Simulation Study On The Effect Of Wind And Sand Two-phase Flow On The Crosswind Effect Of High-speed Train

The Lanxin Passenger Dedicated Line is the most important high-speed railway connecting Gansu,Qinghai,Xinjiang and other high-altitude areas.Among them,Xinjiang is one of the most severe sandstorm natural disaster areas in the world at present.The rapid changes in aerodynamic performance of high-speed trains,coupled with the coupling of other factors,have caused many train derailments and outage accidents.The operation of high-speed trains in such high-altitude,strong-sand-sand areas is especially important for the impact of changes in aerodynamic performance on the trains,in addition to overcoming the extreme temperature difference between day and night and strong ultraviolet radiation.Therefore,this paper applies numerical simulation method based on Fluent software to compare and analyze the aerodynamic performance of high-speed trains with or without wind and sand,which is of great significance for improving the safe operation of high-speed trains in my country under wind and sand environment.Based on the operation status of the Lanxin Line,this paper first selects the high-speed trains used for simulation as CRH2 G EMU trains,and establishes a two-dimensional simplified model of high-speed trains composed of three cars with head car,intermediate car and tail car,respectively from the lateral direction(yz direction)and The vertical(xz direction)sets the calculation field of the flow field around the high-speed train,and meshes the calculation area.Secondly,establish a two-phase flow model of wind and sand,use a custom function to set the lateral wind and sand concentration,determine the boundary conditions of the external flow field of the high-speed train,and select a suitable solution algorithm.Then carry out numerical simulation.In the horizontal direction,the numerical simulation is carried out under the conditions of horizontal net wind and horizontal wind and sand conditions,and the surface pressure distribution,surrounding speed vector distribution,drag and lift,and overturning moment of the high-speed train under different cross-wind speeds are compared;The numerical calculation of the high-speed trains operating under clean wind and sand conditions is carried out,and the pressure distribution on the surface of the high-speed trains,the distribution of the surrounding speed vectors,the resistance and lift,and the pitching moment at different operating speeds are compared.Finally,the aerodynamic performance changes of high-speed trains under different working conditions are analyzed to achieve the purpose of studying crosswind effects.Through the numerical simulation of CRH2 G high-speed train,the calculation results show that:(1)Compared with the clean wind environment,the energy of the fluid in the two-phase wind and sand two-phase flow is changed and the energy has undergone a certain transfer within the fluid;At low crosswind wind speeds,the wind and sand two-phase flow consumes fluid energy compared to the clean wind environment,and the resistance and overturning moment are both reduced;while at higher crosswind wind speeds,the wind and sand two-phase flow compares to the clean wind environment fluid energy Increase,resistance and overturning moment increase greatly.(2)In the longitudinal direction,compared with the pure wind environment,the kinetic energy of the internal wind phase of the fluid is partially transferred to the sand phase so that the velocity of the sand phase and the wind phase are consistent,and the fluid energy of the two-phase wind and sand flow increases.Both drag and pitch moments have increased substantially.(3)In both horizontal and vertical working conditions,the two-phase flow formed by adding sand particles will cause the fluid energy to increase,so that the lift is increasing.(4)Comprehensive analysis shows that the impact of the two-phase wind and sand flow on the crosswind effect of high-speed trains is significantly higher than that of the clean wind environment,which makes the aerodynamic force and torque increase to a certain extent,indicating that the crosswind effect on the train is further intensified,so the high-speed trains Safe operation puts forward higher requirements.The results of this paper hope to provide a useful reference for the design of high-speed trains against wind and sand.