The effect of covering structure in pantograph sinking platform on the aerodynamics of high- speed train

Abstract

The aerodynamic drag of pantograph system hinders the increase of train operating speed, which can be reduced by the covering structure proposed in this study. Exploring the drag reduction mechanism of covering structure is critical. An IDDES method based on the SST κ–ω turbulence model was utilized to study the effect of covering structure on aerodynamic performance of high-speed train. The results show that the covering structure reduces the overall drag by 5.6% for 3-car train-set since the impingement of incoming flow on the surface of sinking platform is alleviated. The aerodynamic drag of the middle car is significantly reduced while that of the tail car increases due to higher pressure on the train joint surface caused by the covering plates. The turbulence of the flow field surrounding sinking platform is suppressed by weakening the flow separations from cavity edge. Vortical structure changes occur to the vortices shed from the leading edge of cavity because the front covering plate delays the process of flow separation, further leading to the alteration of dominant frequencies for folded pantograph. The covering structure will decrease the oscillation of lift force by 24.74% and 37.14% for lifted and folded pantograph.

Keywords

• Pantograph
• covering structure
• sinking platform
• train aerodynamics
• drag reduction