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Finding fluid flow rate in a pipe, given pressure difference, length, and diameter

  1. Nov 8, 2009 #1
    1. The problem statement, all variables and given/known data

    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

    2. Relevant equations

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

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

    3. 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 [tex] f=64/Re [/tex] and iterated. However, my answer finally converged on f=12734.79 which doesn't look at all right. Am I doing something wrong?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 9, 2009 #2
    Re: finding fluid flow rate in a pipe, given pressure difference, length, and diamete

    Probably unit related. The equation for delta_p(your second equation) will have units in pascal.
     
  4. Nov 10, 2009 #3

    stewartcs

    User Avatar
    Science Advisor

    Re: finding fluid flow rate in a pipe, given pressure difference, length, and diamete

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

    CS
     
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