Mean flow characteristics of a 3D turbulent wall jet over an isothermal and an insulating flat surface

1995 ◽  
Vol 31 (1-2) ◽  
pp. 89-93 ◽  
Author(s):  
Y. Belilovsky
Keyword(s):  
Flat Surface ◽  
Flow Characteristics ◽  
Wall Jet ◽  
Mean Flow ◽  
Turbulent Wall

Mean Flow Characteristics of a Turbulent Offset Jet

1986 ◽  
Vol 108 (1) ◽  
pp. 82-88 ◽  
Author(s):  
J. R. R. Pelfrey ◽  
J. A. Liburdy
Keyword(s):  
Strain Rate ◽  
Flat Surface ◽  
Flow Characteristics ◽  
Wall Jet ◽  
Longitudinal Variation ◽  
Mean Flow ◽  
Region Flow ◽  
The Mean ◽  
Plane Jet ◽  
Offset Jet

A detailed study of the mean flow characteristics of a turbulent offset jet is presented. The flow is characterized by a longitudinal variation of curvature, skewed impingement onto a flat surface, a recirculating region, and the development of a wall jet region. Flow structure is described in the preimpingement, recirculation and impingement regions. An interdependence is shown among the pressure differential across the jet, jet curvature and entrainment. The magnitude of the curvature strain rate is found to be significant and implies that this flow cannot be accurately modelled as a thin shear layer. The jet decay and spread rates are similar to those of a plane jet if appropriate curved coordinates are used. The extent of the impingement region is approximately 20 nozzle widths downstream, in agreement with previous studies.

Mean and Turbulence Characteristics of a Class of Three-Dimensional Wall Jets—Part 1: Mean Flow Characteristics

1991 ◽  
Vol 113 (4) ◽  
pp. 620-628 ◽  
Author(s):  
G. Padmanabham ◽  
B. H. Lakshmana Gowda
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Experimental Investigations ◽  
Wall Jet ◽  
Mean Flow ◽  
Wall Jets ◽  
Mean Velocity ◽  
Turbulence Characteristics ◽  
Turbulent Wall ◽  
And Behavior

This paper reports experimental investigations on mean and turbulence characteristics of three-dimensional, incompressible, isothermal turbulent wall jets generated from orifices having the shapes of various segments of a circle. In Part 1, the mean flow characteristics are presented. The turbulence characteristics are presented in Part 2. The influence of the geometry on the characteristic decay region of the wall jet is brought out and the differences with other shapes are discussed. Mean velocity profiles both in the longitudinal and lateral planes are measured and compared with some of the theoretical profiles. Wall jet expansion rates and behavior of skin-friction are discussed. The influence of the geometry of the orifice on the various wall jet properties is presented and discussed. Particularly the differences between this class of geometry and rectangular geometries are critically discussed.

Numerical study of turbulent wall jet over multiple-inclined flat surface

2014 ◽  
Vol 95 ◽  
pp. 132-158 ◽  
Author(s):  
Shantanu Pramanik ◽  
Manab Kumar Das
Keyword(s):  
Flat Surface ◽  
Numerical Study ◽  
Wall Jet ◽  
Turbulent Wall

A Two∼Dimensional Wall Jet with Suction

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.

Experimental Investigation of the Effect of Free Stream Flow on the Thermal Behavior of a Turbulent Wall Jet

2014 ◽  
Author(s):  
Johnny Issa ◽  
Alfonso Ortega
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Stream Flow ◽  
Free Stream ◽  
Flow Characteristics ◽  
Thermal Characteristics ◽  
Wall Jet ◽  
Reynolds Analogy ◽  
Turbulent Wall

A systematic experimental investigation is conducted to understand of the effect of the free stream flow on the thermal characteristics of the turbulent wall jet. The jet Reynolds number varies between 6000 and 10000. The effect of the free stream flow on heat transfer and flow characteristics of the wall jet is investigated for blowing ratio varying between 2.4 to infinity. In the absence of free stream flow, Nusselt number data showed a very good agreement with published correlations. The free stream flow reduced Nusselt number in the region close to the jet exit and increased it in the region far downstream, a behavior explained using Reynolds analogy. The local Nusselt number dependence on Reynolds number and on the downstream location is identified and the obtained experimental results are correlated for the various considered blowing ratios.

The effects of excitation on the coherent and random motion in a plane wall jet

1996 ◽  
Vol 310 ◽  
pp. 1-37 ◽  
Author(s):  
M. D. Zhou ◽  
C. Heine ◽  
I. Wygnanski
Keyword(s):  
Equations Of Motion ◽  
Detailed Comparison ◽  
Random Motion ◽  
Coherent Motion ◽  
Settling Chamber ◽  
Wall Jet ◽  
Mean Flow ◽  
Definition Of ◽  
Turbulent Wall

Three components of velocity fluctuations were measured in a plane turbulent wall jet which was modulated periodically by a sinusoidal pressure fluctuation in its settling chamber. The experiment was carried out in a closed-loop wind tunnel in the absence of an external stream at Reynolds number Rej = Ujb/v = 6900 and Strouhal number Stj = fb/Uj = 9.5 × 10−3, where b is the width of the slot from which the jet emerges at an efflux velocity Uj. A detailed comparison is provided with similar measurements made in a natural, unexcited turbulent wall jet. One of the purposes of this experiment was to establish the kinetic energy transfers which take place in the wall jet under controlled perturbations. More specifically, we were interested in determining the interactions occurring between the steady mean flow, the coherent eddies and the ‘random’ turbulent fluctuations. We used the triple decomposition of the equations of motion as suggested by Hussain (1983) and quickly observed that the usefulness of this decomposition depends on the definition of coherent motion, which is ambiguous in the presence of phase jitter. Two such definitions were considered and the results are discussed in the experimental case-study provided. An attempt is made to define quantitatively the intensities of the coherent motion in externally excited, wallbounded flows. It is a case-study and not a parametric investigation aimed at maximizing the effects of period oscillations on the wall jet.

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