now related to this object anddoes open a special popup menu or a small dialog window for data input.

Bezier splines are used for geometrical contours by default. This continuous polylines are describedby the position of a few Bezier points. Therefore a simple modification of the curve is possible but onthe other hand the numerical representation of the curve is accurate.

For Bezier curves, a popup menu emerges that permits the user toswitch between Bezier spline and polyline and to convert polyline toBezier spline. Loading and saving of curve points (*.CFTPL) and a resetof the curve is also performed using this menu.

An alternate method to specifying Bezier points by themouse, you may enter the accurate coordinates of Bezierpoints in a small dialog window that appears by clicking theright mouse button on the chosen Bezier point.

One or two coordinate values can be entered in dependence of geometrical boundary conditions. Asa rule these values are normalized relative values describing the position of the point betweenextreme values left or bottom (0) and right or top (1). Normalized relative coordinates are giving theadvantageous possibility of an automatic update of the entire design if a parameter is modified.

Coordinates of mouse cursor are displayed in format x:y bottom left in the status bar.Position and size of dialogs are saved to restore it in the same way when they are called again.If CFturbo generates primary design automatically you may see Initial design on the top right of thediagram.

If numerical values are entered in tables, then a new value is only activated and the diagram isupdated if the <Enter> key is pressed or a new cell of the table is selected.

Part

III

33Main window


3 Main window

3.1 Create new design

File | New

When creating a new design one of the following types can be selected:PumpVentilatorCompressorTurbine

In each case Impeller or Volute can be selected.

Alternatively to the menu and the toolbar the large buttons under Create New Design can be used.

34 CFturbo8


After selecting a menu item the Main dimensions dialog for impellers or the Volute inlet dialogfor volutes is started.

3.2 Open/ Save design

File | Open/ Save/ Save as

CFturbo designs are saved as *.CFT files.

To open a list of recently used files can be used by pressing the small arrow right beside the openbutton or by selecting the menu File|Open recent. Alternatively you can select the design directlyfrom the list Open Recent Design if no design is opened.

The user can modify filenames by the Save as- function in order to save modified designs underdifferent file names.

3.3 Project

Menu items and buttons only become active in accordance to the current design state. The user isable to return to former design status from any design step in the program. Design step updatesdependent on its modifications are accomplished automatically. Manual removing of completedesign steps is possible too in order to continue with CFturbo® using its primary design (see Remove design steps ).

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35Main window


For designing the complete geometry you have to run through all items of the appropriate menu stepby step:

Impeller Volute

36 CFturbo8


Project informationFor identification of the project it may be specified:

Project nameClassification (e.g. version or sub name)User nameComments

This information is not mandatory and should support the identification of CFturbo projects &sessions.The working directory, the creation date and the date of last modification are displayed too.

WarningsAll warnings of the design steps are displayed here. It depends on the opinion of the user to acceptthese warnings or to modify the design by adequate actions to avoid these warnings.

HistoryThe history contains all design steps from opening of the project or session in chronological order.By pressing button Remove selected you can undo selected design steps. By pressing the buttonClear history the complete history (and temporary files) can be deleted.

Design informationThe right part of main window shows a tabular form summary of the most important designparameters. You can print these data together with project information (File | Print) or save to file(see Data export ).44

37Main window


see also: Open/ Save design Data export 3D Model

3.4 3D Model

Tab sheet 3D Model contains the three dimensional representation of the current impeller or volutedesign state.The CAD model can be exported as IGES (Export | IGES), STEP (Export | STEP) or STL (Export |STL). Therefore the currently visible geometry elements are considered.

Above the representation you can find some buttons with the following functions:

Reset of representation (default position)

Save representation as JPG or BMP

Print representation

X Viewing direction in positive or negative (< >) x-axis direction

Y Viewing direction in positive or negative (< >) y-axis direction

Z Viewing direction in positive or negative (< >) z-axis direction

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Fit view (zoom all geometry to visible region)

Define point resolution (see Preferences - Export )

Set background color

Switch coordinate system on/off

Line width for curves, points

All this function are only optical and do not affect the export.

3D display can be influenced by mouse:

Left button Middle button Right button

Rotation around pointof origin

Zoom (also wheel)

Rotation around z-axisMove

In the panel Model all available geometry parts are listed in a tree structure, whereby their visibilitycan be switched on or off alternatively.The model tree has 3 main sections:

(1) Section Components contains all parts of the current design:

Impeller Volute

Meridian Spiral

Mean surface Internal bend

Blade Diffuser

CFD extensions Connection surface impeller

Segment Connection surface diffuser

Through-flow area Radial diffuser

Cut-water

Through-flow area

The impeller segment contains curves of a rotationally symmetrical part of the impeller and isusually used for CFD simulation.The meridian contains hub and shroud as well as a circular projection of the blade in a plane.

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39Main window


The connection surfaces (Connection impeller) close the flow area between impeller and radialdiffuser or volute. These surfaces have no constructional relevance, but serve the CFD modelingfor creating simplified closed flow volumes.

(2) Panel Geometry contains all basic geometrical elements, so that the properties can be modifiedglobally:

PointsCurvesSurfacesSolids

(3) In panel Imports all imported parts are listed (see below).

By right click on an item the imported part can be positioned or removed.The z-axis is assumed as rotational axis. The imported part can be moved along the z-axis orrotate around it relative to its initial position.

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The element selected in the tree is highlighted in the 3D view. For the marked component in eachcase the following attributes can be defined below:

Wire frame display

Surface display

Material

Color

Transparency

The selected material affects color and transparency of surfaces and solids. Selecting a materialresults in adjusting its default color without transparency.

Above the tree the following actions can be performed:

Default representation

Import of CAD models (IGES, STEP, STL), CFturbo designs (CFT) (same as File | Import)

Export menu (same as File | Export)

Down right in panel Options several setting due to 3D view can be defined. Please note: These settings also affect the 3D geometry data that is exported.

DisplayResolution of surfaces display (triangulation),affects display and STL export only

41Main window


Surfaces

Interpolation method for surface generation,

Distance tolerance for joining surfaces andcreating solids

Blade

(forimpellersonly)

Single blade display

"manual" trimming of blade (not exact)

Extend blades through hub/shroud andtrailing edge; for trimming in CAD

Trimming of blade on hub/shroud;influences the solids of Flow domain andBlades only

There exist some more features for impellers only:

In order to cut the blades from hub and shroud, you have to use the Trim button on the Options/Blade panel. Trimming is a time-consuming operation (up to 1 minute or some minutes for impellerswith splitter blades). Only solids will be trimmed, the original surfaces remain as they are. Trimmingis only possible if the solids for Flow Domain and Blade are created successfully.

In the panel Blade to Blade Section the display of an approximately perpendicularly flown througharea between hub and shroud as well as between two neighboring blades can be generated. In casethe checkbox Fix to minimum is activated, the 3D-display of this area is shifted to the location ofthe minimum cross section. Otherwise it can be slid to any reasonable position within the blade toblade channel with the help of the track bar Position. By pressing the soft button Showprogression a windows is opened, in which the value of the cross section is displayed independence on the tangential position. The location of the actual 3D-display as well as that of theminimum cross section is marked with special symbols.

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In panel Rotate impeller you can generate uniform rotation of impeller around z axis, wherebyvelocity can be influenced by track bar.

See also: Problems when generating surfaces/solids

Open/ Save design Data export Projekt

3.4.1 Problems when generating surfaces/solids

Errors while generating surfaces or solids

If any errors occur while generating surfaces or solids then thecorresponding part in the model tree is marked by red color.

Furthermore a corresponding message is displayed in the Warnings panel on the Project tab ofthe main window.

Relation solid generation distance tolerance

If solids cannot be created, you can increase the distance tolerance (see Options/Surfaces

42

34

44

34

43Main window


panel). It defines the maximal distance between surfaces of a solid.

Eliminating errors during surface generation

For eliminating errors during surface generation there exist the following possibilities:try a different surface interpolation method: see Options/Surfaces panel of the 3D-Viewertry a different number of data points for the 3D model: see Preferences - Export , 3DModel

The pictures illustratethe influence of pointdensity on the surfacegeneration of the blade.

Slow 3D model

If the handling of the 3D model is very slow, normally an update of the graphic card driver ishelpful.

21

44 CFturbo8


If problems occur inconnection with thegraphic card,sometimes an unsteadymesh is displayed onthe faces of the solids.

3.5 Help

Help

The following features can be used in the help menu:

Help topics Help for main window, index of whole help

CFturbo® website Show www.cfturbo.com in the web browser

Check for updates Check for available updates

About CFturbo® Information about CFturbo

3.6 Data export

File | Export

Export submenu offers file formats of several CAE programs to export designed geometry. Thus asmooth further processing of the geometry data is possible.

Generally there are the following export capabilities:

Export Format Point density Units

3D modelIGES, STEP, STL,BREP

see Preferences - Export, 3D Model

[mm]

Pointbased data All the restsee Preferences - Export

, Point Exportsee Preferences - Export

, Point Export

For the 3D model those parts will be exported that are visible.The quality of the STL export depends on the triangulation resolution. This resolution can bechanged via the Options/Display panel of the 3D-Viewer.

21

21 21

45Main window


Impeller special export requirements (see also CFD setup):

Export format CFD inlet CFD inletvertical

CFDoutlet

CFD smalloutlet

CFD largeoutlet

AxCent X - - - -

Numeca - - - - X

TurboGrid - - - - X

BladeGen - - - - X

TurboDesign - - - - X

Star-CCM+ X R - - X

X = needed, R = recommended

General export formats (for impeller and volute)

Menu item Description

Design reportTEXT

*.CFT-REP general text file

Short design information as text file;Summary of most important design parameters

Geometry TEXT

*.CFT-GEO general text file

Text file containing geometry data of the design for any furtherprocessing.

Impeller:Meridional section:

z, r of hub, shroud, leading edgeBlade mean lines, Blade profiles:

x, y, z (cartesian coordinates), r (radius), t (angle)

Volute:Spiral cross sections, Diffuser cross sections:

x, y, z (cartesian coordinates)Contour lines in circumferential direction:

x, y (cartesian coordinates)

ANSYS ICEMCFD

*.tin ANSYS ICEM CFD 11

A tetin file (native ICEM geometry format) is created. A separatedialog is used for configuration.

File | Change working dirFile | Geometry | Open Geometryselect *.tin

DXF *.dxf neutral format

File contains designed geometry as 3D polylines.

46 CFturbo8


IGES curves *.igs neutral format

File contains designed geometry as 3D splines.

IGES *.igs neutral format

File contains designed geometry as 3D surfaces. Visible 3D viewis the basis.

STEP *.stp neutral format

File contains designed geometry as 3D surfaces. Visible 3D viewis the basis.

STL *.stl neutral format

File contains designed geometry as triangulated 3D surfaces.Visible 3D view is the basis.

BREP *.brep neutral format

File contains designed geometry as triangulated 3D surfaces.Visible 3D view is the basis.

Catia V5 *.catvbs Catia V5R18

The macro generates a surface model + generating splines.

Tools | Macro | MacrosSelect macro library and macro, Run

SolidWorks *.swb SolidWorks 2009


Tools | Macro | Run: select *.swb

AutoCAD *-ACAD.txt AutoCAD 2009

Lisp script xyz2spline (part of CFturbo®) creates splines fromimported points.

Tools | AutoLISP | Load: install xyz2spline.lsp (or loadxyz2spline.lsp)Run: xyz2spline, select *-ACAD.txt

Inventor *.bas Inventor 2010


Tools | Macro | Visual Basic EditorVB: File | New project

File | Import file, select *.basTools | Macro, select “Main”, Run

Uni-graphics *-ug.dat Unigraphics NX4

One file per component will be created.

File | New | <name> (if no file is open)

47Main window


Start | Modeling

For curves (hub, shroud, volute contour curves):

Insert | Curve | Spline | Through pointsPoints from fileselect *.dat

For surfaces (blade, volute, diffuser):

Insert | surface | Through pointsRow degree <= number of blade profile sections; Columndegree <= Row degree-1Points from fileselect *.dat

Please note: If the mentioned menu options are not available,the appropriate commands have to be created:

a) "Tools/Customize" or right click on any toolbar/menu,"Customize..."

b) "Commands", "Insert/Curve/Spline..." or "Insert/Surface/Through Points..."

c) integrate selected item via Drag and Drop in a menu or toolbar

Pro/ENGINEERWildfire

*.ibl, *.pts Pro/ENGINEER Wildfire

*.ibl contains geometry defined by 3D points.

File | New | <name> (if no file is open)Insert | Model Datum | Curve | From FileDefine coordinate system (e.g. with menu) | Selectselect *.ibl

*.pts contains impeller hub and shroud contour defined by 2Dpoints

Insert | Model Datum | SketchSketch | Line | CenterlineSketch | Coordinate SystemSketch | Splineselect spline (double-click)File: select coordinate system, select *.pts

Further export formats exclusive for impellers


ANSYSBladeGen

*.rtzt ANSYS BladeGen 11

The file contains complete 3D impeller geometry point-by-point.

File | Open: select file type „Meanline File (*.rtzt)“select *.rtzt

ANSYSTurboGrid

*.curve ANSYS TurboGrid 11

4 files are created, a session file (<filename>.tse) and

48 CFturbo8


<filename>_hub.curve, <filename>_shroud.curve,<filename>_profile.curve.

Load the saved session file <filename>.tse:

File | New CaseSession | Play Session

or

Open the curve files (<filename>_hub.curve, <filename>_shroud.curve, <filename>_profile.curve) manually:

Launcher: select directory, start ANSYS TGFile | New CaseFile | Load Curvesinput number of blades, define z axis as rotational axis,select cartesian coordinate system and length unit, select *.curve

ANSYSFluent

*.tur GAMBIT (Fluent)

Input file for the Fluent preprocessor GAMBIT for meshing with G/Turbo

NumecaAutogrid

*.geomTurbo Numeca Autogrid 5

File | New Project“Initialize a New Project from a geomTurbo File”select *.geomTurbo

ConceptsNrec

AxCent

*.sur Concepts Nrec Axcent 7.12

File | Start from CADFITSelect Surface data files *.sur

or

Load file in CAE Startup Dialog

adapco

Star-CCM+

*.bndy, *.estg adapco Star-CCM+

Open files in TurboWizard

TURBOdesign *.mri TURBOdesign

Open *.mri files

Further export formats exclusive for volutes


Numeca IGG *.dst, *.dat Numeca IGG 5.5-1

A model file *.dst and 3 data files are generated: section.dat,diffusor.dat, curves.dat

File | Import | IGG Data

49Main window


select *.dst

3.6.1 Autodesk AutoCAD

The data import from CFturbo is realized by a LISP-script.

Loading the LISP-Application and Import of the Geometrie

Extra | Anwendung laden (command: _appload)select file xyz2spline.lsp from CFturbo-installation directory, load and close dialog

execute loaded LISP-application by command xyz2splineselect and open *.txt-file expoted from CFturboAttention: If "; Fehler: Fehlerhafter Argumenttyp: FILE nil" occurs as error message it can bebypassed by typing the filename in the open-file-dialog manually instead of selecting the file bymouseclick.

Construction of Impeller

Sample-view after data import

50 CFturbo8


Creating the blades

starting with version 2009 the creation of blades in AutoCAD is possible any longer, because thefeatures for lofting surfaces has been modified by Autodeskearlier version support the command _loft to create surfaces from non-planar curves

Creating rotational surfaces (Hub, Shroud)

command _revolveselect hub and shroud curvesAchse definieren durch [Objek t/X/Y/Z] <Objek t>: 0,0,0Endpunkt der Achse angeben: 0,0,1Rotationswinkel oder [STartwinkel] angeben <360>: 360

Construction of Volute

Sample-view after data import

Creating the open part of volute geometrie1. command _loft2. select profile-curves to loft (part by part, starting with the open one)

51Main window


3. Option eingeben [Führungen/Pfad/nur Querschnitte] <nur Querschnitte>: nur Querschnitte

4. Settings for lofted surface

5. repeat steps 1 to 4 for remaining parts of the volute

3.6.2 Autodesk Inventor

The data-import is realized by a macro that is created for each geometry individually by CFturbo. Themacro is loaded and executed in Inventor.

To execute a macro it has to be imported into an existing VBA-project.Tools | VBA Editor

open file-open-dialog by File | Import File... and select *.bas macro-file, possibly a new project hasto be created File | New Project

52 CFturbo8


execute imported macro: Run | Run Macro (F5) close dialog by RunThe time for executing depends on the complexity of the geometry.

53Main window


3.6.3 Catia (Dassault Systèmes)

The data-import is realized by a macro that is created for each geometry individually by CFturbo. Themacro is loaded and executed in Inventor.

Open the macro dialogTools | Makro | Makros or <Alt> + <F8>select an existing macro library

orcreate a new macro library: <Makrobibliotheken…>, add directory which contains the macro filescreated in CFturbo (<Vorhandene Bibliothek hinzufügen…>)

select macro library and execute macro

3.6.4 Numeca AutoGrid5

The geometry data for impeller is exported by CFturbo to „geomTurbo“-files which can be loaded byAutoGrid5.

start Numeca IGG

54 CFturbo8


change to AutoGrid5-mode: Modules | AutoGrid5

open a new project: File | New Project

55Main window


close dialog by Initialize a New Project from a geomTurbo File select *.geomTurbo-file

3.6.5 Pro/ENGINEER (PTC)

Construction of impeller

The following files are exported by CFturbo for impellers:*-hub.pts, *-shroud.pts: points of hub and shroud*-profile.ibl: points for blade profiles*.ibl: all points for hub, shroud and blades

Creating hub and shroud

56 CFturbo8


insert sketch: Insert | Model Datum | SketchSketch plane: „RIGHT“Reference: „FRONT“Orientation: „Oberseite“

create reference coodinate system: Sketch | coordinate systemcreate spline by 2 points: Sketch | Splinedouble-click on created splineselect <File>, select reference coordinate system, confirm selection

57Main window


select *.pts-fileconfirm pointcountclose spline menuThere must be only one spline per sketch!

create centerline for rotation: Sketch | Line | CenterlinePosition axis on center point with orientation of y axis (equivalent to z axis in 3D)

return to 3D-view

select sketch and open menu for rotation: Insert | Rotate

58 CFturbo8


confirm created rotational surface

Creating blade profiles

The profile curves for a blade are loaded from *-profile.ibl files. A surface is created from the curvesand displayed as a circular pattern.

creating axis of rotation: Insert | Model Datum | Axispress <Strg> while selection „Right“ and „Top“

59Main window


confirm

loading curves from file: Insert | Model Datum | Curveselect „From File“, confirm by „Done“select coordinate systemselect *-profile.ibl file

60 CFturbo8


connect curves to surface: Insert | Boundary Blendselect profile curves

61Main window


confirm blade surface

creating a circular pattern: select blade surface from model treein the context menu select „Pattern“

Type: Axisselect sketched z axis

number of bladesangle: 360°

62 CFturbo8


confirm

Construction of volute

The construction of a volute uses the same steps like an impeller. By repeating ofloading curves from files

63Main window


andconnecting curves to surfaces

64 CFturbo8


a 3D-geometry of the volute can be created.

65Main window


3.6.6 Ansys ICEM CFD

Export Dialog "Export ICEM-CFD" and "CFturbo2Icem2CFX" script are available with thecorresponding license only.

"CFturbo2Icem2CFX" is a script for automatic geometry generation and meshing of CFturboimpellers and CFturbo volutes.

Export to ICEM-CFD is useful for the "CFturbo2Icem2CFX" script only. 2 files are created: geometryand tetra parameters are saved in the ".tin" file, prism parameters are saved in the ".prism_params"file.

(A detailed description of the parameters you can find in the script documentation.)

66 CFturbo8


globalsettings

localsettings

Error message:

If this message is visible then geometry proportion andselected mesh parameters do not match properly.

67Main window


3.7 Data export limitations

Rental or Permanent licenseWhen using CFturbo with a normal license (rental or permanent) the export is not restricted in anyway.

Demo / Test licenseExport functionality is restricted when using CFturbo with a Demo/Test license.Data export is then disabled for all self designed impellers or volutes.

To demonstrate the performance of the CAD/CFD interfaces, the data export is enabled for CFturbodefault examples only.These default examples you can find(1) in the CFturbo installation directory: c:\Program Files\CFturbo 8\Examples(2) on the CFturbo website: http://www.cfturbo.com/download.html

3.8 CAE-Startup

File | CAE-Startup

The CAE-Startup dialog allows starting available CFD/FEM applications whereas the CFturbocreated geometries are transferred automatically.

Available products are listed in the tree on the left side. On the right side properties of the export tothis product can be set. The version of the product can be selected from a list or the path can be defined manually anddeleted using the buttons. The availability of version to choose from depends on the product vendor.If not either a product version is selected from the list nor a path is defined manually the export forthis product is unavailable and marked grey in the tree.

68 CFturbo8


Version selection and working directory

All data exported by CFturbo is written to the working directory and it's passed to the product whenits' started.

The run mode defines if the product waits after the predefined processing for a user interaction orruns in batch mode without any user activity.

Ansys ICEM-CFDThe Interactive mode exports the geometry and opens it in ICEM. Afterwards the scripts for meshingcan be started manually. The Batch mode enables the configuration of the meshing parameters andruns the scripts automatically.

Create OutPipe for Volutes: An outpipe is created on volute exit.Include Meshing: Defines, if meshing scripts are processed automatically (only available in Batchmode).Meshing parameters: Opens the Export ICEM-CFD dialog.65

69Main window


Simerics PumplinXAdd to existing PumplinX project: The geometry is added to an existing project. If option is notselected, a new project is created.Refinement factor: Defines the precision of the exported geometry data.

70 CFturbo8


Concepts NREC Pushbutton CFDThis export is only available for impeller, because a volute geometry can not be processedseparately.

Define counterpart SUR-file: Add a volute geometry, created using File->Export->CFD->AxCent,for processing.

71Main window


Concepts NREC STRESSPREPThis export is only available for impeller, because a volute geometry can not be processedseparately.

Define counterpart SUR-file: Add a volute geometry, created using File->Export->CFD->AxCent,for processing.Solver: Select the solver used by STRESSPREP.

72 CFturbo8


Part

IV

74 CFturbo8


4 Impeller

4.1 Main dimensions

Impeller | Main dimensions

The Main Dimensions menu item is used to define main dimensions of the impeller.

Details Pump/Ventilator Compressor Turbine

4.1.1 Pump / Ventilator


The Main Dimensions menu item is used to define main dimensions of the impeller. MainDimensions are forming the most important basis for all following design steps.

The real flow in a pump impeller is turbulent and three-dimensional.Secondary flows, separation and reattachment in boundary layers,cavitation, transient recirculation areas and other features mayoccur. Nevertheless it is useful - and it is common practice in thepump design theory - to simplify the realistic flow applyingrepresentative streamlines for the first design approach.

Employing 1D-streamline theory the following cross sections aresignificant in particular: suction area (index S), just before leadingedge (index 0), at the beginning (index 1) and at the end of theblade (index 2) and finally behind the trailing edge (index 3).

Details Design point Parameters Dimensions

74

86

96

75

77

81

75Impeller


4.1.1.1 Design point

On page Design point you have to enter the design point data. The essential Basic values are:Flow rate Qfor pumps: Head H

for ventilators: Pressure difference pNumber of revolutions nDensity of the fluid

On panel Inflow you may define the inflow swirl at hub and shroud. There are two possibilities:

Flow angle Swirl number

uSmSS ccarctan SuSr uc1

Positive swirl

Negative swirl

No swirl

S < 90°

S > 90°

S = 90°

r < 1

r > 1

r = 1

Negative swirl is increasing the head and may often have no good affect to the suction behavior.Inflow through a straight pipe usually leads to swirl-free flow.

r and

S relate as follows:

S2

N2

S2

SS

mSr

tannddd

Q41

tanu

c1

The conversion r -

S is only valid for certain diameters d

N and d

S. Conversion is updated if these

diameters are modified.

In the lower part you can decide to design a shrouded or unshrouded impeller. For unshroudedimpeller you have to define the tip clearance.

Furthermore, you can define rotational direction of the impeller seen from the drive side (axial viewto backside of hub).

Finally you have to specify the number of blades, optionally with splitter blades. The number isusually between 3 and 7 for pumps and 6 and 10 for ventilators.Many blades - causing low blade loading - are related to higher friction losses. By choosing of fewerblades - leading to a higher blade loading - the hydraulic losses may rise due to increasedsecondary flow and stronger deviation between blade and flow direction.

For a new design you can create a fully automated initial design of the impeller with default settings:see Full impeller 106

76 CFturbo8


Some calculated variables are displayed in the right Information sector in case the soft buttonValue has been chosen:

Specific speed nq

(metric units)

points to machine type and general shape of impeller:

43

31

q]m[H

smQminnn

10... 50: Radial impeller50...170: Mixed-flow impeller150...400: Axial impeller

Specific speed NS

(US-units) q43s n6.51]ft[H

]gpm[Q]rpm[nN

„Type number“ s

(ISO 2548) 9.52

n

gH

Qn2

q

43s

Mass flow Qm

Specific energy Y Y = gH

Power output PQ

PQ = gHQ

for pumps: Pressure difference p p = gH

for ventilators: Speed coefficient

8.157

n

gH

Qn1078.2

q

43

77Impeller


In general for cost reasons single-stage & single-intake machines are preferred covering a range ofabout 10 < nq < 400.

In exceptional cases it may become necessary to design an impeller for extremely low specificspeed values (nq < 10). These impellers are characterized by large impeller diameters and lowimpeller widths. The ratio of free flow cross section area to wetted surfaces becomes unfavorable andis causing high frictional losses. To prevent this one may increase either rotational speed n or flowrate Q if possible. An alternative solution could be the design of a multi-stage pump reducing thehead H of the single-stage.

If especially high specific speed values (nq > 400) do occur one can reduce rotational speed n orflow rate Q if feasible. Another option would be to operate several single-stage pumps - having alower nq - in parallel.

Please note: CFturbo® is preferably used between 10 < nq < 150 – radial and mixed-flow impellers.

4.1.1.2 Parameters

On page Parameters you have to put in or to modify assumptions resulting from approximationfunctions in dependence on specific speed nq or flow rate Q (see Approximation functions ).

The panel Parameters allows defining alternative values in each case for the calculation of thefollowing impeller main dimensions:

for pumps for ventilators

22

78 CFturbo8


suction diameter dS

inlet diameter d1

inlet width b1

impeller diameter d2

impeller width b2

For dS-calculation (pumps)

Intake coefficient

Ratio between meridional inflow velocity and specific energy

Y2c0

0.05…0.4 (rising with nq)

Inflow angle 0a

high smaller dimensions, lower friction losses< 20° prevent the risk of cavitation> 15° with regard to efficiency12°...17° recommended for good suction capability

Minimal relativevelocity w

small friction and shock lossesonly if no cavitation risk !fdS

=1.15...1.05 standard impeller, nq=15...40

fdS

=1.25...1.15 suction impeller

suction specificspeed n

SS

43R

31

SS]m[NPSH

smQminnn

Standard suction impeller u1<50 m/s 160...220

Suction impeller, axial inflow u1<35 m/s 220...280

Suction impeller, cont. shaft u1<50 m/s 180...240

High pressure pump u1>50 m/s 160...190

Standard inducer u1>35 m/s 400...700

Rocket inducer >>1000

Min. NPSH

g2

w

g2

cNPSH

21

w

21m

cR

c suction pressure coefficient for absolute velocity c (inflow acceleration

and losses): 1.1 axial inflow; 1.2…1.35 radial inflow casing

w Unterdruckbeiwert für Relativgeschwindigkeit w (Druckabsenkung an

der Vorderkante): 0.10…0.30 standard impeller; 0.03…0.06 inducer

for d1 calculation (ventilator)

Diameter ratio d1/d

2v

65

2

1 25.1d

d

for b1 calculation (ventilator)

79Impeller


Meri. decelerationc

m1/c

mS

216.2d

b4

c

c 61

1

1

mS

1m

For d2-calculation

Pressure coefficient

dimensionless expression for the specific energy:

2uY2

2

0.7 ...1.3 radial impeller0.25...0.7 mixed-flow impeller0.1 ...0.4 axial impeller

high small d2, flat charactersitic curve

low high d2, steep charactersitic curve

Diameter coefficient according to Cordier diagram (see Dimensions )

Outflow angle 3 6°...13°: recommended for stable performance curve (with nq rising)

For b2-calculation

Outlet width ratiob

2/d

20.04...0.30 (with nq rising)

for pumps:Mer. decelerationc

m3/c

mS


for ventilators:Shroud angle

200dd

bb2arctan

12

21

In panel Efficiency you have to specify several efficiencies:Hydraulic efficiency

h

Volumetric efficiency v

Tip clearance efficiency T

Side friction efficiency S


The first four values form the internal efficiency because these losses result in dissipating energyfrom the fluid:

TSvhi

Internal and mechanical efficiency form the overall efficiency (pump/ coupling efficiency):

miD

Q

P

P PQ: pump output, see above

PD: power demand (coupling/ driving power)

The obtainable overall efficiency correlates to specific speed and to the size and the type of the

81

80 CFturbo8


impeller as well as to special design features like bypass installations and auxiliary aggregates.Efficiencies calculated by approximation functions are representing the theoretical reachablevalues and they should be corrected by the user if more information about the impeller or the wholepump are available.

The hydraulic efficiency (or blade efficiency) describe the energy losses within the pump caused byfriction and vorticity. Friction losses mainly originate from shear stresses in boundary layers.Vorticity losses are caused by turbulence and on the other hand by changes of flow cross sectionand flow direction which may lead to secondary flow, flow separation, wake behind blades etc.. Thehydraulic efficiency is the ratio between specific energy Y and the energy transmitted by the impellerblades:

93.085.0Y~Y

h

The volumetric efficiency is a quantity for the deviation of effective flow rate Q from total flow rate

inside the impeller which also includes the circulating flow within the pump casing:

99.093.0Q~Q

v

(rising with impeller size)

The tip clearance efficiency is only relevant for unshrouded impellers. It contains losses due to theflow through the gap between blade tips and housing from the pressure to the suction side of theblades. The flow losses mainly depend on the tip clearance distance x

T and decrease with rising

number of blades and rising blade outlet angle 2.

2TRatioRatioqRatioT bxAA,nffAf1

The side friction efficiency contains losses caused by rotation of fluid between hub/ shroud andhousing:

40nfür995.0985.0

40nfür985.05.0

P

P1

q

qSS

The mechanical efficiency mainly includes the friction losses in bearings and seals:

995.095.0P

P1 m

m


Hydraulic and volumetric efficiency as well as the tip clearance efficiency are most important for the

impeller dimensioning because of their influence to and/or . Mechanical and side frictionefficiency are affecting only the required driving power of the pump.

Please note about the required consistency for Q- and Y (H or p)- values and for h und

v too:

they refer to the same control volume of the viewed fluid domain. For example if Y is representing thedesired energy after the outlet of the spiral casing the assumed hydraulic efficiency

h must contain

all hydraulic losses which occur at the flow through the impeller and through the volute. Clearlydistinguish if you look at the whole pump stage or just viewing to the impeller alone!

In the lower area of the Assumptions column you can find again some calculated values forinformation:

22

81Impeller


Required driving powerQ

D

PP

Power loss 1PPPP DQDL

Internal efficiency Svhi

Overall efficiency miD

Q

P

P

4.1.1.3 Dimensions

On page Dimensions, panel Shaft/ hub, the required shaft diameter is computed and the hubdiameter is determined by the user.

Shaft/Hub

The main dimensions of a designed impeller - suction diameter dS, impeller diameter d

2, outlet width

b2 - can be seen on Main dimensions panel. They can be recomputed by pressing the Calculate-

button. The computation is based on "Euler's Equation of Turbomachinery", on the continuityequation and the relations for the velocity triangles as well as on the parameters and parameterratios given in the tab sheets Design Point and Parameters.

You may accept the proposed values or you can modify them slightly, e.g. to meet a certainnormalized diameter.In case the checkbox Automatic is activated a new calculation will accomplished after any changeof parameter. Then the manual alteration of the main dimensions is not possible.

Regarding the impeller size one should try to attain d2 values as low as possible. But there is a limit

for a specified task: lower impeller diameters are leading to higher blade loading - up to blade angles

2 which may not be suitable anymore.

105

82 CFturbo8


A specific problem exists for ventilator impellers. If the suction diameter dS is calculated by diameter

ratio d1/d

2, then the hub has to be planar, i.e. hub diameter d

N = 0. Otherwise the empirical

correlations are invalid. If the user defines a dN value deviating from 0, a warning symbol points to

this problem. The solution is to select a different parameter for the calculation of the suctiondiameter d

S (see Parameters ).77

83Impeller


You can select a value for the diameters dS from standard

specifications. For that purpose you have to press the button right beside the input field.

The small dialog gives you the possibility to select a diameter fromseveral standard specifications. If material, standard name andpressure range are selected the lower panel shows all diameters ofthe chosen standard. One diameter is highlighted as a proposal.Nominal diameter, outside diameter and wall thickness for the

marked entry is displayed. Using of and buttons additionalstandard specifications and user defined diameters can be addedor existing parameters can be removed from the list.

At File location the name of the file containing the diameters isshown. The file is originally called Diameter.cftdi and is located inthe installation directory of CFturbo. Modifications of the list will besaved if the user is leaving the dialog window by clicking the OK-button. In case there are no write permissions the user can chooseanother directory to save the file. Renaming of files is possible by Save as- functionality. By clicking the Open-button a previouslysaved file can be opened.

In the right panel of any tab sheet an information panel is situated, which holds the computedvariables in accordance to the actual state of design, the resulting Meridional section as well asthe Cordier-Diagramm with the location of the best point. These three sections can be chosen bythe appropriate soft buttons in the heading.

In the Value section the following variables are displayed for information which result from calculatedor determined main dimensions:

Pressure coefficient2u

Y2

2

Average inlet velocity 2N

2S

vmS

dd4

Qc

Average outlet velocity22

v3m

bd

Qc

NPSH valueg2

w

g2

cNPSH

21

w

21m

cR

or34

SSqR nnHNPSH

Outlet width ratio b2/d

2

Meridional deceleration mS3mcm ccd

84

84

84 CFturbo8


Estimated axial force2

N2

Sax dd4gH9.0F

The Meridional section is based on the until now designed min dimensions.

The Cordier diagram is based on an intensive empirical analysis of proved turbomachinery usingextensive experimental data.

85Impeller


4.1.2 Compressor / Turbine

4.1.2.1 General

Fluid Properties have to be specified within the tab sheet General. In case of the consideration ofreal gas behavior a compressibility factor needs to be known. Otherwise (ideal gas behavior) thespecification of the isentropic coefficient, gas constant and specific heat (at constant pressure) issufficient.

In the panel Unshrouded it can be defined whether th rotor has to be shrouded or not. If the choiceis unshrouded the Tip clearance has to be given.

Furthermore one can define rotational direction of the rotor seen from the drive side (axial view tobackside of hub).

The blade number z has to be set as an assumption. Many blades - causing low blade loading - arerelated to higher friction losses. By choosing of fewer blades - leading to a higher blade loading - thehydraulic losses may rise due to increased secondary flow and stronger deviation between blade andflow direction. Beyond it the existence of splitter blades may be specified within the panel Blades.

86 CFturbo8


Depending on blade exit angle ß2 is recommended:

z 12 for ß2

30°

z 16 for ß2

45°...60°

z 20 for ß2

70°...90°

4.1.2.2 Compressor


The Main Dimensions menu item is used to define main dimensions of the impeller. MainDimensions are forming the most important basis for all following design steps.

87Impeller


The real flow in a pump impeller is turbulent and three-dimensional. Secondary flows, separation and reattachment inboundary layers, cavitation, transient recirculation areas and otherfeatures may occur. Nevertheless it is useful - and it is commonpractice in the pump design theory - to simplify the realistic flowapplying representative streamlines for the first design approach.

Employing 1D-streamline theory the following cross sections aresignificant in particular: suction area (index S), just before leadingedge (index 0), at the beginning (index 1) and at the end of theblade (index 2) and finally behind the trailing edge (index 3).

Details General Design point Parameters Dimensions

4.1.2.2.1 Design point

On page Design point you have to enter the design point data. The essential Basic values are:Flow rate by one of the following options:

- mass flow m

- volume flow Q (referring to total state)energy transmission by one of the following options:

- total pressure ratio t

- total pressure difference pt

- specific work YNumber of revolutions n

On panel Inlet conditions you have to define the total state on suction side by total pressure pt and

total temperature Tt.

Furthermore you may define the inflow swirl at hub and shroud, if available. There are twopossibilities:

Swirl number Swirl energy number

SuSr uc1 Ycu uSSY

Positive swirl

Negative swirlr < 1

r > 1

Y > 0

Y < 0

85

87

90

93

88 CFturbo8


No swirlr = 1

Y = 0

Negative swirl is increasing the head and may often have no good affect to the suction behavior.Inflow through a straight pipe usually leads to swirl-free flow.

r and

Y relate as follows:

2s

Yr

u

Y1

Y

1u r2

sY

For a new design you can create a fully automated initial design of the impeller with default settings:see Full impeller


Specific speed nq

(metric units)

points to machine type and general shape of impeller:

43

3t1

q]m[gY

smQminnn

10... 50: Radial impeller50...170: Mixed-flow impeller150...400: Axial impeller

106

89Impeller


Specific speed NS

(US-units) q43

ts n6.51

]ft[gY

]gpm[Q]rpm[nN

„Type number“ s

(ISO 2548) 9.52

n

Y

Qn2

q

43

ts

Speed coefficient

8.157

n

Y

Qn1078.2

q

43

t

Specific work YS,tp

1

t Tc1Y

Total pressure ratio pp= St,t,2t

Total pressure difference 1)-(p=p-p=p tSt,St,t,2t

Power output PQ YmPQ

Inlet speed of sound (total)S,t1,t TZRa

Volume flow (total)

tStStS

ZRTp

mQ

Mass flow tStStS ZRTpQm

Inlet density (total) tStStS ZRTp

Outlet density (total) 2t2t2t ZRTp

Outlet temperature (total)

tSptS2t

Tc

Y1TT

In general for cost reasons single-stage & single-intake machines are preferred covering a range ofabout 10 < nq < 400.

In exceptional cases it may become necessary to design an impeller for extremely low specificspeed values (nq < 10). These impellers are characterized by large impeller diameters and lowimpeller widths. The ratio of free flow cross section area to wetted surfaces becomes unfavorable andis causing high frictional losses. To prevent this one may increase either rotational speed n or flowrate Q if possible. An alternative solution could be the design of a multi-stage pump reducing thehead H of the single-stage.

If especially high specific speed values (nq > 400) do occur one can reduce rotational speed n orflow rate Q if feasible. Another option would be to operate several single-stage pumps - having alower nq - in parallel.

Please note: CFturbo® is preferably used between 10 < nq < 150 – radial and mixed-flow impellers.

90 CFturbo8


4.1.2.2.2 Parameters

On page Parameters you have to put in or to modify assumptions resulting from approximationfunctions in dependence on specific speed nq or flow rate Q (see Approximation functions ).

The panel Parameters allows defining alternative values in each case for the calculation of thefollowing impeller main dimensions:

For d2-calculation

Pressure coefficient

dimensionless expression for the specific energy:

5.18.02u

Y2

2

high small d2, flat charactersitic curve

low high d2, steep charactersitic curve

(Total) Flow coefficient t

dimensionless flow rate

22

2

S,tt

ud4

Q

0.01 narrow radial impeller, untwisted blades0.15 mixed-flow impeller, twisted blades

Diameter coefficient according to Cordier diagram (see Dimensions )

Machine Mach number Mau

dimensionless peripheral speed of impeller related to totalinlet speed of sound

22

93

91Impeller


S,t

2u

a

uMa

Peripheral speed u2 Limiting values due to strength as a function of the material

For b2-calculation


2 0.01...0.15 (with nq rising)

Meridional flow coefficient m

dimensionless flow rate

2

m2

222

2m

u

c

ubd

Q


For d1-calculation (optional)

Diameter ratio d1/d

2d

1/d

2=0.3...0.8

Relative deceleration w2/w

1w

2/w

1>0.7 or f(b

2/d

2)

For b1-calculation (optional)


/cm1

cm2

/cm1

= 0.8...1.25

for dS-calculation


/cmS

or cm2

/cmS

cm1

/cmS

= 0.9...1.1

cm2

/cmS

= 0.7...1.3

In panel Efficiency you have to specify several efficiencies:Impeller efficiency

tt (total-total)

Volumetric efficiency v


The first two values form the internal efficiency because these losses result in dissipating energyfrom the fluid:

vtti

Internal and mechanical efficiency form the overall efficiency (coupling efficiency):

miD

Q

P

P PQ: pump output, see above

PD: power demand (coupling/ driving power)

The obtainable overall efficiency correlates to specific speed and to the size and the type of theimpeller as well as to special design features like bypass installations and auxiliary aggregates.Efficiencies calculated by approximation functions are representing the theoretical reachablevalues and they should be corrected by the user if more information about the impeller or the wholemachine are available.

22

92 CFturbo8


The impeller efficiency tt describes the energy losses caused by friction and vorticity. Friction

losses mainly originate from shear stresses in boundary layers. Vorticity losses are caused byturbulence and on the other hand by changes of flow cross section and flow direction which maylead to secondary flow, flow separation, wake behind blades etc.. The impeller efficiency is the ratiobetween the actual specific energy Y and the energy transmitted by the impeller blades without anylosses:

Y~Y

tt

The volumetric efficiency is a quantity for the deviation of effective flow rate Q from total flow rate

inside the impeller which also includes the circulating flow within the casing:

99.093.0Q~Q

v



995.0...95.0P

P1 m

m


Impeller efficiency and volumetric efficiency are most important for the impeller dimensioning

because of their influence to and/or . The mechanical efficiency is affecting only the requireddriving power of the machine.

Please note about the required consistency for flow rate and energy transmission values and for h

und v too: they refer to the same control volume of the viewed fluid domain. For example if Y is

representing the desired energy after the outlet of the spiral casing the assumed impeller efficiency

tt must contain all flow losses which occur at the flow through the impeller and through the volute.

Clearly distinguish if you look at the whole stage or just viewing to the impeller alone!

In the right panel of the tab sheet Parameter you can find again some calculated values forinformation:

Required driving powerQ

D

PP

Power loss 1PPPP DQDL

Internal efficiency vtti

Overall efficiency miD

Q

P

P

Total-to-static efficiency

1

1Tc2

c1

t

tSp

22

1

t

ts

93Impeller


4.1.2.2.3 Dimensions

On page Dimensions, panel Shaft/ hub, the required shaft diameter is computed and the hubdiameter is determined by the user.

Shaft/Hub

The main dimensions of a designed impeller - suction diameter dS, impeller diameter d

2, outlet width

b2 - can be seen on Main dimensions panel. They can be recomputed by pressing the Calculate-

button. The computation is based on "Euler's Equation of Turbomachinery", on the continuityequation and the relations for the velocity triangles as well as on the parameters and parameterratios given in the tab sheets Design Point and Parameters.

You may accept the proposed values or you can modify them slightly, e.g. to meet a certainnormalized diameter.In case the checkbox Automatic is activated a new calculation will accomplished after any changeof parameter. Then the manual alteration of the main dimensions is not possible.

Regarding the impeller size one should try to attain d2 values as low as possible. But there is a limit

for a specified task: lower impeller diameters are leading to higher blade loading - up to blade angles

2 which may not be suitable anymore.


105

94

95

94 CFturbo8


In the Value section the following variables are displayed for information which result from calculatedor determined main dimensions:

Pressure coefficient 5.16.02u

Y2

2

Tangential force coefficient 63cmtt

t


2 = 0.01...0.15

Inlet Mach number 85.075.0RZT

wwMa

S

2uS

2mS

wS

Outlet Mach number

1

2

1

c

a

1Ma

2

2

2,t

2c

ReactionY2

c1r

22

The Meridional section is based on the until now designed min dimensions.

95Impeller


The Cordier diagram is based on an intensive empirical analysis of proved turbomachinery usingextensive experimental data.

96 CFturbo8


4.1.2.3 Turbine

Rotor | Main dimensions

The Main Dimensions menu item is used to define main dimensions of the rotor. Main Dimensionsare forming the most important basis for all following design steps.

97Impeller


The real flow in a turbine rotor is turbulent and three-dimensional.Secondary flows, separation and reattachment in boundary layers,cavitation, transient recirculation areas and other features mayoccur. Nevertheless it is useful - and it is common practice in theturbine design theory - to simplify the realistic flow applyingrepresentative streamlines for the first design approach.

Employing 1D-streamline theory the following cross sections aresignificant in particular: area just before leading edge (index 0), atthe beginning (index 1) and at the end of the blade (index 2) andfinally behind the trailing edge (index 3).

The cross section (S) is situated at the suction side in theconnection flange of the component following the turbine.

Details General Design Point Assumptions Dimensions

The design of the main dimensions has to be made in a strict order. This will be secured by thefollowing:One step within the design has to be finished completely before the next can beaccomplished. That is to say, the changeability of a tab sheet will be disabled by CFturbo until allnecessary parameters have been specified.

4.1.2.3.1 Design point

In the tab sheet Design Point all design data of the best point need to be given. In the panel Basicvalues these are:

Mass flow m

One of the following options:Total pressure ratio

tt

specific work YMachine-Mach-number M

1

Inlet peripheral speed u1

Inlet diameter d1

Total-to-static pressure ratio ts

Rotational speed n

In the panel In- and outlet conditions the static pressure at the suction flange (pressure in the

85

97

99

99

98 CFturbo8


connection flange of the work piece attached to the turbine at the outlet) as well as the totaltemperature at the inlet has to be specified. This design concept is based on a mean flow area,therefore a mean blade angle

B1 as well as a mean incidence angle i has to be given. In order to

yield best efficiency the angle of incidence should be 20..30°.

For a new design you can create a fully automated initial design of the impeller with default settings:see Full impeller


Total pressure drop Dptt

1t

11pp

Specific work Y

1

tt1tp 1TcY

Rotor power PQ

mYPQ

Total speed of sound at inlet at1 1tGas1t TZRa

Total temperature at outlet Tt2

ptt1t2t

c

YTT

Relative flow angle at inlet 1 1

= iB1

106

99Impeller


4.1.2.3.2 Parameters

In the tab sheet Parameter one of the following parameters have to specified for the calculation ofthe rotor diameter d

1:

Work coefficient~

dimensionless expression of the specific work

21

tt

u

Y2~

big small d1

small big d1

Guideline ca. 2

Flow coefficient

dimensionless mass flow

1

1m

u

c

in accordance to Cordier-Diagramm

Tangential force coefficient

/~

Coefficient of a flow force pointing in tangential direction3 ... 4 Francis high-speed turbine4 ... 8 Normal-speed turbine8 ...10 Low-speed turbine

Coefficient ratio2/~

Ratio of work to the square of the meridional speed6 ...10 Francis high-speed turbine10...12 Normal-speed turbine12...30 Low-speed turbine

Between the work coefficient ~

the relative flow angle 1 and the tangential force coefficient /~

there is the following relation:

1cot/~1

2

1

1~

At a relative flow angle of 1= 90° the work coefficient becomes 2~

. In this case the work

coefficient should not be chosen as a design parameter in the tab sheet Parameters. Otherwiseone has no influence on the meridional flow coefficient and therefore meridional flow, see lastequation.

For all further geometric variables guess values have to be given:

Diameter ratio d2/d

1 ~0.5

Meridional accelerationc

m2/c

m11.005..1.05

Meridional acceleration (suction 1.005..1.05

105

100 CFturbo8


side)c

mS/c

m1 or

Diameter ratio dS/d

1~0.7

Diameter ratio dN/d

S ~0.3

There are three specification modes of the diameter ratio dN/d

S:

Direct inputAutomatic calculation: option "Automatic". Here the diameter ratio will be adjusted in a way thatthe guideline of the geometrical ratios will met.Direct specification of d

N in the tab sheet Dimensions. Here the diameter ratio is not necessary.

With diameter ratio dS/d

1 option "Automatic" is deactivated.

In the group Efficiency the following efficiencies need to be given:Rotor efficiency

tt (total-total)


Internal and mechanical efficiency form the overall efficiency (coupling efficiency):

mttQ

D

P

P PQ: (isentropic) Rotor power

PD: Power output (coupling/ driving power)

The rotor efficiency (or blade efficiency) tt

describes the energy losses within the turbine caused by

friction and vorticity. Friction losses mainly originate from shear stresses in boundary layers.Vorticity losses are caused by turbulence and on the other hand by changes of flow cross sectionand flow direction which may lead to secondary flow, flow separation, wake behind blades etc.. Therotor efficiency is the ratio between the actual specific work Y and the specific work at loss lesstransmission:

Y

Y~

tt


995.0...95.0P

P1 m

m


104

101Impeller


In the right panel of the tab sheet Parameter some variables are displayed for Information:

Specific speed nq

(SI-Unit)

points to machine type and general shape of rotor:

43

2

2

3

1q

g

1

s

mY

smQ

minnn

Specific speed NS

(US-Unit)

q4

3

2

2S n531.51

g

1

s

ftY

gpmQrpmnN

„Type number“ s

(ISO 2548) 9.52

n

Y

Qn2

q

43S

Speed coefficient 8.157

n

Y

Qn1078.2

q

43

Guideline: 0.16..0.32. This has to be matched with the design.

Flow Q

calculated with total density in the outlet:

2t

mQ

Total pressure inlet pt1

pt1

= pt2

102 CFturbo8


Total density inlet rt1 ZTR

p

1tGas

1t1t

Pressure ratio total-total tt

Pressure ratio total-static ts

Efficiency total-total tt

Efficiency total-static ts

In general for cost reasons single-stage & single-intake machines are preferred covering a range ofabout 10 < nq < 400. In exceptional cases it may become necessary to design a rotor for extremelylow specific speed values (nq < 10). These rotors are characterized by large rotor diameters and lowrotor widths. The ratio of free flow cross section area to wetted surfaces becomes unfavorable and iscausing high frictional losses. To prevent this one may increase either rotational speed n or massflow rate m if possible. An alternative solution could be the design of a multi-stage turbine reducingthe pressure drop of a single-stage. If especially high specific speed values (nq > 400) do occur onecan reduce rotational speed n or mass flow rate m if feasible. Another option would be to operateseveral single-stage turbines - having a lower nq - in parallel.

Please note: CFturbo® is preferably used between 10 < nq < 150 – radial and mixed-flow rotors.

4.1.2.3.3 Dimensions

In the panel Shaft, the required shaft diameter is computed. Shaft/ Hub

The hub diameter has to be determined in the panel Main dimensions.

The main dimensions of a designed rotor - suction diameter dS, impeller diameter d

1, outlet width b

1 -

can be seen on the tab sheet Dimensions. They can be recomputed by pressing the Calculate-button within the panel Main dimensions. The computation is based on "Euler's Equation ofTurbomachinery", on the continuity equation and the relations for the velocity triangles as well as onthe parameters and parameter ratios given in the tab sheets Design Point and Parameters.

One may accept the proposed values or can modify them slightly, e.g. to meet a certain normalizeddiameter.In case the checkbox Automatic is activated a new calculation will accomplished after any changeof parameter. Then the manual alteration of the main dimensions is not possible.

105

103Impeller



In the information section of the tab sheet Dimensions the following variables are displayed forInformation:

Work coefficient 21

tt

u

Y2

Peripheral speed at inlettt

1Y2

u

Machine-Mach-number1t

11

a

uM

Diameter at inletn

ud 1

1

Width at inlet11m1

1cd

mb

Mean diameter at outlet 11

22 d

d

dd

104

105

104 CFturbo8


Width at outlet22m2

2cd

m025.1b

Shroud diameter dS

Hub diameter dN

Ratio Width-diameter at inlet b1/d

1 guideline: 0.05..0.15

Diameter ratio

d2/d

2min with:

2N

2Smin2 dd

2

1d

guideline: 1.005..1.05

Ratio radius-width at outlet2

NS

2

NS

b2

dd

b

rrguideline: 1.005..1.05

The guidelines given in the last column of the last three rows, should be be matched within thedesign.

The Meridional section is based on the main dimensions designed until this point.

105Impeller


The Cordier diagram is based on an intensive empirical analysis of proved turbomachinery usingextensive experimental data..

4.1.3 Shaft/Hub

Dimensioning of the shaft diameter is made under application of strength requirements. It is a result

of torque to be transmitted by the shaft and the allowable torsional stress of the material.

You can directly enter allowable stress or select the value from a list by pressing button rightbeside the input area.

106 CFturbo8


In a small dialog window you can see some materialsand its allowable stress. The list can be extended or

reduced by and button. You can confirm selectedvalue by pressing the OK-button.

At File location the file containing material properties isshown. The file is originally called Stress.cftst and islocated in the installation directory of CFturbo.Modifications of the list will be saved if the user is leavingthe dialog window by clicking the OK-button. In casethere are no write permissions the user can chooseanother directory to save the file. Renaming of files ispossible by Save as- functionality. By clicking the Open-button a previously saved file can be opened.

To consider a higher load, e.g. due to operating conditions away from the design point, a safetyfactor SF may be specified leading to a modified proposed shaft diameter d

w.

32wn

SFQY8d

The hub diameter dN is usually selected as small as possible and depends on the kind of connection

of hub and shaft.

4.1.4 Full impeller

The geometry design can be made by 2 different possibilities:

(1) Full impellerThe whole impeller geometry is designed fully automatically by using default settings. Everydesign step can be influenced manually later by starting the appropriate dialog.

(2) Step by stepThe geometry is designed stepwise by starting the appropriate dialogs one after anothermanually.

107Impeller


For automated design you have to press thebutton Full Impeller with Default Settingsin the Basic calculation dialog after definingthe design point values.

4.2 Meridional section

4.2.1 Meridional contour

Impeller | Meridional contour

The design of the meridional contour is the second important step to design the impeller.

Depending on the type of impeller selected hub, shroud and leading edges are represented by Beziersplines or a simple geometry. In case of Splitter blades each leading edge can be designedindividually. Radial ventilator impellers are designed in simple mode by default, all other impeller types in Beziermode. The designs of turbines and compressors have straight leading edges by default, in case ofturbines also z = const.

Details of Bezier-mode Details of Simple-mode

Graphical elements can be manipulated not only by the computer mouse per drag and drop but alsoby using context menus. To this end a right click on the appropriate element is necessary. Doing sothe mode of the leading edge can be changed as well as the coordinates of Bezier points.

110

114

108 CFturbo8


In the panel General curve mode you can set the mode of all elements of the contoursimultaneously. But Simple- and Bezier-mode can be used in a mixed way too. The mode of asingle curve can be set separately by its context menu.

109Impeller


In the panel Progressions diagrams the following curves are displayed:

CurvatureStatic momentArea progression

It can be accessed by the tab on the right side of the diagram where thedialog is docked. When the dialog is open, it can be pinned on orundocked, for moving it. In undocked state the transparency of the dialogcan be adjusted by the track bar above.

The static moment is the integral of the curve length (x) in the blade areamultiplied by the radius (r). It should be similar at hub and shroud:

TE

LE

r

r

rdxS

In the Options panel some graphical representations can be activated for illustration:

Gridfor later blade design

110 CFturbo8


Area circlesfor calculation of cross section area

In the Information panel you can find some numerical values of above mentioned quantities.

4.2.1.1 Bezier-mode

Hub and Shroud are represented by 4th order Bezier-splines. The curve is determined by five Bezierpoints.

Points 0 and 4 are defining the endpoints of the curves while the other three points determining theshape of the curve. The middle point (2) can be moved without any restrictions whereas points 1 and3 have only one degree of freedom. Point 1 is only movable on the straight line between points 0 and2, point 3 between point 2 and 4. Therefore no curvature is occurring at the end of the curves. Inconjunction with a continuous curvature gradient small velocity gradients can be expected. The twostraight lines are defining the gradients in the end points of the curves.

111Impeller


For an automatic primary design of the contours the following values are used:Main dimensions : d

N, d

S, d

2, b

2

Inclination angle of trailing edge to horizontal (see Approximation functions )Inclination angle of hub and shroud to vertical (see Approximation functions )Axial extension: pumps, ventilators according to a), turbines according to b), compressor withaverage of a) and b)

cos2b74nddz)a 207.1

qSa2

2ddz)b N2/1

Point 1 is primary placed at 3/4 of the axial distance of points 0 and 2, point 3 at 2/3 of the radialdistance of points 2 and 4.

The manipulation of the contours can be achieved by shifting the positions of the Bezier points. Asan alternative the position of Bezier points can be realized by input of numerical values (see Graphical dialogs ). Trailing edge can be rotate by moving Bezier points 4. If <Ctrl> key ispressed simultaneously the whole trailing edge can be moved in axial direction with constantinclination angle (change axial extension). Inclination angle of trailing edge can be numericallydetermined by clicking the right mouse button on it.

In the design process for the meridional contours the user should try to create curvatures which areas steady as possible in order to minimize local decelerations. The maximum values of the curvatureshould be as low as possible and should entirely disappear at the end of the contours. Theserequirements are met very well by Bezier curves showing the above mentioned limitations. Localcross section 2 rb should grow from the suction to the impeller diameter as uniformly as possible.

The points of maximum curvature are marked on hub and shroud while their numerical values are

74

22

22

30

112 CFturbo8


displayed in the Max. curvature section.

There are two different options to define hub and shroud contours that can be selected in the right-hand part of the dialog in the Edit section:

Hub, Shroud: Direct design of the two contoursCross section: Design of center line; the contours result from given c

m-course between suction

(dS) and outlet (d

2) cross sections

In the first case hub and shroud can be designed separately or in the coupled mode. If you hit the Coupled check box hub and shroud will be modified simultaneously considering the same relativepositions of the Bezier points.

In the second case only the geometric center line of the flow channel will be modified. The contoursresult in specifying a cross section distribution. It may either be linear or could be loaded from a file.

# cross section distribution# start/end tangential,# midsection linear# (spline interpolation 9points)0.00 0.000000.04 0.017280.08 0.038300.12 0.063680.16 0.094040.20 0.130000.24 0.171640.28 0.216870.32 0.263140.36 0.310180.40 0.360000.44 0.414040.48 0.471020.52 0.528980.56 0.585960.60 0.640000.64 0.689820.68 0.736860.72 0.783130.76 0.828360.80 0.870000.84 0.905960.88 0.936320.92 0.961700.96 0.982721.00 1.00000

On the left side you can see an example of cmprogression.

All lines starting with a # symbol are comments. Allother lines contain the numerical values. The firstvalue of each line is the relative meridionalcoordinate x along the center line, with x=0 at theinlet cross-section and x=1 at the outlet cross-section. The second value is the relative crosssection A

rel, which allows to compute the related

absolute value:

inoutrelin AAAAA

The cross section is used to determine the width bvertical to the flow direction.

This strategy is mainly capable for mixed-flowimpellers, it's suboptimal for radial impellers withrelative sharp direction change from axial to radial.

The leading edge is designed too by a 4th order Bezier spline. Regarding the Bezier points, thestatements made above are applicable in a similar way. The only difference is the manipulation ofthe end points. For the leading edge there is no restriction on hub and shroud contour. The position

113Impeller


of the leading edge always appears at the same relative position in a primary CFturbo design but thisnot mean to be a suggestion.

Leading edge can be designed as a straight line by selecting Straight in the context menu of thecurve (controlled by 2 Bezier points). Additionally the edge can be strictly axial or radial (z = const.or r = const, controlled by 1 Bezier point).

For radial impellers having nq (10…30) rpm the leading edge is often designed parallel to the z-axis. As the trailing edge is parallel to the axis too for such applications 2D-curved blades can becreated. At higher specific speed nq or due to strength reasons the leading edge often is extendedinto the impeller suction area. Various diameters result in different leading edge blade angles -therefore 3D-curved blades are created. This leads to better performance curves, higher efficienciesand improved suction capacity for pumps.

The position of the leading edge should be chosen in a way that the energy transmission should beabout equal on all meridional flow surfaces. A criterion is the approximately equal static momentS = r dx of the meridional streamlines on hub and shroud between leading and trailing edge. In theStatic moment section the corresponding numerical values are displayed. Both ends of the leadingedge should be perpendicular to the meridional contours of hub and shroud if possible. To obtainequal static moments on hub and shroud the trailing edge is often not parallel to axial direction -particularly at higher specific speeds (mixed-flow impellers).

4.2.1.1.1 Converting Polyline / Bezier

If using simple polyline for hub and/or shroud - e.g.for imported meridional geometrie - this curve canbe converted to a Bezier curve. Thus it's possible tomake systematic modifications of existinggeometries.

First the desired polyline is imported via Importfrom file.

The imported curve is displayed red, the originalcurve blue.

114 CFturbo8


By pressing the Start! button the position of theBezier points is calculated in such a way that theimported poyline is replicated as exact as possible.

The number of iterations can be varied if required,whereas the default value of 10 normally results insufficient precision.

The precision of the approximated Bezier curve isdisplayed as Max. and Mean distance from theimported polyline.

4.2.1.2 Simple-mode

Hub and shroud are represented by the segment of a circle and a tangential straight line. The radiusof the segment is defined by Point 1. The points 0 and 2 are defining the axial position of themeridional contour.

The points 0 and 2 of the leading edge can be moved on hub and shroud contour. The angle of theleading edge on the shroud contour can be numerically determined using point 0. Point 1 can bemoved freely between points 0 and 2. The values for the angles

1 and

2 as well as their relative

position can be determined numerically.

115Impeller


For an automatic primary design of the contours the following values are used:Dimensions : d

N, d

S, d

2, b

1, b

2

Radius of the circle segment rSI

: 14% of (d2-d

S)

The manipulation of the contours can be achieved by shifting the positions of the points. As analternative the position of points can be realized by input of numerical values. By moving points 0 or2 the whole geometry can be moved in axial direction.

74

116 CFturbo8


There are some reasonable constraints when working with simple mode curves e.g. the inclinationangle of the trailing edge can only be set when hub and shroud are in Bezier mode both.

4.2.2 Meridional flow

Impeller | Meridional flow

The meridional flow is computed by a streamline curvature method. The flow domain is divided intothin layers of 11 meridional flow surfaces. There a two-dimensional flow computation is possible withsufficient accuracy. The calculation is made on 35 quasi-orthogonal lines - from the suction area upto the extension area behind the trailing edge. The leading and trailing edges are two of these quasi-orthogonal lines.

Since this design program is supposed to deliver just a rough estimation of the meridional flow theinfluence of friction is neglected. Furthermore rotational symmetry has been assumed. Aftercompleting the CFturbo-based pre-design process, one should use an appropriate CFD-code for flowrecomputation of the impeller or of the whole pump stage.

117Impeller


After calculation the meridional contour as well as the cm

and w distribution is represented showing

6 streamlines and 35 quasi-orthogonal lines. You could adjust the size of the diagrams by mouse.

4.3 Blade properties

Impeller | Blade properties

Definition of blade properties i smade in two steps:

(1) Blade setup(2) Blade angles

In the right panel some information are displayed which result from calculated or determined values:

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122

118 CFturbo8


The Velocity triangles of inflow and outflow are displayed. Continuouslines represent flow velocities on hub (blue) and shroud (green). Velocitiesdirectly before and behind blade area are displayed by dashed lines toshow the influence of blockage in the flow domain. Furthermore the bladeangles are displayed by thick lines in order to see the incidence angle onthe leading edge and the flow deviation caused by slip velocity on trailingedge.

Numerical values of velocity components and flow angles are displayed ina table. A short description is at mouse cursor too:

d DiameterAngle of absolute flow to circumferential directionAngle of relative flow to circumferential direction

u Circumferential velocityc

mMeridional velocity (c

m=w

m)

cax

Axial component of absolute velocity

cr

Radial component of absolute velocity

cu

Circumferential component of absolute velocity

c Absolute velocityw

uCircumferential component of relative velocityw

u+c

u=u

w Relative velocityObstruction by blades (see below)

i Incidence angle

Deviation angle w

RDeceleration ratio of relative velocityw

R=w

2/w

1

4.3.1 Blade setup


On tabsheet Blade setup basic blade properties are defined.

119Impeller


(1) Selection of desired Blade shape

There are 5 different types:

Freeform 3D General 2D

Circular 2D Straight 2D

120 CFturbo8


Radial element blades(compressor and turbine only)

The initial blade shape of a radial pump impeller is Freeform 3D, the default selection for aventilator impeller is Circular 2D and for turbines Radial element blade.

For Freeform 3D-blades the design of Ruled surface blades is optionally possible which aregenerated by spatial movement of a straight line.

(2) Defining the blade thickness values at leading (LE) and trailing edge (TE) in panel Bladethickness s

Blade thickness is important for the blade angle calculation due to the blockage effect andflow acceleration.By different thickness on hub and shroud side a tapering to the blade tip can be designed.

121

121Impeller


(3) Specification of incidence angle on blade leading edge (deviation from shockless inflow) on panel ß1: Incidence

Pump, Ventilator, Compressor Turbine

from ratio Q forshockles inflow / Q formax. efficiency

BEPshocklessQ Q/QR fully automatic by theory of WIESNERadapted by Aungier

ordirectly by incidence angle i(RQ=100% or i=0° for shockless inflow)

ordirectly by incidence angle i(i=0° for shockless inflow)

[ Pump-, Ventilator, Compressor impellers only ]

(4) Estimation of slip velocity in panel 2: Deviation flow – blade

fully automatic by selecting WIESNER theoryor input of coefficient a when selecting PFLEIDERER theoryor

manual selection of angular deviation resp. velocity ratio by selecting Self

4.3.1.1 Radial element blade

Radial element blades are used especially with highly loaded fast speed turbines in order to avoidbending stresses within the blades due to centrifugal forces. The blades are composed of radialblade fibres if straight lines can be put into the mean surfaces in a way that they go through the axisof rotation at z = constant.

Radial element blades require the following geometrical boundary conditions:Blade angle at input (turbines) or output resp. (all other types): 90°Inclination angle from hub and shroud to the vertical: < 90°Vertical trailing (turbines) or leading resp. edge (all other types) with z const.Small wrap angle: 360°/number of blades

125

110

122 CFturbo8


4.3.2 Blade angles


On this tabsheet the blade angles are calculated.

123Impeller


The mean lines depend on the number and the meridional position of profile sections as well as theblade angles. Blade angles

B1 and

B2 are calculated from the velocity triangles, whereby the blade

blockage of the flow channel and the slip velocity is considered.

The degree of freedom when designing the blades depends on the selected blade shape. Referring tothe blade angles this means, that they are marked as (auto) and are result of the Mean linecalculation.

Panel Blade angle B:Specifying number of blade profile sections for further blade design using the vertical track barCalculation of blade angles using values from Blade setup by pressing button Calculate BManual adaptation of calculated blade angles if required

Calculation or input of blade angles can be executed for 2 up to 11 blade profiles. Further bladedesign is realized according to the defined blade profile number.When using 2D blade shapes a low number of profiles may be sufficient in dependence of theleading edge shape, e.g. for a straight leading edge. For that reason the initial design for ventilatorsis made by 2 blade profiles.For Radial element blades the number of blade profiles is fixed to 11, for ruled surface blades it islimited to 2.

Blade angles are computed under consideration of the equations listed below. They remainunchanged by default if they are determined once. If main dimensions or meridional contours aremodified or, on the other hand, values of blade thickness or slip velocity are renewed, a recalculationof blade angles should be executed by pressing the button Calculate B. This recalculation is

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124 CFturbo8


made automatically if the checkbox Automatic is selected.

Details of calculation of Inlet triangle Details of calculation of Outlet triangle

The blade angles are calculated for hub and shroud. On panel Distribution from hub to shroud youcan define how the blade angles of the inner sections are defined.

When using splitter blades you can select if the splitter blades is a truncated main blade (Splitterblade linked to Main blade). Otherwise the splitter blade can be designed completelyindependent.

All meridional lines which will be used for blade design are displayed in the diagram. The number oflines can be adjusted with the track bar on panel Blade angle B.

4.3.2.1 Inlet triangle

The inlet triangle is defined by inflow parameters and geometrical dimensions on leading edge.

Between inlet area and leading edge the swirl is constant because transmission of energy fromrotating impeller to fluid occurs in blade area only.Cross sections 0 and 1 (see Main dimensions ) are different only due to blockage of the flowchannel by blades (

1) in section 1. This results in an increased meridional velocity c

m.

1u

1m1

w

ctan

10m1m cc

1

11

11

11

11

sin

s,

z

dtwith

t

t

110m bdQc

1u11u cuw

ndu 11

1

SrS

1

SuS1u

r

r1u

r

rcc

(const. inflow swirl)

Selected blade angle 1B

does only indirectly influence the velocity triangle due to blade blockage.

124

126

74

125Impeller


Differences between selected blade angle 1B

and flow angle 1 is referred as the incidence angle: i

= 1B

-1

In general an inflow without any incidence is intended (i=0). If i 0 the flow around the leading edgeshows high local velocities and low static pressure:

i > 0: 1 <

1B stagnation point on pressure side

i < 0: 1 >

1B stagnation point on suction side

A small incidence angle i can be profitable for best efficiency point. Calculation of 1B

inside CFturbo

gives inflow without incidence.For pumps and ventilators

1B should be lower than 40° due to best efficiency.

For pumps, because of cavitation 1B

should be as small as possible; with regard to efficiency not

smaller then 15…18°.For compressors the optimal blade angle

1B is about 30°.

If the radius of leading edge varies from hub to shroud the blade angle 1B

does not remain constant.

A higher radius on shroud results in a lower value for 1B

- the blade is curved on leading edge.

Possible warnings:

Pumps, Ventilators only:"Leading edge blade angle ß1 > 40°."Small inlet angles are typically for pumps and ventilators. Too high values indicate too small inletcross section.

"Leading edge blade angle ß1 < 10°"Too small inlet angles indicate too high inlet cross section.

"The blade angles are not within the valid range."Usage of CFturbo is limited to inlet angles between 0° and 90° (turbines 180°).

[ Turbine rotors only ]

In case of turbines the following calculation of incidence by Aungier can be used. This is based onthe empirical equation of the outflow coefficient by Wiesner .

According to decreased energy transmission the slip coefficient is defined:

2

1u1u

u

cc1

The cu-difference is called slip velocity.

The smaller the slip coefficient, the higher is the deviation of flow compared to the direction given byblade ( =1: no incidence).

The empirical equation by Wiesner adapted to the incidence is:

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126 CFturbo8


w7.0

1B kz

sin1

with correction factor

519sin 1B

0

0

02

1u1u

lim1

u

cc1

2Hub,2

2Shroud,2m2 dd5.0d

10

lim

lim1

m2

lim1

m2

w

1B

1

d

d

-1

d

d für 1

k

Circumferential component of blade flow at zero incidence can be calculated as follows:

21u1u u1cc

4.3.2.2 Outlet triangle

The outlet triangle is determined by geometrical dimensions of flow channel and selected bladeangle

2B. The blade angle

2B strongly affects the transmission of energy in the impeller therefore is

has to be chosen very carefully.

127Impeller


Similar to the inlet the velocity triangles in cross sections 2and 3 are different due to blockage of the flow channel byblades

2 in section 2.

2u

2m2

w

ctan

23m2m cc

2

22

22

22

22

sin

s,

z

dtwith

t

t

223m bdQc

2u22u cuw

ndu 22

2

r2

1h2u

u

1uYc

0u13u2h

cucuY

Y~

:from

For determination of 2B

it is important to be aware about the deviation between flow angle and blade

angle. The direction of the relative flow w2 at impeller outlet does not follow exactly with the blade

contour at angle 2B

. The flow angle 2 is always smaller than blade angle

2B due to the slip

velocity. This difference is called deviation angle :

2B2

The deviation angle should not exceed 10°…14°, in order to limit increased turbulence losses byasymmetric flow distribution.A reduced flow angle

2 results in smaller circumferential component of absolute speed c

u2, which is

- according to Euler's equation - dominant for the transmission of energy. Blade angle 2B

is

estimated by for blade congruent flow (see figure). Therefore an estimation of slip isnecessary.

Slip can be estimated by empirical models. Two different possibilities are available in CFturbo (notfor Turbines):

128 CFturbo8


(1) Decreased output by PFLEIDERER (2) Outflow coefficient by WIESNER

Blade angle 2B

must be determined to reach the desired energy transmission - respectively the

required head/ pressure difference - under consideration of slip velocity. Common blade angles 2B

are within the range of 15°…45°. For pumps angles of 20°…27° are commonly used, for ventilators50° should not be exceeded at all.

The following recommendations for common blade angles 2B

exist due to optimal efficiency:

Pumps: 15°...45°, commonly used 20°...27°Ventilators: not higher than 50°Compressors: 35°...50°, unshrouded impellers up to 70°...90°Turbines: radius dependent, see sine rule

Radial machines - except for turbines - with low specific speed nq usually have similar values for 2B

. The blades for this type of impellers are often designed with a straight trailing edge (2B

=const.).

Possible warnings:

"Trailing edge blade angle ß2 < 10°"Too small outlet angles indicate too high outlet cross section.

pumpen, ventilators, compressors only:"The deviation (slip) between blade and flow Delta > 20°"Too high deviation (slip) between blade and flow indicate too high blade loading. This can be avoidedby increasing the impeller diameter and/or increasing the number of blades.

"The blade angles are not within the valid range."Usage of CFturbo is limited to outlet angles between 0° and 90° (turbines 180°).

4.3.2.2.1 Decreased output by PFLEIDERER

Reduced energy transmission is expressed by decreased output coefficient p:

1Y~

Y~

p

This coefficient can be empirically calculated in dependence of experience number ':

zS

r'p

22

2

1

r

r

rdxS

static moment from leading to trailing edge

128

129

135

129Impeller


601a' 2 experience number

experience number a:Radial impeller with guided vanes a = 0.6

with volute a = 0.65…0.85with plain diffusor a = 0.85…1.0

Mixed flow/axial impeller a = 1.0 …1.2(the numbers are valid for sufficiently high Re; ’ strongly grows with small Re)

More descriptive is the decreased output factor kL:

u

uL

rc

rc

Y~Y~

p1

1k

(kL=1: for flow congruent to blade)

Circumferential component of the flow, which is congruent to blade, can be calculated as follows:

rL2

21

L

2u2u 1n21

k

1

r

r

k

cc

4.3.2.2.2 Outf low coeff icient by WIESNER

Outflow coefficient is defined for decreased energy transmission:

2

2u2u

u

cc1

The cu-difference is called slip velocity.

The smaller the outflow coefficient, the higher is the deviation of flow compared to the direction givenby blade.

Wiesner has developed an empirical equation for the estimation of outflow coefficient:

w7.0

B21 k

z

sin1f

with correction values

impellersflow -mixed for50n102.102.1

impellers radial for98.0f

q31

3

Lim

Lim2m1

Lim2m1

w

1

dd1

ddfor1

k

130 CFturbo8


2Hub,1

2Shroud,1m1 dd*5.0d

z

sin16.8exp B2

Lim

Circumferential component of blade congruent flow can be calculated as follows:

22u2u u1cc

4.4 Blade design

4.4.1 Mean line

Impeller | Blade mean line

The blade mean lines are designed on the number of meridional flow surfaces which were determinedin Blade properties .

The spatially curved meridional flow surfaces are mapped to aplane by coordinate transformation. This coordinate system hasthe angle in circumferential direction t as abscissa and thedimensionless meridional extension m as the ordinate.

Both quantities are created by the reference of absolutedistances in meridional (M) and tangential direction (T) to thelocal radius r:

r

dTdt

r

dMdm

This conformal mapping allows the uniform handling of various impeller types (radial, mixed-flow,axial).It should be noted that for each meridional flow surface a separate m-coordinate is existing.

Depending on the selected blade shape (see Blade properties ) the design of the mean lines ismore or less restricted.

Freeform blades, 2D blades, Radial element blades Circular blades, Straight blades

The blades of an impeller representing a deceleration cascade for the relative velocity. Therefore therisk of flow separation exists. The user should try to obtain a continuous, smooth change of flow

117

117

131

133

131Impeller


direction, as well as the cross section graduation of the flow channel should be as steady aspossible.

The Frontal view (switch above the diagram) represents the designed mean lines in a frontal view,including diameters d

N and d

2.

Blade properties are displayed in tables and diagrams in order to check the design and forinformational purposes.

Blade Information

The blade lean angle can be manipulated only indirectly:

Blade lean angle

4.4.1.1 Freeform blades, 2D blades, Radial element blades

Freeform blades have the highest flexibility - the mean lines of all blade profile can be designeddirectly.For 2D blades and radial element blades you can design the hub mean line only, all other meanlines are calculated automatically due to the constraints of the blade shape.

In general the mean lines are represented by 3rd order Bezier splines. Constraints are:Meridional extension dm (see Meridional contour )Start angle

0

Wrap angle

Start angle 0 defines the starting point of the mean lines. The absolute value is irrelevant, only the

position of the mean lines to each other can be influenced. If all mean lines have the same startingpoint then the leading edge starts on the same angular position on all mean lines (radial leadingedge). On panel Leading edge points you can select, if the position of points 0 of the mean linesis Constant, Linear or User defined.

Wrap angle can be specified numerically for inner (hub) and outer (shroud) meanline, in betweenthe values are interpolated. For continuous transition between the separate mean lines (blade surface), the matching points ofeach mean line have to be Coupled linear. If you deactivate this option then you can modify allmean lines independently, inclusive individual wrap angles .

134

137

107

132 CFturbo8


CFturbo's primary design is fixing point 0 (leading edge) for all cross sections due to wrap angle andmeridian coordinate m=0, while point 3 is determined by the meridian coordinate of the trailing edge(dm) and t=0.

In case of Splitter blades the design options depends on the link between main and splitter bladesin the Blade properties . If Splitter blade linked to Main blade is activated there, the splitterblade is a shortened main blade. The blade- and wrap-angles are calculated automatically. Under Constraints the relative position of the splitter blade between two main blades can be adjusted. Itcouldn't be set on all profiles user defined like the Start angle 0.

If main and splitter blades are not linked there are all degrees of freedom in design for both.

The m-t-view of the splitter blades is shown on a separate tab (Splitter blade (m-t)). Additionally theprofiles of the contiguous blades are shown. By default they are positioned relatively by their m-coordinate. That can be changed under Display options by selecting another Splitter to mainposition (m-t).

In case of Turbines the situation is vice versa: The leading edge is located at high meridionalcoordinates whereas the trailing edge is at zero.

The wrap angle is initially constant for all cross sections, but it can be modified individually. Thewrap angle tremendously influences the blade angle progression (

B) along the mean line. Beta-

progression can be viewed in a separate diagram.

Two points in the middle, 1 and 2, must be on a straight line at an angle of B1

or B2

to the

horizontal in order to fulfill the boundary condition: dtdmtan B

The primary design shows points 2 at 1/4 of the wrap angle, and points 1 at 3/4.

122

133Impeller


Individual mean lines can be designed separately. If the linear coupling mode is active you can moveand rotate the connecting line. The positions of Bezier points of all mean lines are modifiedcorrespondingly, to get uniform profiles. If you select a point of the inner cross sections you canmove the entire connecting line. On the other hand, if you select any point of the inner or outer crosssections, you can move this point along the related straight line. This line is given by

B1 or

B2

(rotation of the connecting line). Points 0 (leading edge) and 3 (trailing edge) can only be movedhorizontally (m=const). Points 3 can be moved interactively (move/ rotate trailing edge). Points 0(leading edge) can moved only by modifying wrap angles in table Boundary conditions.

In panel Blade angles the blade angles B1

, B2

(see Blade properties ) and the angles in x,y-

plane (frontal view) B1,xy

, B2,xy

are stated for information.

In panel Blade information the angles of overlap of neighboring blades B and the incidence angle i

(see Blade properties ) are stated.

4.4.1.2 Circular blades, Straight blades

For these simple blade shapesall mean lines are completelydetermined by blade shape andblade angles. All mean linesare computed fullyautomatically, so they can’t bemodified interactively.

For circular blades the centerof the circle and the bladeradius is displayed in thefrontal view. Furthermore theappropriate numerical valuesare displayed in the Circularblade information table onthe right side of the dialog.

117

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134 CFturbo8


4.4.1.3 Blade Information

The Blade angles table on the right side of the dialog shows the blade angles B calculated in the

Blade properties dialog or computed due to simple blade shapes.

A dialog that displays the B progression along

every mean line can be accessed by the tab on theright border of the diagram. Too high local extremevalues should be avoided if possible.

The progression of the cross section area within achannel built by two neighboring mean surface aswell as hub and shroud are displayed versustangential coordinate t.

Also, the distribution of the lean angle versus thetangential coordinate t is displayed. With the leanangle the quasi-orthogonal of the blade leans awayfrom the z-direction. The quasi-orthogonal is astraight line connecting corresponding points onhub and shroud mean line. These lines are setup inthe blade property dialog and are displayed in the meridional cut if just two mean lines werechosen. Otherwise the quasi-orthogonal is notdisplayed but internally determined by connectingcorresponding points on hub and shroud mean line.

Docking windows can be undocked or pinned when they are opened. In undocked state thetransparency of the dialog can be adjusted by a track bar.

117

122

135Impeller


Another docking window displays the Blade information table with the resulting angles ofoverlapping

B and the incidence angle i for hub and shroud. Additionally the angles of the frontal

view B,xy

are displayed. In case of strictly radial impellers these values are consistent with the blade

angles.

[ Compressor impeller only ]

The actual Mach-number Ma1 (Act. inlet Ma-number) within the inlet cross section is given in the

table Cross section. It is calculated by:

1

11

a

wMa

and should not be higher than the maximum Mach-number Ma1,max

(Max. inlet Ma-number) within

the inlet cross section to avoid sonic speed.

[ Turbine rotors only ]

With the help of the sine rule blade angles at the outlet can be evaluated. In accordance to this ruleblade angles at the outlet should have almost the same size as the angle that is built by ahypotenuse being the pitch t, and a cathetus (opposite leg) being the smallest distance between twoneighboring mean lines eq at a flow surface. If this is the case the outflow can be regarded asalmost tangential to the trailing edge.

t

eqsin 2'B

This is shown in a picture for a single mean line.

136 CFturbo8


For every mean line the calculated angles as well as their differences to the actual blade angles aregiven in a table when the panel Informational value has been activated.

137Impeller


The actual Mach-number Ma2 (Act. outlet Ma-number) within the outlet cross section is given in the

table Cross section. It is calculated by:

2

22

a

wMa

and should not be higher than the maximum Mach-number Mamax2

(Max. outlet Ma-number) within

the outlet cross section. The maximum Mach-number Mamax2

is calculated on the basis of the sonic

speed within the minimum cross section (Min. cross section) by:

2

min

2

1

2max

2maxA

A

12

1Ma2Ma

This is only valid if the minimum cross section is close to the outlet cross section, because worktransfer in the blade's channel between the two regarded cross sections has been neglected.

4.4.1.4 Blade lean angle

The blade lean angle can not be controlled directly. It is influenced by the meridional contour, themeridional extension, the wrap angle and the mean lines.

With an example of a turbine with radial element blade means for the manipulation ofthe blade lean angle are given:

1: blade angle

B1

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122

138 CFturbo8


1??: move second Bezier point at leading edge

1: wrap angle

1 and enlargement of the curvature: reduction of the meridional extension of the meridional

contour

4.4.2 Blade profile

Impeller | Blade profile

To create blade profiles (main and splitter) the orthogonal blade thickness distribution for the hub andthe shroud profile is used. By default the thickness is defined at leading edge, at trailing edge and atthe control points of the blade. For the initial CFturbo-design typical values in dependence of theimpeller diameter d

2 are used (see Approximation functions ).

The representation of the thickness distribution is made along the relative blade length (0 = leadingedge, 1 = trailing edge).

131

131

107

22

139Impeller


The orthogonal blade thickness values are added to both sides of the blade mean line to create thepressure and suction sides of the blade.

In the panel Geometry the following properties for the profile design can be specified:

Design ModeSimple Linear interpolation between control points

Freeform Bezier splines are used for the thickness distribution

Linked to Main Only for splitter blades: splitter profile is linked to main profile

Identic profiles All profiles have the same thickness distribution

Global point count Global number of control points

Flexible length position Shifting control points in horizontal direction

SS-PS-CouplingNone No coupling between suction side and pressure side

Symmetric Symmetric thickness distribution: control points on suction and

140 CFturbo8


pressure side are coupled

Fixed thickness distribution Shifting the thickness distribution to pressure/suction side whereasthe distribution itself remains constant

Each thickness curve has a popup menu to add/removepolygon/Bezier points, to load or save the curve and to resetthe distribution to default.

For Bezier curves a Polyline to Bezier conversion ispossible.

The Info panel represents information of the designed blade profile.

Actual thicknessActual orthogonal blade thickness values of hub and shroud profiles at leading edge, at trailingedge, after 1/3 and after 2/3 of the blade lengthIf the cells are colored red, then the thickness on leading/trailing edge is differing from the Targetthickness.

Target thicknessOrthogonal blade thickness values for hub and shroud profiles at leading edge and at trailing edgeas defined in the Blade properties dialog.Please note that the blade thickness on leading and trailing edge should be modified in the Bladeproperties dialog only. In this case the blade angle calculation should be updated due to theblade blockage.

The Display options only influence the graphical representation. For instance, the visibility of thesmallest cross section can be toggled.

141

117

117

141Impeller


The Frontal view (switch above thediagram) represents the designed profiles ina frontal view, including diameters d

N and d

2

.

4.4.2.1 Converting Polyline / Bezier

Any existing thickness distribution can beconverted to a Bezier spline for furthermodifications.

First the desired polyline is imported via Importfrom file.

The imported curve is displayed red, the originalcurve blue.

142 CFturbo8


By pressing the Start! button the position of theBezier points is calculated in such a way thatthe imported polyline is approximated.

The control points can be moved for bettermatching the imported curve.

4.4.3 Blade edge

Impeller | Blade edge

The previously designed blade has a blunt leading and trailing edge (connection line betweenendpoints of suction and pressure side). The blade edges are designed by specifying its thickness distribution. The representation of theblade thickness s is made on 15% of the straight blade length l on leading and trailing edge.

If the complete thickness distribution including leading or trailing edge was already designed in the Blade profile dialog, then the Edge position (transition from blade edge to blade suction/pressure side) has to be defined only.

138 145

143Impeller


In panel Geometry the blade edge shape can be selected:

(1) Simple

The blade edge has a blunt end.A straight line is calculated from the endpoint of suction side perpendicular to the mean line.

Trim on radius in the Simple options panel effects turning the blade on the corresponding

144 CFturbo8


diameter. The turning is possible on the trailing edge only (or on the leading edge of turbines).

(2) Ellipse

The blade edge is rounded elliptically.The ratio of the semiaxes can be defined in panel Ellipse options. One axis runs on the meanline, the other perpendicular.

(3) Bezier

For this purpose 4th order Bezier splines are used.Points 0 and 4 representing the transition between the blade sides and the rounded blade edge.You can move these points only along the corresponding blade side. Bezier points 1 and 3 canonly be moved on straight lines which correspond to the gradient of the curve in points 0 or 4,respectively in order to guarantee smooth transition from the contour to the blade edge. Bezierpoint 2 is not restricted to move - it has the most influence to the shape of the blade edge. Itshorizontal position is calculated automatically in such way that the leading edge starts atposition l=0 and the trailing edge ends at position l=blade length. The blade edges are designedat the first or last 10% of the blade length.

There are two different possibilities to determine the shape of the blade edge. In the Beziercurve option panel you can select between:

Coupled linear: only blade edges of hub and shroud will be fixed, while anything betweenwill be interpolated linearlyUniform: when designing blade edge on hub or shroud then Bezier points of all other leadingedges have the same relative positions

Axis-Symmetric results in symmetric geometry, i.e. points 0/4 and 1/3 have the same horizontal

145Impeller


position and point 2 is on the middle line.

Info area represent information of Blade edge design.

Display options only influence the graphical representation. For instance, the visibility of thesmallest cross section can be toggled.

Possible warning:"The blade exceeds the meridional boundaries."

The orthogonal application of thickness on the mean lines can result in some blade position outsidethe meridional boundaries. Dependent upon the location of these areas one have to modify leading ortrailing edge. If the leading edge (or the trailing edge of turbines) exceeds the meridional boundariesyou can adjust it in the Meridional contour dialog only. Exceeding trailing edge (or leading edgeof turbines) can be corrected by trim on radius.

The Frontal view (switch above the diagram)represents the designed blades in a frontalview, including diameters d

N und d

2.

4.4.3.1 Edge position

If the complete thickness distribution including leading or trailing edge was already designed in the Blade profile dialog, then the Edge position (transition from blade edge to blade suction/pressure side) has to be defined only.

107

138 145

146 CFturbo8


In panel Geometry the transition from the blade edge to the suction/pressure side can be defined.

Position in % of the straight blade length.

The leading edge should be within the range of 0% to15%, the trailing edge between 85% and 100%.

4.5 Performance Estimation

Impeller | Performance Prediction

Please note: This is an estimation. The actual performance may differ from the prediction.

147Impeller


General

A performance curve of the current design is estimated on the basis of the Euler-Equation:

1u12u2th cucug

1H and 1u12u2th cucuY respectively.

Kinds of losses

There are different kinds of losses that are considered in different curves:

Kind Description Parameter

Decreasedpower

Based on the Euler-Equation and the decreasedpower that is calculated in the Blade properties .In the design point the decreased power line isshifted by a pressure head loss equivalent to thedecreased power. The decreased power line can beparallel to the Euler-Line as well as positioned thatway, that it intersects the Euler-Line at Q = 0.

cl:cl = 1...parallel position,cl = 0...intersection withEuler-Line at Q = 0.

Hydrauliclosses

Based on the Euler-Line including the decreasedpower minus the losses due to friction. Yields adownwards opened parabola, that touches thedecreased power curve at Q = 0.

:General approach:

2Q~H

Turbulenceandseparation

Includes all the effects listed above plus turbulenceand separation losses at the inlet and outlet. Yieldsa downwards opened parabola. It touches the curve,in which decreased power and hydraulic losses are

ct:General approach:

2optQQct~H

117

148 CFturbo8


considered, in the design point. with ct >

Separate curves considering the pure losses (dashed) as well as the resulting performance curves(solid) can be displayed. The display of these curves can be prevented by the check boxes "Allperformance curves" and "Pure losses". In case the display has been prevented only the actualperformance curve (red color) considering all losses will be visible.The scope to be displayed can be controlled by the check boxes "x (Flow)" and "y (Energy)" as wellas by giving the scope limits in the panel "Operating range".

Variables

All types of turbo machines have in common: The characteristics can be displayed in a diagram withdimensions as well as without dimensions.

Variable

Pump Ventilator Compressor Turbine

H head - - -

Dp - pressure difference

work coefficient

22u

Hg222u

Y221u

Y2

H/Hopt dimensionless head - - -

Dp/Dpopt

- dimensionless pressure difference

ptt - - pressure ratio (total-total)

pts - - pressure ratio (total-static)

η efficiency

NPSHa

NPSH value system(net positive suction

head available)

- - -

Q flow rate

flow coefficient

2

2m

u

c

1

1m

u

c

Q/Qopt dimensionless flow

Qt - -

total flow rate

1t

mQ

2t

mQ

149Impeller


m - - mass flow

redm - -

reduced mass flow

Ref

Refred

p

Tmm

corrm - -

corrected mass flow

Ref

01

Ref

01

pp

TT

mmcorr

All combinations of flow and energy variables are possible.It is common practice in the case of turbines - contrary to all other type of turbo machines - that theflow variable is given as a function of the energy variable. Beyond it characteristics of differentrotational speeds will not be displayed over the whole theoretical pressure interval but onlypiecewise.The choice of the variables is to be made in the panel "Variables".

Surge - compressor and fans only

The prediction of surge line is based on the following model: The pressure difference between outletand inlet yields a back flow within the compressor. Amongst pressure difference and back flow acorrelation exits, that can be found in the table "Kinds of losses", column "Hydraulic losses". Withinthe applied model the compressor is thought as a parallel connection between a flow source and ahydraulic resistance. Then, surge will occur when the back flow in the hydraulic resistance becomesas big as the flow in the flow source. The surge line can be controlled by the pressure loss coefficient "Equivalent surge hydraulicresistance". Of course it is impossible to consider non-steady effects that are characteristic for theonset of the surge with this model. The surge line can be displayed only in case dimensionalvariables has been chosen and the checkbox "Surge line" has been set.With centrifugal fans surge may only happen if the pressure difference is big enough (~0.3 bar).

Choke - compressor only

Choked flow will happen if the flow reaches sonic speed somewhere in a duct. As the rothalpy isconstant at any point in the flow channel the temperature (critical temperature within the narrowestcross section) at a flow at sonic speed can be calculated by:

2

RZc

2

uTc

T

p

2c

01p

c

and critical sonic speed becomes:

cc TRZa

With an approximation of the critical density and the influence of the boundary layer blockage the

150 CFturbo8


choked mass flow is:

B1aAm ccch

The blockage of the boundary layer is expressed by the factor B that is 0.02 by default.

Characteristics with different rotational speeds

With the current set of parameters performance curves with different rotational speeds can becalculated and displayed. This procedure is feasible only if the rotational speeds are not too far fromthe design point. If they are, similarity relations are not valid any longer.

Characteristics with different diameters - pumps and ventilators only

Performance curves for impellers with decreased diameter can be calculated and displayed too. Thedecrease of the impellers means that the geometric similarity is not given anymore. Therefore

performance curve are calculated by the following empirical correlations: H' = H (d'/d)m and Q' = Q

(d'/d)m. The exponent m should be within 2..3.

Reference curves

For comparison purposes with the present design saved designs can be loaded (softbutton"configure").

4.6 CFD Setup

Impeller | CFD setup

The designed geometry can be extended in meridional direction both at inlet and outlet side. Thisextension serves for flow simulation (CFD) only and is only virtual.

151Impeller


The Large outlet extension is reasonable if the flow simulation should be performed in the impelleronly, without bordering casing.The Small outlet extension defines the Rotor-Stator-Interface and represents the interface to thecasing. These values are the inlet geometry in the radial diffuser/volute design as a precondition formatching impeller and casing mesh.

Part

V

153Volute


5 Volute

5.1 Inlet definition

Volute | Inlet definition

The first design step of the volute is to define the inlet side. It consits of 3 steps:

(1) Impeller(2) Diffuser(3) Volute

The button Full volute with Default Settings creates a complete volute by using default settingsfor all design steps.

The meridional view (z, r) of the designed volute inlet geometry is shown on the right side (Meridian).

You can alternatively select a normalized axial position (z = 0 in the middle of volute inlet)or absolute axial position (according to the axial position of the impeller/RSI).

Rotor-Stator-Interface (RSI)

Pump, Ventilator, Compressor Turbine

154

156

157

154 CFturbo8


Fit view results in automatic scaling of the diagram if geometrical values are changing.

5.1.1 Impeller

If the impeller was already designed using CFturbo, the data can be transferred directly from thecorresponding CFT file (Load from Impeller CFT file). Otherwise the data input has to be donemanually.

General data:Flow rate: Volume flow Q or mass flow mEnergy transmission: Head H, pressure difference p or specific energy YNumber of revolutions n

Impeller outlet parameters:Impeller diameter d

2

Impeller outlet width b2

Angle of absolute flow 3

Density of the fluid 2

Rotor-Stator-Interface (RSI)Axial position zRadial position r

for hub and shroud each

155Volute


The axial position, z, ensures correct positioning relative to the impeller concerned.Additionally, the direction of rotation of the impeller, seen from the drive side (looking at the backsideof hub), must be defined.

Various calculated values are shown, for information purposes, on the right side (Values):

Specific speed nq (SI units)43

3t1

q]m[gY

smQminnn

Specific speed NS (US units) q43

ts n6.51

]ft[gY

]gpm[Q]rpm[nN

„Type number“ s (ISO 2548)

9.52

n

Y

Qn2

q

43

ts

Meridional component of the absolute velocity 223m bdQc

Circular component of the absolute velocity 33m3u tancc

156 CFturbo8


5.1.2 Diffuser

The diffuser is an radial area between impeller outlet and volute inlet.

The diffuser can consist of 2 parts:(a) Vaneless radial diffuser"normal" radial diffuser(b) Pinch type diffuserspecial diffuser part after the impeller with special shape

The diffuser parts are characterized by the inlet diameter d, height h, inlet width hIn, outlet width h

Out and axial ofset z to the impeller.

The shape can be:symmetricleft side radialright side radial

The pitch type diffuser can be designed with constant area additionally.


Diffuser inlet diameter ratio dIn

/d2

Diffuser inlet width ratio bIn

/b2

Inlet meridional velocity cm

157Volute


Inlet circumferential velocity cu

Inlet velocity c

Inlet area AIn

Outlet area AOut

Area ratio AR = A

Out / A

In

5.1.3 Volute

General data:Volumetric efficiency

v

Flow factor FQ (for overdimensioning, particularly for a better degree of efficiency at overload

operation)

Volute inlet:Inlet diameter d

4

Inlet width b4

Radial diffuser height h4

Axial displacement z (relative to the centre of the impeller outlet)

For v and F

Q, standard values of 1.0 are used. d

4 and b

4 are determined using the ratios d

4/d

2 and b

4/b

2, which are calculated from functions dependent on the specific speed nq (see Approximation

158 CFturbo8


function ).Clicking on the Calculate-button, to the top right, recalculates the standard values.

A short distance between the impeller and the cut-water is desirable for reasons of flow. For acousticand vibration reasons, however, a certain minimum distance is necessary. The inlet width b

4 should

be chosen such that the width/height ratio at the end cross-section of the volute is close to 1. Theratio b

4/b

2 can be varied within a relatively wide range without significant negative effect on the

efficiency. For radial impellers with open impeller sides, values up to b4/b

2=2 are possible. At higher

specific speeds (wider impellers), however, high width ratios have a negative effect on flow (intensivesecondary flows, turbulence losses). In this case, b

4/b

2 should be between 1.05 and 1.2.


Calculated internal flow rate Qi VQi QFQ

Inlet diameter ratio(if no radial diffuser)

dIn

/d2

Inlet width ratio(if no radial diffuser)

bIn

/b2

Inlet meridional velocity cm

Inlet circumferential velocity cu

Inlet velocity c

5.2 Cross Section

Volute | Cross Section

The shape of the cross-section of the volute can be selected here. The general cross section shapeis illustrated whereas the radial extension is assumed (radial scaling can be modified above thediagram).In general, very small cross-sections width should be avoided. The achievable cross-section shapestrongly depends on manufacturing and the space available.

22

159Volute


Following cross section types are available:

Rectangular

most simple cross-section shape; cannotbe achieved in cast parts; only sensible forlow specific speeds, since otherwise thecross-section becomes too large

Trapezoid

cannot be achieved in cast parts; the angle can be specified; results in a flatter cross-

section than a rectangular cross-section,with less intense secondary flow

160 CFturbo8


Round - symmetric

simple geometry with a beneficial stressdistribution; does not develop on rotationsurfaces

Round - asymmetric, external

more favorable secondary flow structurethan with a symmetrical cross-section; oftenwith mixed-flow impellers

Strictly external: cross sections don't fallbelow inlet radius

Round - asymmetric, internal

limitation of radial extension;additional bend necessary

see Internal cross sections

User defined - Rectangle type

analogous with Rectangle; with chamfers(cast radii)

see Bezier cross section

User defined - Trapezoid type

analogous with Trapezoid; with chamfers(cast radii)

see Bezier cross section

Under Display options, changes can be made which affect only the graphics.

162

161

161

161Volute


5.2.1 Bezier cross section

The shape of a User defined cross-section is described by a Bezier spline.

One half of the shape of the cross-section is described using a 4th degree Bezier polynomial. Points0 and 4 are the end points and cannot be changed. Point 1 can be moved along a straight line whichcorresponds to the cone angle of the cross-section (0° for a rectangle type, for a trapezoid type).Point 3 can only be moved in the horizontal direction in order to guarantee a smooth transitionbetween the two symmetrical halves. The intersection of the two lines which points 1 and 3 are on isdesignated by the letter S and plays an important role in the positioning of Bezier points 1 and 3.Point 2 can be moved freely and therefore he has the major influence on the shape of the cross-section. In the first design, point 2 is identical with point S.

Two basic shapes of the cross-section can be selected, rectangular or trapezoid. Only the endcross-section of the volute is designed, all other cross-sections result from this. Under the heading Inner point position, you can select whether positioning of the inner points 1 and 3 should berelative (0..1; 0=point 0/4; 1=point S) or absolute (distance from point S). The numeric values ofthe positions can be changed by right-clicking on points 1 or 3. If the option Show all points underthe heading Options is selected, the different positioning methods become apparent.

The minimum curvature radius of the designed contour is shown in the box to the bottom right.

162 CFturbo8


5.2.2 Internal cross sections

Internal volutes are limited in its radial and axial extensions (see gray lines in the picture).

The additional bend can be described by the following parameters:

Neck width side distance from volute inlet to actual volute crosssections

Inner bend shape shape of the inner bend wall

Ratio semiaxis ratio for quarter bend

Outer bend shape shape of the outer bend wall

Bend area ratio ratio of outlet to inlet section of the bend

5.3 Spiral development areas

Volute | Spiral areas

The spiral development areas can be designed and calculated in this dialog box.

163Volute


The wrap angle (standard: 360°) can be defined under Extension.

You can select Design rule for volute calculation, whereas 3 possibilities exist: Pfleiderer,Stepanoff, Self.

Details Design Rule

In panel Cut-water you can specify parameters for the cut-water design. Details Cut-water

Some informative values relating to the end cross-section are shown in the lower part:

164 164

166

164 CFturbo8


Radius r5

Height H5

Width B5

Side ratio H5/B

5

Equivalent diameter D5

Area A5

Average velocity c5

Under Display options, changes can be made which affect only the graphics:

Show – refers to the image of volute + diffuser

Section lines radial angle lines

Cut-water compensation cut-water compensation as a larger inner radius

Show in cross section – refers to the image of the cross-section

Cut-water section cut-water cross-section

Equivalent diameter (outlet) equivalent diameter D6 (dashed line)

Filled cross sections filled cross-sections

Radial inlet diffuser radial inlet diffuser between impeller and volute

Impeller outlet impeller outlet (symbolic)

In addition, some diagrams can be displayed:Volute cross sections (z-r)Area distribution (Angle-Area)Area-Radius distribution (Angle-Area/Radius)

5.3.1 Design rule

The flow rate through a cross-section, A, of the circumferential angle, , is generally calculated as:)(r

r

uu

a

4

dr)r(bcdAcQ

Using 2QQ i

results in an equation to calculate the circumferential angle, , dependenton the outer radius r

a:

165Volute


)(r

r

ui

a

4

dr)r(bcQ

2

b(r) is a geometrical function which is defined according to the shape of the cross-section. Thevelocity c

u is chosen in accordance with the design instructions. Under Design rule, two

alternatives can be selected.

PfleidererExperience has shown that the losses can be greatly minimised if the volute housing is dimensionedsuch that the fluid flows in accordance with the principal of conservation of angular momentum. Thecross-section areas are therefore designed in accordance with the principal of conservation ofangular momentum, i.e. angular momentum exiting the impeller is constant. In addition, an exponent

of angular momentum, x, can be chosen so that the principle curx = const. is obeyed. When x=1,

the angular momentum is constant. For the extreme of x=0, the circular component of the absolutevelocity cu remains constant at the impeller outlet.

)(r

rx

i

x44u

a

4

drr

)r(b

Q

rc2

The integral can be explicitly solved for simple cross-section shapes (rectangles, trapezoids,circles). For other, arbitrary, shapes, it can be solved numerically.

StepanoffAlternatively, it can be beneficial to design the volute with a constant velocity in all cross-sections ofthe circumference. According to Stepanoff, this constant velocity can be determined empirically:

gH2kc Su. The constant k

s can be determined dependent on the specific speed n

q (see

Approximation function ).)(r

ri

Sa

4

dr)r(bQ

gH2k2

22

166 CFturbo8


Self

Contrary to and the geometry progression is defined directly. The end cross section is definedby radius or cross section area, the distribution by Radius- or Area progression.

By clicking on Default, you can return to the standard values for each design instruction.

5.3.2 Cut-water

Cut-water is available for external volutes only. For internal volutes the cut-water is a result ofintersection of spiral and diffuser.

The cut-water can be designed in the Cut-water section:

Inner radius r4

Informative, see Inletr4 is the inlet radius of the volute and/or outlet radius of

radial diffusers

Thickness e Thickness of the cut-water at the start of the volute (forcompensation)

Compensation C

Angle, above which cut-water correction begins (standard:270°)

The cut-water does disturb the flow, since the cross-section of theflow is narrowed suddenly by the thickness of the cut-water.

To weaken this negative influence, the cut-water can be corrected.This is achieved by assuming that from the angle

C the inner radius r

4 increases linearly to a value of r

4+e at the end cross-section of the

volute. This results in larger volute cross-sections in this area, so thatthe narrowing of flow caused by the cut-water becomes lesssignificant.

By clicking on Default, you can return to the standard values for thecut-water.

5.4 Diffuser

Volute | Diffuser

The geometry of the outlet diffuser can be designed and calculated in this dialog box.

153

167Volute


In general, 3 basic shapes are differentiated (Direction):

Tangential diffuser

168 CFturbo8


Radial diffuser

Spline-diffuser

The tangential diffuser is easier to manufacture, the radial diffuser has the advantage of minimisingtangential forces. The spline diffuser is similar to the radial but with extended flexibility.

For the tangential diffuser the angle deviation from the tangential direction, , (standard: 0°) can bedefined. In the case of a radial diffuser, the angle between the outlet branch and the line connectingimpeller-centre and outlet branch centre can be selected.

For the Spline-diffuser the angle 6 between connecting line impeller-centre outlet branch centre

and diffuser start section has to be defined. Points 0 and 4 are start and endpoint of the middle lineon th einlet and outlet cross section, point 2 is fixed by the intersection of appropriate perpendicularsof these sections. Position of points 1 and 3 influence the curve shape of the middle line.

The extension of the diffuser can be defined in panel Dimensions. Parameters in the x,y-plane canbe specified, as well as a rake of the diffuser in z-direction.For all diffuser shapes the extension is defined by the diffuser height h6, which is the perpendicular

distance from a center line to the diffuser outlet. Additionally the starting position of the diffuser isdefined by the angle 0, whereas 0° is horizontal right. The whole volute can be rotated by this value.

By using the button Vertical outflow direction the volute can be rotated for vertical direction of the

169Volute


pressure joint.

The diffuser bending in z-direction is described by the parameters shown in the sketch.There exist 2 straight segments 1, 3 and a circular segment 2. The lengths L1, L2 and L3 are

specified percental.The curvature is defined by the radius R, the direction by the angle α.The z-bend is illustrated in the diagram by a green center line.

The end cross-section of the diffuser can be either round or rectangular. The diameter D6 can be

directly defined or selected from standard tables. In the case of a rectangular end cross-section theheight H6 and width B6 can be chosen.

Furthermore the percental position can be specified, where the shape of the end cross section isreached (default = 100%). Afterwards the shape is constant and the cross section area is changingonly.

Cut-water rounding is defined by the angular position C,0

(standard: 0°=start of volute, C,0

<>0

indicates a rounding-off between the actual volute and the diffuser). Underneath the minimumnecessary angular position is displayed to prevent overlap of the actual volute and the diffuser.Cut-water design is not available for internal volutes.

The following values are shown for information purposes:

Equivalent diameter D6 Diameter of the equivalent circle at the diffuser outlet

Length L Length of the diffuser

Angle to middle 6 angle between connecting line impeller-centre outletbranch centre and diffuser start section

Cone angle cone angle from D5 to D

6 over the length L

170 CFturbo8


Deceleration ratio AR

Diffuser radius R radius of middle line (for radial diffuser only)

By clicking on Default, you can return to the standard values for the diffuser geometry.

Under Display options, changes can be made which affect only the graphics.

Part

VI

172 CFturbo8


6 Appendix

6.1 References

GENERAL

Werner FisterFluidenergiemaschinen Bd. 1 und 2, Springer-Verlag, 1984 und 1986

Carl Pfleiderer, Hartwig PetermannStrömungsmaschinen, Springer-Verlag, 1991

Joachim RaabeHydraulische Maschinen und Anlagen, VDI-Verlag, 1989

PUMPS

Johann F. GülichKreiselpumpen, Springer-Verlag, 1999

Kurt Holzenberger, Klaus JungKreiselpumpen Lexikon, KSB AG, 1989

John TuzsonCentrifugal pump design, John Wiley & Sons, 2000

Walter WagnerKreiselpumpen und Kreiselpumpenanlagen, Vogel-Verlag, 1994

Gotthard WillKreiselpumpen, in: Taschenbuch Maschinenbau, Band 5,hrsg. von Hans-Joachim Kleinert, Verlag Technik Berlin, 1989

VENTILATORS

Leonhard Bommes, Jürgen Fricke, Reinhard GrundmannVentilatoren, Vulkan-Verlag, 2003

Bruno EckVentilatoren, Springer-Verlag, 1991

Thomas CarolusVentilatoren, Teubner-Verlag, 2003

COMPRESSORS

Arnold Whitfield, Nicholas C. BainesDesign of Radial Turbomachines, Longman Scientific & Technical, 1990

173Appendix


Ronald H. AungierCentrifugal Compressors, ASME Press, 2000

Klaus H. LüdtkeProcess Centrifugal Compressors, Springer-Verlag, 2004

Bruno Eckert, Erwin SchnellAxial- und Radialkompressoren, Springer-Verlag, 1980

Davide JapikseCentrifugal Compressors Design and Performance, Concepts ETI, 1996

N. A. CumpstyCompressor aerodynamics, Krieger publishing, 2004

Ernst LindnerTurboverdichter, in: Taschenbuch Maschinenbau, Band 5hrsg. von Hans-Joachim Kleinert, Verlag Technik Berlin, 1989

TURBINES

Arnold Whitfield, Nicholas C. BainesDesign of Radial Turbomachines, Longman Scientific & Technical, 1990

Ronald H. AungierTurbine Aerodynamics, ASME Press, 2006

Hany Moustapha, Mark Zelesky, Nicholas C. Baines, Davide JapikseAxial and Radial Turbines, Concepts NREC, 2003

6.2 Contact addresses

Development, Sales, Support

CFturbo Software & Engineering GmbHwww.cfturbo.com

Unterer Kreuzweg 101097 Dresden, GermanyPhone: (+49) 351 40 79 04 74Fax: (+49) 351 40 79 04 80

Bismarckstr. 280803 Munich, GermanyPhone: (+49) 89 189 41 45 0Fax: (+49) 89 189 41 45 20

174 CFturbo8


6.3 License agreement

Software Cession and Maintenance Contract

betweenCFturbo Software & Engineering GmbHUnterer Kreuzweg 1, 01097 Dresden (Germany)- hereinafter designated the 'Licensor' -

andthe CFturbo user- hereinafter designated the 'User' -

§ 1 LICENSE AGREEMENTBy virtue of this agreement, the User acquires from the Licensor the non-transferable and non-exclusive right to use the software 'CFturbo' (hereinafter designated the 'Software') for a period oftime, in exchange for the licence fee agreed between the Licensor and the User.

1. Licence ObjectThe User acquires a nodelocked license or a license for one local office network (LAN) at onedistinguished location of the company.The program package consists of a data medium (CD-ROM or DVD) with the Software and a usermanual in the form of a PDF file. In the event that the Software was downloaded from the officialwebsite of the Licensor, the program package consists of the corresponding installation file includingelectronic documentation.

2. Duration / commencement of the licenceThe User obtains the right to use the Software. The right is obtained after the payment of the fulllicence fee and implicitly expires at the end of the arranged time period.

4. Right of Use(1) In accordance with this contract, the Licensor grants the User a right of use to the Softwaredescribed under 1. as well as a right to use the necessary printed matter and documentation. Theprinting-out of the manual for the purposes of working with the Software is permitted.(2) The User may duplicate the Software only insofar as the duplication in question is necessary forthe use of the Software. Necessary reasons for duplication notably include the installation of theSoftware from the original data medium onto the mass storage of the hardware used, as well as theloading of the Software into the RAM memory.(3) The User is entitled to perform duplication for backup purposes. However, in principle, only asingle backup copy may be created and stored. The backup copy must be labelled as being abackup copy of the ceded Software.(4) If, for reasons of data security or the assurance of a fast reactivation of the computer system aftera total failure, the regular backing-up of the entire dataset including the computer programs used isessential, then the User may create the number of backup copies which are compulsorily required.The data media concerned must be labelled accordingly. The backup copies may only be used forpurely archival purposes.(5) The User is obliged to take appropriate measures to prevent the unauthorized access of thirdparties to the program including its documentation. The supplied original data media, as well as thebackup copies, must be stored in a location protected against the unauthorized access of thirdparties. The employees of the User must be explicitly encouraged to observe these contractualconditions as well as the provisions of copyright law.

175Appendix


(6) Additional duplications, also including the printing-out of the program code on a printer, must notbe created by the User. The copying and the handover or transfer of the user manual to third partiesis not permitted.

5. Multiple Use and Networks(1) The User may use the Software on any hardware available to him, provided that this hardware isappropriate for the use according to the Software documentation. In the event of changing thehardware, the Software must be erased from the previously used hardware.(2) The simultaneous reading in, storage or use on more than one hardware device is not permittedunless the User has acquired multiple-use licences or network licences. Should the User wish touse the Software on multiple hardware configurations at the same time, for example to permit theuse of the Software by several employees, he must purchase the corresponding number of licences.(3) The use of the ceded Software on different computers on a network or another multiple-workstation computer system is permitted, provided that the User has purchased multiple-uselicences or network licences. If this is not the case, the User may only use the Software on anetwork if he prevents simultaneous multiple use by means of access protection mechanisms.

6. Program Modifications(1) The disassembly of the ceded program code into other code forms (decompilation) as well asother types of reverse-engineering of the different manufacturing stages of the software, including amodification of the program, is not permitted.(2) The removal of the copy protection or similar protection mechanisms is not permitted. Insofar asthe trouble-free use of the program is impaired or hindered by one of the protection mechanisms, theLicensor is obliged to remedy the fault on an appropriate request. The User bears the burden of proofof the impairment or hindrance of trouble-free usability as a result of the protection mechanism.(3) Copyright notices, serial numbers and other marks used for program identification purposes mustin no event be removed or modified. This also applies to the suppression of the screen display ofsuch marks.

7. Resale and LeasingResale and leasing of the Software or other cession of the Software to third parties is only permittedwith the written agreement of the Licensor.

8. Warranty(1) The Licensor makes no warranty with respect to the performance of the Software or the obtaineddata and the like. He grants no guarantees, assurances or other provisions and conditions withrespect to the merchantability, freedom from defects of title, integration or usability for specificpurposes, unless they are legally prescribed and cannot be restricted.(2) Defects in the ceded software including the user manuals and other documents must beremedied by the Licensor within an appropriate period of time following the corresponding notificationof the defect by the User. The defect is remedied by free-of-charge improvements or a replacementdelivery, at the discretion of the Licensor.(3) For the purposes of testing for and remedying defects, the User permits the Licensor to accessthe Software via telecommunications. The connections necessary for this are established by theUser according to the instructions of the Licensor.(4) A right of cancellation of the User due to the non-granting of use according to § 543 para. 2clause 1 no. 1 of the Civil Code is excluded insofar as the improvement or replacement delivery isnot to be regarded as having failed. Failure of the improvement or replacement delivery is only to beassumed if the Licensor was given sufficient opportunity to make the improvement or replacementdelivery.(5) Furthermore, the statutory regulations also apply.

9. Liability

176 CFturbo8


(1) The claims of the User for compensation or replacement of futile expenditure conform, withoutregard to the legal nature of the claim, to the existing clause.(2) In the Software, it is a question of a design procedure. It is considered to be purely anapproximation method. The Licensor is not liable for the functioning of the data obtained in practice,for the manufactured prototypes or components, or for possible consequential damages resultingtherefrom.(3) The Licensor is liable for damage involving injury to life and limb or to health, without limitation,insofar as this damage is the result of a negligent or intentional breach of obligation on the part of theLicensor or one of his legal representatives or vicarious agents.(4) Otherwise, the Licensor is liable only for gross negligence and deliberate malfeasance.(5) Liability for consequential damages due to defects is excluded.(6) The above regulations also apply in favour of the employees of the Licensor.(7) The liability according to the Product Liability Act (§ 14 ProdHaftG) remains unaffected.(8) The liability of the Licensor regardless of negligence or fault for defects already existing onentering into the contract according to § 536 a para. 1 of the Civil Code is expressly excluded.

10. Inspection Obligation and Notification Obligation(1) The User will inspect the delivered Software including its documentation within 8 working daysafter delivery, in particular with regard to the completeness of the data media and user manuals aswell as the functionality of the basic program functions. Defects determined or detectable herebymust be reported to the Licensor within a further 8 working days by means of a registered letter. Thedefect notification must contain a detailed description of the defects.(2) Defects which cannot be detected in the context of the described appropriate inspection must bereported within 8 working days of their discovery with observance of the notification requirementsspecified in paragraph 1. (3) In the event of the violation of the inspection and notification obligation, the Software isconsidered to be approved with regard to the defect concerned.

11. Intellectual Property, CopyrightThe Software and all the authorized copies of this Software made by the User belong to the Licensorand are the intellectual property of the latter. The Software is legally protected. Insofar as it is notexpressed stated in this contract, the User is granted no ownership rights to the Software, and allrights not expressly granted by means of this contract are reserved by the Licensor.

12. Return(1) At the end of the contractual relationship, the User is obliged to return all of the original datamedia as well as the complete documentation, materials, and other printed matter ceded to him. Theprogram and its documentation must be delivered to the lessor free of charge.(2) The appropriate return also includes the complete and final deletion of all installation files andonline documentation, as well as any copies that may exist.(3) The Licensor may dispense with the return and order the deletion of the program and thedestruction of the documentation. If the Licensor exercises this elective right, he will explicitly informthe User to this effect.(4) The User is expressly advised that, after the end of the contractual relationship, he may notcontinue to use the Software and, in the event of non-compliance, is violating the copyright of thecopyright holder.

§ 2 SOFTWARE MAINTENANCEThe Licensor performs the maintenance and upkeep of the Software modules included in thiscontract under the following conditions. The maintenance of computer hardware is not the subjectmatter of this contract.

177Appendix


1. Scope of the maintenance obligation(1) The contractual maintenance measures include:a) The provision of the respectively newest program versions of the Software modules named under§ 1 no. 1 as free-of-charge downloads. The Software is installed by the User.b) The updating of the Software documentation. Insofar as a significant change to the functionalscope or operation of the software occurs, completely new documentation will be provided.c) On the expiration of the defect liability period resulting from the Software cession contract, theremedying of defects both in the program code and in the documentation.d) Both the written (also by fax or e-mail) and telephone advising of the customer in the event ofproblems regarding the use of the Software as well as any program errors that may need to berecorded.e) The telephone advice service ('hotline') is available to customers on working days between 9.00 a.m. and 4.00 p.m. (CET).f) Defects reported in writing or requests for advice are answered no later than the afternoon of theworking day following their receipt. As far as possible, this occurs by telephone for reasons ofspeed. The customer must therefore add the name and direct-dial telephone number of theresponsible employee to every written message. For defect reports or requests for advice sent by e-mail, the answer may also be given by e-mail.(2) The following services, among others, are not included in the contractual maintenanceservices of the contractor:a) Provision of advice outside of the working hours specified under § 2 para. 1 letter e).b) Maintenance services which become necessary due to the use of the Software on aninappropriate hardware system or with an operating system not approved by the Licensor.c) Maintenance services which become necessary due to the use of the Software on anotherhardware system or with another operating system.d) Maintenance services after interference of the customer with the program code of the Software.e) Maintenance services with respect to the interoperability of the Software which is the subjectmatter of the contract with other computer programs which are not the subject matter of themaintenance contract.f) The remedying of faults and damage caused by incorrect use by the User, the influence of thirdparties or force majeure events.g) The remedying of faults and damage caused by environmental conditions at the setup location, bydefects in or absence of the power supply, faulty hardware, operating systems or other influencesnot attributable to the Licensor.

2. Payment(1) If the User has acquired the Software for a limited period of time, then the payment for themaintenance has already been effected in full with the payment of the licence fee.(2) In the event of a right of use for an unlimited period of time, the first twelve months ofmaintenance are included in the licence fee. In the following period, the annual maintenance fee canbe found in the enclosed price table. The Licensor is entitled to adjust the maintenance fee on anannual basis in accordance with the general trend of prices. If the increase in the maintenance feeamounts to more than 5%, the customer may cancel the contractual relationship.

3. Duration of the ContractIn the case of a time-limited right of use, maintenance contract ends with the expiration of the rightof use of the Software.In the case of a time-unlimited right of use:the maintenance contract is extended after the first twelve months by a further twelve monthsrespectively, unless the User opposes this in writing to the Licensor within a period of 3 months priorto the expiration.orthe User may demand, after the first twelve months, a continuation of the maintenance contract by a

178 CFturbo8


further 12 months respectively up to the date of the expiration of the contract. The demand must bemade in writing.

4. Cooperation Obligations(1) In the transcription, containment, determination and reporting of defects, the customer mustfollow the instructions issued by the Licensor.(2) The customer must specify its defect reports and questions as accurately as possible. In doingso, he must also make use of competent employees.(3) During the necessary test runs, the customer is personally present or seconds competentemployees for this purpose, who are authorized to pronounce and decide on defects, functionalexpansions, functional cutbacks and modifications to the program structure. If necessary, other workinvolving the computer system must be discontinued during the time of the maintenance work.(4) The customer grants the Licensor access to the Software via telecommunications. Theconnections necessary for this are established by the customer according to the instructions of theLicensor.

5. Liability(1) The Licensor is liable only for deliberate malfeasance and gross negligence and also that of hislegal representatives and managerial staff. For the fault of miscellaneous vicarious agents, theliability is limited to five times the annual maintenance fee as well as to such damage the arising ofwhich is typically to be expected in the context of software maintenance.(2) The liability for data loss is limited to the typical data retrieval expenditure which would havecome about in the regular preparation of backup copies in accordance with the risks.

§ 3 MISCELLANEOUS AGREEMENTS1. Conflicts with Other Terms of BusinessInsofar as the User also uses General Terms of Business, the contract comes about even withoutexpress agreement about the inclusion of General Terms of Business. Insofar as the differentGeneral Terms of Business coincide with respect to their content, they are considered to be agreed.The regulations of the anticipated law replace any contradictory individual regulations. This alsoapplies to the case in which the Conditions of Business of the User contain regulations which arenot contained in the framework of these Conditions of Business. If the existing Conditions ofBusiness contain regulations not contained in the Conditions of Business of the User, then theexisting Conditions of Business apply.

2. Written FormAll agreements which contain a modification, addition or substantiation of these contractualconditions, as well as specific guarantees and stipulations, must be set down in writing. If they aredeclared by representatives or vicarious agents of the Licensor, they are only binding if the Licensorhas granted his written consent to them.

3. Notice and Cognizance ConfirmationThe User is aware of the use of the existing General Conditions of Business on the part of theLicensor. He has had the opportunity to take note of their content in a reasonable manner.

4. Election of JurisdictionIn relation to all of the legal relations arising from this contractual relationship, the parties agree toapply the law of the Federal Republic of Germany, with the exception of the United NationsConvention on Contracts for the International Sale of Goods.

5. Place of JurisdictionFor all disputes arising in the context of the execution of this contractual relationship, Dresden is

179Appendix


agreed to be the place of jurisdiction.

6. Severability ClauseShould one or more of the provisions of this contract be ineffective or void, then the effectiveness ofthe remaining provisions remains unaffected. The parties undertake to replace the ineffective or voidclauses with legally effective ones which are as equivalent as possible to the originally intendedeconomic result. The same applies if the contract should contain a missing provision which requiresaddition.

CFturbo8180


Index

- 1 -1D-streamline 74, 86

- 3 -3D model 37, 42, 44

3D view 42

- A -activation 12

Administrator 9

angle of flow 97, 99

Animation 37

Ansys 65

approximate 113, 141

Approximation functions 22

Area circles 107

Area progression 107

Assumptions 77, 90, 99

asymmetric 158, 162

AutoCAD 49

AutoGrid 53

Automatic update 29

Axial extension 110

Axial impeller 90

Axial position 153

- B -Basic values 75, 87, 97

Batch 15

bend 162

Beta progression 130

Bezier 113, 130, 141, 142, 158, 161

Bezier curves 30

Bezier mode 107, 110

Bezier polynom 137

Blade 145

Blade angle 124, 126

Blade angles 117, 131, 137

Blade blockage 124, 126

Blade lean angle 137

Blade lines 117

blade number 99

Blade properties 117

Blade shape 117

Blade thickness 117, 138

Blade thickness leading edge 22

Blades 37

Boundary conditions 131

- C -CAD 7

CAE-startup 67

Calculate 81, 93, 102, 117

Catia 53

CFD 7, 65, 67

CFDnetwork Engineering 173

CFT 34

CFturbo 7

CFturbo2Icem2CFX 65

Characteristic numbers 77, 90, 99

checksum 11

Circle 114, 158, 166

Circular blades 133

Colors 37

company 9, 11

Compare 26

Compensation 162, 166

compressibility factor 85

Compressor 7

Conformal mapping 130

Constant 138

Contact addresses 173

continuity equation 81, 93, 102

Contour 37

convert 113, 141

Coordinate system 37, 130

Coordinates 30

Copy 30

copy to clipboard 11

Coupled 110

Coupled linear 131, 142

Cross section 110

Index 181


Cross sections 74, 86, 158

Curvature 107

Cut-water 162, 166

Cut-water diameter ratio 22

Cut-water width ratio 22

- D -Data export 44

Deceleration ratio 117

Decreased output 117, 128

Density 75, 87

Design information 34

Design point 75, 87, 97

Design report 44

Design rule 162, 164

Deviation angle 117, 126

Deviation flow - blade 117

Diameter coefficient 22, 77, 90

diameter ratio 77, 90, 99

Diameter.cftdi 81, 105

Diffusor 37

Dimensions 81, 93, 99, 102

Direction of rotation 153

distance 113, 141

- E -Edge 145

Edge position 145

Efficiency 99Hydraulic 77

Impeller 90

Internal 77, 90

mechanical 77, 90, 99

Overall 77, 90

Side friction 77

Tip clearance 77

total- 99

total-to-total 99

Volumetric 77, 90

Ellipse 142

End cross section 162, 166

End shape 166

Errors 42

Euler's Equation of Turbomachinery 81, 93, 102

Exit diameter 107

Exit width 107

Export 15, 65, 67

Export data points 21

Export Units 20

Extension 162, 166

Extension on exit 107

External 158

- F -FEM 67

File location 22, 81, 93, 105

Flow angle 75, 87, 117

Flow angle inflow 22

Flow angle outflow 22

Flow angles 77, 90

Flow rate 75, 87

fluid 85

Freeform 131, 137

Frontal view 130, 138, 142

Full impeller 33, 75, 87, 97

Full volute 33

Function 22

Functions.cftfu 22

- G -gas constant 85

Geometry 44

Graphic 30

Grid 107

- H -Hauptabmessungen 96

Head 75, 87

Help 44

History 34

Hub 37, 105, 107, 110

hub diameter 81, 93, 102, 105

Hydraulic efficiency 22

- I -ICEM 65

CFturbo8182


Impeller 7, 153

Impeller diameter 81, 93

Incidence angle 117, 124

Inclination angle 110

Inclination angle hub 22

Inclination angle shroud 22

Inclination angle trailing edge 22

Inflow swirl 75, 87

information 14

Initial design 30

Inlet definition 153

inlet diameter 102

Inlet triangle 124

Input 15

Intake coefficient 22, 77

internal 158, 162

Interpolation 44

Inventor 51

isentropic coefficient 85

- L -Leading edge 107, 110, 124, 142

licence transfer file 12

license 11, 12, 13, 14

License agreement 174

license file 13

License key 9

Licensing 7, 9

Linear 138

Load from impeller 153

local 11, 13

- M -machine ID 9, 11

Main dimensions 74, 81, 86, 93, 96, 99

Max. curvature 110

Mean line 130

Mean surface 37

Mechanical efficiency 22

Meridian 37

meridinal deceleration 99

Meridional 130

meridional boundaries 138, 142

Meridional contour 107

Meridional deceleration 22, 77, 90

Meridional extension 131, 137

Meridional flow 116

Meridional velocity 116

Minimal relative velocity 77

Mixed-flow impeller 90

mixed-flow rotor 99, 102

modules 11

Mouse 37

- N -neck 162

network 11, 13

New design 33

Normreihen 105

NPSH 77

number of blades 22, 85

Number of revolutions 75, 87

Numeca 53

- O -Obstruction 117

Open 34

Optimimization 15

Options 20, 21, 37

Other 20

Outflow coefficient 129

Outlet triangle 124, 126

Outlet width 81, 93

Outlet width ratio 77, 90

Output 15

- P -Parallel to z 110

Parameter 15, 22

performance 146

performance curve 146

performance line 146

PFLEIDERER 117, 128, 162, 164

Physical variable 22

Points 22, 37

polyline 113, 141

Position 166

Index 183


Power loss 77, 90

Power output 75, 87

Preferences 20, 21

Pressure coefficient 77, 90

Pressure difference 75, 87

Pressure side 124

Primary design 29

Print 30

prism_params 65

Pro/ENGINEER 55

Problems 42

Profile 138

Progressions diagrams 107

Project 34

Project information 34

Pump 7

- Q -Querschnitte 96

- R -Radial 166

Radial blade 121

Radial blade fibre 121

Radial blade section 121

Radial diffusor 153

Radial element blade 121, 131, 137

Radial impeller 90

Radial rotor 99, 102

Radius 114

Rectangle 158, 161, 166

Reference designs 26

References 172

Register 9

Relative velocity 116

Remove design steps 29

request 11

Required driving power 77, 90

Resolution 44

rotational direction 85

rotational speed 97

rotor power 97

- S -Save 30, 34

Segment 37

select 13

send E-mail 11

session code 11

shaft 105

shaft diameter 81, 93, 105

Shaft/ hub 102

Shroud 37, 107, 110

Shroud angle 77

shroud diameter 102

Side friction efficiency 22

Simple 133, 142

Simple mode 107, 114

single-flow 97

Single-intake 75, 87

single-stage 75, 87, 97

Slip 117, 126

Slip velocity 129

Solid 37

Solids 42, 44

Specific energy 75, 87

specific heat 85

specific speed 75, 87, 97

specific work 97

Speed coefficient 75, 87

Spiral 37

Spline 166

splitter blades 85

Stagnation point 124

Standard specifications 81

Start angle 166

start date 11

Static moment 107, 110

Status bar 30

Step by step 33

STEPANOFF 162, 164

Stepanoff constant 22

STL 44

Straight 110

Straight blades 133

Straight line 114

Streamline curvature method 116

CFturbo8184


Streamlines 116

Stress.cftst 81, 93, 105

Strictly external 158

Stromfadentheorie 96

Suction diameter 81, 93

Suction side 124

Suction specific speed 77

Surfaces 42

Swirl 124

swirl number 97

Symmetric 158

- T -Tangential 130, 166

Test 22

Thickness 138, 166

tin 65

tip clearance 85

Tip clearance efficiency 22

Tolerance 44

torque 105

torsional stress 105

Trailing edge 110, 142

Transmission of energy 126

Trapezoid 158, 161

Trim 44

Turbine 7

Two-dimensional 116

Type number 75, 87, 97

- U -Uniform 142

Units 20

unshrouded 85

unwinded length 142

Update 44

User defined 138

- V -Velocity components 117

Velocity triangle 102, 117, 124, 126

Velocity triangles 81, 93

Ventilator 7

Version 34

Visible 37

Volumetric efficiency 22, 153

Volute geometry 162

- W -warning 138, 142

Website 7

Width lines 107

Width number 22

WIESNER 117, 129

Wireframe 37

Work coefficient 22

Wrap angle 22, 131, 137, 162

- Z -Zoom 30

Documents

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