Assessment of Short Rectangular-Tab Actuation of Supersonic Jet Mixing

Ranjan, Abhash; Kaushik, Mrinal; Deb, Dipankar; Mureșan, Vlad; Ungureşan, Mihaela-Ligia

doi:10.3390/act9030072

Cited by 9 publications

(4 citation statements)

References 25 publications

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“…In a convergent-divergent nozzle delivering Mach 1.8, the positioning of two short rectangular vortex-generating actuators, diametrically opposite to each other, led to a significant 75% reduction in the core length for NPR 5. Additionally, the controlled jet exhibited an increase in jet spread downstream of the nozzle exit when compared to the uncontrolled jet at NPRs 4, 5, 6, 7, and 8 (12) . The present research findings are in significant agreement with the previous literature.…”

Section: Core Length Variation With Injection Pressure Ratiomentioning

confidence: 95%

“…In a rectangular sonic jet, fluidic injection using air tabs at the nozzle exit along the minor axis promoted mixing and core length reduction at all NPRs and the mixing increased with increasing IPRs (14) . In a Mach 1.8 supersonic jet generated with a convergent-divergent nozzle, the use of two short rectangular vortex-generating actuators located diametrically opposite to each other, resulted in a 75% core length reduction compared to the uncontrolled jet for NPR 5 (12) .…”

Section: Radial Profiles Of Pitot Pressure Measurementsmentioning

confidence: 99%

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Experimental Investigation of Supersonic Jet Control Using Sonic Air Tabs

Perumal,

Kumar,

Elangovan

et al. 2023

IJST

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Objectives:The primary objective of the study is to understand the influence of two sonic air tabs on the mixing characteristics of a supersonic (Mach 2.1) circular jet. Methods: In the high-speed open jet facility, a convergent-divergent nozzle delivering Mach 2.1 jet was controlled using two air tabs positioned at the nozzle exit. The injection pressure ratio of the air tabs varied from 3 to 6 for a nozzle pressure ratio of 3, 4, 5, and 6. Pitot pressure measurements and flow visualization were performed for controlled and uncontrolled jets. Findings: The results of the pitot pressure measurements showed a significant decrease in core length for the nozzle pressure ratios investigated. The core length reduction was attributed to the accelerated mixing of the Mach 2.1 jet with the surrounding fluid due to the air tabs. Furthermore, with the increase in the injection pressure ratio, the mixing enhancement due to the air tabs was observed to be increasing. The maximum reduction in core length occurred at an injection pressure ratio of 6 resulting in reductions of 86.1%, 64.9%, 61.1%, and 56.4% for nozzle pressure ratios 3, 4, 5, and 6, respectively. The visualization results confirmed the efficiency of the air tabs' in decreasing the strength of waves in the jet core region. Novelty: The novelty of this study lies in the use of two sonic air tabs for controlling supersonic jets. Unlike other control techniques, these air tabs can be activated or deactivated as needed without compromising the overall aircraft performance.

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Section: Core Length Variation With Injection Pressure Ratiomentioning

confidence: 95%

Section: Radial Profiles Of Pitot Pressure Measurementsmentioning

confidence: 99%

Experimental Investigation of Supersonic Jet Control Using Sonic Air Tabs

Perumal,

Kumar,

Elangovan

et al. 2023

IJST

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“…The distortion of shock-cell structures within the core has also been shown to be effective in noise mitigation [8,9]. In addition, it is well-established that the weakening of shock waves suppresses the noise associated with the shock [27][28][29]. Therefore, it can be concluded that wave attenuation using corrugated tabs can augment the jet mixing and reduce the shock-associated noise.…”

Section: Flow Visualizationsmentioning

confidence: 99%

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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“…A commercial computational fluid dynamics (CFD) package was used for the numerical investigations, and for greater accuracy, all simulations were run in three dimensions using the steady Reynolds-averaged Navier-Stokes equations and the shear-stress transport k-ω turbulence model. The barrel shock, the expansion fans, and the Mach waves that are present in the flow field are captured using numerical Schlieren images [24].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

Cican,

Gall,

Bogoi

et al. 2023

Inventions

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In connection with subsonic jet noise production, especially regarding the hot jet from a micro turbojet engine, we encountered a lack of recent high-resolution data in the literature describing the flow field using experimental validation through optical diagnoses. The objective of this paper is to examine and compare the influence on shear layers of the exhaust plug nozzle of a micro turbojet engine with and without chevrons mounted, using a high-speed camera used in Schlieren-type optical system diagnosis. Three different operating regimes are examined for both the baseline configuration and the configuration with 16 triangular-shaped chevrons. In conjunction with the image captures, the sound pressure level was recorded with the help of a microphone placed perpendicular to the flow, 0.4 m from the exhaust of the nozzle which was further processed. In quantitative terms, we found that the OASPL decreases by more than 1% when the engine is operating at higher regimes. Moreover, we found that the average exhaust jet angle, which is a measure of the quality of the fluid mixing layer is increased by 5% with respect to the baseline nozzle. By using the “darkest pixel” technique in Schlieren imaging, we can verify experimentally, for all working regimes, the theory that asserts that subsonic jet noise is a consequence of fine-scale homogeneous turbulence. Additionally, the potential novelty lies in the specific observations related to consistent dispersion of fine-scale eddies and how the presence of chevrons amplifies this uniformity within the turbulent field.

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Assessment of Short Rectangular-Tab Actuation of Supersonic Jet Mixing

Cited by 9 publications

References 25 publications

Experimental Investigation of Supersonic Jet Control Using Sonic Air Tabs

Experimental Investigation of Supersonic Jet Control Using Sonic Air Tabs

Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

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