Numerical Analysis Of Flow Field Of High-speed EMU Open Line Running In Sandstorm Two-phase Flow

Lanzhou-Xinjiang high-speed railway main way Gansu,Qinghai,Xinjiang three provinces,is an east-west modern "Iron Silk Road".Lanzhou-Xinjiang high-speed railway along environment is very bad,especially the most serious sandstorm disasters in Xinjiang region has caused many train overturned accident.Therefore,under the condition of sandstorm two-phase flow,it is very important to study the aerodynamic characteristics of EMU line operation.In this paper,the numerical simulation method is used to analyze the aerodynamic characteristics of EMU under the condition of sandstorm flow,which provide the basis for the research and development of the anti-sandstorm EMU.The main contents of this paper are as follows:(1)Through the numerical simulation of Wang Hongtao’s wind tunnel experiment,the reliability of the calculation model and numerical simulation results are verified,which lays the foundation for the subsequent numerical calculation.(2)According to the sandstorm weather along the Lan-Xin railway,the sand bed model is establish using the Eulerian model,numerical study of the variation of sand particles in wind field under different wind speeds.(3)Refer to a high-speed EMU to establish a three-dimensional calculation model,dividing the computational domain into good quality grids and set the boundary conditions.(4)According to the analysis result of the sand bed model,using the UDF function program of treatment on sandstorm model.(5)Numeral Calculating the EMU line running in conditions of different sandstorm when the train speed is 200km/h,the crosswind speeds were chosen as 15m/s,20m/s and 25m/s,and the crosswind velocity is 25m/s,the wind direction angle as 45°,75°and 90°.Analyzing pressure distribution of EMU surface and average pressure of air conditioning inlet and outlet,the sand-dust concentration distribution of above the inlet of air conditioning,and the rules of change about aerodynamic coefficients of EMU.Numerical analysis of lateral safe retreat distance of EMU under different conditions.Through numerical simulation analysis,conclusion shows: Under the condition of sandstorm,EMU line running speed is 200km/h and crosswind velocity is 25m/s,and the lateral safe retreat distance distance of EMU is 7.5m when the wind direction angle between 75°and 90°.Under the condition of strong sandstorm,average pressure of inlet and outlet of air conditioning on head car is minimum,and relative reduce 27.5% compared with middle car,relative reduce 27.5% compared with rear car;Sandstorm speed is higher or wind direction angle is smaller,the drag coefficient of EMU is larger;EMU speed is 200km/h and crosswind velocity is 25m/s,the overturning moment coefficient of EMU is maximum,reaching 0.1347,which increased respectively by 117.6% and 337.3% compared with the other two sandstorm conditions,and which increased respectively by 41.7% and 576.8% compared with the other two wind direction angle conditions.In this paper,the results provide important guiding significance for the safe operation of high-speed EMU under the condition of sandstorm flow.