Convergent Nozzle Expansion

[jlchard1]

I am currently designing a convergent nozzle for use in experiments and wanted to check something:

Will the pressure and density of the flow always expand to ambient (following the isentropic relations) when it reaches the nozzle exit regardless of nozzle contraction ratio and length?

Any help / advice regarding just CONVERGENT nozzles will be much appreciated.

James

 

[Compositepro]

No, it depends on the design. Google rocket nozzle design. Over and under-expansion is common, paticularly where ambient pressure varies with altitude.