Supersonic Jet Control by Tabs with Slanted Perforation

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
G. Ezhilmaran ◽  
Suresh Chandra Khandai ◽  
S. Pavithrabalan ◽  
K. Udhayakumar
Keyword(s):  
Mach Number ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Pressure Gradients ◽  
Nozzle Pressure Ratio ◽  
Pressure Decay ◽  
Core Length ◽  
Nozzle Pressure ◽  
Jet Control

Abstract Control of Mach 1.8 circular jet with slanted perforated tabs is studied experimentally. Two sets of perforated tabs were used for this study. The perforation angles were 0° and 30° with respect to axis of the nozzle. The blockage areas of the tabs were 5 %. The mixing enhancements caused by these tabs were studied in the presence of adverse and favorable pressure gradients, corresponding to nozzle pressure ratio (NPR) of 4, 5.74 and 8. For Mach number 1.8, jet NPR 4 corresponds to 30 % adverse pressure gradients and NPR 8 corresponds to 39.37 % favorable pressure gradients. The pressure decay characteristics and shadowgraph images of perforated tabs at different NPR were compared. There is 45 % and 65 % reduction in jet core length were observed for the 0° and 30° perforated tabs respectively in both pitot and shadowgraph experiments in comparison to uncontrolled jet.

Numerical Simulation of Supersonic Jet Control by Tabs with Slanted Perforation

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
G. Ezhilmaran ◽  
Suresh Chandra Khandai ◽  
Yogesh Kumar Sinha ◽  
S. Thanigaiarasu
Keyword(s):  
Numerical Simulation ◽  
Mach Number ◽  
Near Field ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Pressure Gradients ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure ◽  
Jet Control ◽  
Different Diameters

Abstract This paper presents the numerical simulation of Mach 1.5 supersonic jet with perforated tabs. The jet with straight perforation tab was compared with jets having slanted perforated tabs of different diameters. The perforation angles were kept as 0° and 10° with respect to the axis of the nozzle. The blockage areas of the tabs were 4.9 %, 4.9 % and 2.4 % for straight perforation, 10° slanted perforation ( {{{\Phi }}_{\ }} = 1.3 mm) and 10° slanted perforation ( {{{\Phi }}_{\ }} = 1.65 mm) respectively. The 3-D numerical simulations were carried out using the software. The mixing enhancements caused by these tabs were studied in the presence of adverse and favourable pressure gradients, corresponding to nozzle pressure ratio (NPR) of 3, 3.7 and 5. For Mach number 1.5 jet, NPR 3 corresponds to 18.92 % adverse pressure gradients and NPR 5 corresponds to 35.13 % favourable pressure gradients. The centerline Mach number of the jet with slanted perforations is found to decay at a faster rate than uncontrolled nozzle and jet with straight perforation tab. Mach number plots were obtained at both near-field and far field downstream locations. There is 25 % and 65 % reduction in jet core length were observed for the 0° and 10° perforated tabs respectively in comparison to uncontrolled jet.

scholarly journals Effect of Micro Jet Control on the Flow Filed of the Duct at Mach 1.5

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1758-1762 ◽  
Keyword(s):  
Mach Number ◽  
Pressure Distribution ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Wall Pressure ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure ◽  
Jet Control ◽  
Flow Through

This article reports the outcome of the windtunnel investigation on the role of micro jets as an active control on the wall pressure distribution. Four tiny jets of 1 mm diameter located at 90-degree intervals along a pcd of 1.3 are employed for the control. The Mach number considered for suddenly expanded flow through the nozzle is 1.5, and the microjets are expanded suddenly into a duct at the base with an area ratio of 3.24 times the CD nozzle exit area. The L/D ratio of the duct was reduced from 10 to 1 in steps of 1. The nozzle pressure ratio (NPR) was operated at 3 to 11 with and without control. The wall pressure distribution is observed in the suddenly expanded axi-symmetric duct. From the results, it has been found that the wall pressure distribution does not adversely influence the micro jet controller

Tab Aspect Ratio Effect on Supersonic Jet Mixing

2015 ◽  
Vol 32 (3) ◽  
Author(s):  
Mrinal Kaushik ◽  
E. Rathakrishnan
Keyword(s):  
Aspect Ratio ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Small Scale ◽  
Jet Mixing ◽  
Core Length ◽  
Nozzle Pressure ◽  
The Waves ◽  
Length Reduction ◽  
Better Than

AbstractThe efficacy of introducing mixing promoting small-scale vortices by two rectangular tabs, of aspect ratio 1.0, 1.5 and 2.0, placed at diametrically opposite locations at the exit of a Mach 1.73 convergent–divergent circular nozzle has been experimentally investigated, for NPRs from 4 to 8, covering overexpanded, correctly expanded and underexpanded states of the jet. The area blockage due to the each tab was 2.5% of the nozzle exit area. Keeping the blockage constant, the aspect ratio (defined as the ratio of length to width of the tab) was varied. A maximum core length reduction of 84.6% was caused by the tabs of aspect ratio 1.0, at underexpanded conditions corresponding to NPR (nozzle pressure ratio) 6. At this NPR, tabs of aspect ratio 1.5 and 2.0 caused core length reduction of 76.9% and 61.5%, respectively. The mixing promoting efficiency of aspect ratio 1.0 is found to be better than 1.5 and 2.0, at all NPRs of the present study, except NPR 5. The shadowgraph pictures of the uncontrolled and controlled jets clearly demonstrate the effectiveness of the tabs in weakening the waves in the jet core.

Triangular tabs for supersonic jet mixing enhancement

2014 ◽  
Vol 118 (1209) ◽  
pp. 1245-1278 ◽  
Author(s):  
Arun Kumar P. ◽  
E. Rathakrishnan
Keyword(s):  
Pressure Ratio ◽  
Supersonic Jet ◽  
Adverse Pressure Gradient ◽  
Mixing Enhancement ◽  
Jet Mixing ◽  
The Core ◽  
Core Length ◽  
Increase With Increase ◽  
Nozzle Pressure ◽  
Length Reduction

AbstractThe 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 levelpe/pa= 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.

scholarly journals Experimental Assessment of Corrugated Rectangular Actuators on Supersonic Jet Mixing

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 88
Author(s):  
Thillaikumar T. ◽  
Tamal Jana ◽  
Mrinal Kaushik
Keyword(s):  
Pressure Ratio ◽  
Supersonic Jet ◽  
Vortex Generators ◽  
Military Aircraft ◽  
Nozzle Pressure Ratio ◽  
Engine Exhaust ◽  
Jet Mixing ◽  
Noise Characteristics ◽  
Nozzle Pressure ◽  
The Waves

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.

Flow Mixing and Screech Characteristics of Elliptical Supersonic Jet

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Manigandan ◽  
K. Vijayaraja
Keyword(s):  
Pressure Ratio ◽  
Expansion Ratio ◽  
Shock Cell ◽  
Nozzle Pressure Ratio ◽  
Potential Core ◽  
Appreciable Change ◽  
Jet Mixing ◽  
Screech Tone ◽  
Core Length ◽  
Nozzle Pressure

Abstract The acoustic and flow characteristics of a jet with elliptical throat is studied at different levels of nozzle expansion ratio. In this study, we have taken two types of CD nozzle configuration (circular and elliptical throat) and it is studied for various NPR ratios of 2, 3, 4 and 6. In addition, the acoustic characteristic of the jet flow is also measured for respective NPRs. Measurements of acoustic data are done using microphones placed at 30, 60 and 90 degrees to imprison the effects of screech tone. At NPR 2, 3 and 4, the jet with elliptical throat witnesses superior mixing and shorter core length compared to the circular throat. Its surprising to see both the configurations provides the identical oscillation at NPR 2, 3 and 4, however the efficiency of jet mixing is larger in elliptical throat jet. As the nozzle pressure ratio increased from 2 to 3 and 3 to 4, the potential core length of the jet reduces marginally about 5 to 10 % for every NPR until nozzle pressure ratio of 5. At NPR 2 and 3, the centerline pitot pressure profile shows, the decay of jet from the elliptical throat is healthier than a circular jet. At various levels of nozzle expansion, shock cell shows an appreciable change with an increase in NPR. Introduction of the elliptical throat on circular modifies the structure of shock cell which significantly changes the magnitude of screech tone due to the weakening of shock waves.

Experimental and Computational Studies on Flow Characteristics of Single Expansion Nozzle

2021 ◽  
Author(s):  
Dakshina Murthy Inturi ◽  
Lovaraju Pinnam ◽  
Ramachandra Raju Vegesna
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Oblique Shock ◽  
Solid Boundary ◽  
Computational Studies ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure ◽  
Flow Field Characteristics

Abstract The present investigation aims to study the flow field characteristics of a single expansion nozzle (SEN). The flow field characteristics of conventional convergent-divergent (C-D) nozzle are also investigated for comparison. The experimental and computational studies were carried out for nozzle pressure ratios of 1.45, 1.55, 1.75, 2, 3, 4 and 5. The studies reveal that, for the single expansion nozzle the oblique shock moves towards the solid boundary with the increase of nozzle pressure ratio, which makes the flow to accelerate continuously in the majority of the divergent portion. The single expansion nozzle delivers the flow with higher Mach number than the C-D nozzle at the exit of the nozzle.

scholarly journals Investigation of the base flow of a generic space launcher with dual-bell nozzle

2020 ◽  
Author(s):  
Sven Scharnowski ◽  
Christian J. Kähler
Keyword(s):  
Mach Number ◽  
Pressure Ratio ◽  
Base Flow ◽  
Nozzle Pressure Ratio ◽  
Flow Topology ◽  
Outer Flow ◽  
Separated Shear Layer ◽  
Nozzle Pressure ◽  
Dual Bell ◽  
Space Launcher

Abstract The typical afterbody flow of a space launcher is characterized by a strong interaction of the engine’s exhaust jet and the separated shear layer emerging from the main body. This interaction is further complicated by strong changes in the spatial and temporal behavior of the afterbody flow during the atmospheric ascent of a launcher. Theoretically, a dual-bell nozzle not only allows for a gain in payload compared to standard single-bell nozzles, but also it alters the wake flow topology due to the two nozzle modes. To predict the benefits as well as the additional risks, the afterbody flow of a generic space launcher model equipped with a cold-flow dual-bell nozzle is investigated in detail. The flow was analyzed for sub-, trans- and supersonic Mach numbers ranging from 0.3 to 2.9 for a variety of nozzle pressure ratios. Particle image velocimetry measurements and schlieren measurements with high repetition rate were performed to determine the dynamics of the separated shear layer, the nozzle jet and their interaction. It is shown that the reattachment length of the base flow decreases with increasing nozzle pressure ratio. Furthermore, the nozzle pressure ratio at which the dual-bell nozzle switches from sea-level mode to altitude mode is reduced by $$15\%$$ 15 % with high subsonic outer flow and by as much as $$65\%$$ 65 % for an outer flow at a Mach number of 1.6. Even for a constant nozzle pressure ratio, the nozzle flow topology depends on the Mach number of the outer flow.

Tab Geometry Effect on Supersonic Elliptic Jet Control

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
Anuj Bajpai ◽  
Ethirajan Rathakrishnan
Keyword(s):  
Pressure Ratio ◽  
Major Axis ◽  
Minor Axis ◽  
Mixing Enhancement ◽  
Core Length ◽  
Nozzle Pressure ◽  
Expansion Level ◽  
Jet Control ◽  
The Waves ◽  
Length Reduction

AbstractThe efficiency of tabs of two geometries in promoting the mixing of a Mach 2 elliptic jet has been studied. Limiting tab of triangular and circular geometry (crosswire) of 5 % blockage placed along major and minor axis at the nozzle exit, are tested for nozzle pressure ratio from 4 to 8, in steps of one. Both tabs are efficient mixing promoters, at all the tested NPRs, when placed along the minor axis. But along major axis the crosswire retards the mixing, at all the NPRs. The triangular tab along the major axis is also found to retard the mixing at NPRs 4 and 5, but for nozzle pressure ratios above 5 it causes mixing enhancement even when placed along the major axis. The triangular tab is found to be a better mixing promoter than the crosswire. The maximum core length reduction of 88 % is caused by triangular tab along the minor axis is at NPR4. The corresponding core length reduction for the crosswire is only 72 %. Shadowgraph pictures of controlled jets show that both tabs weaken the waves in jet core. The geometry and orientation of the tab and the expansion level influence the mixing caused by the tab.

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