To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility par...To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility parameters including the shaft(location L,cross sectional dimension W,height h),tunnel portal(cross sectional area S),and openings(spacing D,side length F)on the evolution of tunnel aerodynamic effects.By integrating three dimensional unsteady flow field numerical simulations with a dynamic model testing system,the research notably reveals the regulatory mechanisms of these parameters on the evolution characteristics of the initial compression wave pressure gradient and the multi peak structure of micro-pressure waves.The results show that shaft parameters significantly affect the initial compression wave.Both the wave amplitude and gradient exhibit a linear negative correlation with cross sectional dimension W and a linear positive correlation with location L,while demonstrating a nonlinear relationship with height h,the amplitude follows a cubic polynomial trend,and the gradient initially increases before plateauing.Under the configuration W=8 m,L=50 m,and h=20 m,substantial reductions in both compression wave amplitude and gradient were achieved.The portal cross sectional area S shows a"U-shaped"relationship with the compression wave gradient,with the maximum gradient reduction of 53.24%occurring at S=210 m^(2),a result comparable to that achieved with optimized opening parameters(D=15 m,F=3.5 m,53.96%).Regarding micro-pressure waves,the amplitude measured 20 m from the tunnel exit shows a linear positive correlation with shaft parameters L and W,while the influence of h saturates beyond 50 m.Reductions exceeding 54%were achieved with portal parameters,either at S=210 m^(2) or using the optimized opening configuration.Furthermore,micro-pressure waves near the portal exhibit a consistent dual peak structure:the first peak originates from the train entry compression wave,and the second results from further wave compression after tunnel exit.The opening location governs selective peak regulation openings near the portal entrance primarily suppress the first peak with minimal impact on the second,whereas centrally located openings reduce the first peak but can amplify the second by up to 3%.Based on these insights,an optimized parameter configuration is proposed:a shaft with a cross-sectional dimension≥8 m located 50 m from the portal,a portal cross sectional area of 210 m^(2),and openings spaced at 15 m intervals.This configuration can reduce the initial compression wave gradient by over 50%.The results provide a theoretical foundation for controlling aerodynamic effects of superconducting maglev train.展开更多
The tunnel-train-air interaction problem is investigated by using a numerical method able to provide relevant information about pressure fluctuations,aerodynamic drag characteristics and the“piston wind”effect.The m...The tunnel-train-air interaction problem is investigated by using a numerical method able to provide relevant information about pressure fluctuations,aerodynamic drag characteristics and the“piston wind”effect.The method relies on a RNG k-εtwo-equation turbulence model.It is shown that although reducing the oblique slope can alleviate the pressure gradient resulting from initial compression waves at the tunnel entrance,the pressure fluctuations in the tunnel are barely affected;however,a large reduction of micro-pressure wave amplitudes is found outside the tunnel.In comparison to the case where no tunnel hood is present,the amplitudes of micro-pressure waves at 40 m from the tunnel reach an acceptable range.The aerodynamic drag of the head and tail fluctuates greatly while that of the intermediate region undergoes only limited variations when the high-speed train passes through the double-hat oblique tunnel.It is shown that the effects of the oblique slope of the portal on the aerodynamic drag can almost be ignored while the train speed plays an important role.展开更多
基金Projects(2022YFB4301201-02,2023YFB4302502-02)supported by the National Key R&D Program of ChinaProjects(52372369,52302447,52388102)supported by the National Natural Science Foundation of China。
文摘To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility parameters including the shaft(location L,cross sectional dimension W,height h),tunnel portal(cross sectional area S),and openings(spacing D,side length F)on the evolution of tunnel aerodynamic effects.By integrating three dimensional unsteady flow field numerical simulations with a dynamic model testing system,the research notably reveals the regulatory mechanisms of these parameters on the evolution characteristics of the initial compression wave pressure gradient and the multi peak structure of micro-pressure waves.The results show that shaft parameters significantly affect the initial compression wave.Both the wave amplitude and gradient exhibit a linear negative correlation with cross sectional dimension W and a linear positive correlation with location L,while demonstrating a nonlinear relationship with height h,the amplitude follows a cubic polynomial trend,and the gradient initially increases before plateauing.Under the configuration W=8 m,L=50 m,and h=20 m,substantial reductions in both compression wave amplitude and gradient were achieved.The portal cross sectional area S shows a"U-shaped"relationship with the compression wave gradient,with the maximum gradient reduction of 53.24%occurring at S=210 m^(2),a result comparable to that achieved with optimized opening parameters(D=15 m,F=3.5 m,53.96%).Regarding micro-pressure waves,the amplitude measured 20 m from the tunnel exit shows a linear positive correlation with shaft parameters L and W,while the influence of h saturates beyond 50 m.Reductions exceeding 54%were achieved with portal parameters,either at S=210 m^(2) or using the optimized opening configuration.Furthermore,micro-pressure waves near the portal exhibit a consistent dual peak structure:the first peak originates from the train entry compression wave,and the second results from further wave compression after tunnel exit.The opening location governs selective peak regulation openings near the portal entrance primarily suppress the first peak with minimal impact on the second,whereas centrally located openings reduce the first peak but can amplify the second by up to 3%.Based on these insights,an optimized parameter configuration is proposed:a shaft with a cross-sectional dimension≥8 m located 50 m from the portal,a portal cross sectional area of 210 m^(2),and openings spaced at 15 m intervals.This configuration can reduce the initial compression wave gradient by over 50%.The results provide a theoretical foundation for controlling aerodynamic effects of superconducting maglev train.
基金supported by the National Natural Science Foundation of China,China Grant(11972028),under the project“Analysis of Unsteady Aerodynamic Characteristics of High-Speed Train”。
文摘The tunnel-train-air interaction problem is investigated by using a numerical method able to provide relevant information about pressure fluctuations,aerodynamic drag characteristics and the“piston wind”effect.The method relies on a RNG k-εtwo-equation turbulence model.It is shown that although reducing the oblique slope can alleviate the pressure gradient resulting from initial compression waves at the tunnel entrance,the pressure fluctuations in the tunnel are barely affected;however,a large reduction of micro-pressure wave amplitudes is found outside the tunnel.In comparison to the case where no tunnel hood is present,the amplitudes of micro-pressure waves at 40 m from the tunnel reach an acceptable range.The aerodynamic drag of the head and tail fluctuates greatly while that of the intermediate region undergoes only limited variations when the high-speed train passes through the double-hat oblique tunnel.It is shown that the effects of the oblique slope of the portal on the aerodynamic drag can almost be ignored while the train speed plays an important role.
