I have a pipe within a pipe. The air is flowing through the "ring area". I suppose that it is called an annulus, this ring-type pipe. The air is flowing through this annulus and I need to find out the pressure drop. I have the length, the air amount.
Can't find it anywhere on the net. Does anyone know this?
Pressure drop
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Ingeniarius
- Posts: 1
- Joined: Fri Oct 01, 2010 2:10 pm
Re: Pressure drop
In order to find pressure drop in a annular duct, you have to find "hydraulic diameter. Hydraulic diameter is defined as Dh=4*net free flow area/wetted perimeter. Wetted perimeter Pw=pi*(D+d). Free flow area of annulus is Ac=pi*(D^2-d^2)/4. It follows that Dh=4*Ac/Pw.
After you have found hydraulic diameter it is easy to find pressure drop as usual: delta p=(f*L/Dh)*v^2*density/2, where f is Darcy factor - not to be confused with Fanning factor. They are simply correlated: Darcy factor=4*Fanning factor.
Best regards!
After you have found hydraulic diameter it is easy to find pressure drop as usual: delta p=(f*L/Dh)*v^2*density/2, where f is Darcy factor - not to be confused with Fanning factor. They are simply correlated: Darcy factor=4*Fanning factor.
Best regards!