空心活塞运动产生的激波  

Shock Wave Generated by Hollow Piston Movement

作　　者：俞鸿儒 

机构地区：[1]中国科学院力学研究所高温气体动力学国家重点实验室,北京100190

出　　处：《气体物理》2016年第1期1-4,共4页Physics of Gases

摘　　要：普通活塞在管道中运动,不论活塞速度高低都能驱动产生激波.空心活塞在管道中运动与普通活塞不同,当其运动Mach数低于壅塞Mach数,活塞前不会形成运动激波;只有活塞运动Mach数超出壅塞Mach数,才能驱动产生激波.壅塞Mach数由空心活塞中心孔直径、长度和内壁面摩擦系数以及外直径横截面积决定.火车通过隧道类似空心活塞在管道中运动.将火车车箱与隧道间的空隙换算成有效水力直径后,可利用空心活塞在管道中运动计算壅塞Mach数的方法,求出火车通过隧道出现激波的条件.文章提出一种新颖的间接测量列车平均摩擦系数新方案.Whether the piston speed fast or slow, an ordinary piston can generate moving shock wave while it moves in a tube. The hollow piston is different from the ordinary one. When the movement Maeh number of a hollow piston is lower than the choked Mach number, the moving shock wave will not appear; only when the movement Mach number is higher than the choked Mach number, the moving shock wave can be generated. The choked Mach number can be determined by diameter, length, averaged friction coefficient of inner hole and outer diameter of a hollow piston. Train in tunnel is similar to hollow piston in tube. According to the shape of cavity between the tunnel wall and the railway carriage, an equivalent hydraulic diameter can be obtained. Then the conditions of generating moving shock wave can be computed by a similar method for calculating choked Mach number of hollow piston. The novel method for measuring averaged friction coefficient of a train was proposed.

关 键 词：激波 摩擦阻力 高速火车 隧道 

分 类 号：O354.4[理学—流体力学]