Numerical study on the aerodynamic pressure of a metro train running between two adjacent platforms

As a fast and efficient short distance transportation means, the subway line has been built and expanded in an increasing number of cities. The pressure in the tunnel fluctuates significantly while metro trains pass. This kind of pressure may damage the equipment and workers in the tunnel. Considering that, the metro train does not have airtightness, and that pressure can spread inside the vehicle, passengers in the vehicle would be directly affected by the alternating aerodynamic pressure, which causes discomfort to passengers. This phenomenon is exacerbated at high speeds. Therefore, it is important to estimate the aerodynamic alternating pressure generated by the metro train in the tunnel before construction. In this study, the aerodynamic performance of a metro train running between two adjacent platforms in a tunnel was simulated by using FLUENT. In this work, the effects of acceleration and speed of the metro train, and of platform spacing, on the alternating pressure on the train and in the tunnel are studied. In the analysis of the impact of train acceleration, the pressure change inside a passenger train in a 1 s timespan was used to evaluate the comfort of passengers. Maximum and average ΔP (pressure changes in amplitude) shows an exponential relationship with a (acceleration), Vc (constant speed) and Lplatform (platform spacing), especially the ΔP measured on tunnel surface. The fluctuation of the train surface pressure is more intense than that of the tunnel. The Pmin (minimum pressure) on the train surface and in the tunnel is not affected by the acceleration of the train, but it is mainly related to the highest train speed in the tunnel. When the platform spacing is higher than 1500 m, Pmax, Pmin, and △P in the tunnel and on the train surface showed little change. These findings contribute not only to the design of the metro train and tunnel system, but also to the guidance of the metro train operation.