...
For a smooth (
) tubular pipeline
Darcy friction factor can be estimated from various
empirical correlations :
where
For non-smooth pipelines
the
Darcy friction factor can be estimated from
empirical Colebrook–White correlation which works for non-
laminar flow:
...
For many practical applications the Churchill correlation provides a fair (< 2 % accuracy and improving towards laminar flow) estimation of Darcy friction factor
for all pipe flow regimes:
| LaTeX Math Block |
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| anchor | Chirchil |
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| alignment | left |
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| f = \frac{64}{\rm Re} \, \Bigg [ 1+ \frac{\big(\rm Re / 8 \big)^{12} }{ \big( \Theta_1 + \Theta_2 \big)^{1.5} } \Bigg]^{1/12} |
|
| LaTeX Math Block |
|---|
| \Theta_1 = \left[ 2.457 \, \ln \left( \left( \frac{7}{\rm Re} \right)^{0.9} + 0.27 \, \frac{\epsilon}{d} \right) \right]^{16} |
|
| LaTeX Math Block |
|---|
| \Theta_2 = \left( \frac{37530}{\rm Re} \right)^{16} |
|
Typical surface roughness of a factory steel pipelines is
= 0.05
mm which may increase significantly under mineral sedimentation or erosive impact of the flowing fluids.
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