Abstract:

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.

Key words: 4WD vehicle, CFD, transient simulation, convection heat transfer, thermal radiation