轿车开窗行驶时的气动阻力分析

Analysis on car aerodynamic drag for open windows

基于计算流体力学(CFD)的数值模拟方法,研究了轿车行驶时不同开窗情况下整车的气动阻力.根据轿车不同的车窗开窗情况,将汽车开窗行驶分成9种情况进行数值模拟,获得了整车的气动阻力系数以及室内流场分布情况.通过流场的显示分析推测气动阻力增加的原因,评价了不同开窗情况下汽车驾驶室内的通风效果.根据汽车理论,分析了开窗行驶对汽车燃油消耗的影响,给出了汽车开窗行驶的建议.研究结果表明:低速(低于90 km/h)行驶时,开窗行驶增加的燃油消耗低于开空调增加的燃油消耗;汽车低速行驶开窗能够对驾驶室进行很好的通风降温,不会大幅提高燃油消耗.车速高于90 km/h时,汽车气动阻力明显增大,功率消耗也快速增加,高速行驶打开车窗,室内的噪声会突然增大.

The aerodynamic drag for driving car on the urban road was studied with different window openings based on computational fluid dynamics（CFD）.There are 9 cases according to the differences of open windows.The reason for aerodynamic drag was postulated and the effect of ventilation in the cab was estimated.The effect of opening windows to fuel consumption is studied based on road vehicle theories.Some advices are provided for driving car in summer.The results show that the fuel consumption of car running with windows open is less than that turning air conditioning on when car runs at low speed（under 90 km/h）.Opening windows will ventilate the cab well and cool the air in the cab with little gas consumed.When the cars run at speed higher than 90 km/h with open windows,the aerodynamic drag of car increases,power consumption of the car increase rapidly,and interior noise will also increase sharply.