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Old Feb 4th 2016, 10:28 PM   #1
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Post surface tension and dropping (NEED HELP İN PROBLEM)

Hello friends;

i want to solve the problem about surface tension and dropping. i find a equation on http://planetcalc.com/2296/
and i enter this formulato excel. But i dont sure this formula is true.

http://picpaste.com/AdsAe_z-km3N3Ktc.jpg

for water :
if pipe outlet diameter is 9,45mm (or less) no dropping occuring cause of surface tension force.

for oil :
if pipe outlet diameter is 7,43mm (or less) no dropping occuring cause of surface tension force.


Last edited by koytos; Feb 4th 2016 at 10:33 PM.
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Old Feb 5th 2016, 06:18 AM   #2
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Originally Posted by koytos View Post
Hello friends;

i want to solve the problem about surface tension and dropping. i find a equation on http://planetcalc.com/2296/
and i enter this formulato excel. But i dont sure this formula is true.

http://picpaste.com/AdsAe_z-km3N3Ktc.jpg

for water :
if pipe outlet diameter is 9,45mm (or less) no dropping occuring cause of surface tension force.

for oil :
if pipe outlet diameter is 7,43mm (or less) no dropping occuring cause of surface tension force.

I get different results: R = 3.34 mm for water and 2.63mm for oil. I think in your Excel calculation you forgot the 2 in the denominator of the equation.

And the interpretation of R is it is the maximum size of pipe that will allow dripping, as opposed to continuous flow. For pipes of smaller radius you get drops, for pipes of larger radius you get continuous flow (according to the author).
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Old Feb 5th 2016, 07:12 AM   #3
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no dropping

http://www.picpaste.com/IMAG0223-7QbcaTyQ.jpg
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Old Feb 15th 2016, 02:58 AM   #4
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how can i calculate this system if the outlets are like in the picture?

5 different outlets
1- elips
2- square
4-circle
5- circle (but it has a filter)
Attached Thumbnails
surface tension and dropping (NEED HELP İN PROBLEM)-ads-z.jpg  

Last edited by koytos; Feb 15th 2016 at 03:01 AM.
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Old Feb 21st 2016, 11:58 PM   #5
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if you dont understand clearly, please write.
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Old Feb 22nd 2016, 06:31 AM   #6
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Given that the formulas for this type of thing are empirical, I think you would have to try some experiments with these shapes and see what you get. But a reasonable estimate might be to use the distance from the centroid of each shape to the furthest part of the perimeter as the equivalent of radius in the formula.

Last edited by ChipB; Feb 22nd 2016 at 06:33 AM.
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Old Feb 26th 2016, 03:35 AM   #7
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Originally Posted by ChipB View Post
Given that the formulas for this type of thing are empirical, I think you would have to try some experiments with these shapes and see what you get. But a reasonable estimate might be to use the distance from the centroid of each shape to the furthest part of the perimeter as the equivalent of radius in the formula.
thank you.
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