Research Of Fluid-Solid Coupling Characteristics In Transient Wind-Train-Wind Barrier System

With the maturing of China's high-speed railway construction,now there are a lot of sections with a wind barrier,on the one hand,blocking the spread of noise,on the other hand increasing train running safety in cross wind.But,after adding the wind barrier,the high-speed train flow field around the structure changed,wind barrier position and height setting unreasonable may play a role of over protection.At the same time,given the nature of fluctuating wind volatility,namely the size of the wind speed value changes over time,influence is more serious than the constant wind speed of the high-speed train under the cross wind.So it is necessary to explore the natural barrier of high-speed train aerodynamic performance and the influence of dynamic performance,by simulating the natural environment in the real transient wind conditions,in order to reasonable set of wind barrier of high speed railway and provide reference for the safe operation of the train on the wind barrier sections.The thesis gets natural transient by actual observation wind with the variation rule of observation time,on the premise of considering the calculation efficiency,yet the natural wind pulsation regularity,at the same time,considering the change of the extreme natural wind,simplify the model properly.Then respectively establish high-speed train aerodynamics model with the multi-body system dynamics model using Fluent software and SIMPACK software,and through user-defined functions UDF to simulate real natural transient wind,loaded into the train aerodynamics,considering the train operation in the embankment and the working condition of the viaduct presence of wind barrier,and the wind barrier height and different running speed on the aerodynamic influence of the train.In terms of dynamics of multibody system,through the Input Function to write the aerodynamic load Function,and loads it into the vehicle system dynamics,get on the train operation safety parameters under the influence of the aerodynamic load.The research results show that the embankment and bridge without wind barrier of constant cross wind conditions,head train's windward appear relatively large positive pressure area,leeward side appear massive negative pressure zone,maximum differential pressure is 8500 pa,and as far away from the head of the train running direction,pressure area is significantly reduced on windward side,and leeward side away from the train running direction pressure increased.After adding the wind barrier,train windward and leeward side pressure difference significantly reduced,and in the area between the train and wind barrier form vortex,vortex of train leeward side is larger when the train is the farther distance.In natural transient wind conditions,train head surface pressure and sectional velocity contours and the velocity streamline diagram represents the characteristics of the changes over the wind speed value,at the same time have a certain delay.In train aerodynamic load,the aerodynamic force and moment obviously decreases after adding wind barrier,aerodynamic moment stay between-200kN · m and 200kN · m,and that the wind barrier protection for car body played a role.When the wind barrier height change,train's lateral force,rolling torque,torque shook change extremely in value direction and the size,which show the characteristic of the changes over fluctuating wind.When the train speed increase gradually with increase of 50 km/h from 200 km/h to 400 km/h,the train operation maximum aerodynamic drag growth rate is 9.82%,10%,8.83%and 10%respectively.When the train runs at a speed,as the instantaneous wind speed value higher or lower,aerodynamic drag and side force also increase or decrease accordingly,showed significant positive correlation.In terms of the train running safety,when adding wind barrier,head train derailment coefficient,lateral wheelset force and vertical force of wheel and rail wheel load rate significantly decreased,when the pulsating wind speed simulation process,the index has been changes over time,showed no change with aerodynamic load rule into the tendency of positive correlation to instead of random fluctuations.