基于中国气象风速数据的汽车风平均阻力系数

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

摘要:

空气动力学阻力是汽车行驶阻力的重要组成部分，也是汽车能耗的重要来源。汽车在真实道路环境中行驶受到道路自然风的影响，为了准确计算和评价汽车在真实道路环境中行驶的气动阻力特性以及能源消耗，提出了循环工况风平均阻力系数计算方法。首先，通过分析气象数据获取近地区域自然风的分布特征，进而分析不同地形条件下汽车的偏航角概率分布特征，通过数值计算的方法分析汽车气动阻力系数随车速和偏航角的变化规律，并基于偏航角的概率分布特征计算获得了给定车速的风平均阻力系数，最后，提出循环工况风平均阻力系数的计算方法，并分析了不同地形条件和速度区间对汽车气动阻力的贡献量。结果表明，对于本文研究的车型，循环工况风平均阻力系数高于零偏航工况的阻力系数9.2%和7.3%，城市工况对气动阻力系数的贡献量小于5%，40 km/h及以上车速区间均对气动阻力系数有较大的贡献量。

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.