Aerodynamic Characteristics Of High Speed Train Under Cross Wind At Tunnel Exit

Sichuan Tibet railway is characterized by large altitude drop,high proportion of bridges and tunnels,dense tunnels and frequent valley wind.Therefore,Sichuan Tibet railway trains need to pass through various long tunnels frequently,and inevitably face the situation of driving out of the tunnel in cross wind environment.The aerodynamic force is very complex when the train leaves the tunnel at high speed.The external aerodynamic load on the train will be more severe,if the train encounters a crosswind when it leaves the tunnel.The dynamic performance of the train will deteriorate sharply,and the safety of train operation will be seriously affected under such a complex aerodynamic load.The loss will be immeasurable once the high-speed train capsizes due to strong wind when it leaves the tunnel.Therefore,it is very necessary to study the aerodynamics of high-speed train in the process of leaving the tunnel,under the background of large-scale construction of Sichuan Tibet railway and other difficult mountainous areas.In this thesis,the transient calculation model of aerodynamic force of high-speed train is established by taking a high-speed train as the research object,based on the basic theory of aerodynamics.This thesis uses the fluid analysis software FLUENT to carry out aerodynamic simulation.The transient aerodynamic characteristics of high-speed train are studied at the exit of tunnel in complex cross wind environment in this thesis.The main research work includes the following parts:(1)This thesis introduces the development history of high-speed railway in China and the research status of train aerodynamics.This thesis explains the significance of calculating the aerodynamic characteristics of the train at the exit of the tunnel in cross wind environment combined with the research background of Sichuan Tibet railway.(2)The calculation model of transient aerodynamic characteristics of high-speed train at tunnel exit in cross wind environment is established based on the basic theory of aerodynamics in this thesis.(3)This thesis studies the aerodynamic characteristics of high-speed train out of the tunnel under cross wind condition.This thesis obtains the relationship between the pressure distribution on the train surface,flow field characteristics,aerodynamic load and cross wind speed and wind direction angle.(4)The aerodynamic characteristics of the head car,the middle car and the tail car are studied when the train leaves the tunnel under certain wind speed in this thesis.This thesis compares and analyzes the surface pressure distribution,flow field characteristics and aerodynamic characteristics of high-speed trains at different speeds.(5)This paper studies the influence of complex plateau meteorological conditions on the transient aerodynamic characteristics of high-speed train at the tunnel exit in cross wind environment by taking the typical section of Sichuan Tibet railway tunnel as an example.The results show that the aerodynamic force of high-speed train increases with the increase of wind speed when it is driven out of the tunnel.The variation trend of aerodynamic force is different under different wind directions,and the aerodynamic force of the train is the largest under 90 ° wind direction.The train aerodynamic force increases with the increase of vehicle speed,and the change trend of vehicle aerodynamic force is basically the same under different vehicle speed.The aerodynamic characteristics of vehicles at different positions in high-speed trains are different.The aerodynamic amplitude of the head car is the largest,the aerodynamic amplitude of the middle car is the smallest.Therefore the aerodynamic safety of the head car is the worst.The plateau meteorological conditions have a great influence on the train aerodynamic force.The higher the altitude,the lower the air pressure,and the lower the aerodynamic force on the train.