Dynamic Behaviors and Mitigation Measures of a Train Passing Through Windbreak Transitions from Ground to Cutting

In this paper, the effects of a right-angle windbreak transition (RWT) from the flat ground to cutting on train aerodynamic and dynamic responses were investigated, then a mitigation measure, an oblique structure transition (OST) was proposed to reduce the impact of RWT on the train aerodynamic and dynamic performance. The results showed that in the RWT region, the airflow was divided into two parts. One part of the airflow induced a strong backflow in the flat ground position, and the other part of the airflow induced a strong backflow in the cutting position. Therefore, there were two lateral impacts on the train. For the head car with the OST, the drop ratios of the peak-to-peak values compared with RWT were 47％, 40％, and 52％ for the side force coefficient CFy, lift force coefficient CFz and overturning moment coefficient CMx, respectively. For the peak-to-peak value of the dynamic parameters, the drop ratios of OST compared with RWT were all larger than 50％. The maximum dynamic overturning coefficients for RWT and OST were 0.75 and 0.3, respectively.