Analysis Of Aerodynamic Load Characteristics Of Train Operating Pressure Wave Under The Most Unfavorable Tunnel Length

Due to the complex terrain in my country,the number of tunnels is second to none in the world.When a high-speed train passes through a tunnel,a series of aerodynamic problems will occur,which will have a great negative impact on the equipment,carriages,passengers and crew in the tunnel.For the design of high-speed railway tunnels,the most unfavorable tunnel length is an important factor that cannot be ignored.Unlike blocking ratio and vehicle speed,the effect of tunnel length on pressure wave loads is obviously non-monotonic.Based on the above two factors,this paper takes a domestic high-speed train as the research object,and establishes an aerodynamic model based on the operation of the most unfavorable length of the tunnel.After model simplification and mesh division,three-dimensional,unsteady,compressible equations and standard two-equation turbulence models were selected,and Fluent software was used to simulate the aerodynamic characteristics of the train running in the tunnel.The specific research contents are as follows:(1)Established a three-dimensional train-tunnel coupling calculation model for a single train running at high speed in the most unfavorable length tunnel,carried out numerical analysis on the aerodynamic characteristics of the tunnel,analyzed the formation mechanism of the single vehicle operating pressure wave in the most unfavorable length tunnel,and summarized the tunnel surface and The distribution characteristics of the pressure load on the train surface and its relationship with the speed change.(2)Took the constant velocity rendezvous operation under the most unfavorable length tunnel as the research object,established a three-dimensional train-tunnel coupling calculation model of train rendezvous,carried out numerical analysis on the aerodynamic characteristics in the tunnel,studied the propagation law of pressure waves,and analyzed the internal and external characteristics of the tunnel.Changes in the surface pressure of the train.(3)Analyzed and compare the tunnel flow field characteristics and train flow field characteristics during single-vehicle operation and rendezvous operation under the most unfavorable length tunnel;studied the pressure wave changes when a single train and a rendezvous train pass through the tunnel respectively,and the tunnel measurement points at different vehicle speeds.The variation law of the pressure peak value;the pressure distribution curve of the two body measuring points and the nose tip measuring point,as well as the pressure difference change on both sides of the vehicle body were studied.The research results show that:(1)The pressure load range of the tunnel during the intersection operation is 2.25 times that of the single train operation,and the train surface pressure load range is 1.70 times that of the single train operation.(2)When the vehicle speed is 400km/h,the positive pressure peak value,negative pressure peak value and pressure peak peak value of the measuring point in the middle of the tunnel are the largest,which are7055 Pa,-9684 Pa and 16740 Pa respectively.And the pressure peak change rate is the largest during interactive operation,and the average increase percentage of pressure peak is 211.(3)When the vehicle speed increases from 300km/h to 400km/h,the peak-to-peak increase of the minimum pressure on the train surface is 7.15 times the peak-to-peak pressure of the maximum pressure during single-vehicle operation,and the increase of the peak-to-peak pressure of the minimum pressure during intersection operation is 1.78 times of the peak-to-peak pressure of the maximum pressure.