Study On Aerodynamic Characteristics And Control Technology Of High Speed Metro Tunnel

With the continuous improvement of the operation speed of the subway,the aerodynamic problems caused by the high-speed train passing through the tunnel cannot be ignored.In order to study the aerodynamic law of high-speed subway train passing through the interval tunnel and propose corresponding control measures,this paper takes the subway train,section tunnel and the ventilation shaft at both ends of the station as the research object,and combines literature investigation,theoretical analysis,model test and numerical calculation.The method is to study the aerodynamic effects of high-speed subway trains passing through tunnels.Based on Fluent calculation software,three-dimensional viscous,compressible,inequitable,unsteady flow control equations and standard k-? two-equation turbulence models are used,and slip mesh technology is used to simulate different influencing factors in high-speed subway tunnels.The aerodynamic laws were analyzed and summarized.In addition,this paper simulates the reasonable clearance area of the tunnel under different speed grades,and studies the influence law of the ventilation shaft and the station screen door on the aerodynamic effect at both ends of the station,and obtains the reasonable shaft area and height.The main research contents and conclusions are as follows:(1)The numerical calculation model of the high-speed subway train passing through the tunnel is established and the dynamic model test is carried out.The pressure variation law of the measured point and the peak value of the compression wave are basically consistent with the numerical calculation results,which explains the correctness of the numerical model and calculation method.(2)The paper studies the influence of different speed,tunnel length and blocking ratio on the pneumatic pressure in the tunnel.The calculations show that the maximum air pressure in the high-speed subway tunnel is proportional to the square of the train speed,and is exponentially related to the blocking ratio.And the power index is in the range of N=1.3±0.25,which is consistent with the conclusions of researchers at home and abroad in the field of high-speed railway tunnels.(3)This paper studies the changes of pressure inside and outside the vehicle under different vehicle speeds and blocking ratios.The research shows that the peak pressure of the vehicle body surface and the vehicle speed and the blocking ratio satisfy the power exponential relationship,and become larger as the train speed increases and the blocking ratio increases.Combined with the existing norms and related literatures,the corresponding relationship between the following car seal index and the blocking ratio of different comfort standards for high-speed subway tunnels is given.(4)The paper studies the influence of the shaft at both ends of the station and screen door on the aerodynamic effect.The results show that the pressure reduction effect is best when the shafts at both ends of the station are simultaneously opened.The reasonable cross-sectional area of the shaft should be about 32%of the tunnel cross-sectional area,and the height should be controlled at about 20m.