contributor author | J. P. Gostelow | |
contributor author | G. J. Walker | |
date accessioned | 2017-05-08T23:36:54Z | |
date available | 2017-05-08T23:36:54Z | |
date copyright | October, 1991 | |
date issued | 1991 | |
identifier issn | 0889-504X | |
identifier other | JOTUEI-28615#617_1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl/handle/yetl/109355 | |
description abstract | Boundary layer transition has been investigated experimentally under low, moderate, and high free-stream turbulence levels and varying adverse pressure gradients. Under high turbulence levels and adverse pressure gradients a pronounced subtransition was present. A strong degree of similarity in intermittency distributions was observed, for all conditions, when the Narasimha procedure for determination of transition inception was used. Effects of free-stream turbulence on the velocity profile are particularly strong for the laminar boundary layer upstream of the transition region. This could reflect the influence of the turbulence on the shear stress distribution throughout the layer and this matter needs further attention. The velocity profiles in wall coordinates undershoot the turbulent wall layer asymptote near the wall over most of the transition region. The rapidity with which transition occurs under adverse pressure gradients produces strong lag effects on the velocity profile; the starting turbulent boundary layer velocity profile may depart significantly from local equilibrium conditions. The practice of deriving integral properties and skin friction for transitional boundary layers by a linear combination of laminar and turbulent values for equilibrium layers is inconsistent with the observed lag effects. The velocity profile responds sufficiently slowly to the perturbation imposed by transition that much of the anticipated drop in form factor will not have occurred prior to the completion of transition. This calls into question both experimental techniques, which rely on measured form factor to characterize transition, and boundary layer calculations, which rely on local equilibrium assumptions in the vicinity of transition. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Similarity Behavior in Transitional Boundary Layers Over a Range of Adverse Pressure Gradients and Turbulence Levels | |
type | Journal Paper | |
journal volume | 113 | |
journal issue | 4 | |
journal title | Journal of Turbomachinery | |
identifier doi | 10.1115/1.2929125 | |
journal fristpage | 617 | |
journal lastpage | 624 | |
identifier eissn | 1528-8900 | |
keywords | Turbulence | |
keywords | Boundary layers | |
keywords | Pressure gradient | |
keywords | Equilibrium (Physics) | |
keywords | Skin friction (Fluid dynamics) | |
keywords | Shear (Mechanics) | |
keywords | Stress concentration | |
keywords | Boundary layer turbulence | |
keywords | Drops AND Matter | |
tree | Journal of Turbomachinery:;1991:;volume( 113 ):;issue: 004 | |
contenttype | Fulltext | |