Research On Wind Induced Driving Safety And Wind Resistance Methods Of Van On Sea Crossing Bridge

As an indispensable part of the transportation network,bridge construction in China has been in full swing.The elevation of bridge is higher than the road,and there is a complex wind environment nearby.The strong crosswind accompanied by bad weather will pose a serious threat to the safety of driving on the bridge.At the same time,crosswind will produce aerodynamic force acting on the wind pressure center of the vehicle.The wind pressure center usually does not coincide with the center of gravity,resulting in aerodynamic side force,aerodynamic lift,yaw moment and roll moment,which will change the driving characteristics of the vehicle and make the vehicle deviating from the normal driving direction,even roll,sideslip,rollover,etc.Because of the large aspect ratio,high body height and center of gravity position,large side area and the trend of lightweight design,the lateral wind sensitivity of vans is intensified.Therefore,it is significance to study the safety of van on the sea crossing bridge.In this paper,the single coupling method is used to study the driving safety of van under different wind speed.Firstly,a 1:10 van bridge model is established,and the starccm+ software is used for numerical simulation.By comparing the data of numerical simulation and wind tunnel test,the reliability of the simulation method is verified.The numerical analysis of the van bridge model is carried out by using the overlapping dynamic grid method.The simulation conditions include the driving conditions of different lanes and different crosswind levels.The analysis shows that there are great differences in the aerodynamic characteristics of van in different lanes.The aerodynamic force of vehicles on a single bridge gradually decreases from the windward side,and the aerodynamic force of the first lane on the windward side is the largest.When the vehicle speed is constant,the drag coefficient,lift coefficient and roll moment coefficient of the vehicle decreased with the increasing of crosswind wind speed,while the lateral force coefficient,trim moment coefficient and yaw moment coefficient increase with the increase of crosswind wind speed.Secondly,Trucksim was used to establish the dynamics model of van,and the multi-body dynamics method was used to realize the driving conditions of van under different wind speeds,different speeds and different road roughness,and qualitative and quantitative evaluation indexes are adopted to analyze the phenomenon of slip and sideslip,and the following conclusions are drawn: when the crosswind speed is less than 22m/s(Level 9 wind),the driver of van is more comfortable in dry,wet and waterlogged road conditions Through reasonable control,the van can drive safely within the speed limit(80km/h);when the crosswind wind speed reaches at 22m/s(Level 9 wind),the van can drive safely on dry road,wet road and waterlogged road at 80km/h,80km/h and 50km/h respectively;when the crosswind wind speed reaches 25m/s(level 10 wind),the van can drive safely on dry road,wet road and waterlogged road.The speed of road safety driving is 50km/h,50km/h and 40km/h respectively.Finally,10 groups of different types of windshield barriers were designed and manufactured,and the windshield performance of different structures was analyzed by model wind tunnel test method.The analysis results show that the windshield barriers can greatly reduce the wind speed of the bridge deck and the aerodynamic force of vehicles,among which the windshield barriers with circular holes on top and bottom are the best.According to the simulation of van with wind barrier,the aerodynamic force of van before and after installing wind barrier is analyzed from the surface pressure of van,the distribution of flow field nearby and the change of vorticity around the car body.After installing the wind barrier,when the lateral wind force is 10 or less,the truck can drive safely on the dry,wet and waterlogged road of the cross sea bridge within the speed limit of 80km/h.