pressure drop, flow, darcy equation 3

[dho]

book "mechanics of fluid" presents darcy equation as
h = 4 f l V^2 / d 2g
and
h = f l v^2 / m 2g
in a circular pipe, m = d/4

but I looked online, most web pages present
h = f l v^2 / d 2g
missing 4.

which one is correct?

 

[Latexman]

It depends on whether you use the Fanning friction factor or Moody/Darcy/Weisbach friction factor. f = 4f_F

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[dho]

thanks to latexman.
any one know an online pressure drop calculation page, for jet fuel, and includes angled entry and exit?

 

[LittleInch]

This lot are usually pretty good, but what do you mean by "angled entry and exit"?

http://www.engineeringtoolbox.com/pipes-fluid-flow-pressure-loss-t_18.html

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[dho]

say a 2 inch pipe to 1 inch then 2 again. the cross section change is a tapered 30, 40.. degree inclusive angle.

 

[LittleInch]

Sounds a bit odd, but you know the details not us...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[katmar]

The angled entries and exits you talk of are usually called reducers (even when used in expanding mode). Sometimes they are made with a conical taper, but more often with a rounded bell shaped profile. Most piping pressure drop programs (stand alone and online) include a facility to handle pipe diameter changes using either conical resucers, pipe reducers or sudden contractions/expansions.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"