Study of Slanted Perforated Jets

Ahmed, Rayhan; Thanigaiarasu, S.; Santhosh, J.; Elangovan, S.; Rathakrishnan, E.

doi:10.1515/tjj-2013-0015

Cited by 13 publications

(4 citation statements)

References 10 publications

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“…The primary and the secondary flows from the perforation meet downstream at a distance that is away from the core. Similar explanation can be put forth for Figure 3(b), which depicts the secondary flow from the slanted perforation is seen to interact at some distance downstream and the point of intersection can be possibly varied by varying the slant angles (Ahmed et al , 2013). The present configuration of tabs positively creates a flow phenomenon that is depicted via Figure 3(c), where the slots are designed to connect the adjacent faces of the solid tabs.…”

Section: Present Studysupporting

confidence: 53%

Influence of slot profiles on the characteristics of jets

Krishnaraj

Vinayagamurthy²

2022

AEAT

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Purpose The purpose of this research is to study and investigate the flow control of 0.8 Mach jet using three tab configurations. The tabs with the slots will eventually lead to generation of vortices and thus enhances the mixing characteristics. Design/methodology/approach The jet flow control is achieved by the usage of three tabs, namely, Tab A, Tab B and Tab C that are placed at the exit plane of the convergent nozzle at 180 degrees apart. Three tabs with different slot profile are designed with the same constant blockage ratio of 7.3%. The tabs produce vortices of varying sizes that directly influence and modify the jet structure, thereby enhancing the efficiency in mass entrainment and mixing. The tabs are studied numerically first and then are compared with the results of the experiments. Findings The results are compared with that of the results of the uncontrolled jet. For Mach 0.8 jet, Tab C is found to reduce the core length and gives reduction of 90.23%, in comparison to Tab A and Tab B, which provides 84.1% and 87.79%, respectively. The results of numerical are then compared with the centerline results obtained via experiments. With the engagement of Tabs A, B and C, the jet structure is seen to have been modified at Mach 0.8 with Tab C performing better. Practical implications The tabs are a passive control device that can be practically enabled in the aircraft nozzles to control the flow and even suppress the noise emanated by the jet. Tabs can be effectively used for better thrust vector control and assist in jet noise suppression. Thus, this study on tabs and its uses are important and essential in aerospace technology. Originality/value This particular study on mechanical slotted tabs is innovatively carried out by designing the tabs in such a way that one such has not been designed before. The slots run through the adjacent sides of the tabs which is a novelty in itself, whereas perforations made only through the opposite sides of the tabs are studied by various researchers till now. The slots in the adjacent faces modify the flow physics in such a way that it enhances mixing by the creation of turbulence because of the interaction between the main stream and the secondary jet exactly at the core. So far, such slots and profiles are not investigated. By the usage of such tabs, the flow to mix faster is much closer to the core of the jet by creating mixed size vortices and thus has higher efficiency.

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Section: Present Studysupporting

confidence: 53%

Influence of slot profiles on the characteristics of jets

Krishnaraj

Vinayagamurthy²

2022

AEAT

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“…The potential core length decreases significantly for various Mach numbers. Ahmed et al (2013) in their experimental study compared the jet mixing effectiveness of tabs with and without perforations (solid tabs) on the jet at different subsonic Mach numbers. The results revealed that the influence of tabs without perforations (solid tabs) dominates in the far downstream directions when compared to perforated tabs.…”

Section: Introductionmentioning

confidence: 99%

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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“…The implementation of tabs with perforations/slots paved the way for further advancements in the jet flow control, as the slots are known to reduce the thrust losses and effectively reduce blockages. A rectangular tab with slanted perforations, with perforations connecting the opposite edges, are found to be equally competent in promoting the jet mixing process (Ahmed et al 2013). To further bring in to the advancements, change of profiles of perforations was analyzed by Ahmed et al (2015), at 30° slant angle and reported that the tab with circular perforation is more efficient in distorting the jet.…”

Section: Introductionmentioning

confidence: 99%

“…For a secondary jet, which intersects the mainstream at a certain inclined angle, the effectiveness improves by controlling the secondary jet from the perforations to impinge into the mainstream at an effective intersection point, which is within the potential core length (Ahmed et al 2013). Therefore, in this article, the rectangular tab with the slot connecting the adjacent sides of the rectangular profile is investigated to improvise the above explained flow phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Jet Mixing Characteristics Using Slotted Rectangular Tabs

Krishnaraj

Vinayagamurthy

2021

J. Aerosp. Technol. Manag.

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This article discusses the jet mixing effectiveness of rectangular tab with slots to distort the jet, thereby creating vortices of differing sizes to enhance the mixing. This article numerically investigates the effectiveness of slanted slotted/perforated rectangular tabs with the slot connecting the adjacent faces of the tab to control Mach 0.4 jet. To intensify the jet mixing process, two similar tabs with equal blockage ratio of 7% are placed at diametrically opposite locations of the convergent nozzle exit. The jet flow development in the axial and radial directions of the jet are investigated in detail. To measure the effectiveness of the slotted tabs, the results are compared with the free jet and with the jet operated with solid rectangular tab. The percentage reduction in the core length obtained is 84.1 and 74% for the jet employed with the slotted tab and the solid tab, respectively, when compared with the free jet. The results exhibit that the slotted tab distorts the jet in the near field to a greater extent when compared with the solid rectangular tab.

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Study of Slanted Perforated Jets

Cited by 13 publications

References 10 publications

Influence of slot profiles on the characteristics of jets

Influence of slot profiles on the characteristics of jets

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

Investigation of Jet Mixing Characteristics Using Slotted Rectangular Tabs

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