| Ahmed 模型的流固耦合数值计算方法探索与实验验证 |
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| 引用本文： | 沈沉,杨志刚.Ahmed 模型的流固耦合数值计算方法探索与实验验证[J].实验流体力学,2014,0(4):37-42. |
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| 作者姓名： | 沈沉 杨志刚 |
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| 作者单位： | 同济大学 上海地面交通工具风洞中心，上海 201804 |
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| 基金项目： | 国家“973”重点基础研究发展计划 |
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| 摘 要： | 流固耦合效应会影响汽车行驶安全性,对该效应的数值模拟方法的可信度需要验证。以 Ahmed 模型作为数值仿真和实验验证的对象,数值计算是流体计算与结构计算两部分耦合,配合风洞实验的位移、压力测量技术与流场显示技术(烟流法、丝线法)与之比较,数值模拟与实验所得位移结果之间的差异始终在20%以内。从流场结构角度分析得到流固耦合效应影响气动力的机理主要在于流场中涡的拓扑结构变化。为将来数值研究时变侧风下车辆的流固耦合问题提供实验及理论依据。
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| 关 键 词： | 流固耦合 ALE 风洞实验 验证 |
Numerical methods exploration and experimental validation of Ahmed model with consideration of fluid-solid-interaction effect |
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| Abstract: | Fluid-solid interaction (FSI)between the crosswind and the moving vehicle exerts an impact on driving safety.The reliability of the FSI numerical simulation method needs to be verified.Numerical simulation method and wind-tunnel test method are used with an Ahmed model in the research.Arbitrary Lagrange-Euler (ALE)method is applied to the Ahmed model FSI numerical simulation under crosswinds at velocities of 20m/s,25m/s,30m/s,35m/s,and 40m/s.Through comparison between numerical solution of the Ahmed model and experimental results,it can be claimed that the displacement difference is less than 20%.The experimental methods contain pressure and deformation measurements and flow visualization technique (plume-tracer technique and thread-tracer technique).The flow visualization results are com-pared with the numerical results to verify the reliability.After the comparison of the coupled and uncoupled numerical results,it is found that variation in aerodynamic forces is mainly caused by ever-changing topologic structure of vortices.In this paper,it is found that:(1)FSI effect main-ly intensifies the aerodynamic lift force on the vehicle under crosswind condition(especially at a velocity higher than 25m/s).(2)Aerodynamic lift force increase is mainly caused by the topolog-ical change of the separation bubble above the Ahmed body.FSI effect significantly expands the scale of the separation bubble.(3)Under crosswind condition,FSI effect will increase the rolling trend,so the actual vehicle security is lower than the yield of numerical results with FSI effect unconsidered.Therefore,the use of non-coupling calculation results as a design basis is some-what risky.The present study has laid a theoretical foundation for the upcoming research on the two-way FSI effect on vehicle under time-dependent crosswind condition.In short,the work aims to quantify crosswind acceleration effect and fluid-structure interaction effect of aerodynamic force,to provide a method to research the real vehicle crosswind stability in a finer and more precise way, and to provide a reference to simulate the vehicle travelling status more thoroughly. |
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