Numerical Analysis on Drag Reduction of High-Speed Train Using Rough Surface

Rough surfaces of flying and swimming animals help to reduce the aerodynamic or hydrodynamic drag when they move in the environment. In this research, biomimetic rough surface is introduced for high-speed train to reduce the aerodynamic drag. CFD tool is used to numerically study how the aerodynamic drag is altered by applying the biomimetic structures to the high-speed train surface. Rough surface is distributed in three areas: pantograph, bogie and windshield areas to reduce the drag at train speed of V = 400km/h. Concave is employed on these areas and orthogonally distributed with diameter of 40mm and center-to-center distance from 60mm to 80mm. The drag force is slightly increased/decreased in the pantograph area, while in the bogie and windshield areas rough structures lead to drag reduction with same distribution configuration. For all cases, the amount of shear drag change is much less than the pressure drag change. The total drag reduction mainly comes from pressure change. Rough surface positively contributes to changing the surface flow and thus reducing the aerodynamic drag.