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Fanning Friction Factor

by Maylis
Tags: factor, fanning, friction
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Maylis
#1
Feb11-14, 01:14 AM
PF Gold
P: 579
Hello,

I was wondering if when calculating the fanning friction factor, do english units need to be used?

The equation for the head friction is

h_f = 4f(L/D)V^2/2

where L is the length, D is the diameter of the pipe, and f is the fanning friction factor. This ends up having units of length squared/time squared, but I think it should be power/mass
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SteamKing
#2
Feb11-14, 04:19 AM
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Thanks
PF Gold
P: 6,755
I don't know about your dimensional analysis. The Fanning friction factor is non-dimensional.

http://en.wikipedia.org/wiki/Fanning_friction_factor

BTW, your formula for head loss due to friction is incorrect. It should be:

h_f = 4f(L/D)V^2/(2g)
Maylis
#3
Feb11-14, 10:19 AM
PF Gold
P: 579
Is the g included whether you use english units or not? I get confused when I need to divide by g or not these days since we keep going back and forth with english and SI units

SteamKing
#4
Feb11-14, 12:24 PM
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PF Gold
P: 6,755
Fanning Friction Factor

Yes, the g is always there, even in SI or furlongs per fortnight units. Do a dimensional analysis and confirm.
Maylis
#5
Feb11-14, 11:11 PM
PF Gold
P: 579
You can see why I was confused, this is directly and repeatedly on the lecture slides
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