Aerodynamic influences of bogie's geometric complexity on high-speed trains under crosswind

The geometries of bogies have a significant influence on the aerodynamic performances of high-speed trains (HSTs) in crosswinds, especially for wind tunnel tests. The delayed detached-eddy simulation (DDES) method was used to calculate the aerodynamic characteristics of 1/8th scaled HST models with differently simplified bogies under crosswinds. The numerical results were verified by wind tunnel tests using a same model. It was proven that the complexity of bogies has a significant influence on the HST models' aerodynamic drag and rolling moment at various yaw angles. The flow field of the HST models under a 30 degrees crosswind was then employed to study the effects of the bogies. With the simplification of the bogie structure, the positive and negative pressure in bogie cabins increased while that on the top surface seldom changed. Various flow patterns were found on the windward side and top surface of bogie cabins. The differences of the flow fields underneath the train models were quantitatively analyzed using the vertical velocity profiles near each bogie.