中文摘要：

以提高汽车冷却系统效率、降低气动阻力为目的,提出一种冷却系统数值模型。对某汽车发动机舱内外流场进行了耦合数值计算,详细分析了发动机舱内部气流特性,重点研究了影响发动机舱内流阻力的关键因素。计算结果表明：发动机舱内流阻力对气动阻力影响较大,占整车气动阻力的10%左右,且随着风扇转速的增大而增大,当车速较低时变化明显,车速较高时变化不明显。当车速一定时,冷却系统阻力随风扇转速的增大而增大,散热器阻力对风扇转速变化比较敏感;当风扇转速一定时,冷却系统阻力随车速的增大而增大,冷凝器阻力对车速变化比较敏感。汽车模型的风洞实验验证了该数值计算方法的准确性。

英文摘要：

For the purpose of increasing the efficiency of cooling system and reducing the aerodynamic drag,a method of numerical model of cooling system instead of experimental model was proposed,which was applied to study the airflow characteristics of underhood coupling internal and external flow fields.The influence on internal drag of the underhood was studied fully.The results show that the influence of internal drag is notable on aerodynamic drag,which for the whole is about 10%.It will become bigger with the increase of speed of fan.The diversification is clear when speed of car is low,but the diversification is not clear when speed of car is high.The drag of cooling system will become bigger with the increase of speed of fan when the speed of car is constant and the drag of radiator is sensitive to speed of fan.The drag of cooling system will become bigger with the increase of speed of car when the speed of fan is constant and the drag of condenser is sensitive to speed of car.The simulation results agree well with the test data in the wind tunnel,which indicates numerical simulation for automotive aerodynamics characteristics is feasible.