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Knorr-Bremse as a supplier of brake systems for rail and commercial vehicles develops electronic devices which are part of virtually all modern rail-bound mass transit systems like Metros, High-Speed Trains or Light Rail vehicles. Electronic devices are furthermore responsible for various processes onboard, including safety critical functions like brake control, door units or emergency systems. To ensure the proper function of electronic brake control units under demanding thermal environmental conditions, Knorr-Bremse uses simulation techniques including AcuSolve in India and other CFD tools worldwide. With the use of AcuSolve it is possible to estimate the air temperatures inside of 19-inch electronic brake control units for different mechanical design, equipment, power loss and environment temperature scenarios. Integrated in the product project development process, this helps to reduce hardware test effort, increases quality and development/project output speed at Knorr-Bremse.
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Knorr-Bremse Group
Simulating Thermal Balance of Electronics – an AcuSolve approach
June 2014
Stephan Pitzing
Knorr-Bremse Systeme für
Schienenfahrzeuge GmbH
Knorr-Bremse Group
Metros
Streetcars
Multiple units
High-speed trains
Locomotives
Passenger rail cars
Freight cars
Knorr-Bremse is the world's leading manufacturer of braking systems for rail and
commercial vehicles
Answers for a World of Mobility
Rail Vehicle Systems
Trucks
Buses
Engines
Special vehicles
Commercial Vehicles
│2
Technical Analysis Department
Munich
India
Knorr-Bremse Group │3
Technical Challenge
2014 Altair Technology Conference
Introduction / Motivation
Brake Control Units (BCU) are safety-critical parts of
Trains and are essential to control the braking
behavior of the vehicle
They contain standardized electronic device modules
in semi-closed 19“ standardized racks and emit
thermal power
BCUs are individually tailored depending on the
vehicle they are used for
Goal / Expectation
Estimate the air temperature inside of BCUs
in a project driven environment
Cut down project development time and
costs through virtual thermal testing for
systems
They need to operate with high environmental
temperatures without fan supported cooling
Knorr-Bremse Group │4
Solution Strategy
Testing the Hardware
Time consuming, High costs due to Test
Equipment but: high accuracy
Results may used as a knowledge base
Challenge: Hard- and Software for Brake Control
device needs to be present
Simulation
Can be done in conception phase
Design versions may be evaluated in short period
of time
Simplification of real BCU needed -> accuracy of
simulation result reduced
Try with AcuSolve!
2014 Altair Technology Conference
Knorr-Bremse Group │5
Using AcuSolve
Approach
AcuSolve can be used as Air velocities very low
(only free convection) -> incompressible flow
Steady State Simulation
Preprocessing is done using AcuConsole
Standard Template.
Effect of Radiation is considered
Ambient air temperature : 50°-70°C
Height from sea level : 1000-4000m
Mesh size : 42 million
Model Summary
2014 Altair Technology Conference
Knorr-Bremse Group │6
Using AcuSolve
Convergence Check
Monitor solution in AcuProbe
Power loss through electronic devices (I/P) = Heat flux over the outer boundary
of Air (O/P)
Residual ratio: Temperature, Radiation
I/O (Power loss) = 92W
O/P (Air heat flux) = 92W Convergence tolerance = 0.01
2014 Altair Technology Conference
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Results
How to evaluate the simulated temperature field?
The resulting temperature plots are defined by planes and temperature plot lines
These lines and planes represents the environment temperature for the electronic
devices inside the BCU and are a criteria for proper function of the BCU
Acu-Field View is used for Viewing & Plotting the results.
2014 Altair Technology Conference
Knorr-Bremse Group │8
Results
Examples
The diagram and temperature field plot are used for rate the thermal design of the BCU
2014 Altair Technology Conference
Knorr-Bremse Group │9
Results
Comparison to test results
BCU with simplified electronic
devices (resistors only) has been
used for thermal test in climate
chamber
Same model has been simulated
with CFD software
Matching of both results (with
sufficient accuracy) has been
detected
2014 Altair Technology Conference
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Using AcuSolve
Meshing influence
Mesh size in small holes has to be carefully observed
2014 Altair Technology Conference
Knorr-Bremse Group │11
Using AcuSolve
Advantages
Licensing system is based on HyperWorks Units (HWU), doesn’t require separate
license
Model Setup is very easy.
Simulation is very fast and result accuracy is comparable with other CFD software
Live Monitoring of results
Why using AcuConsole and not HyperMesh for PreProcessing?
Automatically separates internal faces
No geometry cleanup required
Mesh generation process is comparatively easier and faster
Drawbacks
AcuSolve can be used only when Air velocity is low (only free convection)
Geometry Modifications is not allowed
2014 Altair Technology Conference
Knorr-Bremse Group │12
Summary / Outlook
AcuSolve for Thermal Simulation
Automation of simulation process using database template file
Python Scripting
Template Driven Analysis
2014 Altair Technology Conference
Knorr-Bremse Group
Thank you! Questions?
Knorr-Bremse Systeme für
Schienenfahrzeuge GmbH
Moosacher Strasse 80
80809 München
Tel: +49 89 3547 1320
E-Mail: [email protected]
Website: www.knorr-bremse.com
Mr. Sauraba Gupta
Ms. Neha Sharma
E-Mail: [email protected]
Acknowledgement/Credits
Slide 4; Picture Climate Chamber: Weiss Group
www.weiss.info
