高速磁浮隧道扩大等截面斜切型缓冲结构减缓初始压缩波机理研究

Mechanism of expanded equal-section inclined hood to reduce initial compression wave by high-speed maglev passing through the tunnel

  • 摘要: 高速轨道车辆驶入隧道,在车前产生初始压缩波,以声速传播至隧道出口处并向外辐射产生微气压波,对环境造成严重危害。采用三维非定常可压缩流动N–S方程和SST kω湍流模型,以国内某型600 km/h的磁浮列车为研究对象,通过模拟磁浮列车驶入扩大等截面无斜切缓冲结构、扩大等截面斜切型缓冲结构和无缓冲结构隧道产生的初始压缩波情况,分析缓冲结构斜切端及斜切角度对初始压缩波的减缓作用及机理。结果表明:初始压缩波最大压力梯度的形成与车头最大横截面积变化率部位进入隧道/缓冲结构入口直接相关,同时与隧道内流量变化率最大值相对应;设置扩大等截面无斜切缓冲结构可较大幅度降低压缩波最大梯度,降低率为49.92%;将扩大等截面缓冲结构的垂直端改为正斜切端可进一步提高降低率,当斜切角分别为10°、20°、30°和39°时,降低率增幅分别为12.93%、10.32%、8.18%和6.28%;扩大等截面斜切型缓冲结构斜切角为10°时对初始压缩波的压力梯度峰值降低作用最明显,总降低率为62.85%。本文采用头型横截面积变化率、空气流量和观测点压缩波三方面耦合分析方法,探究影响初始压缩波最大压力梯度的头型、空气流量之间的相互映射关系,合理解释了缓冲结构减缓初始压缩波机理,可为今后进一步优化列车头型和不同型式缓冲结构设计及其气动效应分析提供了参考。

     

    Abstract: The initial compression wave is generated when the high-speed rail vehicle enters the tunnel. The compression wave propagates to the exit of the tunnel at the speed of sound and radiates outward to form a micropressure wave, which brings serious environmental problems. Using the three-dimensional unsteady, compressible flow N–S equation and the SST kω turbulence model, and taking the maglev train with a speed of 600 km/h as the research object, the initial compression wave generated by maglev train entering the tunnel with extended equal-section hood, extended equal-section oblique hood and no hood was simulated. The mitigation effect and mechanism of the inclined end and the oblique angle of the hood on the initial compression wave were analyzed. The following conclusions are mainly drawn: the formation of the maximum pressure gradient of the initial compression wave is directly related to the entrance of the part of the train into the tunnel/hood where the change rate of the cross-sectional area of the train head is the maximum, which corresponds to the maximum change rate of the flow in the tunnel. The maximum gradient of the compression wave can be greatly reduced by setting the extended constant section hood, and the relief rate is 49.92%. Changing the vertical port of the expanded isocross section hood to the positive oblique port can further improve the mitigation rate. When the oblique angle is 10°, 20°, 30° and 39°, the increase of the mitigation rate is 12.93%, 10.32%, 8.18% and 6.28%, respectively. It is suggested that the oblique hood has the most obvious effect on the peak pressure gradient of the initial compression wave when the oblique angle is 10°, and the total relief rate is 62.85%. In this paper, the coupling analysis method of the change rate of the cross section area of the head, the air flow rate and the compression wave at the observation point, and the mutual mapping relationship between the head shape and the air flow rate, which affect the maximum pressure gradient of the initial compression wave, can reasonably explain the mechanism of the hood at the entrance to the cave to reduce the initial compression wave. It provides a new method for further optimization of the train head shape and design of different types of hood and analysis of aerodynamic effects.

     

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