Fluid dynamics - Header pressure

[Raai2015]

Hallo all,
its about the Header pressure derviation. I didnt understand the derivation on the red mark (Massflux term) in the picture. If anybody can clarify would be helpfull.

 

[Raai2015]

Sorry if the attachments is missed!

 

[LittleInch]

Well we only have a snapshot here, but I think what it is saying is that the mass flow is equal down each down tube so mass flow in the header is proportional to lenght if the down tubes are equally spaced out.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Raai2015]

@ Littleinch : Yes tubes are mostly equal spaced. For the Derivation we can assume equally spaced.but by Chance can you derive? I am also going to post this is in Boiler group.

 

[Latexman]

Why don't you derive, and post it here, and we'll check it.

Do not cross post. This is a "maldistribution" type fluid flow problem. It should have been put in Pipeline, Piping and Fluid Mechanics.

If you'll use Search with maldistribution or manifold, under the thread title, between Forum and FAQs, you should find a lot of relevant threads.

Good Luck,
Latexman
Pats' Pub's Proprietor

 

[chicopee]

The first equation in your attachment has all the elements of the Bernouilli's equation.
PH= pressure head (units in ft)
VH= velocity head(units in ft)
friction loss= (fL/d)V^2/2g (units in ft)

 

[Raai2015]

chicopee.Offcourse this is Bernaoullis

 

[ione]

Mass flux varies linearly from the section 1 onward, as you are going to have part of the mass flow leaving the header at each branch. In order to have even flow distribution you have to minimize the pressure drop along the header in comparison to that of the branches.

 

[Raai2015]

ione: It is clear , appreciable if any Body could derive!i have tried and failed!