Unsteady flow and aerodynamic behavior of high-speed train braking plates with and without crosswinds

Owing to continuous improvement in train running speeds, braking safety has become increasingly important, challenging braking approaches such as adhesion, eddy current, and electric magnet wheel brakes. Aerodynamic braking is an effective braking supplement whose braking effect is particularly outstanding in trains running at high speed. However, the flow field around the train can be significantly changed with the aerodynamic plate opening, degrading the aerodynamic performance of the train and even causing the train to sway violently. In this study, the unsteady aerodynamic characteristics of the full course of the braking plate, with and without crosswinds, were simulated and analyzed. The results show that pulse aerodynamic forces appear during the plate motion process, especially in the opening stage, and crosswinds increase the maximum values of these forces. Aerodynamic forces on the plate in the opening process are greater than those on the plate in the same position in the closing process. The difference in the flow field behind the plate in these processes is aggravated by crosswinds. Therefore, aerodynamic braking devices should be designed very carefully to minimize the impact of plate motion on the catenary and pantograph.