A prompt design method of railway tunnel hoods for micro-pressure wave mitigation using CFD-based POD reconstruction

The micro-pressure wave (MPW) is a major source of noise pollution around the railway tunnel environment and adversely affects the local building structure and the daily lives of residents. The main approach for alleviating MPWs is to install the tunnel hood at the mouth, and the specification design of the tunnel hood is of great significance to effectively mitigate the MPW. However, the traditional CFD and model-based experimental methods usually utilized for tunnel hood design are time-consuming and inefficient. Therefore, this paper presented a rapid design method that combined the CFD method and proper orthogonal decomposition (POD) to design the parameters of the tunnel hood more efficiently. The initial transient database was first obtained from the numerical calculation verified by the model experiment, and then the database was extracted characteristically and reconstructed considerably using the POD method. The feasibility and accuracy of the proposed method were validated by implementing the demonstration case of a typical tunnel hood design. It can be seen from the research results that the determination coefficients (R2) of all test cases for transient results between the CFD method and the proposed method are over 0.99; the optimal parameter of this tunnel hood obtained from the POD reconstruction can achieve an approximately 60 % mitigation rate of the MPWmax, which is further verified by the numerical result with a discrepancy of merely 1.87 %. Compared with the traditional CFD method, the proposed method can reduce nearly 98 % of the total design time with a favourable prediction precision.