基于OpenFOAM的发动机舱回流计算方法研究

研究车辆在怠速工况下的发动机舱热空气回流问题，基于OpenFOAM 软件进行回流计算方法的开发。通过设置监控面及组分转换面来重新定义格栅新空气和舱内回流热空气等组分，可直接计算出回流在监控面上的分布及回流率和回流量。根据开发的方法对某款插电式混合动力汽车（Plug-in Hybrid Electric Vehicle，PHEV）车型进行计算并提出不同的优化方案，使其发动机舱回流率从32.7% 分别降低至24.0%和9.3%，回流量从0.169 kg/s分别降低至0.128 kg/s和0.048 kg/s，从而降低了冷凝器等散热器的进风温度，提高了怠速工况下热管理系统的性能。

Research on Engine Compartment Backflow Simulation Method Based on OpenFOAM

The backflow in the vehicle engine compartment is studiedat idle speed, and a new CFD method has been developed based on OpenFOAM. The proposed method can distinguish the different components offresh air, i.e. the air from the grilleor the air back from the engine compartment by setting the transformation function and monitoring surfaces for air flow and flow fields. Meanwhile, the backflow ratio and the flow rate were calculated according to the output results. The simulation of plug-inhybrid electric vehiclewas performed.The sealing of cooling module and the air duct were optimised, which reduced the back flow ratio from 37.2% to 24.0% and 9.3% respectively for the two schemes, and the back flow rate was decreased from 0.169 kg/s to 0.128 kg/s and 0.048 kg/s as well. The proposed CFD method can reduce the inlet air temperature of the radiator and improve thermal management efficiency under idling conditions.