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Hi everyone!
My task is to estimate a presure drop in piping with 4 bends, diaphragm valve, 1 contraction and one nelargement. This task would not be anything special, if flow was turbulent (as in almost any industrial aplication). In my case flow is lamninar, so my question is, are minor loss coeficient, found in literature, aplicable for laminar flow or not? I suspect, that they are not, but in literature I did not find any statement, that would support this.
Thanks for answer and best regards!
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Loss Coeficients
Started by Guest_majster_*, Jan 15 2008 06:11 AM
2 replies to this topic
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#2
pleckner
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Posted 15 January 2008 - 06:24 AM
It kind of depends.
If you will be using Crane TP 410 (which is a book you should have and if you don't I strongly suggest you get it) then the K factors can be used for laminar flow. The better correlations to use are those from Hooper who devised the 2-K method or those from Darby who devised the 3-K method. The 2-K method was the first that finally broke what was the common thought that fitting and valve losses are independent of Reynolds Number. Darby took it one step further with the development of the 3-K method, which just refines the K values of Hooper.
I invite you to read my article on this subject that can be found on this website, link below:
http://www.cheresour.../eqlength.shtml
In this article I talk about why, if using Crane TP 410, you must be very careful when using the equivalent length method to calculate the pressure loss in valves and fititngs. As a matter of fact, I'm dead set against this. Read the article to find out why, especially for your situation.
If you will be using Crane TP 410 (which is a book you should have and if you don't I strongly suggest you get it) then the K factors can be used for laminar flow. The better correlations to use are those from Hooper who devised the 2-K method or those from Darby who devised the 3-K method. The 2-K method was the first that finally broke what was the common thought that fitting and valve losses are independent of Reynolds Number. Darby took it one step further with the development of the 3-K method, which just refines the K values of Hooper.
I invite you to read my article on this subject that can be found on this website, link below:
http://www.cheresour.../eqlength.shtml
In this article I talk about why, if using Crane TP 410, you must be very careful when using the equivalent length method to calculate the pressure loss in valves and fititngs. As a matter of fact, I'm dead set against this. Read the article to find out why, especially for your situation.
#3
Guest_majster_*
Guest_majster_*
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- guestGuests
Posted 16 January 2008 - 09:06 AM
Dear Mr. Leckenr,
thank you very much. Your answer was very usseful.
Best regards,
Matic
thank you very much. Your answer was very usseful.
Best regards,
Matic
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