Mechanism of train tail lateral sway of EMUs in tunnel based on vortex-induced vibration

Aiming at the train tail lateral sway of 160 km·h^-1 electric multiple units (EMUs), which occurs in single-track tunnels, the mechanism was put forward that the vortex shedding effect of gas flow in the train tail causes the vortex-induced vibration of the car-body and results in the lateral sway of the train tail. Relevant mitigation measures, such as the optimization of vehicle suspension parameters, were studied. Based on the structural parameters of a certain type of locomotive, the vehicle lateral dynamics model was established and combined with the semi-empirical nonlinear vortex-induced vibrator model to enable the fluid-solid coupling lateral dynamics calculation during the vortex-induced vibration. Calculation results show that a large lateral vortex-induced force acting on the train tail of EMUs in a single-track tunnel and the resonance between the vortex-induced frequency and the car-body hunting frequency are the main causes of car-body sway. Reducing the lateral vortex-induced force and improving the vehicle hunting stability are effective measures to reduce the amplitude of the car-body sway. For this type of locomotive, avoiding wheel-rail contact with a lower equivalent conicity is required to prevent aggravation of the vortex-induced vibration by vehicle primary hunting behavior. When the damping of the yaw damper is reduced from 800 kN·s·m^-1 to 400 kN·s·m^-1, the lateral vibration acceleration amplitude in the rear end of the car-body during vortex-induced resonance is reduced by 40%. When the semi-active control with skyhook damping in the secondary lateral suspension is adopted, the lateral vibration amplitude of the car-body in the vortex-induced resonance zone is effectively reduced. Moreover, the lateral ride comfort at the front and rear ends of the car-body can be guaranteed. 1 tab, 9 figs, 29 refs.