Selection of Head Car Model for High Speed Train in Open-section Wind Tunnel Test

Abstract:

Reasonable scaled model of high-speed train is very important for aerodynamic evaluation and research in wind tunnel. Based on the computational fluid dynamics method， the selection method of the shortest tail model and the reasonable scale model of the head car in wind tunnel test was studied. The results reveals that： the drag coefficient of the head car increases with the shortening of the tail model， and the negative pressure of the tail moves upstream， which reduces the pressure at the inter-coach space. The deviation between the drag of the head car +0.4L tail model and that of the three cars model is 2.8%， which can be used as the shortest model of the head car. The selection of the scale model of the head car is affected by the wind tunnel boundary effect， Reynolds number effect and ground effect. The Reynolds number effect reduces the frictional drag， while the ground effect increase the pressure drag. The 1：8， 1：4 scale model and full-scale model's head car pressure drag deviation are 12.7% and 7.2%， which account for 63.9%， 67.2% and 72.5% of the head car's total drag respectively. The result shows that， it’s more reasonable to choose the 1：4 scale model as high-speed train experiment model in open-section wind tunnel.