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摘要：由于汽车工业持续发展和高速公路系统日益完善，我国汽车运行速度逐渐提高。高速下的车身空气流固耦合效应正成为影响汽车性能的重要因素。而当面临复杂风向和风力的自然风，以及经过桥梁、隧道和复杂地形时，侧风对稳定性、安全性和舒适性有着更为显著的影响。传统的汽车气动性能研究使用实物车型和风洞实验，花费时间长，费用也较高。随着计算流体力学和模拟仿真技术和软件平台的发展，越来越多的车身气动性能研究都可利用计算机来实现。不仅能有效缩短实验周期，减少实验费用，而且能更全面量化的研究汽车高速行驶中的各种特性。
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本文基于计算流体力学基础理论，运用三文造型软件UG，建立多种不同外表面流线形式的车身模型。以此模型进行侧风作用下汽车外流场的数值模拟。采用ANSYS-ICEM 为前处理模块，对模型进行修补和建立计算域，划分网格；使用ANSYS-CFX进行求解和后处理，输出汽车所受751分力，压力云图，速度流线图，气流流线图。对比分析气动阻力、侧向力与横摆力矩的数值模拟数据，总结侧风对汽车行驶稳定性的影响，基于汽车经济性，稳定性，舒适性等方面提出车身外形的侧围曲率优化建议。10380
关键词： 汽车气动性能；侧风稳定性；数值模拟；流体力学
Crosswind driving safety for the body of turbulent flow field numerical Simulation and Optimization
Abstract：With the development of China's automobile industry and the improvement of the highway system, the increased speed of the car, there are more requirements to the car's economy, stability. So it is more important to do research about the performance of automotive aerodynamic . The traditional way, wind tunnel tests need much experimental requirements with a long peroid, as well as the high cost. With the development of Computational Fluid Dynamics and the simulation software, computer technology is used to more and more research. It is not only an effectively way to shorten the experimental period and cost, but also to study cars with various features.
In this paper, based on the theory of the computational fluid and with the help of CAD software UG, I establish a sample car model and simulate the external flow field of the car in the crosswind. During the process, ICEM CFD, a part of ANSYS is used to repair the model and mesh. ANSYS CFX is used to do pre-processing, solving and post-pocessing. According to the force, torque and pressure, speed flow chart and air flow chart, I make some analysis of the results, sum up the impact of corsswind on the stabilization of vehicle and put forward optimization suggestions on the aspects of the automotives' economy, stability, comfort and so on.
Keywords: automobile aerodynamic performance; crosswind stability; numerical simulation; hydrodynamics
目 录
1.绪论 5
1.1 研究背景与意义 5
1.2 国外CFD模拟汽车外流场研究状况 6
1.3国内CFD模拟汽车外流场研究状况 7
1.4 汽车流场数值模拟面临的问题及发展趋向 7
2.侧风稳定性研究方法 8
2.1侧风对汽车的影响分析 8
2.2汽车侧风特性的研究方法 11
2.2.1风洞实验法 11
2.2.2道路实验法 14
2.2.3数值模拟法 15
2.3本次研究所选方法 15
2.3.1本次研究具体方案 17
2.3.2选用软件介绍 19
3.侧风作用下汽车外流场的数值模拟 20
3.1侧风模拟方法 20
3.2侧风作用下汽车外流场模拟过程 22