Theoretical And Experimental Research On The High-Speed Railway Tunnel Hood

Since 1960's, high-speed railway has grown up in developed country and railway developed into a new age. High-speed railway thrived to internationally lead to a revolution in traffic transportion. However, with the train increasing speed, aerodynamic effects generated by a train passing through a tunnel will become more serious to generate aerodynamic problems that did not appear at lower speed. At a higher speed, the train entry into a tunnel will cause obvious pressure fluctuation in tunnel and micro-pressure wave radiated from the exit of the tunnel, which will influence passengers' comfort and environment around a tunnel. Therefore, lucubration of tunnel aerodynamic effect's mechanism and corresponding alleviation measure is very necessary.With the help of model experiment and reasoning, maximum pressure and pressure gradient were investigated. Two formulae were obtained that described the relation between the maximum pressure or pressure gradient and train speed, train/tunnel area ratio, train nose length/height ratio. The coefficients of the formulae might be found.The finited volume method and a total variation diminishing (TVD) numerical scheme were used to solve the axisymmetric Euler equation, which was utilized to simulate the micro-pressure wave. The results from numerical calculation and foreign experiments agreed well, which could presume that could well simulate the micro-pressure wave. With the help of the numerical method, related influence factors were investigated. The results made clear that the size of the baffle at the tunnel exit importantly influenced space distribution of the maximum pressure of micro-pressure wave and in the thesis the influence of the baffle was quantificationally analysized. Otherwise, the maximum pressure of the micro-pressure wave when the compression wave was a weak shock wave and not a shock wave was carefully analysized and the formulae calculating the maximum pressure were given in the thesis.With the help of model experiment, enlarged transect windowless hoods were investigated parametrically. Its action mechanism on the first compression wave was analysized. The influence mechanism of hood length and enlarged transect...