Study On Aerodynamic Characteristics Of High Speed Trains Under Crosswind

With the development of high-speed trains,the running speed of high-speed trains continues to increase,and high-speed trains are increasingly affected by aerodynamic force.Especially when the high-speed train runs at high speed under cross-wind conditions,the aerodynamic problems of the train are particularly prominent.Therefore,in order to ensure the safe operation of high-speed train,it is necessary to study the aerodynamics of high-speed train under cross-wind.This paper is based on the CRH2 type high speed train model,ICEM 15.0 is used to build the model and mesh the whole computational domain based on the train model.The flow field and aerodynamic parameters of the train running under various operating conditions are analyzed and calculated by using the fluid dynamics software Fluent.Among them,the flow field structure and aerodynamic parameters of vehicles running on the ground and bridge deck under crosswind are simulated using synthetic wind method and large eddy calculation model.When the trains meeting at the same speed on the ground and bridge deck the flow field pressure distribution and aerodynamic parameters are simulated and calculated,using the slip grid method and the k-? two equation turbulence model.The results show that:(1)The ground structure has little influence on the flow field around the train under cross-wind conditions,while the bridge deck structure will makes the flow field around the train more complex.When a single train runs on the ground and bridge deck under cross-wind,the head train receives the maximum lateral aerodynamic extreme value and amplitude.(2)In the process of train passing by each other on the ground under crosswind conditions,the aerodynamic force of the train will be affected by the compression waves of the head and tail of the opposing train.The greater the speed of the train rendezvous and the crosswind speed,the greater the lateral aerodynamic extremes and amplitudes of the windward train and the leeward train.(3)In the process of train passing by each other on the ground and bridge deck under crosswind conditions,the head of the windward train and leeward trains suffer the maximum lateral aerodynamic extremes and amplitudes.Moreover,the extreme value and amplitude of lateral aerodynamic force suffered by the head of the leeward train are larger than that of the head of the windward train,so the leeward train is more dangerous.(4)In the process of train passing by each other under crosswind conditions,the head of the leeward train on the bridge deck will be subjected to greater lateral aerodynamic extremes and magnitudes than the head of the leeward train on the ground.Therefore,the trains are more dangerous to run on the bridge deck than on the ground.