Aerodynamic characteristics and vibration analysis of high-speed trains equipped with WRBD

With the rising speed of high-speed trains, the unsteady aerodynamic characteristics of wind resistance braking devices (WRBD) notably affect operational stability. This study established a three-car train model with a proprietary encapsulated WRBD, simulating its unsteady flow field at 250–400 km/h via the IDDES method based on the SST k-ω turbulence model. The simulation is validated by 1:12 scale wind-tunnel tests, with a maximum 8.9% deviation in aerodynamic drag coefficient that meets engineering accuracy. WRBDs increase aerodynamic drag by 75.2% at 400 km/h compared to the non-WRBD train, and the drag shows quadratic speed dependence with the head car as the main contributor. WRBDs optimize lift distribution and enhance wheel-rail adhesion by reinforcing negative lift; the head car lift decreases by 4.26 kN and the total train lift decreases by 3.91 kN as speed rises from 250 km/h to 400 km/h. Combined with dynamic mode decomposition (DMD), the vortex evolution characteristics are revealed, and WRBDs induce resonance risks due to overlapping vortex shedding and train suspension vibration frequencies. WRBDs alter the spectral characteristics of unsteady aerodynamic loads, raising low-frequency energy density and shifting dominant frequency bands. These results reveal the unsteady aerodynamic–vibration coupling mechanism of the WRBD–train system, providing support for the aerodynamic optimization, vibration suppression, and dynamic stability control of wind resistance braking systems.