The Platform Piston Wind Velocity Variation Analysis with Different Conditions

In a subway environment control system without screen doors, the tunnel piston wind enters the platform with the train and significantly affects the platform’s thermal environment. The piston wind distributed on the platform here is defined as the platform piston wind. In this case, the diffusion regularity of platform piston wind is regarded as a wall jet along the platform’s length and width, and its origin is a piston wind jet at the tunnel exit. According to classical wall jet theory, the jet can be approximately divided into initial and main sections in the development process. This study is based on the mathematical theory model. The model divided the platform piston wind velocity distribution into the initial section and the main section. This platform piston wind mathematical theory model is solved with time circle and along the vertical wall directions. The various conditions include changing the tunnel cross sections, train cross sections, the maximum train velocities. It is concluded that the cross-sectional ratio and maximum train velocities are the main factors on this velocities distribution. The building up and solution of this platform piston wind mathematical model serve as an important reference for the optimal design of practical thermal environments in engineering.