Research On The Safety Of Vehicles On Long Span Bridge Under Crosswind

All along,the sudden crosswind in the transportation process is an urgent problem to be solved,the fluid environment around the vehicle body will change dramatically when the vehicle is running at high speed encountering sudden crosswind,the stability of the car will be affected to a certain extent,and serious traffic accidents may occur.In real life,because of some characteristics of atmospheric boundary layer near the ground,the environment of long span bridge is relatively special compared with other environments,sudden crosswind in this state may be more destructive,and more unpredictable.In recent years,the construction of long span bridges in China has been accelerating and increasing,and the impact of sudden crosswind on vehicles in such scenarios is also greater,the flow field after crosswind passing through the windbreak of bridge is very complex,and the complex flow field will make the vehicle produce variable aerodynamic load,and the sudden aerodynamic load may cause the vehicle to lose the driving stability.Therefore,it is necessary to study the safety of the vehicle on the long span bridge in crosswind environment.In this paper,the real vehicle is modeled in equal proportion,and the integrity of the model is ensured on the basis of considering the feasibility of calculation.Based on the theory of computational fluid dynamics,the Large eddy simulation(LES)is used in the turbulence model to establish the windbreaks with different heights,clearances and diameters on the bridge.The aerodynamic loads of the car body and the flow field around the vehicle body are obtained.By comparing the calculated aerodynamic force with the aerodynamic load of the vehicle under different crosswind levels,the change of vehicle stability under different forms of protective windbreaks is understood.The results show that: to a certain extent,the stability of the vehicle will increase with the increase of the height of the windbreak.The change of the lift and lateral force of the vehicle is mainly caused by the turbulence after the crosswind passes through the windbreak.The change of the windbreak diameter will cause the change of the crosswind flow state.Therefore,the stability of the vehicle will increase to a certain extent with the increase of the diameter It does not increase linearly,but also decreases.Through the analysis of these working conditions,this paper also evaluates the safety of the vehicle driving state according to the data obtained from the numerical simulation,and gives the corresponding suggestions for the design of windbreaks.