Aerodynamic Numerical Simulation For High Speed Train Under Crosswind

With the construction of high speed railway in recent years, the scale of the railway network and the speed of the train have reached the forefront of the world. Nevertheless, some problems of aerodynamics appear as the speed of the train rises. One of the most important research aspects is to study the aerodynamic characters when the train is moving under the crosswind for the crosswind will deteriorate the air current and enhance all kinds of dynamics of the train. When the wind is fierce, the train may even be overturned.In this paper, the high speed train CRH3was studied. By using SC/Tetra the software based on finite volume method, the numerical simulation of the train is proceeded under three situations, running on open lines, running under steady crosswind and running under unsteady crosswind. According to the difference among meshing size on the surface and the thickness of the girding on the boundary layer,23kinds of girding structure are meshed and calculated. In addition, the relationship between meshing method and the calculation result is studied and the preparations for further study are made. At last, by the comparison of result of the numerical simulation and the one of wind tunnel experiment, the consistency between them is obvious.When analyzing the train moving under the crosswind, the wind shall be divided into steady state and unsteady state. By the numerical calculation of18kinds of working conditions when the train is moving under crosswind, the changes in the aerodynamic characters of the train are studied, including the distribution of pressure on the surface of the train and the inlet of the air conditioning, the resistance, elevating force, lateral force toward the train, and the overturning moment to the geometric centre of the train. The research shows that as the speed of train and crosswind change, the surface pressure and aerodynamic parameters change in a certain rule.By using transient calculation method, the working condition when the train is moving under unsteady crosswind is studied. The speed of the wind is the linear function of the time, which is shown as VW=VW (t)=kt. According to difference of change rate of the wind, the numerical calculation is proceeded. The result manifests that there will be sudden changes in all the parameters of train under the effect of unsteady crosswind, and the incremental quantity is proportional to K.The study in this paper provides supported reference to the further development of the aerodynamics in train, and is of practical value in protecting safe operation of the high speed train.