Numerical investigation of bogie-induced flow disturbances around a streamlined high-speed train

The bogie-induced flow characteristics of two referenced variations of a streamlined high-speed train model, with and without bogie shields, are numerically studied by performing improved delayed detached eddy simulation. The results show that covering the bogies reduces the overall aerodynamic drag by 45%, primarily due to a significant reduction in pressure drag caused by the smoother underbody. While a localized increase in slipstream velocity is observed near the train's rear, the wake activity is diminished, resulting in a substantial drop in the nondimensional slipstream velocity to approximately 0.01 in the wake region, with decreases of 93% and 80% at a height of z* = 0.11 and 0.44, respectively. Additionally, the maximum turbulence intensity downstream of the bogie region decreased by 97% and the lateral motion of wake vortices was found to stabilize, with dominant frequencies occurring at StW = 0.139 and 0.425. These findings provide good references for the aerodynamic assessment of future high-speed trains.