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Unformatted text preview: ulent friction is predicted most accurately when we use an effective diameter Deff equal to 0.64 times the hydraulic diameter. The effect on f itself is much
less, about 10 percent at most. We can compare with Eq. (6.83) for laminar flow, which
This close resemblance (0.64Dh versus 0.667Dh) occurs so often in noncircular duct
flow that we take it to be a general rule for computing turbulent friction in ducts:
Deff | v v 360 | e-Text Main Menu | Dh 4A reasonable accuracy Textbook Table of Contents | Study Guide 6.6 Flow in Noncircular Ducts Deff(laminar theory) extreme accuracy 361 (6.89) Jones  shows that the effective-laminar-diameter idea collapses all data for rectangular ducts of arbitrary height-to-width ratio onto the Moody chart for pipe flow. We
recommend this idea for all noncircular ducts. EXAMPLE 6.13
Fluid flows at an average velocity of 6 ft/s between horizontal parallel plates a distance of 2.4
in apart. Find the head loss and pressure drop for each 100 ft of...
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- Spring '08