Study On Wind-induced Vibration Characteristics Of Pantograph/Catenary Under Canyon Terrain

With the promotion of the western development strategy,the West needs to build many railways running in the canyon.The western mountains overlap and the wind field is complex,which is easy to form canyon wind with high wind speed and strong angle of attack.As the only power supply facility of an electrified railway,the pantograph catenary system must ensure its safe and stable current collection under the canyon wind field.In the wind-resistant design of the pantograph catenary system,it is necessary to study the distribution characteristics of wind speed in the canyon and its impact on the pantograph catenary system of high-speed railways.This paper summarizes the variation law of wind field in the canyon through Computational Fluid Dynamics(CFD),deduces the wind load along the catenary according to the formula,establishes the catenary pantograph finite element model,and analyzes the influence of canyon wind on catenary and pantograph systems through finite element simulation.Firstly,CFD is used to simulate the canyon wind field data.By establishing simplified canyon models with different canyon topographic parameters,this paper explores the changes of wind field characteristics in the canyon,and summarizes the changes of wind field in the transverse,longitudinal and vertical directions.The results show that under the influence of the canyon on the characteristics of the incoming wind field(Canyon Effect),the amplitude of the contact line along with the canyon trend and vertical direction increases greatly;When the ratio of mountain height and valley width is large,and the angle between the incoming wind and the axis of the valley mouth is small,the effect of wind on the increase of wind-induced vibration response displacement of the catenary is very obvious under the action of "Canyon Effect".Through the study of a real canyon in the southwest mountainous area,it is found that the spatial distribution characteristics of canyon wind tend to be consistent with typical canyons,but the complex terrain of the real canyon leads to more complex spatial distribution characteristics of wind speed and angle of attack in the canyon,resulting in more complex wind-induced vibration behavior of catenary.Then,aiming at the wind stability of the catenary,based on the research of the canyon wind field,this paper fits the average wind field along the catenary in the canyon.Considering the spatial and temporal correlation of fluctuating wind field,based on autoregressive(AR)model,the fourth-order AR method is used to generate the three-dimensional random wind field along the catenary in mountain canyon.The three-dimensional Timoshenko beam element is used to simulate the spatial large deformation nonlinearity of the catenary,and the nonlinear spring element is used to simulate the nonsmooth nonlinearity of the suspension string.The nonlinear model of the catenary is constructed in the finite element software.By applying static and fluctuating wind loads on the catenary,the wind-induced vibration characteristics of the catenary under a typical canyon are studied.The results show that the crosswind characteristics of the pantograph in the canyon are the same as those in the plain area,but the crosswind has a greater effect on the lifting force of the pantograph.The greater the crosswind speed,the greater the lifting force of the pantograph,the longer and more complex the tail vortex length of the pantograph,and the stronger the asymmetry of the flow field;The steeper the canyon slope is,the greater the aerodynamic lifting force of pantograph is.However,in the wider canyon,the variation range of lifting force caused by slope is small.Finally,aiming at the current collection stability of the pantograph catenary system,this paper constructs a simplified model of the pantograph and deduces the calculation formula of the aerodynamic lifting force of the pantograph.Based on computational fluid dynamics,the variation law of aerodynamic characteristics of pantograph in is deduced.The canyon pantograph model is constructed,and the effects of different incoming wind and canyon parameters on the aerodynamic characteristics of the pantograph are studied.The finite element model of pantograph and catenary is established,and the dynamic simulation characteristics of pantograph and catenary in the canyon are studied by applying catenary wind load and pantograph wind load.The results show that when the pantograph operates in a typical canyon,the greater the crosswind,the steeper the canyon,the greater the contact pressure of the pantograph,the greater the standard deviation,and the higher the off-line rate.