CFD model to assess parameters influencing piston wind in a subway tunnel and station

Quantifying the train-induced wind affecting the climate of subway stations can be applied to improve underground networks air quality. In this paper, numerical simulations of train-induced airflow in a subway station are performed, using a CFD model with dynamic meshing techniques. A preliminary study is done in a double-track tunnel with blockage ratios of 0.30, 0.37 and 0.46 with a train running at constant speed in the order of 10 m/s. The tunnel length necessary to obtain a stable flow around the train body is determined, and this upstream tunnel length is included in a subway station model. Two different architectures and three train speeds are simulated, and the effect of these configurations on the station airflow is evaluated through the air velocity and the mass flow rate at a location on the platform. The results evidence an increase in air circulation with blockage ratio and train speed.