汽车外流场数值仿真k-ε模型适用性研究
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摘要
由于目前的湍流模型并非针对汽车空气动力学进行数值仿真,因而造成潜在的计算误差。因此,为探寻适合的数值计算模型,以MIRA阶梯背汽车1/3比例模型为研究对象,对常用的Standard k-ε、RNG k-ε和Realizablek-ε3种k-ε涡黏湍流模型进行数值仿真,以计算所得的气动力系数、尾部流场及表面压力系数为适用性评价指标,并与HD-2风洞试验数据对标。研究结果表明:3种模型中,Standard k-ε模型收敛速度和效率最优,但气动阻力的计算精准度最差;RNG k-ε模型的表现一般,而Realizable k-ε模型能获得最高的气动阻力计算精度,与风洞试验结果对比,误差在5%以内,但收敛速度和效率相对较差;同时,3种湍流模型对气动升力的计算结果与风洞试验对比存在较大误差。
Due to the fact that the current turbulence model is not intended for the numerical simulation of aerodynamic especially,there will be some potential calculation errors in this process.In order to find the suitable numerical model,taking the 1/3 proportion MIRA ladder model as the research object,a numerical simulation test has thus been carried out of three normal vortex viscous turbulence models,i.e.Standard k-ε,RNG k-ε and Realizable k-ε,with the obtained statistics of the aerodynamic drag coefficient,the tail flow field and the surface pressure coefficient as the applicability evaluation indices,which are then compared with HD-2 wind tunnel test data.The results show that the convergence speed and efficiency of the Standard k-ε model are the best among three models,while with the least accuracy in its aerodynamic drag.The performance of RNG k-ε model is general.The realizable k-ε model has the highest aerodynamic drag calculation precision,with its error less than 5% compared with the wind tunnel test results.However,the convergence rate and efficiency are relatively poor.Meanwhile,the results of the three turbulence models are quite different from those of the wind tunnel experimental data.
Due to the fact that the current turbulence model is not intended for the numerical simulation of aerodynamic especially,there will be some potential calculation errors in this process.In order to find the suitable numerical model,taking the 1/3 proportion MIRA ladder model as the research object,a numerical simulation test has thus been carried out of three normal vortex viscous turbulence models,i.e.Standard k-ε,RNG k-ε and Realizable k-ε,with the obtained statistics of the aerodynamic drag coefficient,the tail flow field and the surface pressure coefficient as the applicability evaluation indices,which are then compared with HD-2 wind tunnel test data.The results show that the convergence speed and efficiency of the Standard k-ε model are the best among three models,while with the least accuracy in its aerodynamic drag.The performance of RNG k-ε model is general.The realizable k-ε model has the highest aerodynamic drag calculation precision,with its error less than 5% compared with the wind tunnel test results.However,the convergence rate and efficiency are relatively poor.Meanwhile,the results of the three turbulence models are quite different from those of the wind tunnel experimental data.
引文
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[11]潘正宇,谷正气,张勇,等.汽车CFD流场仿真集成高效优化技术研究[J].湖南工业大学学报,2018,32(2):31-37.PAN Zhengyu,GU Zhengqi,ZHANG Yong,et al.Research on the Simulation Integration and Efficient Optimization of CFD Flow Field in Automobiles[J].Journal of Hunan University of Technology,2018,32(2):31-37.
[12]杨易,刘政,谷正气,等.MIRA阶梯背模型尾部非光滑表面优化设计方法[J].重庆大学学报,2015,38(4):10-17.YANG Yi,LIU Zheng,GU Zheng qi,et al.Optimization and Design Method of Non-Smooth Surface at Stepped Back MIRA Mode's Tail[J].Journal of Chongqing University,2015,38(4):10-17.
[13]谷正气,赵万东,张勇,等.网格质量评价指标对汽车外流场模拟结果影响的研究[J].汽车工程,2015,37(11):1265-1269.GU Zhengqi,ZHAO Wandong,ZHANG Yong,et al.A Research on the Effects Mesh Quality Evaluation Criteria on the Results of Vehicle External Flow Field Simulation[J].Automotive Engineering,2015,37(11):1265-1269.
[14]张勇.基于LBM-les法改进与试验数据修正的汽车气动升力研究[D].长沙:湖南大学,2018.ZHANG Yong.Vehicle Aerodynamic Lift Study Based on LBM-les Method Improved and Wind Tunnels Experiments Data Correction[D].Changsha:Hunan University,2018.
[15]于丽波,罗敏.基于CFD不同湍流模型的超高层连体结构风荷载和流场对比研究[J].特种结构,2017,34(5):44-51.YU Libo,LUO Min.Research on Wind Loads and Flow Field of High-Rise Tower of Conjoined Buildings Based on Different CFD Turbulence Models[J].Special Structures,2017,34(5):44-51.
[2]谢金法,张靖龙.凹坑型非光滑单元体排列方式对汽车气动阻力影响分析[J].郑州大学学报(工学版),2016,37(5):86-90.XIE Jinfa,ZHANG Jinglong.Influence Analysis of Pit-Type Non-Smooth Elements Arrangement on Aerodynamic Drag of Vehicle[J].Journal of Zhengzhou University(Engineering Science),2016,37(5):86-90.
[3]MAJIDI K.Numerical Study of Unsteady Flow in a Centrifugal Pump[J].Journal of Turbo Machinery,2005,127(2):363-371.
[4]雷林,王智祥,孙鹏,等.计算流体力学k-ε二方程湍流模型应用研究[J].船舶工程,2010,32(3):5-8.LEI Lin,WANG Zhixiang,SUN Peng,et al.Application Study on the Turbulence Models of k-εQuadratic Equation on CFD Calculation[J].Ship Engineering,2010,32(3):5-8.
[5]朱晖,杨志刚.两方程模型计算轿车气动性能的适用性研究[J].汽车工程,2016,38(11):1283-1287,1337.ZHU Hui,YANG Zhigang.A Study on the Applicability of Two-Equation Models to the Calculation of Aerodynamic Performance of Sedan[J].Automotive Engineering,2016,38(11):1283-1287,1337.
[6]LAUNDER B E,SPALDING D B.Lectures in MathemArticle Models of Turbulence[M].London:London Academic Press,1972:1-169.
[7]YAKHOT V,ORSZAG S A.Renormalization-Group Analysis of Turbulence[J].Physical Review Letters,1986,57(14):1722.
[8]SHIH T H,LIOU W W,SHABBIR A,et al.A New k-εEddy Viscosity Model for High Reynolds Number Turbulent Flows[J].Computers&Fluids,1995,24(3):227-238.
[9]AHMAD N E,ABO-SERIE E F,GAYLARD A.Mesh Optimization for Ground Vehicle Aerodynamics[J].CFDLetters,2001,2(1):54-65.
[10]谷正气,王师,仇健,等.MIRA模型组尾部造型风洞试验研究[J].科技导报,2011,29(8):67-71.GU Zhengqi,WANG Shi,CHOU Jian,et al.Wind Tunnel Tests of MIRA Model Group for Study of Vehicle's Rear Shape[J].Science&Technology Review,2011,29(8):67-71.
[11]潘正宇,谷正气,张勇,等.汽车CFD流场仿真集成高效优化技术研究[J].湖南工业大学学报,2018,32(2):31-37.PAN Zhengyu,GU Zhengqi,ZHANG Yong,et al.Research on the Simulation Integration and Efficient Optimization of CFD Flow Field in Automobiles[J].Journal of Hunan University of Technology,2018,32(2):31-37.
[12]杨易,刘政,谷正气,等.MIRA阶梯背模型尾部非光滑表面优化设计方法[J].重庆大学学报,2015,38(4):10-17.YANG Yi,LIU Zheng,GU Zheng qi,et al.Optimization and Design Method of Non-Smooth Surface at Stepped Back MIRA Mode's Tail[J].Journal of Chongqing University,2015,38(4):10-17.
[13]谷正气,赵万东,张勇,等.网格质量评价指标对汽车外流场模拟结果影响的研究[J].汽车工程,2015,37(11):1265-1269.GU Zhengqi,ZHAO Wandong,ZHANG Yong,et al.A Research on the Effects Mesh Quality Evaluation Criteria on the Results of Vehicle External Flow Field Simulation[J].Automotive Engineering,2015,37(11):1265-1269.
[14]张勇.基于LBM-les法改进与试验数据修正的汽车气动升力研究[D].长沙:湖南大学,2018.ZHANG Yong.Vehicle Aerodynamic Lift Study Based on LBM-les Method Improved and Wind Tunnels Experiments Data Correction[D].Changsha:Hunan University,2018.
[15]于丽波,罗敏.基于CFD不同湍流模型的超高层连体结构风荷载和流场对比研究[J].特种结构,2017,34(5):44-51.YU Libo,LUO Min.Research on Wind Loads and Flow Field of High-Rise Tower of Conjoined Buildings Based on Different CFD Turbulence Models[J].Special Structures,2017,34(5):44-51.