Characteristics of 3D Turbulent Wall Jets and Offset Jets With Small Offset Ratios

2009 ◽  
Author(s):  
M. Agelinchaab ◽  
M. F. Tachie
Keyword(s):  
Three Dimensional ◽  
Symmetry Plane ◽  
Shear Stresses ◽  
Wall Jets ◽  
Particle Image Velocimetry Technique ◽  
Image Velocimetry ◽  
Turbulent Wall Jets ◽  
The Mean ◽  
Turbulent Wall ◽  
Proper Orthogonal

This paper reports an experimental study of turbulent three-dimensional generic wall jets and offset jets. The jets were created from a long circular pipe. A particle image velocimetry technique was used to conduct velocity measurements in the symmetry plane of the jet. From these measurements, the salient features of the flows are reported in terms of the mean velocities, turbulence intensities and Reynolds shear stresses. The energy spectra and profiles of reconstructed turbulence intensities and Reynolds shear stresses from low order proper orthogonal decomposition modes are also reported.

Mean and Turbulence Characteristics of a Class of Three-Dimensional Wall Jets—Part 2: Turbulence Characteristics

1991 ◽  
Vol 113 (4) ◽  
pp. 629-634 ◽  
Author(s):  
G. Padmanabham ◽  
B. H. Lakshmana Gowda
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Mean Flow ◽  
Wall Jets ◽  
Turbulence Characteristics ◽  
Turbulent Wall Jets ◽  
The Mean ◽  
Turbulent Wall

The mean flow characteristics of three-dimensional, incompressible, isothermal turbulent wall jets generated from orifices having the shapes of various segments of a circle are presented in Part 1 of this paper. In this part, the turbulence characteristics are presented. Turbulence quantities measured include normal stresses and Reynolds shear stresses in the characteristic-decay and in the radial-decay regions of the wall jets investigated. These results are compared with those available for two-dimensional and three-dimensional wall jets. The presence of counter-gradient regions and the feature of “energy reveral” are discussed.

Three-Dimensional Turbulent Wall Jets

2009 ◽  
Author(s):  
M. Agelinchaab ◽  
M. F. Tachie
Keyword(s):  
Reynolds Number ◽  
Turbulence Intensity ◽  
Large Scale ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Wall Jets ◽  
Turbulent Statistics ◽  
Turbulent Wall Jets ◽  
The Mean ◽  
Turbulent Wall

Particle image velocimetry (PIV) measurements were carried out on generic three-dimensional turbulent wall jets. The wall jets were created from a long circular pipe at Reynolds number based on the jet exit velocity (Uj) and inside diameter of pipe (d) of Rej = Ujd/v = 7680 to 19500. The profiles of the mean velocities, turbulence intensities and Reynolds shear stresses in the streamwise/wall-normal and streamwise/lateral planes are presented. Consistent with previous results, the profiles of the mean velocities and turbulent statistics are independent of Reynolds number. The mean velocity attained self-similarity before the turbulence quantities. The decay rate and spread rates obtained in the present study fall in between the values reported in previous studies. The contours of the two-point velocity correlations in the inner region of the 3D wall jet are qualitatively similar to those reported in boundary layer studies. The results from proper orthogonal analysis revealed that large scale structures are largely responsible for the distribution of the streamwise turbulence intensity and Reynolds shear stresses than the distribution of the wall-normal turbulence intensity.

scholarly journals Erratum for “Three-Dimensional Turbulent Wall Jets”

1974 ◽  
Vol 100 (12) ◽  
pp. 1849-1849
Author(s):  
Nallamuthu Rajaratnam ◽  
Bidya Sagar Pani
Keyword(s):  
Three Dimensional ◽  
Wall Jets ◽  
Turbulent Wall Jets ◽  
Turbulent Wall

Characteristics of Turbulent Three-Dimensional Offset Jets

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
M. Agelin-Chaab ◽  
M. F. Tachie
Keyword(s):  
Three Dimensional ◽  
Symmetry Plane ◽  
Outer Region ◽  
Decay Rates ◽  
Wall Region ◽  
Mean Flow ◽  
Particle Image Velocimetry Technique ◽  
Similar Region ◽  
The Mean ◽  
Turbulence Transport

Three-dimensional turbulent offset jets were investigated using a particle image velocimetry technique. Three jet exit Reynolds numbers, Rej = 5000, 10,000, and 20,000, and four offset heights, h/d = 0.5, 1.0, 2.0, and 4.0, were studied. The mean flow and turbulence statistics were studied over larger downstream distances than in previous studies. The decay and spread rates were found to be nearly independent of Reynolds number and offset height at certain exit diameters (x = 73d) downstream and h/d ≤ 2. The decay rates of 1.18 ± 0.03 and spread rates of 0.055 ± 0.001 and 0.250 ± 0.005 in the wall-normal and lateral directions were obtained, respectively. The reattachment lengths are also independent of Rej but increase with offset height. The locations of the maximum mean velocities increased linearly with streamwise distance in the self-similar region. It was observed that profiles of the mean velocities, turbulence intensities, and Reynolds shears stresses are nearly independent of Rej and h/d far downstream. The triple products in the symmetry plane indicated turbulence transport from the outer region of the jet towards the wall region.

Three-Dimensional Turbulent Wall Jets

1974 ◽  
Vol 100 (1) ◽  
pp. 69-83 ◽  
Author(s):  
Nallamuthu Rajaratnam ◽  
Bidya Sagar Pani
Keyword(s):  
Three Dimensional ◽  
Wall Jets ◽  
Turbulent Wall Jets ◽  
Turbulent Wall

PIV Study of Three-Dimensional Wall Jet Over Smooth and Rough Surfaces

2007 ◽  
Author(s):  
Martin Agelinchaab ◽  
Mark F. Tachie
Keyword(s):  
Open Channel ◽  
Rough Surfaces ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Jet Flows ◽  
Wall Jet ◽  
Image Velocimetry ◽  
The Mean ◽  
Turbulent Wall ◽  
Insight Into

This paper reports experimental study of three-dimensional turbulent wall jet over smooth and rough surfaces. The wall jet was created using a square nozzle of size 6 mm and flow into an open channel. The experiments were performed at a Reynolds number based on the nozzle size and jet exit velocity of 4800. A particle image velocimetry was used to conduct detailed measurements over the smooth and rough surfaces at various streamwise-transverse and streamwise-spanwise planes. From these measurements, mean velocities and turbulent quantities were extracted at selected locations. The distributions of the mean velocities, turbulent intensities and Reynolds shear stress were used to provide insight into the characteristics of three-dimensional wall jet flows over smooth and rough surface.

Turbulent Flows Over Rough Forward Facing Steps

2014 ◽  
Author(s):  
Weijie Shao ◽  
Martin Agelin-Chaab
Keyword(s):  
Turbulent Flows ◽  
Large Scale ◽  
Reattachment Length ◽  
Particle Image Velocimetry Technique ◽  
Large Scale Structures ◽  
Image Velocimetry ◽  
The Mean ◽  
Scale Structures ◽  
Scale Turbulence ◽  
Proper Orthogonal

This paper reports an investigation of the effects of rough forward facing steps on turbulent flows. The surfaces of the rough steps were covered with sandpapers. A particle image velocimetry technique was used to conduct measurements at the mid-plane of the test section and at several locations downstream to 68 step heights. A Reynolds number of Reh = 4800 and δ/h = 4.7 were employed, where h is the mean step height and δ is the incoming boundary layer thickness. The results indicate that mean reattachment length decreases with increasing roughness. In addition, the effect of the step roughness decreases with downstream distance. The proper orthogonal decomposition results showed that the step roughness affects even the large scale structures. Furthermore, the reconstructed turbulence quantities suggest that the step roughness suppresses the large scale turbulence.

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