| China has a vast territory with complex and diverse landforms,with plains accounting for only 12%of the country’s total area.Therefore,the railway is bound to pass through mountainous areas,and it is necessary to build tunnels and tunnel groups of different lengths to meet the operational requirements.With the increase of train speed,the aerodynamic problems of high-speed trains passing through tunnels are becoming more and more obvious,which have adverse effects on the safety,economy,comforts of passengers and surrounding environment of the tunnel.A high-speed train with 8-carribage formation is taken as the research object,and a coupled aerodynamic model of train-tunnel is established in the research.Based on three-dimensional,unsteady,compressible N-S equation andκ-εturbulence model,the Fluent is used to simulate the whole turbulence process of a single high-speed train passing through tunnel with a length of 1000 m and an effective area of 100 m~2.The specific research contents are as follows:(1)The results of one-dimensional flow model,three-dimensional flow model and theoretical calculation formula in aerodynamics industry standards are compared and analyzed for the first time.(2)The three-dimensional effect of tunnel surface pressure,the change characteristics of tunnel longitudinal position and the influence characteristics of train speed on tunnel surface pressure during the process of a single high-speed train passing through the tunnel are studied.(3)The variation of surface pressure,internal pressure and pressure difference between inside and outside of a single high-speed train during the process of passing through the tunnel are studied.Including train surface pressure three-dimensional effect,three kinds of pressure change characteristics of different carriage,dynamic airtight index for interior pressure characteristics and the influence of train speed on three kinds of pressure.(4)According to the current relevant standards of high-speed railway in China,The aerodynamic effect of tunnel is evaluated,including the air tight load and human comfort.The results show that:(1)the relative error of maximum pressure peak-peak under one-dimensional flow model,three-dimensional and theoretical calculation formula in aerodynamics industry standards is 10.70%,verifying the accuracy of the calculation results and the applicability of the numerical calculation method.(2)The three-dimensional effects of pressure at the entrance of tunnel are significant,and the increase of train speed will aggravate the effect.The amplitude of pressure change is larger in the middle of the tunnel,and smaller at both ends of the tunnel.The maximum pressure peak-peak in the middle of the tunnel is twice as high as that of both ends of the tunnel.(3)At the same speed,from the front to the rear of the train,the peak value of positive pressure gradually decreases,while the peak value of negative pressure gradually increases.The greater the train speed is,the greater the pressure on the surface of the train body is,and the maximum pressure peak-peak in the center of the side of the train is approximately squared with the train speed.(4)The amplitude of internal pressure fluctuation is far less than that of external pressure fluctuation,and it lags behind that of external pressure fluctuation in time.With the increase of the train speed,the variation range of the pressure inside the train and the pressure difference between inside and outside the train body is larger,and the maximum pressure peak-peak of the pressure difference between inside and outside the train body is approximately proportional to the square of the train speed.(5)After examination,the airtight load of the train body and the comforts level of human body meet the relevant standards of China’s high-speed railway. |
PDF Full Text Request