Unidirectional/bidirectional simulations for vortex-induced vibration characteristics of pantograph–overhead contact system

Increase of train speed intensifies the interaction between the pantograph–overhead contact system (OCS) and the high-speed airflow, amplifies the pantograph vortex-induced vibration, degrades the pantograph–OCS interaction, and reduces the quality of the current collection, which is difficult to simulate. In this study, the user defined function in Fluent and overset grid technology were employed to enable real-time data acquisition and grid updates, respectively. The process involved obtaining the aerodynamic loads of each pantograph component in its current posture through Computational Fluid Dynamics calculations, calculating the multibody system dynamics using a dynamic code, adjusting the posture of each component of the pantograph based on the motion of the pantograph mechanism, and updating the grids around the pantograph using overset grid technology. Results show that the bidirectional (Bi.) method resulted in a small contact force in the pantograph–OCS, possibly because of changes in the position of the pantograph–OCS, which significantly affected the surrounding flow field, altered the aerodynamic force, modified the posture, and ultimately led to substantial variations in contact force. Pantograph–OCS in knuckle-upstream direction calculated by Bi. method is more prone to offline state. A Bi. coupling calculation of pantographs is used to better approximate the critical state of the pantograph–OCS, especially for high-speed trains.