The aerodynamic performance of a metro train passing through different shield transfer structures

With the increase in the speed of metro trains, the aerodynamic effects caused by the train passing through the tunnel, especially the pressure change, will be significantly enhanced. This pressure will have a significant effect on the auxiliary facilities in the tunnel and the passengers in the carriage. Based on the sliding grid technique, Fluent software was used to simulate the aerodynamic performance of six trains passing through different shield transfer structures, and the influences of the shield cross-section area, length, and form on train aerodynamic performance were studied. The results show that when the cross-sectional area of the shield transfer structure increases from 42 m2 to 62 m2, the positive pressure peak Pmax on the train surface increases significantly, and the peak-to-peak value and positive pressure gradient peak in the large-section tunnel are increased by 20.50 % and 106.83 %, respectively; when the length of the shield transfer structure is increased from 80 m to 120 m, the positive pressure peak and pressure gradient peak in the large-section tunnel are increased by 22.53 % and 21.70 %, respectively; for constant cross-sectional area and ellipsoidal structural forms, the slanting structural form has a smaller train surface pressure amplitude as well as a smaller peak pressure and peak pressure gradient in a large-section tunnel. These findings will contribute to the design of shield transfer structure in subway and tunnel systems.