flow rate through a perforated pipe
flow rate through a perforated pipe
(OP)
I am currently having an issue with figuring out the flow rate of a perforated pipe. My problem that I am having is that most equations I find for this require the change in pressure from the inlet to the outlet of the pipe, which I have no way of measuring. Also that the cross section of the perforation is for a hole, and since this perforated pipe is for a MWD pipe screen for the oil fields it actually has holes which have a diameter of .25 inches and slots that are 6.625 inches long by .25 inches wide. Also the pipe is closed on one end and it is also perforated on this end with .25 inch holes. The pipe is also hung vertically and is not horizontal. The things that I know are what my minimum and maximum flow rate can be which is between 240gpm – 900gpm (but I don’t know the actually flow rate of the perforated pipe), and that the fluid which is water is being pumped in under 2400psi. I don’t know what the velocity of the water would be in converting it from psi to in^3/min or ft^3/min. I have attached a link to a site that sells these type of screens so that you can look at them and maybe it will give you a better understanding of what I am talking about.





RE: flow rate through a perforated pipe
You could ignore the length of the screen as a first approximation, because it's fairly short. Once you have a math model, you could break up the screen's length into sections, and factor in differences in head and axial pressure drops, but it may not be worth the effort.
The idea is get one value of Cv for the cone.
It may be easier (but less educational) to just measure the screen's Cv, using a pump that's big enough to make it flow full and measuring the pressure drop. Yeah, it will make water go everywhere. It will look like you are doing something.
From there, you use the Cv of the screen (or actually, of the entire system) to plot a line on a Q-h diagram. You also plot the pump's curve on the same diagram. The operating point is where the two lines cross. With a little practice, you can do it in Excel.
The 2400 psi is probably just the pump's limit; don't let that confuse you.
Mike Halloran
Pembroke Pines, FL, USA