Numerical analysis on dynamic airtightness of a high-speed train passing through tunnels based on equivalent leakage coupling

Abstract

When a high-speed train passes through a tunnel, pressure waves are transferred inside and outside the train through equivalent leakage holes. This study focuses on the flow field coupling of the train's interior and exterior by establishing a numerical model. Using the RNG k-ε turbulence model and sliding mesh approach, numerical simulations are conducted to investigate the dynamic airtightness of the train during tunnel transit. The simulations analyze the effects of equivalent leakage hole parameters and operational environments, including leakage hole area and position, train speed, and tunnel length. The accuracy of the simulation method is validated by comparing results with full-scale tests, demonstrating consistency with theoretical calculations. Results show that the dynamic airtightness index decreases as the leakage hole area increases, indicating an inverse relationship. Pressure variations inside the train are primarily influenced by external pressure near the leakage hole. The greatest airtightness index of 10.82 s occurs when the leakage hole is located at the train's top. The most significant internal pressure changes occur when the train passes through a 110 m tunnel, leading to the lowest dynamic airtightness index. For tunnels longer than 110 m, the dynamic airtightness index stabilizes, with variations remaining below 2 %.