Transient Numerical Simulation and Experimental Evaluation of Vehicle Under-Hood and Underbody Component Temperatures

In this paper, a transient vehicle under-hood/underbody component temperature simulation system is applied to a mass production vehicle of ChangAn, and a wind tunnel experiment is conducted for comparison and validation. The effects of heat radiation from exhaust, heat conduction through the components and heat convection by air flow are included in the simulation system. Three types of modeling method are coupled in the simulation: the 1D modeling of exhaust flow/coolant flow, the 2D/3D modeling of heat radiation/heat conduction and the 3D modeling of heat convection by external air flow. The energy loss of exhaust through the turbocharger and the energy generation from the catalyst are also modeled in the system. The detailed structure of the muffler is taken into consideration. Various vehicle driving conditions are considered both in simulation and in the wind tunnel experiment, including high speed driving、uphill climbing、traffic jam condition and soak. The transient temperatures are recorded at more than 160 probes located in the engine bay/underbody zone during the experiment. The numerical simulation results are compared to the experimental measurements, and very good agreement can be seen; which indicates that the present simulation system is a reliable method for transient temperature prediction and a powerful tool for thermal protection design at the early stage of vehicle development.