摘  要：尾端气流分离和尾流结构对汽车气动阻力的产生有重要影响，气动减阻优化开发需要有效的控制汽车尾端的边界层分离特性和尾涡的产生、发展及其流动规律。本文结合边界层控制方程和边界层分离原理分析了顺流向和横流向压力梯度对边界层分离和纵向涡的形成所起的重要作用，建立了通过两个方向的压力梯度识别气流分离和涡流形成的方法，并给出了通过矢量计算获得压力梯度结果的计算方法和过程，以及通过压力梯度结果识别车身表面气流分离位置的方法，分析了相应的尾涡产生与发展特点。通过正交实验设计对复杂外形的尾流分离外形特征进行了减阻优化，获得了低风阻设计方案。所提出的基于压力梯度识别和正交试验设计相结合的方法，为尾端气流分离和整车气动减阻优化设计提供了有益参考和支持。

关键词：汽车空气动力学;边界层分离;顺流向压力梯度;横流向压力梯度;气动减阻优化

中图分类号：U461.1    文献标识码：A    文章编号：1005-2550（2021）01-0020-06

Optimization of Aerodynamic Drag Reduction Based on Flow Separation Identification and Control

WANG Fu-liang

（Pan Asia Technical Automotive Center Co.， Ltd.， Shanghai 202106 ， China）

Abstract： The flow separation and wake structure at the end of a vehicle have an important influence on the generation of aerodynamic drag. The optimization development of aerodynamic drag reduction needs to effectively control the boundary layer separation characteristics at the end of the vehicle and the generation， development and flow law of the wake vortex. Based on the boundary layer governing equation and boundary layer separation theory， this paper analyzes the important effect of streamwise and transverse pressure gradients in boundary layer separation and longitudinal vortex formation， establishes a method to identify the flow separation and vortex formation by pressure gradients in these two directions， and gives the calculation method and process to obtain the pressure gradient results by vector calculation， as well as the calculation method by pressure gradient The gradient results are used to identify the separation position of the airflow on the body surface， and the characteristics of the generation and development of the wake vortex are analyzed. Through the orthogonal experimental design， the drag reduction optimization of wake separation shape characteristics of complex shape is carried out， and the low drag design scheme is obtained. The proposed method based on pressure gradient identification and orthogonal experimental design provides a useful reference and support for the separation of tail flow and the optimization design of vehicle aerodynamic drag reduction.

Key Words： Automotive Aerodynamics; Boundary Layer Separation; Streamwise Pressure Gradient; Transverse Pressure Gradient; Aerodynamic drag reduction optimization

王夫亮

畢业于吉林大学汽车工程学院，博士学历，现就职于上海泛亚汽车技术中心有限公司，任气动性能工程师，主要从事汽车气动性能设计与开发，气动CFD仿真与风洞试验等领域研究，已发表论文10篇。

前    言

目前对传统燃油汽车节能减排以及电动车延长续航里程的要求越来越严格，使得汽车空气动力学减阻开发受到越来越多的重视。有数据显示，当车速超过70km/h时，气动阻力成为行驶阻力的最主要组成部分[1]。……