고속전철 터널입구 형상이 공력특성 및 터널입구 압축파에 미치는 영향

Abstract

The work presented in this paper concerns the aerodynamic characteristics and compression wave generated in a tunnel when a high speed train enters it. A large number of solutions have been proposed to reduce the amplitude of the pressure gradient in tunnels and some of the most efficient solutions consist of (a) addition of a blind hood, (b) addition of inclined part at the entrance, and (c) holes in the ceiling of the tunnel. These are numerically studied by using the three-dimensional unsteady compressible Euler equation solver with ALE, CFD code, based on FEM method. Computational results showed that the smaller inclined angle leads to the lower pressure gradient of compression wave front. This study indicated that the most efficient slant angle is in the range from 30˚ to 50˚. The maximum pressure gradient is reduced by 26.81% for the inclined angle of 30˚ as compared to vertical entry. Results also showed that maximum pressure gradient can be reduced by 15.94% in blind hood entry as compared to 30˚ inclined tunnel entry. Furthermore, the present analysis showed that inclined slant angle has little effect on aerodynamic drag. Comparison of the pressure gradient between the inclined tunnel hood and the vertical entry with air vent holes indicated that the optimum inclined tunnel hood is much more effective way in reducing pressure gradient and increasing the pressure rise time.