不同前车车型对后车前端进气影响.docVIP

不同前车车型对后车前端进气影响摘要： 针对尾随行驶过程中前车对后车发动机舱冷却性能产生影响的问题，以轿车、皮卡车、面包车和城市公交客车作为前车车型，以轿车作为后车车型，分析不同车距下后车发动机舱进气质量流量比以及冷凝器入口的速度分布和流场.结果表明，当前车为轿车时对后车前端进气影响较小；当前车为皮卡车时后车前端进气随着车距的增加会先减少后增多，在车距为1倍后车车长时减少约7%；当前车为面包车或城市公交客车时对后车发动机舱的进气影响的变化规律一致，当车距为0.2倍后车车长时减少约13%. 关键词： 发动机舱； 前端进气； 尾随行驶； 质量流量比； 速度分布； 流场 中图分类号： U464.138 文献标志码： B Effect of different front vehicles on back vehicle front end intake ZHOU Xiaoli, JIA Qing, YANG Zhigang (Shanghai Automotive Wind Tunnel Center, Tongji University, Shanghai 201804, China) Abstract： As to the fact that the cooling performance of back vehicle engine compartment is affected by front vehicle during trailing running process, sedan, pickup vehicle, microbus and city bus are taken as the front vehicles, sedan is taken as the back vehicle, and the intake mass flow ratio of back vehicle engine and the condenser velocity distribution and flow field are analyzed under different vehicle distance. The results indicate that there is less effect on front end intake of back vehicle when the front vehicle is sedan; when the front vehicle is pickup, the front end intake of back vehicle decreases and then increases with the increase of vehicle distance, and it decreases by 7% approximately when the vehicle distance is one length of back vehicle; there is the same effect on front end intake of back vehicle when the front vehicle is microbus or city bus and it decreases by 13% approximately when the vehicle distance is 0.2 times length of back vehicle. Key words： engine compartment; front end intake; trailing running; mass flow ratio; velocity distribution; flow field 汽车前端进气对发动机冷却有着极其重要的作用，在交通拥挤的城市环境下，汽车尾随成为最常见的市区行车工况之一.汽车行驶时会在其尾部形成非常复杂的尾流区和数倍车长的尾涡耗散区，当后车进入前车的尾流区时会导致二者的流场发生相互作用，对前、后车气动性能产生很大影响［13］，同时也会对后车前端进气特性造成一定影响［4］. 本文采用数值模拟方法，选取有代表性的4种前车车型为对象，研究汽车在尾随行驶工况下前后车距对后车前端进气的影响范围，完善对汽车发动机舱冷却性能的不同工况研究，为城市工况下发动机降低燃料消耗的合理设计提供参考. 1 模型建立 城市交通工具具有多样性，考虑到在路面行驶时不同前车车型会对后车产生不同的气流阻塞效应，故选取有代表性的轿车模型、皮卡车模型、面包车模型和城市公交客车模型等4种车型进行研究.采用与实物模型1∶ 1的比例建模，前车计算模型见图