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Due to the deterioration of the crosswind-protection performance of the original earth embankment windbreak walls on the train with increased speed, researching the influence of the heightened windbreak walls on aerodynamic performances of trains as well as the protection of the catenary is necessary for optimizing the windproof performance. The improved delayed detached eddy simulation based on the shear stress transport (SST) κ-ω turbulence model was employed to simulate flow structures. Furthermore, the effect on the displacement of the catenary was investigated using the finite element method (FEM). The numerical case was validated against the field tests. The results show that the aerodynamic performances of the train were improved as the windbreak wall was heightened by 0.5 m. Whereas, further heightening the windbreak wall worsened the aerodynamic performance. When the windbreak wall was heightened by 0.5 and 1 m, the wind speed of the catenary was reduced by 31.17% and 53.87%, and the displacement of the catenary was reduced by 48.09% and 74.11%, respectively, compared with that of the original windbreak wall. These results reveal that the wind-protection performance on the train and catenary can be both improved by reasonably heightening windbreak walls.

Wind tunnel tests for trains under large yaw angles are usually limited due to the width of the wind tunnel. Therefore, the leading car and a downstream dummy vehicle model are often employed instead of a real train, but there are no clear regulations regarding the shape of the end of the dummy vehicle. This paper studied the impact of the trailing edge shape of the downstream dummy vehicle on train aerodynamics subjected to crosswind based on the shear-stress-transport k-ωturbulence model of the delayed detached eddy simulation. Three types of end shapes, namely the rectangular end shape, the arc end shape, and the streamlined end shape were chosen for comparison, and the simulation results of the three-car-group train were selected as the benchmark. First, the reliability of the numerical method was validated by wind tunnel tests. Then, the aerodynamic coefficients under yaw angles of 0°–60° and the surface pressure distributions and flow structures around the train under the yaw angle of 60° of the head cars with different end shapes were compared and analyzed.

This paper investigates the effect of a wind barrier on the aerodynamic performance of a train–bridge system under crosswind using a numerical simulation method. The studied bridge is a long-span cable-stayed bridge with a flat steel box girder, located in Chongqing, China. The flow field around the train–bridge system with and without a wind barrier is numerically simulated. Wind barrier porosities varying from 10 to 60% are evaluated. The tricomponent coefficients of the train, bridge, and train–bridge system are obtained and investigated in detail. The effect of the wind barrier on the aerodynamics of the train–bridge system is revealed through the determination of the aerodynamic forces, pressure mapping, and flow visualization. The results show that a wind barrier successfully decreases the mean velocity above the girder and consequently decreases the drag force and moment on the train; however, the wind barrier also significantly increases the drag force on the girder. Therefore, installation of a wind barrier improves the running safety of the train but is detrimental to the wind resistance of the bridge. Additionally, the efficiency of the wind barrier depends on the porosity. A lower porosity improves the train safety but is more detrimental to the bridge safety. An optimal wind barrier porosity of 30% is obtained based on the aerodynamic forces of both the train and the bridge. Compared to a train–bridge system without a wind barrier, the drag force and moment on the train decrease by 66.1 and 62.9%, respectively; the drag force on the bridge girder increases to 0.86, and the drag force on the train–bridge system equals that without the wind barrier.

Slipstreams are generated when high-speed trains pass through the open air causing safety threat to passengers, trackside workers and infrastructure. This study calculates the slipstream induced by trains with different longitudinal section lines using a detached-eddy simulation. The slipstream velocities and pressure at various lateral distances from the centre of the rail position and various vertical distances from the top of the rail position are calculated at a Reynolds number of 1.8 × 106, and the flow field around the trains is analysed. The results of the calculation are compared with the results of a full-scale test to validate the numerical method adopted in this work. The results demonstrate that the variations in the slipstream velocities induced by the four types of trains are similar as are the variations in the trackside pressures. The amplitudes of the slipstream velocities and trackside pressures are different due to the influence of the longitudinal section line, and both the slipstream velocity and the trackside pressure increase with the slope of the longitudinal section line. The slipstream velocity and trackside pressure decrease with increasing distance from the centre of the rail and the top of the rail. The large difference in the slipstream induced by the four types of trains occurs in regions where the distance from the centre of the rail is greater than 2.5 m and the distance from the top of the rail is greater than 1.5 m, and those regions are also the areas where platform passengers and track infrastructure are located. The results demonstrate that the slipstream in those regions can be reduced by adopting relatively lower slopes of the longitudinal section line.