Aerodynamics Analysis Of High-Speed Train Exit Tunnel Under Cross Wind

In recent years,the speed of trains has increased significantly,and the effect of air on the movement of trains has become more and more important.By 2020,there are 37,000 km of high-speed railways in operation.The popularity of high-speed railway lines has made the environment along the train operation more diversified and complicated.When the train passes through the mountain canyon,it will inevitably be affected by the canyon wind after exiting the tunnel.In view of this situation,the aerodynamic characteristics and operating safety of the train leaving the tunnel under the action of crosswind are studied.This paper takes a certain type of EMU as the research object.After model processing and meshwork,the aerodynamics of high-speed trains are calculated based on the three-dimensional unsteady and incompressible Navier-Stokes equations and the standard k-εturbulence model.Simulation study.Different train speeds and crosswinds at different tunnel exits were used as variables for comparative analysis.When studying a single vehicle passing through the tunnel,carefully analyzed the pressure distribution of the flow field and the characteristics of the tunnel pressure change;compared the pressure distribution of the train body under different conditions in the tunnel;compared the pressure value changes of the vehicle body and the tunnel wall under different working conditions Analyzed the changes of aerodynamic load and the surrounding flow field during the exiting process of the train.The study found that the tunnel compression port has three-dimensional and onedimensional characteristics;when the expansion wave and compression wave act on the car body separately,the maximum amplitude of the pressure change on the car body surface is about 2650 Pa.The pressure in the straight area of the car body must always be lower than that of the open line operation.When the tunnel is fully driven into the tunnel and the expansion wave is applied and the compression wave is applied,the average body pressure is reduced by-1100 Pa,-3200 Pa and-550 Pa.Crosswinds have little effect on the pressure wave in the tunnel,but have a greater effect on the change in the nose pressure of the train.when the train is running at 350km/h,after the crosswind wind speed at the exit of the tunnel increases from 15m/s to 20m/s,the amplitude of the second peak pressure at the tip of the nose increases from 9.77% to 15.33%,which is about 870 Pa higher than when there is no wind.When exiting the tunnel in a crosswind,the aerodynamic lift experienced by the leading car changes from negative to positive,the leading car has the largest increase in lift ratio of79.74%,the CR car has the largest increase in lift,20.645 KPa,and the change in overturning moment on the trailing car the smallest.