Effects of an Initial Gap on the Flow in a Turbulent Wall Jet

SummaryThe flow in a two-dimensional plane wall jet with different initial gaps between the nozzle exit and the leading edge of the wall was probed at various stations along the jet. The jet slot thickness and the velocity were kept constant. It was found that the region close to the leading edge of the wall behaved like a transforming region where the type of flow changed from a free jet to a wall jet. The length of this region, which depended directly on the gap size, was so short for small gaps that the gap effects were found to be negligible. In addition, it was found that the inner layer velocity distribution of a wall jet did not follow the classic one-seventh power law.

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Effects of an Initial Gap on the Turbulent Jet Flow over a Curved Wall

The Aeronautical Journal ◽

10.1017/s0001924000083494 ◽

1968 ◽

Vol 72 (685) ◽

pp. 63-67

Author(s):

S. C. Paranjpe ◽

K. Sridhar

Keyword(s):

Angular Position ◽

Leading Edge ◽

Turbulent Jet ◽

Hysteresis Phenomenon ◽

Wall Jet ◽

Exit Velocity ◽

Free Jet ◽

Surface Pressure Distribution ◽

Turbulent Jet Flow ◽

Gap Effects

Summary The flow in a two-dimensional curved wall jet with different initial gaps between the nozzle exit and the leading edge of the wall was probed at various stations along the jet. The jet slot thickness, the jet exit velocity and the radius of the wall were kept constant. It was found that the region close to the leading edge of the wall behaved like a settling zone. In this zone the type of flow changed from a free jet to a curved wall jet. The length required for settling depended on gap size and was less than that of the plane wall jet. Gap effects on surface pressure distribution and angular position of separation were examined. The hysteresis phenomenon associated with gaps was investigated.

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A Two∼Dimensional Wall Jet with Suction

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-1972-0029 ◽

1972 ◽

Vol 1 (4) ◽

pp. 182-188

Author(s):

T.B. Hedley ◽

J.F. Keffer

Keyword(s):

Viscous Sublayer ◽

Transport Processes ◽

Wall Jet ◽

Two Dimensional ◽

Mean Flow ◽

Law Of The Wall ◽

Free Jet ◽

The Mean ◽

Turbulent Wall ◽

Large Eddies

The mean flow field of a two-dimensional turbulent wall jet which encounters a uniform suction is examined. A marked increase in wall shear stress was observed for all suction levels as the jet moved into the suction zone. When the suction level is moderate a viscous sublayer exists next to the surface. The dominance of the flow by the free jet motion however prevents any law-of-the-wall representation for the adjacent turbulent region and a velocity defect model is found to be more satisfactory. One can interpret this lack of an extensive equilibrium layer to mean that the transport processes are controlled by the action of the large eddies over almost the entire wall jet zone, with or without suction.

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Analysis of a two-dimensional, turbulent wall jet along a circular cylinder. 3rd Report, Effects of nozzle exit velocity profile and injection angle.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.56.3650 ◽

1990 ◽

Vol 56 (532) ◽

pp. 3650-3657 ◽

Cited By ~ 1

Author(s):

Toshihiko SHAKOUCHI ◽

Yoshinori ONOHARA ◽

Seizo KATO

Keyword(s):

Circular Cylinder ◽

Velocity Profile ◽

Nozzle Exit ◽

Wall Jet ◽

Two Dimensional ◽

Injection Angle ◽

Exit Velocity ◽

Nozzle Exit Velocity ◽

Turbulent Wall

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Analytical solution in parametric form for the two-dimensional free jet of a power-law fluid

International Journal of Non-Linear Mechanics ◽

10.1016/j.ijnonlinmec.2016.06.005 ◽

2016 ◽

Vol 85 ◽

pp. 94-108 ◽

Cited By ~ 2

Author(s):

A.B. Magan ◽

D.P. Mason ◽

F.M. Mahomed

Keyword(s):

Analytical Solution ◽

Power Law ◽

Parametric Form ◽

Two Dimensional ◽

Power Law Fluid ◽

Free Jet

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Plane Turbulent Free Jet and Wall Jet

Journal of the Royal Aeronautical Society ◽

10.1017/s000192400005507x ◽

1967 ◽

Vol 71 (680) ◽

pp. 585-587 ◽

Cited By ~ 1

Author(s):

N. Rajaratnam ◽

K. Subramanya

Keyword(s):

Velocity Distribution ◽

Smooth Boundary ◽

Wall Jet ◽

Length Scales ◽

Ambient Environment ◽

Free Jet ◽

Turbulent Wall

The aim of this note is to compare the plane turbulent free jet diffusing in an infinite stagnant ambient environment with the corresponding plane turbulent wall jet on a smooth boundary regarding the three important characteristics, namely the velocity distribution and the variation of the velocity and length scales, in the region of developed flow.

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Buoyant convection from horizontal surfaces at const ant pressure

Journal of Fluid Mechanics ◽

10.1017/s0022112075001851 ◽

1975 ◽

Vol 68 (3) ◽

pp. 609-624 ◽

Cited By ~ 4

Author(s):

S. C. Traugott

Keyword(s):

Pressure Gradient ◽

Boundary Layers ◽

Line Source ◽

Leading Edge ◽

Wall Jet ◽

Two Dimensional ◽

Buoyant Plume ◽

Grashof Number ◽

Buoyancy Driven Flows ◽

Streamwise Pressure Gradient

A two-dimensional horizontal flow is discussed, which is induced by other, buoyancy-driven flows elsewhere. It is an adaptation of the incompressible wall jet, which is driven by conditions a t the leading edge and has no streamwise pressure gradient. The relation of this flow to the classical buoyancy-driven boundary layers on inclined and horizontal surfaces is investigated, as well as its possible connexion with a two-dimensional buoyant plume driven by a line source of heat. Composite flows are constructed by patching various such solutions together. The composite flows exhibit$Gr^{\frac{1}{4}}$scaling (Grbeing the Grashof number).

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Effect of initial condition on a two dimensional turbulent wall jet

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2019.s05116p ◽

2019 ◽

Vol 2019 (0) ◽

pp. S05116P

Author(s):

Koji NAKANO ◽

Koji IWANO ◽

Yasuhiko SAKAI ◽

Yasumasa ITO

Keyword(s):

Wall Jet ◽

Initial Condition ◽

Two Dimensional ◽

Turbulent Wall

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Analysis of a Power Law and Log Law for a Turbulent Wall Jet Over a Transitional Rough Surface: Universal Relations

Journal of Fluids Engineering ◽

10.1115/1.4004763 ◽

2011 ◽

Vol 133 (9) ◽

Cited By ~ 1

Author(s):

Noor Afzal ◽

Abu Seena

Keyword(s):

Experimental Data ◽

Rough Surface ◽

Power Law ◽

Power Laws ◽

Velocity Profiles ◽

Wall Jet ◽

Log Law ◽

Jet Velocity ◽

Turbulent Wall ◽

Momentum Integral

The power law and log law velocity profiles and an integral analysis in a turbulent wall jet over a transitional rough surface have been proposed. Based on open mean momentum Reynolds equations, a two layer theory for large Reynolds numbers is presented and the matching in the overlap region is carried out by the Izakson-Millikan-Kolmogorov hypothesis. The velocity profiles and skin friction are shown to be governed by universal log laws as well as by universal power laws, explicitly independent of surface roughness, having the same constants as a fully smooth surface wall jet (or fully rough surface wall jet, as appropriate). The novel scalings for stream-wise variations of the flow over a rough wall jet have been analyzed, and best fit relations for maximum wall jet velocity, boundary layer thickness at maxima of wall jet velocity, the jet half width, the friction factor, and momentum integral are supported by the experimental data. There is no universality of scalings in traditional variables, and different expressions are needed for transitional roughness. The experimental data provides very good support to our universal relations proposed in terms of alternate variables.

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