A novel vortex control method for improving anti-overturning performance of a high-speed train with leeward airbag structures under crosswinds

Abstract

The high-speed train's head and cross sections have been designed in an innovative way to meet the requirements of aerodynamic drag reduction and crosswind stability of the train. However, with the continuous increase in the running speed of high-speed trains and the continuous reduction of the total weight of the car body, it is critical to develop new strategies to ensure train safety in crosswind environment. In the current study, a novel vortex control method with airbag structure installation on the leeward side (LWS) of the train was proposed to disturb the leeward large vortices, with expectation to weaken the vortices adjacent the train body and increase the surface pressure on the leeward side. The leeward airbag structures (LASs) contribute to reducing the pressure difference between the windward and leeward sides of the train body. As a result, a reduction of the lateral force and overturning moment coefficients is obtained. An amazing observation is that an extra lift force is achieved by LASs, which leads to an anti-overturning moment, further improving the anti-overturning performance of the high-speed train. Compared with the original model, the LASs can decrease the lateral force coefficients by 7.1%, while the lift coefficient is increased by 12.8%, which together reduces the overturning moment coefficient by 13.1%. It indicates that the main influence factor for crosswind stability of the train tends to be changed after the installation of LASs. The aerodynamic performance of the tail car is more sensitive to the LASs as compared to that of the head and middle cars, i.e., the reduction of the overturning moment coefficient is about 44.6% for the tail car, whereas it is only 7.8% and 12.5% for the head and middle cars, respectively. Thus, the LASs proposed in the current work can significantly improve the anti-overturning performance of high-speed trains, which will provide a novel anti-overturning approach for higher-speed trains.