Preliminary Study on the Effect of Nose Shape of 400 km/h High Speed Trains on Initial Compression Waves in Tunnel
An overlapping grid method is used to explore the effect of nose shape of 400 km/h high-speed trains on the initial compression wave in tunnels based on the three-dimensional non-constant compressible N-S equations and the SST k-w turbulence model.For a certain type of CR450 train developed in China at present,this paper studies the proposed new nose shape with two nose lengths of 15 m and one nose length of 22 m,and analyzes the basic charac-teristics of the initial compression wave generated by the three different nose shapes of trains entering the tunnel at 400 km/h under the existing tunnel conditions in China;and finally the effect of different speeds(350 km/h,400 km/h,450 km/h)on the value of the maximum pressure gradient of the initial compression wave as the train enters the tun-nel is analyzed.Comparison of the pressure and pressure gradient values at 72 m from the tunnel entrance shows that:The initial compression waveforms and the maximum pressure gradient values generated by the two trains with 15 m nose lengths are basically the same;Compared with the 15 m nose lengths,the initial compression waveforms generated by the 22 m nose lengths are significantly different,and the maximum pressure gradient values are reduced by 27％;The higher the train speed,the higher the maximum pressure gradient value corresponding to the initial compression wave,and the less obvious the mitigating effect of the hood.The results of the study have practical ref-erence value for the design of new generation of high-speed train nose shape and aerodynamic performance compari-son.
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