An Integrated Method for Predicting Tunnel Pressure Wave Effects

摘要

This paper presents the development of an integrated method for predicting pressure fluctuations in high speed railway tunnels and micro pressure waves at the tunnel exit within the same framework. The method incorporates the aerodynamic acoustic theory of compression wave generation and the one-dimensional unsteady compressible flow model of tunnel pressure wave propagation. The amplitude and the form of the initial compression wave are calculated with the approximate Ffowcs Williams-Hawking equation describing the generation of aerodynamic sound by moving surfaces. The three-dimensional effects of the geometry of the tunnel portal and of the configuration of the tunnel entrance hood are effectively taken into account via a potential function. The profile of the train nose is modeled by a distribution of volume sources traveling at the train speed. As the length of the tunnel is much larger than the hydraulic diameter of the cross-sectional area of the tunnel the flow generated by the train in the tunnel is essentially one dimensional; thus the plane wave propagation approximation can be applied, and the wave propagation, reflection and superposition can be dealt with by the one-dimensional unsteady compressive flow model. The method is computationally efficient and has the potential to be developed into a simulation tool for tunnel designers to examine tunnel aerodynamic effects both in sizing the cross-sectional area of the tunnel and in optimizing the configuration of the entrance hood.