Ernst-Peter Weidmann, et.al. – Daimler AG

at MpCCI UF 2007

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 StarCD™, the radiation code POSRAD™ and the finite element code PERMAS™ by the Coupling Software MpCCI™.

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.