CFD Analysis of the Flow around Simplified Next-Generation Train Subjected to Crosswinds at Low Yaw Angles

Abstract

The development of Next-Generation Trains (NGT) made of lightweight materials is a challenging task for the transport industry. It reduces axle loads, which saves money by lowering rail track maintenance costs and the amount of energy needed to drive vehicles. However, the increasing speed and decreasing mass of high-speed trains, on the other hand, raises concerns about the effects of strong crosswinds on their aerodynamics and train stability. As a result, the purpose of this research is to investigate the unsteady flow structure around an NGT in crosswind using a Computational Fluid Dynamics (CFD) technique known as Unsteady Reynolds Averaged Navier-Stokes (URANS). Based on the height of the train model and the velocity, the Reynolds number for the simulation used was . The simulation run in four different crosswind angles: 5°, 10°, 15°, and 20°. The simulation results were compared with experimental results. The findings revealed that a larger yaw angle, which is primarily determined by the incoming wind velocity, can lead to higher flow separation and a more complex three-dimensional flow around the train. Additionally, when the wind angle is small, separation of flow and wakes is limited to the train's end; however, as the wind angle increases, separation of flow occurs from the train's upper and lower corners, indicating that the vortices formed as a result of the flow passing over the roof top and underbody. Finally, the study's findings will contribute to a better understanding of the flow characteristics around an NGT in crosswinds, which is simply impossible to achieve through full-scale testing due to the cost, resources, and accuracy.