Research on numerical simulation of transient pressure for the high-speed train passing through the most unfavorable length tunnel

The length of the high-speed railway tunnel is an important factor affecting the transient pressure. When the tunnel length is the most unfavorable, the transient pressure changes in the tunnel and on the surface of the train are the most severe, which may affect the safe operation of the train or damage the structure in the tunnel. Based on the three-dimensional, compressible, unsteady N-S equation and finite volume method, this paper uses the CFD numerical simulation method to study the change and amplitude distribution of the transient pressure on the train surface and the tunnel when the high-speed train passes through the most unfavorable length tunnel. And a fast calculation method is proposed to save the cost of calculation, it has a great applicability of pressure amplitude. The results show that the pressure distribution in the tunnel and on the surface of the train is affected by the train speed, the length of the train and the position of the measuring point. The minimum negative peak value in the tunnel appears at the position where the superposition phenomenon is most severe, and the position will change with the speed of the train. There are two negative peak waveforms of the train surface pressure, and the first waveform is greatly affected by the train speed. It improves a reference for studying the strength requirement of the most unfavorable length tunnels and trains and ensures the safe operation of trains in tunnels of different lengths.