Effect of vertical offset of the tail car on the aerodynamic performance of a high-speed train
In the long-term operation of high-speed trains,it is prone to generate different forms of offsets between the adjacent cars,resulting in changes in the train aerodynamic performance and may even cause stability issues,which greatly affects the ride comfort and safety of trains.The current study adopted the tail car of a high-speed train as the research object,and explored the changes in the flow field and aerodynamic characteristics of the tail car when it is subjected to vertical offsets.Based on the SST k-ω double-equation turbulence model,seven cases with no vertical offset,20 mm down offset,40 mm down offset,60 mm down offset,20 mm up offset,40 mm up offset,and 60 mm up offset,were simulated at the train speed of 350 km/h to investigate the train aerodynamic performance,to analyze the change law of the aerodynamic drag of the high-speed train,and to reveal the wake flow characteristics of the high-speed train and the pressure distribution on the train surface,respectively.The results show that the vertical offset of the tail car has a small effect on the total aerodynamic drag of the high-speed train,but it has a certain impact on the distribution of aerodynamic drag and the flow field characteristics of the high-speed train.When the vertical offset of the tail car reaches 60 mm,the aerodynamic drag of the train body is reduced by-1.11%and 2.64%,and the aerodynamic drag of bogies is reduced by 11.35%and-17.43%,respectively,as compared to the case without any vertical offset.In addition,the vertical offset of the tail car has a certain impact on the near wake structure of the train.The vortex structure around the cowcatcher and below the tail nose changes from a double-vortex structure to a single-vortex structure.The vortex structure close to the nose tip becomes larger with the down offset increasing,while it's gradually smaller as the tail car moves up.The results of this study enrich the research on the aerodynamic characteristics of the tail car offset,and have important guiding significance for the train maintenance and CR450 high-speed train design.
high-speed traintail car offsetwake flownumerical simulation
国家科技期刊平台
NSTL
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