Research On Aerodynamic Characteristics Of EMU In Sandstorm Environment

Lanzhou-Xinjiang high-speed railway traversed Gansu,Qinghai,Xinjiang and other high altitude areas,and Xinjiang is one of the most serious natural sandstorm disaster areas.Under the influence of sandstorm,dramatic changes in the aerodynamic characteristics of the train resulted in many train derailments and decommissioning accidents.Therefore,it is very important to study the aerodynamic characteristics of the train in the regions of high altitude and strong sandstorm.It has an important guiding significance to improve safe operation of Chinese high-speed train in the sandy environment by applying the method of numerical simulation analyzed aerodynamic characteristics of EMU under the sandstorm.The main contents of this study includes:(1)Setting up a three-dimensional model of 3 vehicles,and planning the calculation model of the EMU,and dividing the computational domain into good quality grids.(2)Define the sand model of flow field,and using a custom function program of treatment on sand model,define boundary conditions of EMU external flow field to solve the basic equations.(3)Calculating the EMU in conditions of no wind and crosswind and different sandstorm.Analyzing pressure distribution of windward and leeward side,nose and air conditioning shroud and relevant import and export in different conditions.Contrasting velocity vector distribution of EMU around,and researching the rules of change about aerodynamic coefficients of EMU in different conditions.Through the numerical simulation of CRH380B EMU,conclusion shows:The crosswind has certain influence on the surface pressure distribution of EMU,but sandstorm has a greater influence.The faster the sandstorm blown,the greater the pressure range of the air conditioning shroud,the lower pressure of the air conditioning condenser inlet and condenser outlet and the fresh air inlet.Sandstorm speed is higher,the pressure difference between EMU windward and leeward is bigger,and the lateral force is bigger.When the sandstorm speed is 30 m/s,the pressure difference on both sides is 953.5 Pa,the lateral force is 175663.50 N,which increased respectively by 28.37%and 93.12%,compared with the other two sandstorm conditions.When EMU speed is 200 km/h,and the sandstorm speed is 25m/s,the lift of EMU is maximum,reaching 13959.88 N,which increased respectively by 74.93%and 41.36%,compared with the other two sandstorm conditions.The larger lateral force and lift force will result in poor stability of the EMU operation.The results obtained in this paper provide technical reference for the design of EMU in high altitude and strong sandstorm regions.