Three-Dimensional Wall Jet Originating from a Circular Orifice

1972 ◽  
Vol 23 (3) ◽  
pp. 188-200 ◽  
Author(s):  
B G Newman ◽  
R P Patel ◽  
S B Savage ◽  
H K Tjio
Keyword(s):  
Three Dimensional ◽  
Plane Wall ◽  
Similarity Analysis ◽  
Length Scale ◽  
Wall Jet ◽  
Mean Velocity ◽  
Lateral Direction ◽  
Rate Of Growth ◽  
Circular Orifice ◽  
Turbulent Wall

SummaryAn incompressible three-dimensional turbulent wall jet originating from a circular orifice located adjacent to a plane wall is studied both theoretically and experimentally. An approximate similarity analysis predicts that the two transverse length scales,l0and L0, and the inverse of the mean velocity scale grow linearly with distance downstream x from the orifice. Experimental measurements of mean velocity and longitudinal turbulence intensity profiles were made both in air and water with hot-wire and hot-film anemometers respectively. The behaviour predicted by the similarity analysis was verified. It was found that the rate of growth of the length scale normal to the plane wall, dl0/dx, was somewhat less than that found for a two-dimensional wall jet, whereas the rate of growth of the length scale in the lateral direction, dL0/dx, was about seven times greater than dl0/dx.

Mean and turbulence characteristics of three-dimensional wall jets

1975 ◽  
Vol 71 (3) ◽  
pp. 541-562 ◽  
Author(s):  
N. V. Chandrasekhara Swamy ◽  
P. Bandyopadhyay
Keyword(s):  
Skin Friction ◽  
Three Dimensional ◽  
Longitudinal Direction ◽  
Experimental Investigations ◽  
Length Scale ◽  
Wall Jet ◽  
Similar Form ◽  
Turbulence Characteristics ◽  
Self Similar ◽  
Turbulent Wall

This paper reports experimental investigations on the characteristic decay and the radial-type decay regions of a three-dimensional isothermal turbulent wall jet in quiescent surroundings. The velocity and the length scale behaviour for both the longitudinal and the transverse directions are studied, and compared with the results of other workers. The estimated skin friction is discussed in relation to the available data from earlier investigations. Wall jet expansion rates and the behaviour of skin friction are also discussed. The rate of approach of turbulence components to a self-similar form is found to be influenced by the fact that the expansion rate of the wall jet in the longitudinal direction is different from that in the transverse.

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.

Comparative study of a turbulent wall-attaching offset jet and a plane wall jet

KSME Journal ◽  
1993 ◽  
Vol 7 (2) ◽  
pp. 101-112 ◽  
Author(s):  
Soon Hyun Yoon ◽  
Kyung Chun Kim ◽  
Dae Seong Kim ◽  
Myung Kyoon Chung
Keyword(s):  
Comparative Study ◽  
Plane Wall ◽  
Wall Jet ◽  
Turbulent Wall ◽  
Offset Jet

Turbulent Vorticity Diffusion in the Stronger Wall Jet Managed by a Flat Plate Wing in the Outer Layer

2015 ◽  
Author(s):  
Takuma Katayama ◽  
Shinsuke Mochizuki
Keyword(s):  
Shear Stress ◽  
Flat Plate ◽  
Outer Layer ◽  
Large Scale ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Quantitative Relationship ◽  
Wall Jet ◽  
Mean Velocity ◽  
The Mean

The present experiment focuses on the vorticity diffusion in a stronger wall jet managed by a three-dimensional flat plate wing in the outer layer. Measurement of the fluctuating velocities and vorticity correlation has been carried out with 4-wire vorticity probe. The turbulent vorticity diffusion due to the large scale eddies in the outer layer is quantitatively examined by using the 4-wire vorticity probe. Quantitative relationship between vortex structure and Reynolds shear stress is revealed by means of directly measured experimental evidence which explains vorticity diffusion process and influence of the manipulating wing. It is expected that the three-dimensional outer layer manipulator contributes to keep convex profile of the mean velocity, namely, suppression of the turbulent diffusion and entrainment.

An Experimental Study of a Turbulent Wall Jet on Smooth and Transitionally Rough Surfaces

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
N. Rostamy ◽  
D. J. Bergstrom ◽  
D. Sumner ◽  
J. D. Bugg
Keyword(s):  
Friction Coefficient ◽  
Skin Friction ◽  
Laser Doppler Anemometry ◽  
Skin Friction Coefficient ◽  
Wall Jet ◽  
Roughness Effects ◽  
Mean Velocity ◽  
Turbulent Wall ◽  
Inner Region ◽  
Effect Of Surface

The effect of surface roughness on the mean velocity and skin friction characteristics of a plane turbulent wall jet was experimentally investigated using laser Doppler anemometry. The Reynolds number based on the slot height and exit velocity of the jet was approximately Re = 7500. A 36-grit sheet was used to create a transitionally rough flow (44 < ks+ < 70). Measurements were carried out at downstream distances from the jet exit ranging from 20 to 80 slot heights. Both conventional and momentum-viscosity scaling were used to analyze the streamwise evolution of the flow on smooth and rough walls. Three different methods were employed to estimate the friction velocity in the fully developed region of the wall jet, which was then used to calculate the skin friction coefficient. This paper provides new experimental data for the case of a plane wall jet on a transitionally rough surface and uses it to quantify the effects of roughness on the momentum field. The present results indicate that the skin friction coefficient for the rough-wall case compared to a smooth wall increases by as much as 140%. Overall, the study suggests that for the transitionally rough regime considered in the present study, roughness effects are significant but mostly confined to the inner region of the wall jet.

A Comparison of Classic and Snapshot Proper Orthogonal Decomposition on the Three Dimensional Wall Jet Flow Field

2014 ◽  
Author(s):  
Mahdi Hosseinali ◽  
Stephen Wilkins ◽  
Lhendup Namgyal ◽  
Joseph Hall
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Energy Content ◽  
Near Field ◽  
Three Dimensional ◽  
Orthogonal Decomposition ◽  
Wall Jet ◽  
Polar Coordinate ◽  
Wall Jet Flow ◽  
Turbulent Wall ◽  
Proper Orthogonal

In this paper, classic Proper Orthogonal Decomposition (POD) on a polar coordinate and snapshot POD on a Cartesian grid will be applied separately in the near field of a turbulent wall jet. Three-component stereoscopic PIV measurements are performed in the transverse plane of a wall jet formed using a round contoured nozzle with a Reynolds number of 250,000. Eigenfunctions and energy distributions of the two methods are compared. Reconstructions using same number of modes and same content of energy have been compared. The effect of grid resolution on the energy content of the classic method has also been studied.

Enhancement of heat transfer using turbulent wall jet

2019 ◽  
Vol 234 (1) ◽  
pp. 123-136
Author(s):  
Tej Pratap Singh ◽  
Amitesh Kumar ◽  
Ashok Kumar Satapathy
Keyword(s):  
Heat Transfer ◽  
Goodness Of Fit ◽  
Stokes Equations ◽  
Cooling System ◽  
Plane Wall ◽  
The Self ◽  
Wall Jet ◽  
Enhancement Of Heat Transfer ◽  
Self Similar ◽  
Turbulent Wall

Enhancement of heat transfer is very important in many engineering applications. The present study explores one of such possibilities by increasing the surface area of a plane wall. The effect of wavy wall on thermal and flow characteristics of a turbulent wall jet is studied in detail. The amplitude of the wavy surface is varied between 0.1 and 0.7 with an interval of 0.1. The Reynolds number is set to 15,000. The Reynolds averaged Navier Stokes equations are solved using the finite volume approach. The semi-implicit pressure linked equation algorithm is used to couple the pressure and velocity. A new scale, other than the traditional outer scaling, is defined for carrying out the self-similar behavior of the flow. Unlike the plane wall case, the self-similar characteristic is obtained at the respective crests and the troughs. However, it is also noticed that the two characteristics differ significantly with each other. Even, these characteristics are found to differ with each other for different amplitudes. The minimum pressure near the nozzle decreases as the amplitude increases and it is noted to be equal to −0.541 for the highest amplitude, i.e. A = 0.7. It is observed that the strength of convection near the exit of the jet is very high, and it decreases in the downstream direction. This increase in convection augments heat transfer by almost 10% as compared to the plane wall case. Based on the results, a quartic curve is fit for the average Nusselt number with a 99.75% goodness of fit. It is expected that the present study opens a new line in designing a proper cooling system.

The forced turbulent wall jet

1992 ◽  
Vol 242 ◽  
pp. 577-609 ◽  
Author(s):  
Y. Katz ◽  
E. Horev ◽  
I. Wygnanski
Keyword(s):  
Maximum Velocity ◽  
Wall Stress ◽  
Coherent Motion ◽  
Settling Chamber ◽  
Wall Jet ◽  
Appreciable Effect ◽  
External Excitation ◽  
Mean Velocity ◽  
The Mean ◽  
Turbulent Wall

The effects of external two-dimensional excitation on the plane turbulent wall jet were investigated experimentally and theoretically. Measurements of the streamwise component of velocity were made throughout the flow field for a variety of imposed frequencies and amplitudes. The present data were always compared to the results generated in the absence of external excitation. Two methods of forcing were used: one global, imposed on the entire jet by pressure fluctuations in the settling chamber and one local, imposed on the shear layer by a small flap attached to the outer nozzle lip. The fully developed wall jet was shown to be insensitive to the method of excitation. Furthermore, external excitation has no appreciable effect on the rate of spread of the jet nor on the decay of its maximum velocity. In fact the mean velocity distribution did not appear to be altered by the external excitation in any obvious manner. The flow near the surface, however, (i.e. for 0 < Y+ < 100) was profoundly different from the unforced flow, indicating a reduction in wall stress exceeding at times 30%. The production of turbulent energy near the surface was also reduced, lowering the intensities of the velocity fluctuations. External excitation enhanced the two-dimensionality and the periodicity of the coherent motion. Spectral analysis and flow visualization suggested that the large coherent structures in this flow might be identified with the most-amplified primary instability modes of the mean velocity profile. Detailed stability analysis confirmed this proposition though not at the same level of accuracy as it did in many free shear flows.

scholarly journals Experimental Investigation on Mean Flow Development of a Three-Dimensional Wall Jet Confined by a Vertical Baffle

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 237
Author(s):  
Ming Chen ◽  
Haijin Huang ◽  
Xingxing Zhang ◽  
Senpeng Lv ◽  
Rengmin Li
Keyword(s):  
Three Dimensional ◽  
Wall Jet ◽  
Lateral Growth ◽  
Mean Flow ◽  
Particle Image Velocimetry Technique ◽  
Mean Velocity ◽  
Flow Development ◽  
Velocity Decay ◽  
The Mean ◽  
Vertical Baffle

Three-dimensional (3D) confined wall jets have various engineering applications related to efficient energy dissipation. This paper presents experimental measurements of mean flow development for a 3D rectangular wall jet confined by a vertical baffle with a fixed distance (400 mm) from its surface to the nozzle. Experiments were performed at three different Reynolds numbers of 8333, 10,000 and 11,666 based on jet exit velocity and square root of jet exit area (named as B), with water depth of 100 mm. Detailed measurements of current jet were taken using a particle image velocimetry technique. The results indicate that the confined jet seems to behave like an undisturbed jet until 16B downstream. Beyond this position, however, the mean flow development starts to be gradually affected by the baffle confinement. The baffle increases the decay and spreading of the mean flow from 16B to 23B. The decay rate of 1.11 as well as vertical and lateral growth rates of 0.04 and 0.19, respectively, were obtained for the present study, and also fell well within the range of values which correspond to the results in the radial decay region for the unconfined case. In addition, the measurements of the velocity profiles, spreading rates and velocity decay were also found to be independent of Reynolds number. Therefore, the flow field in this region appears to have fully developed at least 4B earlier than the unconfined case. Further downstream (after 23B), the confinement becomes more pronounced. The vertical spreading of current jet shows a distinct increase, while the lateral growth was found to be decreased significantly. It can be also observed that the maximum mean velocity decreases sharply close to the baffle.

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