中文摘要：

以降低汽车气动阻力、获得最优气动造型为目的,应用计算流体动力学方法对某轿车内外流场进行了数值仿真,分析并总结了车身附件气动干涉和发动机舱内空气流动对整车气动性能的影响。计算结果表明：车身附件对整车气动特性有较大影响。其中,底部结构和轮胎的影响较大;余者（后视镜、雨刮器和门把手）的影响很小。考虑了车身附件的影响后,气动阻力约增加23%;加上发动机舱内空气流动的影响,整车气动阻力共增大约35%。分析还表明,车轮的转动有利于改善车底气流与尾流的相互作用,使气动阻力稍有降低。

英文摘要：

Aiming at reducing aerodynamic drag and obtaining optimal aerodynamic shape,CFD technique is applied to the numerical simulation on the external and internal flow field of a car.The effects of car body attachments and underhood airflow on vehicle aerodynamic characteristics are analyzed and summarized.The results of simulation show that the influence of attachments is notable on aerodynamic characteristics,in which the effects of under-body structure and tires are more significant,while those of the remains（rearview mirror,windshield wiper and doorhandle） are trivial.When the effects of attachments are considered,aerodynamic drag increases by around 23%;and if adding on top of it the influence of underhood flow,the total aerodynamic drag will rise by some 35%.The analysis also indicates that the rotation of tires is conducive to the improvement of the interaction between underbody flow and wake flow,leading to a little reduction in aerodynamic drag.