New Types Of Wind Barrier On High-speed Railway And Aerodynamic Numerical Simulation Under Crosswind

With the high-speed railway speeding up, gale limit the speed of the train. And operational safety of the train is threatened under cross wind. In order to maintain the stability of trains, wind barriers on both sides of the line was set to provide a narrow weak wind zone for trains operating environment in windy area. Current studies mainly focus on the aerodynamic performance of the train behind the barrier. This research funding by the National Natural Science Fund Project (NO.51178471&NO.51322808). Basing on an overall consideration of train and barrier-bridge aerodynamics under cross wind, several new types of wind barriers have been proposed. While considering the aerodynamic performance of the train, the effects of different parameters of the Grid-type and new types wind barriers also been studied in using numerical simulation. In this study, protection effect and wind load on bridge and wind barrier are investigate both. Specific studies are as follows:Primarily, several new types of wind barrier, which named Shutter-type, Hinge-type and Combination-type, are put forward. Different heights and ventilation rates (or deflector rotation) of wind barrier models have been created. Considering both cases as a train or not on the bridge, the numerical calculation for each kind of wind barrier with different heights and deflector angles had been done. Protection effect and self-load of wind barrier can be obtained in the cross-wind.Studies shows that bridge aerodynamic coefficients change little in different condition and it has no significant relationship with wind barrier height and ventilation rate. With the wind barrier height increases, the coefficients of wind force of train showed a decreasing trend; when ventilation rate increases, the coefficients of wind force of bridge increases. When transforming the rotational angle of Shutter-type Barrier, the angle of reflection fluid flow and direction of the force to barrier also changes. Keeping the angle into vertical small, the aerodynamic performance of the train can be guaranteed, which can also improve the aerodynamic performance of wind barriers and bridges in the absence train. In contrast with Grill-type wind barriers, the Hinge-type have only slightly better effect on blocking wind to the train in the same ventilation rate, but it perform excellent in overall suffering aerodynamic aspect about barrier-bridge. Combination-type wind barrier, which relative to the Shutter-type wind barrier, can formed two opposing airflow behind the barrier to offset part of the vertical speeds, what will reduce the impact to train or bridge. When train absent from the bridge, the Shutter-type wind barrier in a small rotation angle and Combination-type wind barrier in large rotation angle both have their advantages. The same conclusion can be reach while the train present on the bridge.Transient impact induce by train wind on the wind barrier is characterized by head wave and tail wave, and the combined effect of train wind and crosswind on aerodynamic force of wind barrier is mainly superposition of them.