Simulation Research Of The Aerodynamic Drag Reduction Characteristics Of Microstructured Surfaces On High-speed Trains

The percentage of the aerodynamic drag of high-speed trains increases with the increase of the speed of high-speed tranis.When the speed reaghes 300km/h,the percentage of the aerodynamic drag takes 85%.Therefore,to reduce the aerodynamic drag of high-speed trains is significant to reducing the energy consumption and speed increase of high-speed trains.In this paper,the aerodynamic drag reduction characteristics of microstructured surfaces on highspeed trains with speed of 250km/h(70m/s)was sdudied by numerical method.The main contents are as follows:1)the numerical solution of the skin friction coefficient of the smooth plane was figured out by numerical method.To ensure the accuracy of the numerical solution of microstructured surfaces,the computational domain size,the boundary conditions,the turbulence model and the near-wall treatment were verified by comparing the numerical value of the skin friction coefficient of the smooth plane with the empirical value.2)Tree types of microstructured surfaces were designed: V-shaped,rectangular-shaped and U-shaped based on the drag reduction mechanism of grooved microstructured surfaces.The drag reduction efficiency of these surfaces was figured out by numerical method,and optimal parameters are obtained.According to the variation law of drag reduction efficiency,the influence of geometric parameters on drag reduction efficiency was analyzed.Moreover,according to the velocity and the wall shear stress distribution in the near wall region,the drag reduction mechanism was analyzed.3)A method of using simplified model to study the drag reduction efficiency of microstructured surfaces applied to high-speed train models was proposed.The simplified model was designed according to the size of the high-speed train model.moreover,the similarity between the simplified model and the high-speed train model is verified.Next,the drag reduction efficiency of the optimal surface attached to the simplified model was figured out,which can reflect the drag reduction efficiency of the optimal surface attached to the highspeed train model.Then,geometric parameters of the microstructured surface was adjusted,and the drag reduction efficiency of the adjusted microstructured was figure out by the above method.Finally,the conclusion is drawn: when applying microstructured surfaces to long models,it is necessary to adjust geometric parameters appropriately to improve drag reduction efficiency.