文档介绍：斜波产生的根源
普朗特—梅耶膨胀波
斜激波关系式
流过尖楔与圆锥的超音速流
激波干扰与反射
脱体激波
激波-膨胀波理论及其在超音速翼型中的应用
第九章路线图
Wave angle: β激波角, 激波与激波上游来流的夹角。
Deflection angle:θ,通过斜激波的气流偏转角
β
θ
• What is the physical mechanism that creates waves in a supersonic flow? 超音速流中产生波的物理机理是什么?
If the upstream flow is subsonic , as shown in , the disturbances have no problem working their way upstream, thus giving the ing flow plenty of time to move out of the way of the body.
,如果上游是亚音速的, 扰动可以毫不困难地传播到远前方上游,因此,给了来流足够的时间以绕过物体。
The information is propagated upstream at approximately the local speed of sound.
物体存在的信息以近似等于当地音速的速度传播到上游去。
On the other hand, if the upstream flow is supersonic, as shown in , the disturbances cannot work their way upstream; rather, at some finite distances from the body, the disturbance waves pile up and coalesce, forming a standing wave in front of the body.
在另一方面,,如果上游是超音速的,扰动不能一直向上游传播,而是在离开物体某一距离处聚集并接合,形成一静止波。
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 flow? 为什么大部分激波与来流成斜角而不是垂直的呢?
()
马赫波
马赫角
If the disturbances are stronger than a simple sound wave, then the wave front es stronger than a Mach wave, creating an oblique shock wave at an angle to the freestream, where β>μ. parison is shown in Fig. . 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。。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。
OBLIQUE SHOCK RELATIONS (斜激波关系式)
以上图虚线包围区域为控制体,应用连续方程:
()
()
通过斜激波流动的切向速度分量保持不变.
()
()
通过斜激波的流动特性变化只由垂直于斜激波的速度分量决定.
方程()、()、()与正激波控制方程()、()、(