Flow by gravity in a not full pipe
Flow by gravity in a not full pipe
(OP)
Dear all,
I need to perform a calculation of the flow by gravity in a not full pipe. I used in the past Manning equation for that purpose with water pipes, but this time the fluid is diesel oil. I am not sure of the correction to be done in Manning equation, since I guess that diesel viscosity must have some impact.
I appreciate any help. I'm trying to find some reference or alternative equation without success so far.
Thanks in advance.
I need to perform a calculation of the flow by gravity in a not full pipe. I used in the past Manning equation for that purpose with water pipes, but this time the fluid is diesel oil. I am not sure of the correction to be done in Manning equation, since I guess that diesel viscosity must have some impact.
I appreciate any help. I'm trying to find some reference or alternative equation without success so far.
Thanks in advance.





RE: Flow by gravity in a not full pipe
Froude number is the key baboo.....
www.freecalc.com....
RE: Flow by gravity in a not full pipe
If I forget Manning, what equation could I use to perform the calculation? Any idea?
Thank you once again.
RE: Flow by gravity in a not full pipe
RE: Flow by gravity in a not full pipe
Good luck,
Latexman
RE: Flow by gravity in a not full pipe
You can use the Darcy-Weisbach equation together with the Colebrook-White formulation for friction factor. This approach is more common for full pipe flow, anyway introducing the concept of hydraulic radius and making the opportune corrections it can be adopted even for open channels and so to partially full pipe flow.
RE: Flow by gravity in a not full pipe
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Flow by gravity in a not full pipe
This is the scenario where you have an existing pipe size and you want to calculate the flow capacity. Similar calculations can be done if the flow is known, but not the pipe size. Determine the pipe size with this available head for full flow and then if you use a larger pipe you know it will run less than full.
All of this assumes an evenly sloped pipe. If you have high and low points you can get slack flow and the problem is more complicated.
If it is important to know how full the pipe is then you need to do the analysis described by ione.
Katmar Software - Uconeer 3.0
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Flow by gravity in a not full pipe
Interesting that some would use Manning's equation here...My experience is mostly in process piping where there are no slopes to speak of, only horizontal & vertical segments. I suppose long pipeline runs would have a general slope, however.
RE: Flow by gravity in a not full pipe
Manning's is not the appropriate equation to use here with a heavy fluid, since it is developed for water's viscosity (sanitary or storm) and there are no adjustments in the standard Manning's equation for higher or lower viscosity. The empirical equation was also developed in the turbulent flow range.
RE: Flow by gravity in a not full pipe
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Flow by gravity in a not full pipe
For a non full flow manning is fine for _near horizontal lines_
For vertival lines avoind entainment of air will prevent "gurgling" and this is the key issue and here its the Fround no=V/(sqrt(D*G) (V:m/s, D (ID, m), g grav constant (m/s²) this should be less than 0.3
Best regards
Morten
RE: Flow by gravity in a not full pipe
(TD2K: I do not believe that this information is contained in Crane 410)
http://en.wikipedia.org/wiki/Froude_number
www.freecalc.com
Prevent gurgling !
RE: Flow by gravity in a not full pipe
Best regards
Morten
RE: Flow by gravity in a not full pipe
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Flow by gravity in a not full pipe
Baboo, what is your situation?
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Flow by gravity in a not full pipe
Katmar Software - Uconeer 3.0
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Flow by gravity in a not full pipe
My exact situation is the lube oil drain line from a steam turbine back to the lube oil storage tank. They are short lines (20 m approx) with continuous slope (2% approximately).
RE: Flow by gravity in a not full pipe
Katmar Software - Uconeer 3.0
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Flow by gravity in a not full pipe
http://dictionary.reference.com/browse/belch
RE: Flow by gravity in a not full pipe
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek