Subsonic diffuser is an expanding pipe

[omgitsroy326]

Anyhow

books says
Subsonic diffuser is an expanding pipe.

In a picture it shows A -> B the radius of pipie decreases.

I was under the impression that subsonic and expanding pipe meant radius getting larger.

please clarify .. thanks again

 

[omgitsroy326]

also is there a definition for shock... or formula? my book doesn't give a definition

 

[Clausius2]

Anyhow

books says
Subsonic diffuser is an expanding pipe.

In a picture it shows A -> B the radius of pipie decreases.

I was under the impression that subsonic and expanding pipe meant radius getting larger.

please clarify .. thanks again

Maybe your book is upside down . A subsonic diffuser is a pipe whose radius becames larger as we advance in axial direction (flow direction).

As far as shocks are concerned, a Shock Wave is a flow discontinuity in compressible flow. Variables such as velocity, pressure and temperature have a "virtual" discontinuity across the Shock Wave.

And I have mentioned the word "virtual" because such discontinuity doesn't happen in real flow. In fact Navier-Stokes formulae don't admit any discontinuity, because viscous diffusion always make a smoothing effect over the flow. Only the unreal theory of inviscid flow deals with discontinuities. Traditionally such discontinuities have been called "Shock Waves", and they have a mathematical structure based on the Rankine-Hugoniot jump conditions.