Virtual Temperature Cycle Testing of Automotive Heat Exchangers by Coupled Fluid Structure Simulation

Temperature cycling is a major load for all automotive heat exchangers. A simulation method based on coupled fluid structure simulation was developed to analyze the thermal cycle behavior of the heat exchanger even in an early phase of the development process. The method is based on the modeling of transient heat transfer from the coolant and the air to the solid parts as well as heat conduction in the solid structure. In a first step, the temperature transients are simulated with Computational Fluid Dynamics (CFD). In a second step, the temperature distribution at specified time steps is mapped to a Finite Element Model (FEM) used for structural analysis. Compared with measurements, all relevant physical phenomena are well predicted in the simulations. This method helps to get a better understanding of the basic failure mechanisms. Finally, the calculated local stress values are the basis for subsequent lifetime prediction based on component Wöhler (S-N) curves or fatigue software tools.