Analysis Of Erosion Characteristics And Aerodynamic Characteristics Of High-speed Train In Strong Wind-sand Environment

China is currently building a well-off society at critical moments.Speeding up the development of high-speed railways is of great significance for the great revival and the realization of the Chinese dream.Located in the 100-kilometer Wind Area of the second double line of Lanzhou-Xinjiang Railway in China,due to its geographical factors,sandstorms often occur.The maximum instantaneous wind speed is 64 m/s and sand particles are mixed in the strong wind along the line,which seriously endangers the safety of trains.Therefore,this paper studies the influence of wind-sand coupling on the erosion characteristics and aerodynamic characteristics of high-speed trains through the following aspects.(1)Combined with CFD theory,an aerodynamic model for high-speed trains was established.This paper used three-dimensional,steady,incompressible Reynolds time-averaged Navier-Stokes equations and standard κ-ε two-turbulence control models.The Eulerian-Lagrangian method was used to simulate and calculate the erosion characteristics of the head train under different incident angles,different sand diameters and different concentrations.The results showed that the windward side of the high-speed train was the area with the largest positive pressure in the strong wind and sand environment,and the erosion was the worst.When the incident angle of the sand particles increases,the maximum positive pressure area of the leading vehicle increased,and the erosion area also increased.The main erosion area was in the maximum positive pressure area of the train.When the incident angle of the sand particles is 45°,the erosion rate reached the maximum.When the wind speed and the sand concentration are unchanged,the erosion rate of the head train showed a trend that decreased first and then stabilized as the particle size of the sand increased.When the wind speed and the sand particle diameter are constant,the erosion rate of the head car increased linearly with the increase of the sand particle concentration,and the erosion area continued to be dense,but the erosion shapes did not change significantly,and all were polygonal shapes.(2)This paper studied the aerodynamic characteristics of trains traveling on flat ground,embankments and bridges in wind-sand environments.The results showed that the surface pressure of high-speed trains in wind-sand environments was much greater than sandless environment.Under the influence of lateral wind,the maximum positive pressure area of the train deviated from the nose of the train to the windward side.In the sandy environment,the positive pressure area on the windward side of the train was significantly expanded,which seriously affected the safe driving of the train.The aerodynamic resistance of the head train was the largest,and the impact of sand on the head train resistance was extremely significant,which increased by 10%-12%compared with the resistance of the head train in the sandless environment.The overturning moment received by the head train was the largest,and the overturning moment received by the tail train was the smallest.The direction was opposite to that of the front train.(3)The paper simulated the pressure cloud maps and streamline maps of the surrounding trains under different road conditions and different embankment heights.The results showed that the maximum positive pressure area on flat road conditions was the smallest,and the pressure difference between the two sides of the train was relatively small;The road condition of the bridge had the largest positive pressure zone,and the pressure difference between the two sides of the train was relatively large;Vortex was generated on the windward side of the bridge,and double backflow occurred on the leeward side of the bridge.With the increase of the height of the embankment,the vortex area also increased,and the vortex mainly appeared in the negative pressure area,which seriously affected the driving safety.