Tab Aspect Ratio Effect on Supersonic Jet Mixing

Kaushik, Mrinal; Rathakrishnan, E.

doi:10.1515/tjj-2014-0032

Cited by 12 publications

(7 citation statements)

References 5 publications

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“…Based on the formula, Blockage ratio = Nozzle exit area/Probe area, the blockage ratio as a result of the probe's presence was calculated to be 1111.11. The tolerable probe blockage value of 64 established by Kaushik (2012) is very mush lesser than this value; therefore the probe blockage doesn't radically affect the pressure reading. Also, since the Reynolds number for the jet Mach numbers considered in this investigation are comparatively greater than 500, the effects of viscosity are deemed negligible on the pressure measurements.…”

Section: Pitot Probementioning

confidence: 92%

Experimental Study on the Effect of Tabs with Asymmetric Projections on the Mixing Characteristics of Subsonic Jets

2023

JAFM

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This study experimentally explores the effect of tabs with asymmetric projections on the mixing effectiveness of jets at different nozzle exit Mach numbers with subsonic ranges of 0.4, 0.6, and 0.8. The results obtained with the tab-controlled jet are compared with those of uncontrolled jets. In this experimental investigation, a pair of identical tabs is deployed along a diameter of a convergent nozzle with inlet and exit cross sections of a circle, where each tab has two triangular projections configured at locations offset to each other at a distance of 1 mm on a plain rectangular stem. The geometrical blockage due to the presence of both tabs is maintained at 5.09% to minimize the thrust loss incurred due to tabs. The counter-rotating vortices generated at different locations of the tabs, caused instability or shear distortions at the nozzle exit, promoting jet mixing and eventually leading to rapid velocity decay along the jet axis and accentuating the reduction of the potential core. Compared to plain jet, reductions in core length of about 70%, 76%, and 81% at Mach 0.4, 0.6, and 0.8, respectively, are observed with the tab-controlled jets. The total pressure decay characteristics in the radial profile along the tab and normal-to-tab orientations have shown significant distortion in the jet structure, making it asymmetrical again owing to the asymmetrical positioning of projections on the tabs. Besides, in comparison with the plain nozzle, the total pressure decay characteristics in the radial profiles of tab-controlled jets are significantly different along the axial locations in the downstream direction due to the same reason of the asymmetrical positioning of triangular projections on the tabs. The primary research goal of this experimental investigation with asymmetrical tabs is to promote jet mixing asymmetrically to achieve thrust vectoring of jets.

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Section: Pitot Probementioning

confidence: 92%

Experimental Study on the Effect of Tabs with Asymmetric Projections on the Mixing Characteristics of Subsonic Jets

2023

JAFM

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“…Kaushik and Rathakrishnan [34] experimentally investigated the tab aspect ratio effect on mixing, promoting effectiveness at Mach 1.73 nozzle. They have used three different plain rectangular tabs with aspect ratios of 1.0, 1.5, and 2.0, placed diametrically opposite positions at the nozzle outlet.…”

Section: Supersonic Jet Controlled With Tabsmentioning

confidence: 99%

Survey on Vortex Shedding Tabs as Supersonic Jet Control

et al. 2022

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This study provides an overview of the tab-controlled jets to understand and predict the influence of mixing promoting vortices at speeds ranging from subsonic to supersonic. A detailed description of various features of the circular jets controlled by tab-like vortex generators is provided. Here, both the experimental and the numerical investigations on the impacts of tabs on the mixing enhancement and noise suppression are presented. Following a brief introduction about subsonic and supersonic circular jets, this study discusses the influences of certain key parameters on mixing characteristics, including the effect of tab geometry, tab number, tab orientation, tab size, and tab position relative to nozzle outlet. Subsequently, their effect on noise suppression is also reviewed. The detrimental effect of tabs in terms of thrust penalty is described. Finally, the future direction of research on the tab-controlled jets is outlined.

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“…Delta-tabs were used and it was found that two delta-tabs, spaced 180 • apart, absolutely dichotomized the jet. Kaushik andRathakrishnan (2013, 2015) clearly revealed that the magnitude and potency of vortices actuated from control tabs can be enhanced with geometrical alterations [8,9]. A recent work by Thillaikumar et al (2020) suggested that the introduction of vortex actuating tabs in the divergent section of the supersonic nozzle changes the structure of the shock cell, thereby reducing the jet core length [10].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Short Rectangular-Tab Actuation of Supersonic Jet Mixing

et al. 2020

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This work explores the extent of jet mixing for a supersonic jet coming out of a Mach 1.8 convergent-divergent nozzle, controlled with two short rectangular vortex-generating actuators located diametrically opposite to each other with an emphasis on numerical methodology. The blockage ratio offered by the tabs is around 0.05. The numerical investigations were carried out by using a commercial computational fluid dynamics (CFD) package and all the simulations were performed by employing steady Reynolds-averaged Navier–Stokes equations and shear-stress transport k-ω turbulence model on a three-dimensional computational space for more accuracy. The numerical calculations are administered at nozzle pressure ratios (NPRs) of 4, 5, 6, 7 and 8, covering the overexpanded, the correctly expanded and the underexpanded conditions. The centerline pressure decay and the pressure profiles are plotted for both uncontrolled and the controlled jets. Numerical schlieren images are used to capture the barrel shock, the expansion fans and the Mach waves present in the flow field. Mach contours are also delineated at varying NPRs indicating the number of shock cells, their length and the variation of the shock cell structure and strength, to substantiate the prominent findings. The outcomes of this research are observed to be in sensible concurrence with the demonstrated exploratory findings. A reduction in the jet core length of 75% is attained with small vortex-generating actuators, compared to an uncontrolled jet, corresponding to nozzle pressure ratio 5. It was also seen that the controlled jet gets bifurcated downstream of the nozzle exit at a distance of about 5 D, where D is the nozzle exit diameter. Furthermore, it was fascinating to observe that the jet spread increases downstream of the nozzle exit for the controlled jet, as compared to the uncontrolled jet at any given NPR.

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Tab Aspect Ratio Effect on Supersonic Jet Mixing

Cited by 12 publications

References 5 publications

Experimental Study on the Effect of Tabs with Asymmetric Projections on the Mixing Characteristics of Subsonic Jets

Experimental Study on the Effect of Tabs with Asymmetric Projections on the Mixing Characteristics of Subsonic Jets

Survey on Vortex Shedding Tabs as Supersonic Jet Control

Assessment of Short Rectangular-Tab Actuation of Supersonic Jet Mixing

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