Study Of Aerodynamic Effect On High-speed Train In Wind-sand Environment

With the increasing speed of high-speed train operation,the aerodynamic effect becomes more and more obvious.In the northwest of China,the development of high speed railway under the condition of strong sand environment,and Lanzhou-Xinjiang High-speed Railway is the most serious area of China's railways affected by sandstorm,the local sand-carrying gale weather seriously affects the safety performance of the high-speed train running smoothly.Therefore,it is of great theoretical and practical significance to explore the aerodynamic effect of high speed trains under sand environment.Based on the theoretical knowledge of aerodynamics,this paper studies the flow characteristics of EMU under sand environment,and analyzes the aerodynamic effects of high and cold wind-blown EMU.Firstly,this paper introduces the research status of the influence of the wind and rain on the aerodynamic characteristics of the train by experts and scholars at home and abroad,and also briefly discusses the research methods of the gas-solid two-phase flow on the surface erosion effect of the material.Secondly,in the open open-wire area,the flow around the train body can be regarded as a typical turbulent movement.Therefore,the SST k-? turbulence model is selected to simulate the flow characteristics of the gas phase,and the discrete particle orbital model in the Lagrangian coordinate system is used to trace and analyze the complex motion of solid phase.Then,using computational fluid dynamics(CFD)technology,aiming at the unique operating environment of Lanzhou-Xinjiang High-speed Railway,the grid model of the CRH5G-size EMU is designed,which lays a solid foundation for the reasonable analysis of the aerodynamic effect of high speed EMU in steady state without natural wind and transverse wind.Thirdly,the paper verifies the two sets model of gas-solid two-phase flow around the cylinder and the particle erosion of the current limiter,compared the results of reference and numerical simulation,and concludes the agreement,and determines the numerical simulation calculation method.The boundary conditions in the flow field and the initial conditions of the gas-solid two-phase are assigned.In this paper,the aerodynamic characteristics of CRH5G-size EMU in open-wire without natural wind environment and transverse wind environment are simulated,and the velocity vector map,velocity roll integral map and pressure cloud chart of the train around trains without sand and sand are displayed.This paper discusses the aerodynamic changes of CRH5G-size EMU in open-wire without natural wind environment and transverse sand environment: the simulation data of four kinds of incident sand concentration,three kinds of sand diameter and three train speed total 20 working conditions are compared,and the variation law of train aerodynamic value is concluded.In addition,the erosion effect of sand on the train surface is analyzed: the trajectory of the sand in the train is shown,the relative position of the sand on the surface of the train is analyzed,and the overall erosion rate of the train surface is estimated.The research method and conclusion are eager to provide a useful reference for the aerodynamic performance of high speed trains under the sandstorm environment.