Abstract： 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.
2010, Vol. 31 
