Influence of lift wings on aerodynamic characteristics and operation safety of trains
Based on the theory of train aerodynamics and vehicle multi-body system dynamics,aero-dynamic and vehicle system dynamics models of a high-speed train with or without lift wings were established to explore the feasibility of a lift-wing high-speed train.The aerodynamic characteristics and running safety of a high-speed train with or without lift wings were simulated and studied in calm and crosswind environments.The results showed that the aerodynamic lift and lift-to-drag ratio of high-speed trains can be improved by installing lift wings;however,the aerodynamic drag also in-creases significantly.Furthermore,the differences in the flow-field characteristics of high-speed trains with or without wings were significant.After installing the lift wings,the surface pressure dis-tribution and the streamline flow direction of the train changed.The peak value of the slipstream ve-locity of the train increased,and the velocity distribution in the areas on both sides and in the wake of the train changed.Under crosswinds,the surface pressure distribution and backflow-vortex struc-ture of the train changed.The aerodynamic drag,lift,lateral force,and pitching moment on the head train increased significantly compared to when wings were not present.The difference in the lift and rolling moments was evidentwith a change in direction and an increase in the numerical value of the rolling moment.The change in yaw moment was minimal.When no wind exists on the open line,the installation of lift wings can reduce the wheel-rail vertical force by 6%～13%,with the largest reduc-tion occurring in the tail car owing to the maximum aerodynamic lift.The lift-wing high-speed train could operate safely and stably at speeds up to 450 km/h,and the wheel-rail vertical force and wheel load reduction rate exceeded the limit at a speed of 500 km/h.The main reason for the impact on safety is that the lift wings increase the difference in the aerodynamic loads between each car.The aerodynamic layout of the lift wings requires further improvement,and the reduction of the lift on the head and tail cars is suggested.Under crosswind conditions,the head car suffers from a signifi-cant increase in the lift,lateral force,and rolling moment,thereby deteriorating its operational safety and reducing the crosswind safety domain.
vehicle engineeringlift wingshigh speed trainaerodynamic characteristicsdynamic performancecrosswind safety zone
万方数据
维普
