Abstract
Vehicle thermal protection is of vital importance for the development process of passenger
cars. Tightly-packaged engine compartments and strongly increased engine power demand
extensive testing and more and more numerical analysis. Underhood component temperatures
are sensitive to all three modes of heat transfer, conduction, convection and radiation. Due to
very high temperatures next to the exhaust system, in particular, a thermal radiation analysis
is required. The different numerical properties of the three physical modes can be handled
separately by sophisticated but specialized simulation codes. This paper proposes a
partitioned approach for the multi physics 3-D simulation methodology based on coupling the
commercial CFD code StarCDTM, the radiation code POSRADTM and the finite element code
PERMASTM by the Coupling Software MpCCITM.
The applicability of this methodology is demonstrated by a simplified exhaust system. The
surface temperature is computed considering both - internal and external flow. Air and
exhaust gas temperatures are coupled with the thermal analysis.
In the near future a similar methodology will be used to perform thermal analyses of the
engine compartment and the entire car. The new trilateral coupling approach is supposed to be
more accurate, especially in regions with a very strong coupling between temperature and
velocity field.
Keywords - CFD, Underhood Thermal Analysis, component temperature