Simulation and experimental study on aerodynamic characteristics of urban rapid trains in tunnel operation

This study addresses the aerodynamic challenges faced by urban rapid trains during full-tunnel operation, focusing on transient pressure fluctuations induced when trains pass through tunnels and micro-pressure waves at tunnel exits. By elucidating the distribution patterns of aerodynamic loads in complex flow fields, a technical index system was developed to harmonize passenger comfort and environmental noise control. A comprehensive approach integrating multi-physics numerical simulations, a dynamic model test system for train aerodynamics, and real-train dynamic testing was employed to conduct systematic aerodynamic performance simulations and experimental studies within tunnels. The findings indicate the following: a. The amplitude of pressure on the car body surface is positively correlated with the operating speed raised to the power 2.0-2.2, with the maximum pressure (positive/negative) peaks remaining below the train fatigue strength threshold of 4000 Pa. b. The positions of pressure peaks on the tunnel walls are relatively fixed, with a consistency of pressure fluctuations exceeding 95% at the same cross-section. c. When the train’s dynamic airtightness index is 6 s, the pressure fluctuations inside the car can be effectively controlled to no more than 296 Pa within 1 s and no more than 645 Pa within 3 s, meeting passenger comfort requirements. d. The amplitude of micro-pressure waves increases with speed following a power function, all below the environmental noise sensitivity threshold under the study conditions. These findings validate that the aerodynamic performance of urban rapid trains in full-tunnel operation can reliably satisfy the requirements for passenger comfort and environmental noise control, providing a solid scientific basis for the optimal design and safe operation of full-tunnel urban rapid trains.