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.

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.

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

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.

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.

Corrugated Truncated Triangular Tabs for Supersonic Jet Control

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
P. Arun Kumar ◽  
E. Rathakrishnan
Keyword(s):  
Experimental Investigation ◽  
Pressure Gradient ◽  
Near Field ◽  
Supersonic Jet ◽  
Adverse Pressure Gradient ◽  
Small Scale ◽  
Nozzle Pressure ◽  
Jet Control ◽  
The Waves ◽  
Different Levels

An experimental investigation has been carried out to assess the effectiveness of truncated triangular tabs, provided with corrugations (semicircular, triangle, and square shapes) all along their edges, capable of shedding small-scale vortices of continuously varying size, in enhancing the mixing of axi-symmetric Mach 2 jet, at different levels of expansion. The performance of all the tabs were found to be effective only in the near-field of the jet at all levels of expansion of the present investigation. Both the semicircular and square corrugated tabs were found to bifurcate the jet, in two parts (lobes), at x/D ≤ 1, than the triangular corrugated tab, at all the nozzle pressure ratios (NPRs) of the present study. Among the controlled jets, the semicircular corrugated tab is found to be the best mixing promoter at NPRs 6 and 7, for the Mach 2 jet. However at NPRs 4, 5 and 8, the mixing promoting performance of uncorrugated tabs is the best; as high as 91% reduction in jet core length is achieved with semicircular corrugations. Therefore, the mixing promoting capability of truncated triangular tabs with semicircular corrugated tab assumes a maximum, around the overexpansion level with adverse pressure gradient of around 10% (corresponding to NPR7). Shadowgraph images reveal, that the waves prevailing in the near-field for the controlled jets are rendered weaker than those of uncontrolled jet.

Numerical investigation of separation pattern and separation pattern transition in overexpanded single expansion ramp nozzle

2014 ◽  
Vol 118 (1202) ◽  
pp. 399-424 ◽  
Author(s):  
Y. Yu ◽  
J. Xu ◽  
J. Mo ◽  
M. Wang
Keyword(s):  
Numerical Simulation ◽  
Pressure Ratio ◽  
Hypersonic Vehicle ◽  
Small Range ◽  
Nozzle Pressure Ratio ◽  
Rocket Nozzle ◽  
Nozzle Pressure ◽  
Separation Pattern ◽  
Separation Results ◽  
Free Shock

Abstract Flow separation results in many problems to single expansion ramp nozzle (SERN) and hypersonic vehicle. However, little research has been conducted on the separation patterns and their effects on SERN’s performance. In the present paper, the numerical simulation is adopted to get the intuitive results and help to analyse the separation phenomena in SERN thoroughly. The main separation pattern is the restricted shock separation (RSS) in SERN, and the free shock separation (FSS) only appears in a small range of the nozzle pressure ratio (NPR), which is much different from the axisymmetric rocket nozzle. Further CFD results show that the separation pattern transition makes great effects on the performance of SERN, especially the lift. Moreover, the performance of SERN has an extreme in the separation pattern transition because of the main jet impinging on the expansion ramp. The transitions occur in both the startup and shutdown processes but the critical nozzle pressure ratios of the separation pattern transitions are different, which leads to a hysteresis loop of SERN performance.

scholarly journals Experimental Research on Wall Pressure Distribution in C-D Nozzle at Mach number 1.1 for Area Ratio 3.24

2019 ◽  
Vol 8 (2S3) ◽  
pp. 971-975 ◽  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Wall Pressure ◽  
Circulation Zone ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure

In this experimental investigation the work reported is about the influence of control on the flow field in the suddenly expanded duct at low supersonic Mach number. A Convergent-divergent (CD) nozzle was designed and fabricated out of brass material assembled with the suddenly expanded duct which was also made of brass material. At the re-circulation zone, the flow field was controlled by using the micro jets of 1 mm diameter as an orifice and the control was arranged at an interval of 90 degrees at 6.5 mm from the central axis of the main jet. The measured wall pressure distribution was presented for Mach number 1.1 for the duct diameter of 18 mm leading to the area ratio 3.24. The L/D ratio of the duct was varied from 1 to 10, and the nozzle pressure ratio (NPR) considered for the experiments was from 3, 5, 7, 9 and 11. The present results have demonstrated that the micro jets do not influence the flow field in the duct adversely and the flow field remained identical in the presence of control or absence of control

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