四驱SUV车辆的高温瞬态热害仿真与优化研究

High-Temperature Transient Thermal Damage Simulation and Optimization Research of a Four Wheel Drive SUV Vehicle

汽车在高温环境下高负荷行驶后怠速或熄火,会导致位于发动机舱和下车体的部分零件温度瞬间升高,造成零件的热害。四驱车型由于四驱传动系统与排气系统在下车体中通道并行布置,使排气管和周边需要温度保护的零件之间的距离进一步压缩,零件的热害风险加大。本文中采用瞬态CFD仿真方法,模拟车辆在高温环境、高负荷行驶后怠速工况下零部件热害的发展过程。车辆环境风洞测试结果表明,高温瞬态热害CFD仿真误差基本在10%以内;把导致零件温度发生变化的对流换热功率和辐射换热功率分离,能准确地确定零件高温的原因,有利于快速找到优化方案。

When the vehicle idles or stalls after continuous driving under high load conditions in a high temperature environment,the temperature of some components located in the engine compartment and the underbody may rise instantaneously,resulting in thermal damage to the components.Due to the 4WD drive system and exhaust system are arranged in parallel in the middle channel of the underbody,which further compresses the distance between the exhaust pipe and the surrounding components that need temperature protection,increasing the risk of thermal damage to the components.In this paper,the transient CFD simulation method is used to simulate the development process of thermal damage of components under idling condition after the vehicle running under high load in high temperature environment.The environmental wind tunnel test results of the vehicle show that the CFD simulation error of high temperature transient thermal damage is basically within 10%.Separating the convection heat transfer power and radiation heat transfer power that cause the temperature of the component to change can accurately determine the cause of the high temperature of the component,which is beneficial to quickly find out the optimization schemes.