Optimized Design For Type B Metro Vehicle Head Shape And Its Aerodynamic Performance Research

With the acceleration of urbanization,the pressure of urban traffic is increasing.In the big cities of the world,the metro vehicle has become an important measure to alleviate the traffic pressure.It is also one of the important measures to strengthen suburban relationship and drive the development of the surrounding city.The metro vehicle with its characteristics of high efficiency,energy saving and environmental protection,has attracted more and more citizen.And people’s requirements of the speed is constantly improving.Some cities in our country have opened the metro vehicle of which speed is 120 km/h.Several cities have already planned to build faster subway between urban and suburb.Increasing train speed brings a series of aerodynamic problems.Therefore,the head shape of type B metro vehicle is optimized by three-dimensional digital method,and its aerodynamic performance is researched by CFD(Computational Fluid Dynamics).The results provide valuable reference for optimization and redesign of metro vehicle head.This thesis regarded the type B metro vehicle in some domestic city as the research object.The geometric model was assembled with three cars,the NURBS(Non-Uniform Rational B-Splines)curve surface modeling method was adopted in CATIA.Two kinds of type B metro vehicle was designed by adjusting the distance from the front of car to the center line of side door and the radian of head car on the basis of certain length,width and height.The speed of metro vehicle is generally lower than the high speed train,so the streamlined size of head car should be extended appropriately.The curved surface quality of head car was evaluated by the method of illumination line and gaussian curvature.The flow field of three different metro vehicle were simulated by ANSYS Fluent16.0 under the seven different speed conditions.The incompressible N-S equations and the standard turbulence k-? model were adopted in the external flow field.The aerodynamic drag,the aerodynamic lift and the front surface pressure of three different metro vehicle were analyzed under the certain speed conditions.In addition,by fitting the data,the research showed that the drag coefficient of three different metro vehicle were 0.39,0.33 and 0.22 as well as the lift coefficient were 0.22,0.24 and 0.08,respectively.The coefficient of drag and lift is generally decrease along with the increasing of the streamlined size of head car.Finally,The aerodynamic performance of three different metro vehicle were analyzed under the seven different speed conditions.The results show that the aerodynamic performance of the two optimized streamlined metro vehicle is better than the blunt body with the increasing of train speed.The optimized result of plan 3 is better than others,whose aerodynamic performance is best.