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-   -   shockwaves (https://www.pprune.org/professional-pilot-training-includes-ground-studies/116542-shockwaves.html)

muck-savage 24th January 2004 06:30

shockwaves
 
Could someone please tell me what happens to the speed, lss, temperature, density and pressure in normal, compressive,
oblique and expansive shockwaves and any other things I've left out ?

Electric Sky 24th January 2004 17:36

Normal Shockwave - Airstream is slowed to subsonic / Static Pressure, Temperature and Density all go Up / The Energy of the airstream (total pressure) is greatly reduced

Expansion Wave - Velocity Up / Pressure, Density and Temp all Down

Oblique Shockwave - Same as Normal Shockwave, only difference being that airflow passing through the oblique shockwave changes direction and the airflow behind the shockwave doesn't necessarily all become subsonic.

I can't recall compressive shockwaves as I suffered all of this too long ago :confused: With regard to LSS, rule is that the lower the temperature, the lower the speed of sound. Hope this helps and good luck!

ES ;)

Keith.Williams. 24th January 2004 23:11

The only thing that really needs to be added to the comments from Electric Sky is that LSS is proportional to temperature (38.94 x square root of absolute temp). So if temp goes up or down, LSS does the same. As air passes through a shock wave the temperature increases, so the LSS increases. As air goes through an expansion wave the temperature and LSS both decrease.


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