Truncated Triangular Tabs for Supersonic-Jet Control

Kumar, Pankaj; Rathakrishnan, E.

doi:10.2514/1.b34642

Cited by 37 publications

(38 citation statements)

References 16 publications

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“…It is also evident that, for an efficient mixing of the mass entrained by the large scale vortices, at the boundary of a free jet, an appropriate proportion of mixing promoting vortices need to be introduced into the jet flow, to ensure rapid mixing (69) . It is well known that, the vortex shed by an object is proportional to the half-width of the object (70) , therefore a tab capable of shedding mixing promoting vortices of continuously varying size might prove to be a better mixing promoter than vortices of uniform size (71) .…”

Section: Introductionmentioning

confidence: 99%

Triangular tabs for supersonic jet mixing enhancement

Rathakrishnan

2014

Aeronaut. j. (1968)

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The mixing promoting capability of right-angled triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the exit of a Mach 2 axi-symmetric nozzle. The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and marginally favourable pressure gradients at the nozzle exit. It was found that, at all levels of expansion of the present study though the core length reduction caused by both the tabs are appreciable, but the mixing caused by the truncated tab is superior. The mixing promoting efficiency of the truncated tab is found to increase with increase of nozzle pressure ratio (that is, decrease of adverse pressure gradient). For all the nozzle pressure ratios of the present study, the core length reduction caused by the truncated vertex tab is more than that of sharp vertex tab. As high as 84% reduction in core length is achieved with truncated vertex right-angled triangular tabs at moderately overexpanded level, corresponding to expansion level p e /p a = 0·90. The corresponding core length reduction for right-angled triangular tabs with sharp vertex and rectangular tabs are 65% and 31%, respectively. The present results clearly show that the mixing promoting capability of the triangular tab is best than that of rectangular tabs at identical blockage and flow conditions.

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Section: Introductionmentioning

confidence: 99%

Triangular tabs for supersonic jet mixing enhancement

Rathakrishnan

2014

Aeronaut. j. (1968)

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“…Further details regarding the Pitot tube is available in Ref. 23,24 Since, the subsonic jet is always perfectly expanded; the static pressure in the jet field is the same that of back pressure (atmospheric pressure). The velocity in the jet field is calculated from the measured total pressure using the Equation 1, where, p 0 is the Pitot pressure, ρ x =ρ atm , since the jet is incompressible.…”

Section: Methodsmentioning

confidence: 99%

“…In active control, an auxiliary power source, for example, fluid tabs [9][10][11][12][13][14][15][16][17] is used to control the jet characteristics. On the other hand, passive control finds its importance in the research area due to its simple geometric modification, leading the mixing enhancement without requiring any power source, such as non-circular nozzles, 2,18 implementation of tooth like tabs [19][20][21][22][23][24] and chevron nozzles. [25][26][27][28][29][30][31] In spite of the extensive study of tabs and non-circular nozzles, they have lost its scope while implementing on practical situations because of its disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Flow visualization of the jet exiting a chevron nozzle

Sruthi

Suriyaprabha

et al. 2018

AAOAJ

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An experimental investigation has been carried out to visualize the jet development, issuing from chevron nozzles, for a Reynolds number of 25000. Flow visualization was performed by laser illumination on the Titanium Tetrachloride smoke to visualize jet structure at different cross-sections along the jet axis; which was used to study the behavior of the flow development. Pitot pressure measurements were also carried out along the jet centreline in the near-field, to quantify the potential core and characteristic decay of the jets. The flow features reveals that, the non-axisymmetric structure of the jet results in enhanced mixing of the jet. It is also evident from the Pitot measurement that, the reduction in potential corelength is appreciable for both the chevron configurations, implying that the ability of the chevron to break down large scale coherent structures to refine the small-scale mixing of the jet. Moreover, it is also found that the number of the chevron tooth has a pronounced effect on the mixing characteristics.

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“…Therefore, supersonic jet core is the axial distance from the nozzle exit, up to which supersonic flow prevails. The supersonic core length was estimated from centerline Pitot pressure surveys 26,46 and is the main parameter used to compare the mixing efficiency of the different tab configurations. Therefore, to investigate the effect of tabs on jet mixing, the measured Pitot pressure p 0t along the jet axis is nondimensionalized with the settling chamber pressure p 0s and plotted as a function of nondimensionalized axial distance (x/D).…”

Section: Effect Of Corrugation On Sharp Vertex Right-angled Triangulamentioning

confidence: 99%

“…24,25 Even though the isosceles tabs shed vortices of continuous variation in size, the vortices shed from the opposite edges at a given height from the tab base are of identical size. 26 To improve the mixing process by introducing vortices of continuously varying size, even from the opposite edges at a given height and with the aim of providing an environment to modify the shape of triangular tab, right-angled triangular tabs with sharp and truncated vertex were studied by Arun Kumar and Rathakrishnan 27 and reported that the right-angled triangular tabs are effective mixing promoters in a free jet.…”

Section: Introductionmentioning

confidence: 99%

Corrugated right-angled triangular tabs for supersonic jet control

Kumar

Rathakrishnan

2014

Proceedings of the Institution of Mechanical Engineers, Part G:

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This paper compares the mixing promoting efficiency of two identical sharp and truncated vertex right-angled triangular tabs provided with semicircular, triangular, and square corrugations along its edges, offering geometrical blockage of 2.5% each, placed at the exit of a Mach 2 circular nozzle was studied experimentally. To quantify the effectiveness of the controlled jets in mixing, Pitot pressure along the jet axis and the jet spread along and normal to the tabs were measured, covering highly overexpanded and marginal underexpanded levels at the nozzle exit. The results reveal that the corrugated tabs enhance mixing higher than the uncorrugated (plain) tabs, for both sharp and truncated vertices. For the jet controlled with sharp vertex right-angled triangular tabs, a maximum reduction of about 91% in core length is caused by the square corrugation at NPR7. The corresponding core length reduction caused by semicircle, triangular corrugated, and plain tabs is about 87, 85, and 65%, respectively. For the jet controlled with truncated vertex right-angled triangular tabs also, the core length reductions are of the same order as those for the sharp vertex triangular tabs. The jet mixing is strongly influenced by the combined effect of tab geometry, corrugation shape, tip effect, and expansion ratio. The shadowgraph pictures clearly show that the waves in the controlled jets are made weaker than those of the uncontrolled jet.

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Truncated Triangular Tabs for Supersonic-Jet Control

Cited by 37 publications

References 16 publications

Triangular tabs for supersonic jet mixing enhancement

Triangular tabs for supersonic jet mixing enhancement

Flow visualization of the jet exiting a chevron nozzle

Corrugated right-angled triangular tabs for supersonic jet control

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