Influence Of Sudden Change Of Wind Loads On The Safety Of High-speed Trains

Strong wind in natural environment has a great impact on the safety of high-speed operation.When the train runs at high speed in windy environment,its aerodynamic load and safety index will change significantly,and the safety of train operation will be reduced,which is easy to cause traffic accidents.Therefore,it is necessary to study the impact of sudden changes in aerodynamic and dynamic performance of trains caused by sudden changes in wind load on the safety of high-speed train operation,so as to provide reference for safe operation of trains in natural environment.In this paper,the domestic CRH3 high-speed emu is taken as the research object to study the aerodynamic characteristics and operational safety of high-speed trains under different wind load environments when there is no wind barrier and when there is wind barrier.Firstly,Fluent software was used to simulate the external flow field of high-speed trains in the calm and windy environment,and to analyze the changes of the external flow field of high-speed trains in the calm,crosswind,step wind and crosswind environment,as well as the rules of aerodynamic load changes in the wind.Then,in combination with vehicle multi-body dynamics,the aerodynamic loads calculated in fluid mechanics were loaded into vehicle system dynamics using the Input Function,and the train operation safety index parameters under the influence of aerodynamic loads were obtained.The results show that the sudden change of wind load has great influence on the safety operation of the train.In the natural wind environment,the aerodynamic characteristics of the train are the most complex,and the aerodynamic load changes the most.When the wind load suddenly changes,the transverse force of the head car increases by 67%,the lift force changes from negative to positive,and the roll torque of the head car changes little.In natural wind environment,the four indexes of evaluating train safety coefficient are the largest,step wind is the second,and cross wind is the smallest.Over without wind barrier of lines,natural environment of the derailment coefficient,wheel load ratio of load,lateral wheelset force and the maximum wheel/rail vertical force,respectively,than the step of gust environment increases 26%,24%,64%,14%,than the horizontal wind environment increased 83%,39%,78%and 31%,respectively,the wind load is an important factor affecting the safe operation of the high-speed train.To reduce the wind load effect,after the installation of wind barriers,natural environment train derailment coefficient,wheel weight reducing load rate,lateral wheelset force and wheel/rail vertical force,respectively,compared with no wind barrier fall by up to 41%,47%,55%,30%,horizontal wind environment,train derailment coefficient,wheel weight reducing load rate,lateral wheelset force and wheel/rail vertical force,respectively,compared with the most don't wind barrier reduced by 67%,30%,10%,8%,step wind environment train derailment coefficient,wheel weight reducing load rate,lateral wheelset force and wheel/rail vertical force,respectively,compared with no wind barrier fall by up to 69%and 38%.17%and 21%indicate that the wind barrier has a blocking effect on crosswind.After installing the wind barrier on the line,the running safety of the train is improved.