Wind Averaged Drag Coefficient of Automobile Based on China Weather Air Speed

Abstract:

The aerodynamic resistance of automobile is an important part of driving resistance and an important source of automobile energy consumption. Automobiles are driving in a real road environment affected by the natural wind on the road. In order to accurately calculate and evaluate the aerodynamic drag characteristic and energy consumption of an automobile driving in a real road environment， a calculation method for the wind averaged aerodynamic drag coefficient based on cycle conditions was proposed. First， the distribution characteristic of natural wind near the ground was obtained by analyzing meteorological data. Then， the probability distribution characteristic of the yaw angle of the automobile under different terrain conditions was analyzed. The changes of the aerodynamic drag coefficient of the automobile with the speed and yaw angle were analyzed by numerical calculation. The wind averaged drag coefficient of a given automobile speed was calculated based on the probability distribution characteristic of the yaw angle. Finally， the calculation method of the wind averaged drag coefficient based on cycle conditions was proposed， and the contribution of different terrain conditions and speed ranges on the aerodynamic drag of the vehicle was analyzed. The results show that for the models studied in this paper， the wind averaged drag coefficient based on cycle conditions is higher than that of the zero-yaw condition by 9.2% and 7.3%， and the contribution of urban condition to aerodynamic drag coefficient is less than 5%. The speed range of 40 km/h and above all has a greater contribution to aerodynamic drag coefficient.

Key words:aerodynamic resistance of automobile;wind averaged drag coefficient;averaged wind