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Compressible Flow · Problem type

Overexpanded, ideally expanded or underexpanded

Use this for “A nozzle with pₑ = 40 kPa fires at sea level, where the air is at 101.3 kPa. Is it overexpanded?”

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Is the nozzle overexpanded, ideally expanded or underexpanded?
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Compare the exit pressure pₑ with the back pressure pb.

Assumptions

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The nozzle runs supersonic and shock-free inside, with exit pressure pₑ set by its area ratio.
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The back pressure pb is the pressure of the air around the exit; in space it is 0.
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