not,Strictly in terms of performance, flow separation *increases* the
performance of a nozzle in such conditions ie. It eliminates much of
the negative pressure thrust which is a consequence of over expansion.
Less so than one might at first think, because jet aspiration can pump the
region around a separated jet down to well below ambient pressure. It's
alas, equivalent to just truncating the nozzle at the separation point.how
However, I think the original statement is quietly assuming that flow
separation is unacceptable -- which is certainly the widespread modern
superstition -- so the shape's susceptibility to flow separation *defines*
long the nozzle can be. In that case, a shape which tends to suppressflow
separation can be made longer, and the resulting higher expansion ratiogives
better performance.Which, (and you've appeared to have gone to great lengths not to spell it
