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February 7, 2003 MDO MDO - 1
Multidisciplinary Design Optimization
Activities at CASDE, I I T, Bombay
http://www.casde.iitb.ac.in/MDO/activities-at-a-glance.ppthttp://www.casde.iitb.ac.in/MDO/activities-at-a-glance.ppt
February 7, 2003 MDO MDO - 2
Aug 1999 - CASDE initiates MDO activities
Aug 2000 - First meeting of SIG-MDO
Jan 2001 - Professional Development Course on MDO
Jun 2002 - Second meeting of SIG-MDO, Workshop
on MDO
Feb 2003 - Third Meeting of SIG-MDO
Sep 2003 - International Conference on MDO
MDO@CASDE Over the Years
February 7, 2003 MDO MDO - 3
Design / MDO Studies @CASDE
AEW System Level Optimization
Aero-elastic Design of Transport A/C wings
Aircraft Intake (3D-Duct) design Low Fidelity Analysis High Fidelity Analysis (CFD)
February 7, 2003 MDO MDO - 4
Design / MDO Studies @CASDE
MDO Studies in formative stages
Hypersonic Vehicles - Integrated System Optimization (with DRDL)
Launch Vehicles - Reliability Based Design (with VSSC)
Launch Vehicle – Simultaneous optimization of trajectory & system (with VSSC)
February 7, 2003 MDO MDO - 5
Rotodome PlatformRadar Heat exchanger
AEW System
P, H, V, CL
Mission
D2 D3
P H, V
D4
H, V, CL
D1
E
WHX CD,H D, T L, W EWR QrBAntLAnt
WAnt
WRot CD,RWds
User requirements
DC
Design Optimization of AEW
February 7, 2003 MDO MDO - 6
Stage I : Analysis based on empirical formulae
Stage II : semi-empirical analysis realistic aerodynamic loading - VLM simplified structural analysis - EPM
Stage III : Hi-fidelity analysis with aeroelasticity
VLM FEM - NASTRAN
MDO of Transport Aircraft Wing
February 7, 2003 MDO MDO - 7
~150 seater aircraft Mission profile shown B 737-200 candidate for numerical study
1 2
3 4
5
67 8
Takeoff at sea leveld ≤ 2150 m
Climb to 11000 mat best
ROC ≥ 11 m/s
Loiter 45 min(Reserve)
Land at sea leveld ≤ 1220 m
Descend to1500 m
Cruise for 3000 Km at best range M ≥ 0.74
MDO of Transport Aircraft Wing – Baseline Problem
February 7, 2003 MDO MDO - 8
Simultaneous aerodynamic and structural optimization variables - wing aerodynamic shape + wing structural sizing constraints - mission, aerodynamics, structural, aeroelastic
Optimizers : FFSQP / NPSOL (SQP) Aerodynamic analysis : Vortex Lattice Method (VLM) Structural analysis :
Medium fidelity – Equivalent Plate Method (EPM) High fidelity – Finite Element Method (MSC NASTRAN)
MDO of Transport Aircraft Wing
Analysis tools
MDO Problem
February 7, 2003 MDO MDO - 9
Aerodynamic Geometry
• Planform• Geometric Pre-twist• Camber• Wing t/c
y
x
• single sweep, tapered wing
• divided into stations
• S, AR, ,
citp
b/2
croot
AR = b2/S
= citp/croot
Wing stations
MDO of Transport Aircraft Wing
February 7, 2003 MDO MDO - 10
MDO of Transport Aircraft Wing
Structural Geometry
• Cross-section• Box height• Skin thickness• Spar/ribs
yA
A
A
x
A
• symmetric
• front, mid & rear boxes
• r1, r2
l1 l2
c
r1 = l1/c
r2 = l2/c
February 7, 2003 MDO MDO - 11
MDO of Transport Aircraft Wing
Function Evaluations
Structural Stresses (x , y , xy ) Structural Weight (Wt) Deformation Function (W(x,y)) / Nodal displacements
Aerodynamic & Mission CL ,sectional Cl , CDi (VLM)
Mdiv (semi-empirical) & CDo (empirical)
Vstall, , Takeoff & Landing Distance Ceiling, ROC, Cruise Mach No.
Geometric Fuel volume (Vf)
February 7, 2003 MDO MDO - 12
MDO of Transport Aircraft Wing
Loads
Load case - quasi-static pull-up maneuver Aerodynamic pressure loads Engine loads Inertia Relief
Fuel Weight Inertia Relief Wing Mass Inertia Relief Both are distributed as equivalent uniform pressures over
wing stations
February 7, 2003 MDO MDO - 13
MDO of Transport Aircraft Wing
Aerodynamic
Arstsh’2h’
1hrootr2r1d/ch/ciARW/S
StructuralAerodynamic
System Analysis
Structural
VfWtMdddtoRCLCl Cdo
February 7, 2003 MDO MDO - 14
MDO of Transport Aircraft Wing
Aerodynamic
Arstsh’2h’
1hrootr2r1d/ch/ciARW/S
StructuralAerodynamic
Structural
VfWtMdddtoRCLCl
VLM
FEM
Cdo
February 7, 2003 MDO MDO - 15
MDO of Transport Aircraft Wing
Aerodynamic
Arstsh’2h’
1hrootr2r1d/ch/ciARW/S
StructuralAerodynamic
Structural
VfWtMdddtoRCLCl
VLM
FEM
Cdo
February 7, 2003 MDO MDO - 16
MDO of Transport Aircraft Wing
Aerodynamic
Arstsh’2h’
1hrootr2r1d/ch/ciARW/S
StructuralAerodynamic
Structural
VfWtMdddtoRCLCl
VLM
FEM
Cdo
Fidelity level forMdd and Cdo ?
February 7, 2003 MDO MDO - 17
Optimizer FSQP
I
N
T
E
R
F
A
C
E
History Block
Input Processor
Output Processor
Aerodynamics(VLM)
Structures MSC/
NASTRANNASTRANI
nterface
Analysis Block
AeroelasticityIterator
Optimization Framework ArchitectureMDO of Transport Aircraft of Wing
February 7, 2003 MDO MDO - 18
MDO of Transport Aircraft Wing
• For more information
http://www.casde.iitb.ac.in/MDO/
• Contact : mujumdar@aero.iitb.ac.in
February 7, 2003 MDO MDO - 19
3D-Duct Design
Composite team ADA, Bangalore CFD Centre, IIT Bombay CASDE, IIT Bombay
Bring in CFD into Optimization loop Commercial codes? In-house codes?
February 7, 2003 MDO MDO - 20
3-D Duct DesignDesign Problem in Brief
Entry Exit Location and shape known
Geometry of duct from Entry to Exit ?
• Pressure Recovery?• Distortion?• Swirl?
February 7, 2003 MDO MDO - 21
3D-Duct Design Parametrization
Y
X
Z
XDuct Centerline
A
X
Control / Design Variables
• Ym, Zm
• AL/3, A2L/3
Cross Sectional Area
February 7, 2003 MDO MDO - 22
Y
X
Z
XDuct Centerline
A
X
Control / Design Variables
• Ym, Zm
• AL/3, A2L/3
Cross Sectional Area
3D-Duct Design Parametrization
February 7, 2003 MDO MDO - 24
3D-Duct Design Using Low Fidelity Analysis
Low Fidelity Design Criteria (Constraints) Wall angle < 6° Diffusion angle < 3° 6 * Equivalent Radius < ROC of Centerline
Low fidelity analysis for pressure recovery (Objective function)
No low fidelity analysis for distortion or swirl
For results & discussionhttp://www.casde.iitb.ac.in/MDO/3d-duct/
February 7, 2003 MDO MDO - 25
3D-Duct Design Using High Fidelity Analysis
Low Fidelity Design Criteria (Constraints) Wall angle < 6° Diffusion angle < 3° 6 * Equivalent Radius < ROC of Centreline
CFD (Fluent) for pressure recovery & distortion Doyle Knight’s Group @Rutger’s University
Optimization of width-depth of bump for minimising distortion.
Grid quality required to capture distortion?
February 7, 2003 MDO MDO - 26
3D-Duct Design Using High Fidelity Analysis
?
X1-MINX1-MAX
X2-MAX
X2-MIN
Domain for search using high fidelity code is large
February 7, 2003 MDO MDO - 27
3D-Duct Design Using High Fidelity Analysis
Low Fidelity Design Criteria Wall angle < 6° Diffusion angle < 3° 6 * REQ < ROC
Fluent for CFD RSM / DOE DACE
X1-MINX1-MAX
X2-MAX
X2-MIN
February 7, 2003 MDO MDO - 28
3D-Duct Design Using High Fidelity Analysis
Low Fidelity Design Criteria Wall angle < 6° Diffusion angle < 3° 6 * REQ < ROC
Fluent for CFD RSM / DOE DACE
X1-MINX1-MAX
X2-MAX
X2-MIN
http://www.casde.iitb.ac.in/MDO/3d-duct/
February 7, 2003 MDO MDO - 29
MDO Framework
Easy integration of analysis modules Support for distributed analysis Optimization environment . . .
Salas & Townsend AIAA-98-4740 Commercial Frameworks are available
February 7, 2003 MDO MDO - 30
Why do you want my program?
I have a new version of analysis software
You have to know my code to be able to execute it!
(it’s all in Russian)
System Designer’s Nightmare!
I cannot find the correct tuning parameters!
MDO Framework Issues
February 7, 2003 MDO MDO - 31
MDO Framework Issues
Aerodynamics Expert
Structures Expert Controls ExpertSystem Analysis
Analysis codes should reside with experts.
System analysis should execute analysis codes on experts’ computers.
February 7, 2003 MDO MDO - 32
Framework Development @CASDE
Distributed computing (CORBA based)
Database driven Tools to integrate analysis modules
using wrappers Automatic data exchange between
analysis modules
February 7, 2003 MDO MDO - 33
Framework Architecture
Database
ConfigurationManager
ExecutionManager
Sequence Logic
MDOController
NameServer
DataServer
OPT1
Optimizer Manager
OPT2 OPT3
AM1
AnalysisManager
AM2 AM3
GUI
February 7, 2003 MDO MDO - 34
Optimization Issues
• Gradient based optimization
• Evaluation of gradients? Finite Difference. Requirements on convergence more severe than that required for engineering analysis.
• Noisy functions?
X
f
February 7, 2003 MDO MDO - 35
User Supplied Gradients
Complex AnalysisCode in Fortran
Manually extractsequence of mathematical
operations
Code the complex derivative evaluator
in Fortran
Manually differentiatemathematical
functions - chain rule
FORTRANsource code
that can evaluategradients
February 7, 2003 MDO MDO - 36
User Supplied Gradients
Manually extractsequence of mathematical
operations
Use symbolic math packages to automate derivative evaluation
Code the complex derivative evaluator
in Fortran
Complex AnalysisCode in FORTARN
FORTRANsource code
that can evaluategradients
February 7, 2003 MDO MDO - 37
User Supplied Gradients
Parse and extract the sequence
of mathematical operations
Use symbolic math packages to automate derivative evaluation
Code the complex derivative evaluator
in Fortran
Complex AnalysisCode in FORTARN
FORTRANsource code
that can evaluategradients
February 7, 2003 MDO MDO - 38
Gradients by ADIFOR
Complex AnalysisCode in FORTARN
FORTRANsource code
that can evaluategradients
Automated Differentiation
PackageEuler
Recommended