Numerical simulation of pressure variation during train passage in tunnel

Abstract

When a train travels through a tunnel at high speed, large pressure variations, which act on tunnel lining, equipments inside the tunnel, and the train, are generated in the tunnel. To predict these pressure variations, numerical simulations have been developed. Usually, one-dimensional simulations are used for such purposes. Although the pressure variations caused by the pressure waves can be calculated accurately by one-dimensional simulations, they can underestimate the pressure variations in the area very close to the passing train. The resulting accuracy can be increased by using computational fluid dynamics (CFD), but CFD requires high computational costs. Therefore, this paper proposes a three-dimensional but an efficient method to calculate accurately the pressure variation in the area very close to the passing train in the tunnel. It takes into account the distribution of cross-sectional areas of the train nose and treats the flow around the train nose as three-dimensional potential flow, and the upstream and downstream boundary conditions are specified by a one-dimensional simulation in order to calculate the effect of the pressure waves. The results by this method agree well with those of model experiments by using axisymmetric train model although the discrepancy to the model experiments by using actual shape train still remains.