车速对散热器进风效率的影响和回流机理分析

Effect of Vehicle Speed on Inlet Efficiency of Radiator and Backflow Mechanism Analysis

为了提升散热器在不同工况下的进风效率,针对车速、格栅开口面积和风扇工作状态等参数对冷却流量的影响,通过数值仿真和风洞试验开展发动机舱流场研究。结果表明:散热器进风效率受冷却模块回流影响,车速和格栅开口面积共同影响冷却模块前后压力差,动态变化的压力差导致回流状态产生差异,存在充分发展的回流区和临界车速诱发的不稳定回流区;当车辆以中低速行驶(风扇开启)时,增大格栅开口面积,冷却模块回流程度加剧;车辆高速行驶(风扇关闭)状态下,提高车速或缩小格栅开口面积对进风效率影响较小。

In order to improve radiator inlet efficiency under different work conditions,this paper studied the flow field of engine compartment by numerical simulation and wind tunnel test to examine the effect of parameters including vehicle speeds,grille opening area and fan operating state on the cooling flow.The results indicate that the inlet efficiency is affected by the backflow of the cooling module.The vehicle speed and the opening area of the grille jointly affect the pressure difference around the cooling module.The dynamic pressure difference leads to the different backflow.There are fully developed backflow zone and an unstable backflow zone induced by the critical vehicle speed.When the vehicle is driven at medium and low speed(fan is on),backflow of the cooling module is intensified when the grille area increases.With driving at high speed(fan is off),the increase of vehicle speed or the reduction of grille area has little impact on the inlet efficiency.