Aerodynamic degradation of high-speed maglevs meeting in crosswind environments and mitigation using symmetrical slit jets

When maglev trains operate at 600 km/h, the coupled interaction between crosswind and pressure waves generated during train meetings leads to significant aerodynamic performance degradation, threatening operational safety. This study investigates this issue and explores mitigation using symmetrical slit jets (SSJs). A coupled computational fluid dynamics model integrating crosswind, trains, bridge, and air is established using the dynamic overset grid method and the unsteady Reynolds-averaged Navier–Stokes approach, validated against moving-model tests. Results show that under crosswind conditions, the amplitudes and rates of change of aerodynamic coefficients during meetings are significantly greater than those in no-wind conditions. The leeward train experiences higher aerodynamic loads than the windward train. These amplitudes and change rates follow a power-function relationship with both average wind speed and train speed. Compared to mid or upper configurations, lower-section SSJs provide the most effective mitigation, reducing the amplitudes of lift force, lateral force, rolling moment, and yaw moment by 6.1%, 8.6%, 16.7%, and 9.2%, respectively. During the train meet process, significant vortex shedding occurs from the head and tail carriages. The continuous generation and shedding of vortex structures lead to increased fluctuations in the aerodynamic loads on the train. Throughout the motion, the aerodynamic load fluctuations on the head and tail carriages are markedly greater than those on the middle carriages. The SSJs generate finer and more fragmented vortex structures between the trains. The reduction in vortex volume contributes to a decrease in aerodynamic loads. The SSJs can significantly reduce the pressure difference in the blowing region. These findings offer theoretical support for the wind-resistant design of 600 km/h maglev trains.