Aerodynamic characteristics of fully enclosed sound barrier induced by the passing trains with 400 km/h

Abstract

The fully enclosed sound barrier (FESB) has excellent sound reduction effect, but the relatively closed space will make train-induced wind effect more obvious. This study aims to quantify the aerodynamic characteristics on FESB during the trains passing through using a computational fluid dynamic (CFD) method, considering the effects of opening spacing ΔH, train length, and trains passing each other. An overset grid approach is applied to stimulate the relative motion between the train and the FESB, which is verified by correlated test data. The results demonstrate that compression and expansion waves induced by passing trains are the primary sources of pressure fluctuations within the FESB. Implementing a pressure relief scheme with a top opening, which modifies the propagation law of pressure fluctuations inside the FESB, can effectively mitigate the train-induced aerodynamic effects on the structure. Moreover, the head-wave effect on the FESB is less affected by the train length in such schemes. When the opening spacing ΔH value exceeds 1.5 m, the peak-to-peak pressure ΔPH induced by a train passing by gradually reaches a stable state, and there exists a perfectly negative exponential relationship between the aerodynamic force per unit length of FESB and the opening spacing ΔH. However, the train-induced aerodynamic effect on the FESB is amplified when two trains pass each other. In pressure relief scheme with ΔH of 1.5 m, compared to the ΔF observed on the near and far line sides during a single train passing by, those obtained during trains meeting operation are found to be 0.66 times and 2.64 times higher.