3624 ピストン効果(S49-1 トンネルの空気力学と換気(1),S49 トンネルの空気力学と換気)  [in Japanese] 3624 Piston Effect  [in Japanese]

The piston effect means the uniform airflows are caused by the motion of trains in a tunnel. There are two processes the moving train give the momentum to the air in the tunnel, one is friction and the other is the collision. A variable to describe the collision is presented in terms of fluctuations of density and velocity of airflows in the annular region composed of the train and the tunnel wall. This is utilized to discuss the self-consistent equations describe the behavior of uniform airflows in the tunnel. The result of calculation has a good agreement with the data of experiment.