Flow Through a Circular Annulus

[sandriver]

Does any body have a way to calculate the flow through a smooth concentric circular annulus (assumming water at STP)?

Also would like to know if there is a way to calculate the flow through an concentric circular annulus which has (what looks like) square threads? I believe that this is some type of pumping ring, which is machined on a throttle bushing in a pump.

 

[zdas04]

See faq378-1142 for a discussion of this topic.

David

 

[JJPellin]

Our terminology may be different, but it seems as if you are describing a smooth bore bushing around a rotating sleeve or shaft. Is this correct? There are programs out there for estimating flow though a bushing. The one we use was provided free from our mechanical seal vendor. Any seal company would have a similar program for flow through a bushing, orifice or combination of both. The one with the spiral groove would be a different matter. If it is a stationary thread with smooth spinning sleeve, it would produce one result. If it was a rotating thread with a smooth bore bushing, it would produce quite a different result. I don't recall every seeing a program which could estimate flow in this configuration. If I misunderstood and neither part is rotation, then the flow would be somewhat less than the program would estimate for a smooth sleeve and bushing. But I would not know how much less.

 

[sprintcar]

For water, I'm using a velocity/flow equation:

Q = 2.48* (d2^2 – d1^2) *V
Q = flow, US gal/minute
d2 = bore
d1 = shaft
V = velocity in feet/second

Using the Petro Eng formula to find Hydraulic Diameter
Hd(eff) = [(d1+d2)^2 *(d2-d1)^3]^0.2
then
Q=19.636* Hd^2 *h^.5 *C
where
h = head in feet
C = orifice coefficient
Q = US gpm

This will let you vary pressures.
Adjust 'C' as needed. I started with Cameron's nozzle data.


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