Large Eddy Simulation Study On Turbulent Coherent Structure Of High Speed Railway With Wind Break Wall In Gale Area

Since the beginning of this century,China’s high-speed railway technology has been fully developed.With the great improvement of the speed of high-speed trains,the aerodynamic performance and safety of high-speed trains are also widely concerned by the community.Especially in the five strong wind areas of Anxi wind area,Yandun wind area,Baili wind area,Sanshili wind area and Dabancheng wind area in Xinjiang,there have been several overturning and rollover accidents caused by high-speed trains due to excessive wind speed,which caused serious losses of personnel and property.In order to solve this problem,windproof devices have been set up on both sides of the high-speed railway,which greatly reduced the accident rate However,when the high-speed train is running near the wind barrier,the phenomenon of "shaking" will occur,which will reduce the comfort of the passengers and cause different degrees of harm to the safety of the high-speed train.Therefore,it is very important to study the aerodynamic characteristics and vortex coherent structure of the high-speed train running near the wind barrier.This paper is based on the three-dimensional,unsteady incompressible flow,unsteady turbulence control equations,turbulence model is respectively using K-ε,K-ω and large eddy simulation three turbulence models for calculation comparison,as well as near wall processing analysis method for the wind barrier calculation domain and high-speed train aerodynamic characteristics and vortex coherent structure under the action of cross wind.The main research contents are as follows:(1)the geometric simulation model of windbreak device and the geometric simulation model of harmony A certain type EMU are established.(2)Three turbulence models,k-ε,k-ω and large eddy simulation,are used to calculate the pressure distribution and vortex coherent structure in the calculation domain without motor car passing by.The cloud image and numerical analysis are carried out to obtain the aerodynamic characteristics and vortex coherent structure between the wind barrier and the rail without motor car.(3)Then,the aerodynamic characteristics and vortex coherent structure of EMU are calculated by using k-ε,k-ω and large eddy simulation models,respectively.The flow field distribution nephogram and numerical analysis are carried out,and the variation laws of pressure distribution and torque coefficient on the surface of each section of vehicle body are obtained.The results show that the vortex coherent distribution and pressure distribution in the calculation domain are in the same order when there is no EMU passing by in cross wind environment From the calculation and analysis of the large eddy simulation,it can be seen that when there is no car,when the airflow passes through the windshield,the windshield separates the airflow into two turbulences with different speeds,and forms a huge vortex near the rail through a series of mutual interference.Spin.When there is a high-speed train near the wind break wall and the airflow passes through the wind break wall,the coherent structure of turbulence between the wind break wall and the high-speed train is further obtained by using the large eddy simulation method,and the relevant flow field characteristics are calculated.The turbulent coherent structure of wind break wall and high-speed train in strong wind area is calculated,and the mechanism of "car shaking" in turbulent coherent structure is studied,which is helpful to the discussion of later research.