Calculating Flow Rate: Oil in a Pipe

[Vidatu]

Homework Statement

Oil flowing through a pipe, measured to be 135kPa 15m from the end and 88kPa discharging from the end. The diameter of the pipe is 1.5cm, the density of the oil is 876kg/m^3, and the dynamic viscosity is 0.24kg/m*s.
Find flow rate for:
a) horizontal
b) inclined 8 degrees
c) declined 8 degrees

Homework Equations

Re=V*D*\rho / \mu
\Delta P = h_L * \rho *g
h_L = f*(L/D)*(V^2)/(2*g)
f=64/Re (laminar flow only)

where:
Re = Reynolds Number
rho = densityf=64/Re
mu = dynamic viscosity
delta P = pressure loss
h_L = head loss
L = length
D = diameter
f = Darcy friction coefficient

The Attempt at a Solution

I solved for Re in terms of V, and for V in terms of f, and then I guessed f=0.0150 for a starting point. I got an Re of 13.8, indicating laminar flow, so I used f=64/Re and iterated. However, my answer finally converged on f=12734.79 which doesn't look at all right. Am I doing something wrong?

 

[defunc]

Probably unit related. The equation for delta_p(your second equation) will have units in pascal.

 

[stewartcs]

Homework Statement

Oil flowing through a pipe, measured to be 135kPa 15m from the end and 88kPa discharging from the end. The diameter of the pipe is 1.5cm, the density of the oil is 876kg/m^3, and the dynamic viscosity is 0.24kg/m*s.
Find flow rate for:
a) horizontal
b) inclined 8 degrees
c) declined 8 degrees

Homework Equations

Re=V*D*\rho / \mu
\Delta P = h_L * \rho *g
h_L = f*(L/D)*(V^2)/(2*g)
f=64/Re (laminar flow only)

where:
Re = Reynolds Number
rho = densityf=64/Re
mu = dynamic viscosity
delta P = pressure loss
h_L = head loss
L = length
D = diameter
f = Darcy friction coefficient

The Attempt at a Solution

I solved for Re in terms of V, and for V in terms of f, and then I guessed f=0.0150 for a starting point. I got an Re of 13.8, indicating laminar flow, so I used f=64/Re and iterated. However, my answer finally converged on f=12734.79 which doesn't look at all right. Am I doing something wrong?

You need to show your work so we can give you guidance.

CS