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# Flow in a S-duct

## Flow in a S-duct

(OP)
Hello everybody,

I am actually studying the aerodynamics of an S-duct and I had a question : how does the total pressure increase in both subsonic and supersonic cases? Indeed I read somewhere that it was because the duct is slightly diverging, however it is then a diffuser for subsonic flows, so how can it explain the increase of total pressure? Moreover I also read a paper about mach distribution in the S-duct, it decreases, which is the role of the duct in supersonic speed but I can't understand how can the total pressure increase when the mach number decreases?

### RE: Flow in a S-duct

simplify the question ... how can total pressure increase ?  total pressure is analgous to total energy of the flow, for total pressure to increase work has to be done, ie energy supplied to the flow by the duct.  normally i'd expect this to be energy is lost from the flow (appearing as a reaction force on the duct; the duct has to be held in place).

oh, and btw, student posts are not allowed.

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