ENHANCED MIXING OF A CIRCULAR JET USING AN ANNULAR SYNTHETIC JET ACTUATOR(Flow Control 1)

Koso, Toru

doi:10.1299/jsmeicjwsf.2005.385

Cited by 3 publications

(7 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5 Half width (diameter) of jet d 1 Inner diameter of annular slot d 2 Outer Figure 1 shows a schematic view of a jet nozzle with an annular synthetic jet actuator. Figure 1(a) is a cross section of the actuator.…”

Section: Nomenclature Dmentioning

confidence: 99%

“…The area ratio of the annular slot to the jet nozzle is 1.12. The main size of this actuator is the double of the previous study (5) .…”

Section: Nomenclature Dmentioning

confidence: 99%

“…Figure 7 shows the change in maximum velocity m u along the jet axis. The red symbols represent the present study at Re = 6400 and the blue symbols represent the experiments at Re = 3100 by Koso (5) .…”

Section: Synthetic Jet Formationmentioning

confidence: 99%

“…However, this multi-actuator device may be too complicated for practical use. One of the authors (5) used an annular synthetic jet actuator around a jet pipe and showed that the actuator increases the mixing in a circular jet at a low Reynolds number of 3100. However, the effect on the agitation at other Reynolds numbers is not clear.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Agitated Turbulent Flowfield of A Circular Jet with An Annular Synthetic Jet Actuator

Koso

Kinoshita

2008

JFST

Self Cite

View full text Add to dashboard Cite

An agitated circular turbulent jet with a coaxial annular synthetic jet actuator is investigated experimentally. The mean and turbulent velocities are measured by a hot-wire anemometer at a jet Reynolds number of 6400. The measured iso-velocity contour maps indicate that the width of the circular jet is increased even when the intensity of the alternating flow is too weak to generate a synthetic jet. This can be attributed to the periodic disturbances by the actuator, which agitates the instability in the initial shear layer and displaces the shear layer growth upstream. With a strong agitation so as to generate a strong synthetic jet by itself, the agitated jet has the higher velocity and the larger width than those of unagitated jet. With this agitation, the momentum of the agitated jet is increased and its increment is equal to the momentum of the synthetic jet. Smoke visualization shows clearly that the actuator enhances the dispersion of primary jet fluids. These results are compared with those of a jet at a low Reynolds number of 3100 and it is found that the mixing enhancement is qualitatively same for both Reynolds numbers, but the weak agitation is more effective in the low Reynolds number jet.

show abstract

Section: Nomenclature Dmentioning

confidence: 99%

“…The area ratio of the annular slot to the jet nozzle is 1.12. The main size of this actuator is the double of the previous study (5) .…”

Section: Nomenclature Dmentioning

confidence: 99%

Section: Synthetic Jet Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Agitated Turbulent Flowfield of A Circular Jet with An Annular Synthetic Jet Actuator

Koso

Kinoshita

2008

JFST

Self Cite

View full text Add to dashboard Cite

show abstract

“…Synthetic jets have attracted much attention in recent years because of their potential for flow separation control (Glezer and Amitay, 2002;Gilarranz and Rediniotis, 2001), flow vectoring (Smith and Glezer, 2002) and mixing enhancement (Davis and Glezer, 1999;Koso, 2005;. A synthetic jet is an outward flow produced by an oscillatory flow with a zero-mean velocity through an orifice.…”

Section: Introductionmentioning

confidence: 99%

Effects of stroke and Reynolds number on characteristics of circular synthetic jets

Koso¹,

Morita

2014

JFST

Self Cite

View full text Add to dashboard Cite

The circular jet flows generated by a piezoelectric disk were studied experimentally. The velocity distributions were measured using a single hot-wire anemometer, and the effects of the oscillatory flow conditions though a circular orifice were examined. The effects of the dimensionless stroke and Reynolds number of the oscillatory flow on the synthetic jet flows were examined. The stroke was the length of the fluid ejected in an oscillatory cycle and non-dimensionalised by the orifice diameter. The mean velocity distributions were examined for a dimensionless stroke range of 0.60-2.40 with a constant Reynolds number (Re) of 2700. The stroke was found to have a remarkable effect on the streamwise variation in the jet centerline velocity and jet width. As the stroke was increased, the starting point of the jet growth was shifted downstream. This change is discussed by examining the instantaneous velocity signals and attributes in relation to the change in the collapse of vortex rings emitted from the orifice. The momentum of the synthetic jet increased sharply above a critical stroke for the jet formation, and seemed to be saturated for strokes longer than the orifice diameter. The flow field was also examined for a Re range of 1900-3000 with a constant dimensionless stroke of 1.02. In the Re range studied, no significant changes in the jet flows were observed.

show abstract

Effect of stroke on structure of vortex ring array in circular synthetic jets

Koso¹,

Matsuda

Masuda

et al. 2014

JFST

Self Cite

View full text Add to dashboard Cite

Array of vortex rings in circular synthetic jets was investigated experimentally by instantaneous velocity measurements using a hot-wire anemometer. The ensemble averaged velocities were derived by referencing the oscillatory flow in a circular orifice. The contours of the ensemble averaged velocity showed that the elliptical shaped high-velocity regions were generated per a cycle of the oscillatory flow. These high-velocity regions were caused by vortex rings, consequently their travelling and disappearance in the downstream indicated the convection and collapse of the vortex rings. The structures of vortex array were examined for seven dimensionless strokes of the oscillatory flow range of L/d = 0.712-7.10, where the stroke L was the length of the fluid ejected in an oscillatory cycle and d is the diameter of the orifice. It was found that vortex rings with nearly equal intervals along the jet axis travelled downstream, and collapsed in a further downstream location. In the process of vortex collapse, no direct interactions with the neighbouring vortices were observed. For the dimensionless strokes larger than 3.6, it was observed the vortex ring accompanied weak and small trailing vortex rings. It was also found that dimensionless convection velocities of vortex ring were independent of the stroke, but the spatial intervals of vortex rings increased as the stroke was increased. As the stroke was increased, the location of the vortex collapse moved downstream. The correlation between the location of the vortex collapse and the starting point of jet width growth was good. The effect of the stroke on the jet evolution was attributed to the change in the location of the vortex collapse.

show abstract

ENHANCED MIXING OF A CIRCULAR JET USING AN ANNULAR SYNTHETIC JET ACTUATOR(Flow Control 1)

Cited by 3 publications

References 3 publications

Agitated Turbulent Flowfield of A Circular Jet with An Annular Synthetic Jet Actuator

Agitated Turbulent Flowfield of A Circular Jet with An Annular Synthetic Jet Actuator

Effects of stroke and Reynolds number on characteristics of circular synthetic jets

Effect of stroke on structure of vortex ring array in circular synthetic jets

Contact Info

Product

Resources

About