Motivation
One of the key challenges in Pipe Flow Dynamics is to predict the pressure distribution along the pipe during the stationary fluid transport.
In many practical cases the stationary pressure distribution can be approximated by Isothermal or Quasi-isothermal homogenous fluid flow model.
Pipeline Flow Pressure Model is addressing this problem with account of the varying pipeline trajectory, gravity effects and fluid friction with pipeline walls.
Outputs
Assumptions
Equations
Pressure profile | Pressure gradient profile | Fluid velocity | Fluid rate |
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| p(l) = p_s + \rho_s \, g \, z(l) - \frac{\rho_s \, q_s^2 }{2 A^2 d} \, f_s \, l |
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| \frac{dp}{dl} = \rho_s \, g \cos \theta(l) - \frac{\rho_s \, q_s^2 }{2 A^2 d} \, f_s |
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| q(l) =q_s = \rm const |
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| u(l) = u_s = \frac{q_s}{A} = \rm const |
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where
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body | --uriencoded--f(%7B\rm Re%7D, \, \epsilon) |
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| Darcy friction factor |
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body | --uriencoded--\displaystyle %7B\rm Re%7D = \frac%7Bu(l) \cdot d%7D%7B\nu(l)%7D = \frac%7B4 \rho_s q_s%7D%7B\pi d%7D \frac%7B1%7D%7B\mu(T, p)%7D |
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| Reynolds number |
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body | --uriencoded--\displaystyle d = \sqrt%7B \frac%7B4 A%7D%7B\pi%7D%7D |
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| characteristic linear dimension of the pipe (or exactly a pipe diameter in case of a circular pipe) |
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| Incompressible fluid LaTeX Math Inline |
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body | \rho(T, p) = \rho_s = \rm const |
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| means that compressibility vanishes and fluid velocity is going to be constant along the pipeline trajectory LaTeX Math Inline |
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body | --uriencoded--u(l) = u_s = \frac%7Bq_s%7D%7BA%7D = \rm const |
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| .For the constant viscosity LaTeX Math Inline |
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body | \mu(T, p) = \mu_s = \rm const |
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| along the pipeline trajectory the Reynolds number LaTeX Math Inline |
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body | --uriencoded--\displaystyle %7B\rm Re%7D = \frac%7B4 \rho_s q_s%7D%7B\pi d%7D \frac%7B1%7D%7B\mu_s%7D = \rm const |
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| and Darcy friction factor LaTeX Math Inline |
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body | --uriencoded--f(%7B\rm Re%7D, \, \epsilon) = f_s = \rm const |
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| are going to be constant along the pipeline trajectory.Equation LaTeX Math Block Reference |
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| becomes: LaTeX Math Block |
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| \frac{dp}{dl} = \rho_s \, g \, \frac{dz}{dl} - \frac{\rho_s \, q_s^2 }{2 A^2 d} f_s |
which leads to LaTeX Math Block Reference |
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| after substituting LaTeX Math Inline |
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body | --uriencoded--\displaystyle \cos \theta(l) = \frac%7Bdz(l)%7D%7Bdl%7D |
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| and can be explicitly integrated leading to LaTeX Math Block Reference |
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| . |
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The first term in the right side of
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defines the hydrostatic column of static fluid while the last term defines the friction losses under fluid movement:
In most practical applications in water producing or water injecting wells, water can be considered as incompressible and friction factor can be assumed constant
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body | f(l) = f_s = \rm const |
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along-hole ( see
Darcy friction factor in water producing/injecting wells ).
References
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title | ARAX |
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