BAKER HUGHES - Drilling Fluids Reference Manual

HYDRAULICS
Then solve for Q c ,
where:
Q c
= 2.45( V c )[( D 2 ) 2 – ( D 1 ) 2 ]
Q c = critical flow rate, gal/min
Fanning Friction Factor
The Fanning Friction Factor (f) expresses the resistance to flow of a fluid at the pipe wall and is a
function of the Reynolds Number and of the surface conditions at the wall.
Laminar flow in pipe,
f
p
= 16
Re
p
Transitional flow in pipe,
f
⎡Re
p
−
= ⎢
⎣
p
( 3470 −1370n
)
800
p
⎤
⎥
⎦
×
⎡
⎢
⎢⎣
a
−
16
⎤
+
⎥⎦
⎥
( 4270 −1370np
) 3470 −1370np
3470 −1370np
16
where:
log n
p
3.93
a =
+
50
1.75 − log n
b =
7
Turbulent flow in pipe,
p
f p
=
--------
a
b
Re p
where:
logn a p + 3.93
= -----------------------------
50
1.75 – logn b = -----------------------------
p
7
Laminar flow in annulus,
f =
a
24
Re
a
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 9-14