Analysis Of Aerodynamic Characteristics Of High Speed Train-Bridge System Under Gusts

In the gust environment,when a high-speed train enters a bridge from an existing line,it may cause a derailment accident due to a large change in its own aerodynamic characteristics.This is because the wind field in the real environment is not a constant wind field,but is constantly changing in direction.Even if the average wind speed of the gust is not enough to cause the train to derail,when the wind speed is superimposed over time to the extreme wind speed,the train The probability of derailment shows an exponential increase.Therefore,it is important to study the safety of the following vehicles on the bridges to ensure the safety of the trains in operation.This paper firstly analyzes the pressure distribution of the train surface when the flow field of the train is no wind,constant wind and gust,and analyzes the characteristics of the external flow field around the following vehicles in different wind environments.Second,select different operating conditions and analyze how the changes affect the aerodynamic loads on the train.Contrasive analysis of gusts and constant winds respectively,changing the impact of a single working condition on the aerodynamic load of the train.On this basis,we study the similarities and differences between the gusts and the effects of constant wind on the aerodynamic loads of trains.In addition,the trend of the aerodynamic load of the train under different working conditions with time is analyzed in a complete time course of gust action.Calculate the aerodynamic loads of the following vehicles under the various working conditions and analyze the variation of the aerodynamic load between different working conditions.Comparative analysis In the same time,when the gust and constant wind respectively act,the aerodynamic load of the train changes with time.Finally,calculate the security domains for the following vehicles with different safety indicators.On this basis,the changes of different safety indicators under the influence of gusts and constant winds are compared and analyzed,and the variation range of gusts relative to the safety indicators of constant winds acting on trains is analyzed.Based on all the results,the operating safety zone of the high-speed train on the bridge in the gust environment is obtained.Through research,it is found that the speed of the head car is up to 375.8%during the speed of 350?380 km/h.In the process of wind direction angle from 30?45°,the lift of the head car is the fastest,the increase.252.1%;in the process of wind attack angle from 10?25°,the head vehicle received the largest change in nodding moment,which increased by 165.3 kN·m;in the process of extreme wind speed from 27.3?53.2 m/s,the head car and The shaking moment of the tail car showed an opposite trend.When the extreme wind speed is 49.3 m/s,even if the vehicle speed is 200 km/h,the train cannot travel safely and it is necessary to continue to reduce the speed.When the extreme wind speed is 49.3 m/s and the vehicle speed is 350 km/h,even if the wind direction angle is 15°,the train can't drive safely,and it is necessary to reduce the speed in time.When the extreme wind speed is 49.3 m/s and the vehicle speed is 160 km/h,the train can travel safely above the 15°wind angle of attack.When the vehicle speed is 160 km/h,the extreme wind speed should not exceed 34.1 m/s.In addition,by changing the wind environment and analyzing the safety of the head car,it can be seen that the vertical force of the wheel and rail changes at different times under the same set of working conditions is not obvious,and the fluctuation range under the gust is only 54.72%.The increase and decrease of the wheel load shedding rate is more obvious,and the fluctuation range under the gust is 204.74%.Therefore,the wheel load shedding rate should be considered as the main safety evaluation index.