Analysis and Optimization of Aerodynamic Performance of Train at Transitional Zone Between Cut and Wind-Break Walls

In this thesis, The numerical simulation calculation was carried out to the aerodynamic characteristics of the train under wind-break wall, high cut or at the transition under cross wind with three-dimension incompressible viscous N-S equation and the k-epsilon turbulence model. In addition, this paper focused on analysis and optimization of the various transitions. Analysis by calculating, the important conclusions were as follows: (1)Under cross wind, the side force and overturning moment suffered by the train at the open transition, are much bigger than those under the wind-break wall or cut, aerodynamic characteristics of trains at transition are worst. (2)Under cross wind, the resistance suffered by the train will be mainly unchanging with the transitional angle, while the lift force will be bigger and bigger with the angle´s increase. The side force will be in the opposite direction after the angle is 45°, and the overturning moment will be smaller and smaller until the angle arrives at 30°, and then it will increase with the angle. (3)The best optimization for transition is to connect wind-break wall and cut with the transitional angle of 30°, which has good wind-proof effect but smaller consumption, and is applicable to transitions between many different types of wind-break walls and cut.