Corrugated Limiting Tab for Jet Mixing

Kaushik, Mrinal; Rathakrishnan, E.

doi:10.1515/tjj-2013-0016

Cited by 9 publications

(8 citation statements)

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“…Moreover, it can be seen that triangular corrugations can produce a more nonuniform vortex structure compared to the rectangular and semicircular corrugated tabs due to continuous change in the half-width of the corrugated edges. Thus, the triangular corrugated tab is the most effective in mixing enhancement [11,19].…”

Section: Centerline Pressure Decaymentioning

confidence: 99%

“…Essentially, the mixed size vortices from the additional sharp corners cause more intense interactions locally with the incoming flow, which might result in early jet bifurcation. It is noted from the literature that the deployment of the semicircular and rectangular corrugated tabs of aspect ratio 1.0 at the outlet of the nozzle produces efficient mixing, particularly at It is noted from the literature that the deployment of the semicircular and rectangular corrugated tabs of aspect ratio 1.0 at the outlet of the nozzle produces efficient mixing, particularly at overexpanded conditions [10,19]. By contrast, the triangular corrugated tabs of aspect ratio 1.5 showed superior performance by encouraging the mixing at the correctly expanded state.…”

Section: Flow Visualizationsmentioning

confidence: 99%

“…As a consequence, the triangular corrugated tab of aspect ratio 1.5 is observed to be a superior mixing promoter. overexpanded conditions [10,19]. By contrast, the triangular corrugated tabs of aspect ratio 1.5 showed superior performance by encouraging the mixing at the correctly expanded state.…”

Section: Flow Visualizationsmentioning

confidence: 99%

“…Thus, the variation in the tab's half-width can promote the generation of vortices. One way of achieving this is by providing corrugations along the tab edges, which, in turn, vary the half-width of the tab Kaushik and Rathakrishnan (2013) were the first in investigating the three geometries of corrugations, namely, rectangular, semicircular, and triangular, along the tab edges [19]. They found that the efficacy of semicircular corrugated tabs in promoting mixing is much superior to the tabs with rectangular and triangular corrugations.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Jana

Kaushik

2020

Actuators

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To improve the stealth capability of a military aircraft, the reduction in core length is essential to reduce the heat signature and the noise characteristics of the engine exhaust. The efficacy of rectangular vortex generators in achieving these objectives has been demonstrated by several researchers, owing to their simplicity. One way of producing the mixed-size vortices is by providing corrugations on the edge of the tab (actuator). Therefore, in the current study, two tabs of aspect ratio 1.5, mounted diametrically opposite to each other at the outlet of a Mach 1.73 circular nozzle, are examined at varying levels of expansions, ranging from overexpanded to underexpanded jet states. In addition, to generate the mixed-size vortices, three corrugation geometries, i.e., rectangular, triangular, and semicircular, are configured along the tab edges. Both quantitative and qualitative investigations are carried out by using the pitot probe to measure the stagnation pressures and by utilizing a shadowgraph technique to visualize the flow field. The corrugated tabs generated a significant mixing, and among them, the tabs with triangular corrugations are found to be most effective. A maximum reduction of about 99.7% in the supersonic core is obtained with triangular corrugated tabs at near-correct-expansion, corresponding to nozzle pressure ratio (NPR) 5. Interestingly, the semicircular corrugated tab significantly reduces the asymmetry near the nozzle exit plane. The shadowgraph images confirm the efficacy of different corrugated tabs in reducing the strength of the waves, prevalent in the supersonic core.

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Section: Centerline Pressure Decaymentioning

confidence: 99%

Section: Flow Visualizationsmentioning

confidence: 99%

Section: Flow Visualizationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Jana

Kaushik

2020

Actuators

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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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Performance of corrugated actuator-tabs of aspect ratio 2.0 on supersonic jet mixing enhancement

Jana

Kaushik

2021

J Mech Sci Technol

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Corrugated Limiting Tab for Jet Mixing

Cited by 9 publications

References 0 publications

Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Assessment of Short Rectangular-Tab Actuation of Supersonic Jet Mixing

Performance of corrugated actuator-tabs of aspect ratio 2.0 on supersonic jet mixing enhancement

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