Quick questions about Area-Velocity relation

[piano_girl]

Is it valid for real gases? My initial thought would be no, since the derivation is based on the assumption that the flow is isentropic.

Is it valid for square ducts?

 

[mybsaccownt]

area velocity relation?

the continuity equation?

It can only be applied to incompressible flow, the density must remain constant.

 

[piano_girl]

No, the area velocity relation is dA/A = (M^2 -1) dV/V

 

[machinest]

hi piano girl-
what is the M?-can u tell us about this equation more clear?,and please tell us which kind of gases this equation can be applied?-continuity equation can't be applied for the gases-its only as Mr:mybsaccownt said-for incompressible flow-and the gases is an compressible fluids-in which the density not constant.
waiting you to tell us about this equation-it might be important,thanks .

 

[FredGarvin]

M is mach number. I'd venture a guess that it is not terribly accurate if you needed good numbers for an experiment. However, I think that the results derive from it are useful.

http://www.aeromech.usyd.edu.au/aero/gasdyn/areavelocity.html