Estimating the area of a slot in a pipe
Estimating the area of a slot in a pipe
(OP)
Hi everyone,
I'm currently trying to estimate the area of a crack in a pipe based on the pressure difference and leakage rate out of the crack. I've been assuming that the crack is a rectangular slot and trying to use a variation of the orifice eqution, but the results I've been getting seem ridiculous (1400 L/min through a slot area of 0.000583 square meters). I have the following data:
Pressure difference: 1300 psi (8.96 MPa)
Leakage Flow Rate: 1600 L/min (0.026667 cubic meters/sec)
Viscosity: 1750 cP
Specific Gravity: 1.2
Pipe is capped at the end so all flow must be going through slot
If anyone has any ideas they would be much appreciated.
I'm currently trying to estimate the area of a crack in a pipe based on the pressure difference and leakage rate out of the crack. I've been assuming that the crack is a rectangular slot and trying to use a variation of the orifice eqution, but the results I've been getting seem ridiculous (1400 L/min through a slot area of 0.000583 square meters). I have the following data:
Pressure difference: 1300 psi (8.96 MPa)
Leakage Flow Rate: 1600 L/min (0.026667 cubic meters/sec)
Viscosity: 1750 cP
Specific Gravity: 1.2
Pipe is capped at the end so all flow must be going through slot
If anyone has any ideas they would be much appreciated.





RE: Estimating the area of a slot in a pipe
even given your rather high viscosity, with 89 bar across it, getting 85 m3/hr to 96 m3/hr through it sounds in the right order of magnitude to me - why the difference between your two flow rates by the way?)
Is this real or just homework?
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Also: There's usually a good reason why everyone does it that way
RE: Estimating the area of a slot in a pipe
RE: Estimating the area of a slot in a pipe
what is the fluid and what sort of depth is this / type of ground etc? "underground formation" sounds more like reservoir rock than sand and gravel...
A photo would be good!
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Estimating the area of a slot in a pipe
RE: Estimating the area of a slot in a pipe
RE: Estimating the area of a slot in a pipe
As this is quite likely then to get the same flow your open area would need to increase. A bit of site testing would seem to be the best way to match your actual size / results to the theoretical one.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Estimating the area of a slot in a pipe
The complicating factor is that the crack is a labyrinth that is formed by the fractured crystal boundaries where the crack is formed, so the passage is not only narrow at it's maximum, it is, potentially, very rough. Discontinuities on the order of the width of the crack opening, for comparison.