Prediction of micro-pressure wave with the CAA model based on high order spectral difference

Nonlinear acoustical effects of micro-pressure waves at the tunnel portal are shown obviously when 300 km/h high-speed trains run through the tunnel. The micro-pressure wave is about of the order of the magnitude of 10² Pa which can not be simulated accurately by using the traditional CFD method (2 order precision). The CAA model based on the high-order spectral difference method is an alterative way. The CAA method can keep the accuracy of fluid and acoustic variables simultaneously for the region apparant with strong nonlinear acoustical effects. In this paper, the high-order spectral difference method was used to involve the unstructured grid to achieve high computational efficiency and good geometric flexibility. Micro-pressure wave experiments were performed by using the scaled tunnel model and scaled train model for the speed of 200~350 km/h. Computational analysis was made to model the micro-pressure waves by using the 2 dimensional axis-symmetric CAA model with the 3-order spectral difference method. The results of the experiments were in good agreement with the results of numerical calculations.