Study On Aerodynamic Performance Of High Speed Maglev Train Passing Through Tunnel

In 2003,Shanghai opened the world's first commercial maglev line,with an average operating speed of 430km/h.In 2016,China started the research and development of high-speed maglev at a speed of 600 kilometers per hour,and developed a high-speed maglev transportation system with China's independent intellectual property rights.The high-speed maglev train runs at a speed of 600km/h,and its aerodynamics will be more complicated than ordinary wheel-rail high-speed.Generally speaking,the aerodynamic problems and phenomena of maglev trains and wheel-rail trains are basically the same.However,because of the different rail relationship between high-speed maglev trains and wheel-rail trains,the aerodynamic problems of maglev trains have their unique characteristics.It is necessary to carry out systematic research work to provide some certain technical preparations for the development of high-speed magnetic levitation in China.This thesis is completed with the support of the national key research and development program"advanced rail transit","Maglev Train/Tunnel Coupled Aerodynamic Behavior Numerical Simulation Study"(2016YFB1200602-39)and the project"Study on the airtightness and airtightness index of high-speed maglev train with a speed of 600 km/h"(SF/GY-D-2018-105)commissioned by CRRC Qingdao Sifang Co.,Ltd.In this thesis,the head shape of a 600km/h high-speed maglev train is being researched in China.The three-dimensional compressible unsteady flow N-S equation and SST?-?turbulence model are used to establish a calculation model of a high-speed maglev train entering a tunnel.The data comparison with the Japanese spin body dynamic model test shows that the numerical simulation method and the mesh division are correct.By analyzing the data of the measurement points arranged in the tunnel and on the train,it is concluded that when the train speed is 600km/h,the tunnel length is 500m,and the tunnel clearance area is140m~2,the external flow field structure,cabin pressure distribution,spatial distribution characteristics and propagation feature of the initial compression wave,also the initial compression wave at different speeds are obtained after the maglev train enters the tunnel.At the same time,the resistance,lateral force and lift characteristics of the maglev train during the stable operation of the open line and through the tunnel are also obtained,and the impact of different head types on the above data is analyzed.Finally,the similarities and differences of the static mesh model and overset dynamic mesh model are analyzed.The main conclusions are as follows:1.The pressure distribution at different measuring points on the same section of the lead train is different.The average pressure fluctuation of the bottom measuring point of the vehicle is the largest,and the other points have approximately the same pressure fluctuation.The pressure of the third car is roughly the same at different monitoring points on the same section.The pressure distribution at different measuring points on the same section of the tail train is different.2.When the train enters the tunnel,the air in front of the train is compressed and propagates forward due to the compressibility of the air,causing the pressure in the tunnel to rise suddenly.When the train's straight body enters the tunnel,an initial compression wave is formed.the pressure near the wall of the tunnel near the car body is significantly greater than the pressure away from the side of the car body,and the pressure wave shows a clear three-dimensional characteristic.When the train enters the tunnel about 36m,the pressure increase near the head of the train tends to be saturated,the pressure distribution is relatively stable,the compression wave has propagated to a distance,and the pressure wave has changed to a one-dimensional wave.The initial compression wave pressure increases with the increase of the speed of the maglev train,but the change trend is the same.According to the curve fitting relationship,the amplitude of the initial compression wave pressure is proportional to the 2.5th power of the velocity,and the amplitude of the pressure change rate is proportional to the 3rd power of the velocity.3.The friction resistance and differential pressure resistance of the train change with time,but the variation amplitude of friction resistance is relatively small.The variation trend of total resistance and differential pressure resistance of the train is relatively consistent.Differential pressure resistance plays a leading role in the variation of train resistance.The existence of the tunnel will have a greater impact on the lateral force and lift.4.The pressure changes of the measuring points on the surface of the maglev train body of different head types are the same,and the amplitude of the pressure fluctuation is slightly different.The pressure changes in the tunnel caused by different head trains are the same,but the pressure fluctuations are different.Compared with the TR08 train,the new head has a lower resistance value,a smaller lateral force,and a higher lift.5.For the analysis of train surface pressure and simple aerodynamic calculation,both the static mesh model and overset dynamic mesh model are applicable.If the flow field structure needs to be analyzed more carefully,the f static mesh DES model or overset dynamic grid DES model is better.