Mitigation of abnormal vibration on high-speed trains under unsteady aerodynamic loadings using bogie skirts

As train speeds increase and operating environments diversify, the issue of abnormal vibration of tail car in high-speed train has become a significant threat to operational stability and safety. In this study, numerical simulation was employed to develop aerodynamic and multi-body dynamics models for 3-car and 8-car train formations. Using the proper orthogonal decomposition method for reduced-order analysis, the research has examined the unsteady flow field distribution, surface pressure, and aerodynamic performance of the train cars at speeds of 200, 300, and 400 km/h, and the aerodynamic optimization was achieved by installing bogie skirts to improve the vehicle stability. The results indicate that the pressure fluctuation regions contributing to lateral aerodynamic loadings vibration are concentrated on the sidewalls near the bogie cabins at heights of z = 0.0 m to 0.8 m. The installation of bogie skirts optimizes the pressure mode distribution and the amplitude of temporal coefficients at these locations, effectively reducing the intensity of lateral aerodynamic loadings. Additionally, the main frequency of the loadings has been increased, thereby avoiding the possibility of resonance caused by aerodynamic loadings frequencies approaching the vehicle suspension's natural frequency. Across all three speed levels, varying degrees of tail car stability improvement were observed. In particular, at 400 km/h, the lateral and vertical Sperling indices were reduced by 6.96% and 9.41%, respectively, effectively mitigating the abnormal vibration in the tail car of long-formation trains caused by aerodynamic loadings during operations.