【作者】 骆建军；

【导师】 高波；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2003， 博士

【摘要】 高速列车进入隧道时，一方面，在隧道入口处与列车运动方向相反的方向产生出口流。另一方面在隧道内产生以声速向前传播的压缩波。这些压缩波对列车车体产生较强的作用力，并且与压缩波相关的压力梯度对列车内的乘客和隧道内的维修人员产生生理上的不舒服感。在隧道出口处，产生一种叫做微气压波的压力脉冲，并造成环境问题。 为了解决这个问题，本文以西南交通大学承担的国家自然科学基金项目“隧道缓冲结构空气动力学特征试验”的研究为依托，同时根据高速列车进入隧道所产生的流场的特征，建立了三维粘性、可压缩、不等熵非定常流模型。对高速列车通过有或无缓冲结构的隧道所产生的压缩波的机理进行了大量的实验和数值计算研究。研究结果表明： 压缩波是列车进入隧道时形成的。隧道中正压最大值是由列车头部突入隧道时形成的压缩波引起的，并且该压缩波在隧道中以声速传播，而隧道中负压最大值是由列车尾部经过测点时形成的。在影响隧道压缩波的压力以及压力梯度的各种因素中，列车速度以及隧道阻塞比是主要因素，同时得出了隧道内压缩波的最大压力与列车速度的平方成正比，对于给定的列车断面积，隧道断面积越大，则压缩波的压力峰值及压力梯度越小。同时，还与列车在隧道内的运行方式有关。 列车进入隧道的过程中，在隧道内产生活塞风，在隧道出口处产生出口流。隧道内活塞风不仅具有水平方向的波动，而且也有垂直方向的波动变化，其风速流场结构十分复杂，具有非定常的特性。同时，高速列车进入隧道时在隧道入口附近发生出口流现象，并形成涡流。在整个涡流的形成过程中，可以将这个过程分为连续的4个阶段，即① 涡的形成之前阶段；② 涡的发展阶段；③ 涡的传播阶段；④ 涡的破坏阶段。列车头部形状和列车速度对喷射流速度没有多大影响。 三角形、钝头形、椭圆形、圆锥形和抛物线形共5种基本的列车头部形状对降低压力及压力梯度有一定的效果，其原因在于变化的列车头部形状延缓了压缩波上升的时间。其中，三角形列车头部形状具有最好的降低压力梯度的效果，其次为抛物线形，效果最差的为钝头形列车。列车头部长细比越大，降压效果越明显。 竖井断面积的变化和竖井位置的改变均能够有效地降低隧道内的最大压力峰值和压力梯度的大小，其原因在于竖井的存在可以改变初始压缩波的波形，西南交通大学博士研究生学位论文第日页将初始压缩波分成几个小的波形。对于竖井的断面积对压力变化的影响，一般是断面积越大，压力变化越明显，但继续增大竖井的断面积后，降压效果反而不明显，最理想的竖井的断面积的大小为隧道断面积的30%~40%。对于竖井位置对压力变化的影响，在某一确定长度的隧道中，总存在着一个最佳的位置，在这个位置的竖井具有最佳的降压效果。 缓冲结构的设置能够有效地降低隧道内的压力和压力梯度的最大值，其原因在于缓冲结构延长了压缩波压力上升的时间，降低列车突入隧道时所形成的最大压力梯度。 当缓冲结构长度一定时，三种形状的缓冲结构对压缩波最大压力的影响的差异是很小的。而压缩波的压力梯度最大值，以不连续型最小，其次是线形的，而二次函数型最大。至于压缩波的压力梯度的平均值，按二次函数型、线形、不连续型缓冲结构的顺序变小。不管何种形式的缓冲结构，都是缓冲结构越长，断面积越大，则压力梯度值越小。但缓冲结构长度超过隧道的等效直径时，缓冲结构长度的影响变得很小。 在缓冲结构上开口，能够继续降低最大压力梯度。最大压力梯度值，在缓冲结构的长度一定时，随开口率增大而增大。通过实验及计算表明，开口率在0.05~0.1的缓冲结构，是比较优越的。更多还原

【Abstract】 The train entry into a tunnel generates an exiting flow at the portal with a direction opposite to the train movement and a compression wave that propagates into the tunnel at the speed of sound. Developments of high-speed trains have generated numerous engineering problems related to the presence of strong compression waves in tunnels. The high amplitude of compression waves provokes strong mechanical stresses on the train body and the associated high pressure gradients are responsible for both the aural discomfort of train passengers and the impulsive acoustical wave called the micro-pressure wave emitted in the surrounding area of tunnel exits. The micro-pressure wave is similar to the aeronautical sonic boom and caused serious environmental damages.To discover this problem, the paper relies on the item of the national natural science fund undertaken by Southwest Jiaotong University for the experimental studying on the aerodynamic feature of tunnel-hood, according to the field features induced by a high-speed train entering into tunnels with or without hood to establish three-dimensional unsteady viscous compressible isentropic flow to model compression wave.The experiment and calculation show that the compression wave which propagates along the tunnel at the speed of sound is formed when the train enters into the tunnel. The pressure amplitude of the compression wave creases to the positive maximum at the time the train nose just enters into the tunnel entrance while the negative pressure amplitude is formed when the train tail just passes by the measurement points. The train speed and the train/tunnel ratio are the main factors which influence the pressure amplitude and the pressure gradient of the compression wave, and draws that the maximum amplitude of the fully established compression wave is approximately proportional to the square of the train speed, the maxim- um of the pressure gradient is approximately proportional to the cube of the train speed. For a given train section area, the larger the tunnel section is, the weaker the compression wave amplitude and gradient are. It is also related to the train passing through the single or dual tracks tunnel.The calculation show that there are horizontal and vertical fluctuation for the wind induced by the train passing through tunnel, and the field of velocity is verycomplex, so it has the feature of unsteady fluid. At the same time, there is phenomenon of the annulus jet accompanied by a vortex ring when the train enters into the tunnel. The formation of the vortex ring constitutes four phases, the pre-vortex phase, the vortex development phase, the vortex convection phase and the vortex breakdown phase. The duration of each of these steps is found to be independent of both the studies parameters. Furthermore, neither the train speed nor the train nose geometry induced significant changes on the vortex ring evolution.The various shapes of train can decrease effectively the maximum pressure gradient because of modifying the generation process of the compression wave. The calculation releases that the maximum pressure gradient of the compression wave in the case of triangle of revolution is the smallest of the five fundamental nose shapes: a triangle of revolution, a quardrilateral of revolution, an ellipsoid of revolution, a paraboloid of revolution, and a circular cone. Then in the case of paraboloid of revolution, and the quardrilateral of revolution is biggest. At the same time ,the more the length of nose is ,the more the maximum pressure gradient is.The maximum pressure gradient of compression wave front increases during propagation in duct sections of constant cross-section in slab track tunnels and decreases at branched sections. The effective of the branch for reducing the maximum pressure gradient depends on the branch length, the branch cross-section area and the position of the branch from tunnel entrance.The change of the shaft cross-section area and the position from the tunnel entrance can decrease the maximum pressure amplitude and更多还原