In
this study, the steady, incompressible and axis symmetric flows in the pipe
entrance region has been simulated numerically for the Reynolds numbers between
1000 and 25000 and for the square edged pipe inlets. The developing boundary
layer at the pipe entrance region first grows as laminer then disturbed to a
turbulent state at downstream away of the inlet. From pipe inlet to a
downstream distance where laminer to turbulent transition begins is called the
transition length. Determination of the transition length has been significiant
for hydro and aeromechanics and yet it seems not to be defined clearly. The
effects of wall surface roughness, pipe diameter and Reynolds numbers on
transition length has been investigated numerically by covering transition and
turbulent flow regimes too. On the purpose, water flows were simulated
numerically including five different relative roughness. The numerical results
obtained has shown that the transiton length is the power function of the
Reynolds number inverse proportionally. Likewise the numerical study has also
shown that changing the pipe diameter but keeping the relative roughness the
same has left no effect on the transition length. As an outcome, a numerical
correlation which define the dimensionless transition length and well fitting
the numerical values was derived as a function of Reynolds number.
Primary Language | English |
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Subjects | Engineering |
Journal Section | Articles |
Authors | |
Publication Date | August 19, 2018 |
Published in Issue | Year 2018Issue: 2 |