Flow dynamics of train under turbulent inflow at different crosswind yaw angles

Abstract

The turbulence intensity and yaw angle of crosswinds exert a substantial impact on the aerodynamic characteristics of trains traveling in windy regions. It is urgent to study how the yaw angle and turbulence intensity of incoming flow jointly affect the aerodynamic characteristics of the train and the corresponding flow field under turbulent crosswind. A high-speed train scaled at a ratio of 1/8 of its actual size at different yaw angles was investigated. Three inflow conditions were adopted, including uniform inflow, Iu = 0.05 inflow, and Iu = 0.2 inflow (Iu is turbulence intensity). The turbulent inflow was generated by the synthetic eddy method. The instantaneous and time averaged characteristics of aerodynamic loads and pressure loads of the train were analyzed. The vortex structures, vorticity, swirling strength, mean velocity, reverse flow, and Reynolds stresses are analyzed to explore the flow pattern and flow evolution. The results found that the fluctuation of the aerodynamic loads, the average side fore, and the average rolling moment of the train are remarkably enhanced under turbulent inflow. These results stem from the alterations in the flow field around the train induced by turbulent inflow, consequently leading to variations in surface pressure on the train. As the turbulence intensity of the inflow increases, the stability of the vortex structures decreases, and the position of the large-scale vortex structure has been changed. Moreover, the yaw angle (β) exerts a more significant influence on the vortex structure's flow pattern on the leeward side compared to the inflow turbulence intensity.