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.

On the spreading mechanism of the three-dimensional turbulent wall jet

2001 ◽  
Vol 435 ◽  
pp. 305-326 ◽  
Author(s):  
T. J. CRAFT ◽  
B. E. LAUNDER
Keyword(s):  
Three Dimensional ◽  
Lateral Spreading ◽  
Wall Jet ◽  
Streamwise Vorticity ◽  
Rate Of Spread ◽  
Self Similar ◽  
Spreading Rates ◽  
Turbulent Wall ◽  
Marching Scheme ◽  
Accurate Numerical Solution

The paper explores, using different levels of turbulence closure, the computed behaviour of the three-dimensional turbulent wall jet in order to determine the cause of the remarkably high lateral rates of spread observed in experiments. Initially, to ensure accurate numerical solution, the equations are cast into the form appropriate to a self-similar shear flow thereby reducing the problem to one of two independent variables.Our computations confirm that the strong lateral spreading arises from the creation of streamwise vorticity, rather than from anisotropic diffusion. The predicted ratio of the normal to lateral spreading rates is, however, very sensitive to the approximation made for the pressure–strain correlation. The version that, in other flows, has led to the best agreement with experiments again comes closest in calculating the wall jet, although the computed rate of spread is still some 50% greater than in most of the measurements. Our subsequent calculations, using a forward-marching scheme show that, because of the strong coupling between axial and secondary flow, the flow takes much longer to reach its self-preserving state than in a two-dimensional wall jet. Thus, it appears very probable that none of the experimental data are fully developed.

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.

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.

Boundary layer over spinning blunt body of revolution at incidence including Magnus forces

1978 ◽  
Vol 363 (1714) ◽  
pp. 357-380 ◽  
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Blunt Body ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Longitudinal Direction ◽  
Meridional Flow ◽  
Meridional Plane ◽  
Magnus Force ◽  
Displacement Thickness

An incompressible laminar flow over a spinning blunt-body at incidence is investigated. The approach follows strictly the three-dimensional boundary layer theory, and the lack of initial profiles is readily resolved. The rule of the dependence zone is satisfied with the Krause scheme, and complete numerical solutions are obtained for an ellipsoid of revolution at 6° incidence and two spin rates. Spinning causes asymmetry which, in turn, introduces the Magnus force. The asymmetry is most pronounced in crossflow, but is also noticeable in the skin friction and displacement thickness of the meridional flow. A variety of crossflow profiles are determined as are the streamline patterns in the cross- and meridional-plane which are especially useful in visualizing the flow structure. Detailed distribution of skin friction, displacement thickness, and centrifugal pressure are presented. A negative crossflow displacement thickness is found to be physically meaningful. The Magnus forces due to the crossflow skin friction and the centrifugal pressure are determined; these two forces partly compensate for each other. At lower spin rate, the frictional force is larger, resulting in a positive Magnus force. At high spin rate, the opposite is obtained. At high incidence (30°) the present boundary layer calculations could be carried out in the longitudinal direction, only up to the beginning of an open separation.

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.

Sign in / Sign up

Export Citation Format

Share Document