Numerical study on longitudinal impact of a high-speed maglev train in aerodynamic plate braking with impact mitigated by optimization of buffer damping at car-connection

Maglev train speeds exceed 600 km/h, with significant longitudinal impact between vehicles during braking and acceleration affecting ride comfort. Studying the unsteady aerodynamic and longitudinal impact characteristics of a 600 km/h high-speed maglev train during plate braking with and without crosswind, we realized braking plate motion using dynamic grid technology and simulated the flow field around the train using the time-averaged Reynolds equation and shear-stress-transport k–ω turbulence model, which were verified by wind tunnel test data. Braking force of the plate under crosswind stabilized faster than under no crosswind. Meanwhile, the aerodynamic drag fluctuation of the plate under the crosswind was more severe, particularly the top braking plate of the middle car. Aerodynamic drag fluctuation of plate 4 on top of the middle car increased by 90% under crosswind, intensifying the longitudinal impact between vehicles. Plate braking effectively assists the eddy current braking system in performing emergency braking under high-speed conditions, reducing the load on the eddy current braking system. To address the longitudinal impact issue stemming from the combined emergency braking of plate and eddy current under crosswind, the impact was effectively mitigated by strategically placing longitudinal dampers between the vehicles, optimizing their damping value through particle swarm optimization. After optimization, positive peak value of longitudinal deceleration of the middle car 1, with the worst stability under crosswind, decreased by ∼8%, and negative peak increased by ∼14%, reducing maximum impact amplitude by ∼22%. The results provide reference for the emergency braking and longitudinal impact issues of high-speed maglev trains.