Hence, the physical generation of waves in a supersonic flow-both shock and expansion waves--is due to the propagation of information via molecular collisions and due to the fact that such propagation cannot work its way into certain regions of the supersonic flow 因此,超音速流中溦波和膨胀波产生的物理原因是:通 过分子碰撞引起的信息传播和这种传播不能到达超音 速流中某些区域
Hence, the physical generation of waves in a supersonic flow—both shock and expansion waves—is due to the propagation of information via molecular collisions and due to the fact that such propagation cannot work its way into certain regions of the supersonic flow. 因此,超音速流中激波和膨胀波产生的物理原因是: 通 过分子碰撞引起的信息传播和这种传播不能到达超音 速流中某些区域
Why are most waves oblique rather than normal to the upstream fow?为什么大部分激波与来流成斜角而不是垂直的呢? 马赫波 Supersonic Subsonic v>a < 马赫角 at a 1 FIGURE 9.3 Another way of visualizing the propagation of disturbances in(a) subsonic and(b)supersonic dow. SIn M (9.1)
• Why are most waves oblique rather than normal to the upstream flow? 为什么大部分激波与来流成斜角而不是垂直的呢? V M a Vt at 1 sin = = = M 1 sin −1 = (9.1) 马赫波 马赫角
M>t FIGURE 9A Relation between the oblique shock-wave angle and the Mach angle. If the disturbances are stronger than a simple sound wave then the wave front becomes stronger than a mach wave, creating an oblique shock wave at an angle to the freestream, where B>u. This comparison is shown in Fig. 9.4. However, the physical mechanism creating an oblique shock isis essentially the same as that described above for the mach wave 如果扰动比一个简单声波强,其引起的波前就会比马赫波强,产生 个与来流夹角为β的斜激波,且β>μ。这一比较在图94中给出。然而, 斜激波产生的物理机理与上面描述的马赫波的产生完全相同
If the disturbances are stronger than a simple sound wave, then the wave front becomes stronger than a Mach wave, creating an oblique shock wave at an angle to the freestream, where β>μ. This comparison is shown in Fig. 9.4 . However, the physical mechanism creating an oblique shock is is essentially the same as that described above for the Mach wave. 如果扰动比一个简单声波强,其引起的波前就会比马赫波强,产生一 个与来流夹角为 β的斜激波,且β>μ。这一比较在图9.4中给出。然而， 斜激波产生的物理机理与上面描述的马赫波的产生完全相同
补充:激波与膨胀波的形成机理的进一步理解 可电时 P1D·T 激波的形成: 以右图活塞在一维长管中压缩为 例.设有一根很长的直管,管内 气体原是静止的.热力学参数是 a p,p,T1从=0起到t=t1为止活塞 向右作急剧地加速运动,tt1以 后匀速前进 特征 (b) 居后的波比前边的波快,每道波 都在追赶它前面的波.过渡区 AA-BB的长度随时间增长而越来 越短,最后压缩到一起形成激 r=1 波
补充：激波与膨胀波的形成机理的进一步理解 激波的形成： 以右图活塞在一维长管中压缩为 例．设有一根很长的直管，管内 气体原是静止的．热力学参数是 p1 ,ρ1 ,T1 ．从t=0起到t=t1为止活塞 向右作急剧地加速运动， t=t1 以 后匀速前进． 特征： 居后的波比前边的波快，每道波 都在追赶它前面的波．过渡区 AA-BB的长度随时间增长而越来 越短，最后压缩到一起形成激 波．