吉林大学学报(工学版) ›› 2023, Vol. 53 ›› Issue (5): 1289-1296.doi: 10.13229/j.cnki.jdxbgxb.20210940

• 车辆工程·机械工程 • 上一篇    

基于Laplacian算法的汽车外流场畸变网格优化

张勇1,2(),毛凤朝1,刘水长1(),王青妤1,潘神功1,曾广胜1   

  1. 1.湖南工业大学 机械工程学院,湖南 株洲 412007
    2.湖南大学 汽车车身先进设计制造国家重点实验室,长沙 410082
  • 收稿日期:2021-09-17 出版日期:2023-05-01 发布日期:2023-05-25
  • 通讯作者: 刘水长 E-mail:834130255@qq.com;289714423@qq.com
  • 作者简介:张勇(1979-),男,副教授,博士.研究方向:车辆工程.E-mail:834130255@qq.com
  • 基金资助:
    湖南省重点研发项目(2022GK2065);湖南省自然科学基金项目(2023JJ50192);湖南省教育厅科学研究重点项目(20A157)

Optimization on distortion grid of vehicle external flow field based on Laplacian Algorithm

Yong ZHANG1,2(),Feng-zhao MAO1,Shui-chang LIU1(),Qing-yu WANG1,Shen-gong PAN1,Guang-sheng ZENG1   

  1. 1.School of Mechanical Engineering,Hunan University of Technology,Zhuzhou 412007,China
    2.State Key Laboratory of Advanced Design and Manufacturing of Automotive Bodies,Hunan University,Changsha 410082,China
  • Received:2021-09-17 Online:2023-05-01 Published:2023-05-25
  • Contact: Shui-chang LIU E-mail:834130255@qq.com;289714423@qq.com

摘要:

为实现汽车外流场高精度计算,以某款实际在用简化车模为研究对象,分析畸变网格评价指标基础上,应用综合评价指标探寻网格畸变位置。为防止体网格优化时中心节点偏离而出现的负体积现象,提出了基于边长加权的Laplacian算法,开展畸变网格局部优化仿真计算,并以HD-2实验进行验证。结果表明:车身侧面特征线、前后风挡玻璃与机罩、行李箱盖过渡区域易生成体畸变网格,边长加权Laplacian算法可降低畸变网格数量,风阻系数仿真精度提高3.90%,与风洞实验误差为2.26%。对比粒子图像测速(PIV)实验,车模尾部流场模拟相比优化前更加准确,表明了建立的边长加权Laplacian算法的有效性。

关键词: 车辆工程, 网格畸变优化, Laplacian算法, CFD仿真精度, 风洞实验

Abstract:

In order to realize the high precision simulation of the vehicle external flow field, the grid distortion position is explored on the basis of analyzing the distortion grid quality evaluation criteria,with the simplified car model in actual use as the research object. In order to prevent the negative volume phenomenon caused by the deviation of the center node during the optimization of the volume mesh, the length weighted Laplacian algorithm is proposed to carry out the simulation calculation of the local optimization of the distortion grid, and verified by the test results of HD-2. The results show that the transition areas of the body side feature line,the front windshield and hood,the rear windshield and luggage lid are prone to volumetric grid distortion.The length weighted Laplacian algorithm can reduce the number of distorted grids, increase the simulation accuracy of the drag coefficient by 3.90%, and the error from the wind tunnel test is 2.26%.The simulation of vehicle tail flow field is more accurate than before the optimization compared with the PIV test, which shows the effectiveness of the length weighted Laplacian algorithm.

Key words: vehicle engineering, grid distortion optimization, Laplacian algorithm, CFD simulation accuracy, wind tunnel experiment

中图分类号: 

  • U461.1

图1

四边形纵横比定义"

图2

三角形纵横比定义"

图3

四面体纵横比定义"

图4

三角形歪斜率定义"

图5

四边形歪斜率定义"

图6

任意直边四边形单元整体坐标"

图7

Laplacian算法失效示意图"

图8

Laplacian优化算法示意图"

图9

车模的模型尺寸(单位:mm)"

图10

车模的模型计算域"

图11

纵对称面网格"

图12

四面体网格"

图13

棱柱体网格"

图14

优化后四面体和棱柱体网格"

表1

边界条件"

计算域边界边界条件设置
入口速度/(m·s-1)30
入口湍流强度/%0.5
水力直径/m2.496
压力出口/Pa1.01×105
出口湍流强度/%5
水力直径/m2.496
地面边界滑移壁面
车身壁面固定壁面
其余壁面对称壁面

图15

PIV实验现场图"

图16

CFD仿真速度流线图和风洞实验速度流线图"

图17

CFD仿真速度云图和风洞实验速度云图"

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