Numerical analysis on the dynamic airtightness of a railway vehicle passing through tunnels

Artikel i vetenskaplig tidskrift, 2020

A high-speed train passes through a tunnel, the generated pressure wave largely impacts train body and will propagate into carriages through gaps, which brings passengers ear discomfort issues in the daily traffic. The dynamic airtightness of railway vehicle indicates the sealing performance of carriages that means how much the interior room will be influenced by the tunnel pressure wave acting on the train body surface. This paper presents an investigation on the dynamic airtightness of high-speed trains and the unsteady pressure changes that are transmitted from outside to inside compartment of the train. Unsteady compressible Reynolds-Averaged Navier-Stokes simulations were used to study the dynamic sealing performance of a railway vehicle as a function of factors such as amplitude and frequency of the exterior pressure variations, the equivalent leakage area, and the scaling ratio of the carriage model. It is found that the dynamic airtightness coefficient exhibits a close inversely proportional relationship with the leakage area; the leakage area plays a decisive role in the dynamic airtightness of the carriage. For a given leakage area, the mechanism of pressure transmission from the outside to the inside of the carriage is found not to change with variations in the amplitude and frequency of the exterior pressure. In the same time, the dynamic airtightness coefficient τdyn is found to have a direct and fixed inversely proportional relationship with the scale factor of the carriage model.