Effect Of Cutting Structure Under Sudden Wind On Aerodynamic Performance Of High-speed Train

With the rapid development of China’s railway industry,the running speed of trains is constantly increasing,and the aerodynamic problems of trains are becoming more and more prominent.The terrain and landforms along the railways in China are complex,and many areas are subject to strong winds throughout the year,forming numerous different forms of cuts.Due to unique cutting structures such as slope gradient and depth,the aerodynamics of the vehicle increased sharply.Wind speed and wind direction in nature often changes abruptly as the terrain changes.Therefore,it is very important to study the influence of the cutting structure under abrupt wind on the aerodynamics of high-speed trains to ensure the safety of train operation.In this paper,an aerodynamic simulation model of high-speed trains driving in the cuttings is established to study the influence of the cutting structure on the aerodynamic performance of high-speed trains under the action of cross winds and sudden winds,and the lift,lateral force,rolling moment,swaying moment and nod of the train are analyzed.Changes in torque,etc.,discuss the velocity traces and pressure distributions of crosswinds and abrupt winds at different locations;compare the different effects of crosswinds and abrupt winds on the aerodynamic performance of trains,and use the aerodynamic force obtained by the simulation of aerodynamic performance as an excitation guide In the aerodynamic simulation model of high-speed trains,the derailment coefficients are studied to analyze the safety of train operation.The results show that in cross-wind environments,the aerodynamic characteristics of the trains running on the cuttings are significantly changed from the aerodynamic characteristics of the trains on the flat ground.Each aerodynamic force on the 3m cut is lower than that of the trains running on the flat ground,especially the change of the head car Obviously,the lift of the head car is reduced by 77.86%,the lateral force is reduced by 54.49%,the rolling moment is reduced by 67.05,and the shaking moment is reduced by 53.19%.The structure of the cutting has an obvious effect on the aerodynamics of the train;(1)The increase in the depth of the cutting is conducive to reducing the aerodynamic force of high-speed trains.For example,the lift of the 8-meter deep(8-meter)cut is reduced by 46% compared to the 3-meter-deep shallow,The lateral force is reduced by 81.8%,the rolling moment is reduced by 86.7%,and the shaking head torque is reduced by 82%;(2)The aerodynamic force of the high-speed train increases gradually with the slope ratio of the cut becoming slow,the aerodynamic force of high-speed trains gradually increases,and the lateral force of the head car increases by 55.4%.Rolling torque increased by 598% and shaking head torque increased by 86.3%.The abrupt wind load has a great impact on the aerodynamic characteristics of high-speed trains.(1)Compared with the constant wind field,the lift fluctuation of the train in the 3 m deep cutting is 25%,the lateral force fluctuation is 90%,and the rolling torque and the shaking torque fluctuation are respectively Reaching 27% and 40%;(2)With the increase of the depth of the cutting,the fluctuation value of the lift force first rises and then decreases,the fluctuation value of the lateral force first decreases and then rises,the fluctuation value of the rolling moment gradually increases,and the shaking head moment First descend and then rise;(3)Within the slope of 1: 0.5 ～ 1: 1.5,the rolling moment fluctuation value is below 30%,while the fluctuation range of lift,lateral force and rolling moment is large.In the sudden wind environment,with the unusual cutting structure,the train’s operating safety index also changes.(1)Compared with deep cutting(8 meters)and shallow cutting(3 meters),the lateral force increases by 34%,vertical The direction force is reduced by 18%,the wheel load reduction rate is reduced by 31%,the derailment coefficient is increased by 26%,and the overturning coefficient is reduced by 28%;(2)When the cut depth is constant,As the cutting slope slows down As the cutting slope slows down,the vertical force increases by 10%,the lateral force increased by 33%,the wheel load reduction rate increased by 22%,the derailment coefficient increased by 33%,and the overturning coefficient increased by 24%.