scholarly journals Numerical Investigation of an Integrated Ejector Nozzle with the Nozzle Pressure Ratio of 2.97

2021 ◽  
Vol 1985 (1) ◽  
pp. 012022
Author(s):  
Changjie Ge ◽  
Lianghua Xiao ◽  
Yinhui Shang
Keyword(s):  
Numerical Investigation ◽  
Pressure Ratio ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure ◽  
Ejector Nozzle

scholarly journals Investigation of efficacy of low length-to-diameter ratio and nozzle pressure ratio on base pressure in an abruptly expanded flow

2018 ◽  
Vol 172 ◽  
pp. 01004
Author(s):  
Fharrukh Ahmed ◽  
S. A. Khan
Keyword(s):  
Pressure Ratio ◽  
Flow Regulation ◽  
Base Pressure ◽  
Regulation Mechanism ◽  
Nozzle Pressure Ratio ◽  
Control Efficacy ◽  
Remarkable Change ◽  
Cross Sectional ◽  
Circular Duct ◽  
Nozzle Pressure

This study has been carried out to assess the efficacy of the flow regulations in the form of tiny jets to regulate the pressure in the base region of an abruptly expanded duct. Four tiny jets of 1mm diameter placed at 90° intervals at 6.5 mm distance from the main jet in the wake region of the base were employed as flow management mechanism. The experiments were conducted at the inertia level of M = 2.5 & 3.0. The jets from the nozzles were expanded abruptly into a circular duct with four cross-sectional areas of 2.56, 3.24, 4.84 and 6.25. The L/D ratio of the enlarged duct considered was from 10 to 1 and experiments were conducted for Nozzle Pressure Ratio (NPR) from 3 to 11. Since the jets Mach numbers are high and the highest NPR tested was 11 which imply that the flow remains over expanded, even though, with increase in the NPR, the level of over expansion will decrease. It is well known that for over expanded nozzles an oblique shock will be formed at the nozzle lip, which in turn will result in the increase of the base pressure once it passes through the shock wave. From the results it is observed that for the NPRs 3 and 5 there is no appreciable gain in the base pressure, and hence, control employed as tiny jets are not effective, however, at NPR 7, 9, and 11 there is remarkable change in the base pressure values. This clearly indicates that NPR plays a significant role to decide on the magnitude of the base pressure and the control efficacy of the flow regulation mechanism as the tiny jets. It is found that the present method of flow regulation mechanism can be used as effective regulator of the base flows in an abruptly expanded duct. The control does not alter the nature of the flow in the enlarge duct.

Optimum structure of a laval nozzle for an abrasive air jet based on nozzle pressure ratio

2020 ◽  
Vol 364 ◽  
pp. 343-362 ◽  
Author(s):  
Yong Liu ◽  
Juan Zhang ◽  
Jianping Wei ◽  
Xiaotian Liu
Keyword(s):  
Laval Nozzle ◽  
Pressure Ratio ◽  
Optimum Structure ◽  
Nozzle Pressure Ratio ◽  
Air Jet ◽  
Nozzle Pressure

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.

Mixing Characteristics and Enhancement of Sonic Elliptic Jets from a Twin Elliptic Orifice

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
S. Parameshwari ◽  
Pradeep Kumar ◽  
S. Thanigaiarasu ◽  
E. Rathakrishnan
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
System Design ◽  
Pressure Ratio ◽  
Jet Noise ◽  
Nozzle Pressure Ratio ◽  
Jet Mixing ◽  
Nozzle Pressure ◽  
Mixing Characteristics ◽  
Ir Signature

The knowledge of jet mixing and its enhancement of elliptic jet are important in a propulsion system of aircraft, rocket, and missile’s system design for advancement of combustion via fuel-air mixture increment, lowering the jet noise and reduction of the plume infrared (IR) signature. The jet issuing from a twin elliptic orifice is non-uniform in shape that promotes the faster mixing and it influences by orifice exit conditions, so knowledge of absence of boundary layer and jet mixing characteristics is important. Hence, an experimental work helps to study the jet mixing for a twin elliptic orifice of aspect ratio two at nozzle pressure ratios of one, two, and three. The proximity between the orifices kept as one to 3mm in steps of one. The experimental readings were taken using pitot probe. The results revealed that jet mixing is faster and effective when the proximity between the orifices is closer to each other than the faraway distances at measured nozzle pressure ratios. Difference in orifice jet core exerted a noticeable influence at high proximity levels of nozzle pressure ratio of three and four for elliptic orifice.

Control of Subsonic and Sonic Jets with Limiting Tabs

2017 ◽  
Vol 34 (1) ◽  
Author(s):  
T. Berrueta ◽  
E. Rathakrishnan
Keyword(s):  
Nozzle Exit ◽  
Pressure Ratio ◽  
Nozzle Pressure Ratio ◽  
Jet Mixing ◽  
Downstream Distance ◽  
The Core ◽  
Maximum Reduction ◽  
Sonic Jet ◽  
Nozzle Pressure ◽  
Mach Numbers

AbstractAerodynamic mixing of subsonic and sonic jets with limiting tabs, with and without corrugations, has been studied experimentally. Limiting tab located at the nozzle exit and at a downstream distance of 0.5D has been considered in this study. Mixing caused by the tab at nozzle exit is found to be better that of tab at 0.5D, for both plain and corrugated geometries. Also, both tabs caused better mixing for underexpanded sonic jets than the correctly expanded sonic jet and subsonic jets. At nozzle pressure ratio 3 the plain tab at the nozzle exit reduced the core by about 56 % and the corrugated tab by about 51 %. But when the plain tab is placed at 0.5D the jet mixing is retarded. However, the corrugated tab at 0.5D enhances the mixing, though not up to the level of the same tab at 0D, at all Mach numbers except 0.6. The maximum reduction of core caused by shifted corrugated tab is 14 % for Mach 0.8 jet.

scholarly journals Evaluation of Flip-Flop Jet Nozzles for Use as Practical Excitation Devices

1994 ◽  
Vol 116 (3) ◽  
pp. 508-515 ◽  
Author(s):  
Ganesh Raman ◽  
Edward J. Rice ◽  
David M. Cornelius
Keyword(s):  
Flow Visualization ◽  
Pressure Ratio ◽  
Tube Length ◽  
Nozzle Pressure Ratio ◽  
Velocity Perturbation ◽  
Flip Flop ◽  
Nozzle Pressure ◽  
Jet Nozzle ◽  
And Performance ◽  
Made In

This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above-mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.

PIV measurements in a twin-jet STOVL fountain flow

2005 ◽  
Vol 109 (1100) ◽  
pp. 439-449 ◽  
Author(s):  
P. M. Cabrita ◽  
A. J. Saddington ◽  
K. Knowles
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Turbulent Jets ◽  
Spreading Rate ◽  
Nozzle Pressure Ratio ◽  
Mean Velocity ◽  
Fountain Flow ◽  
Image Velocimetry ◽  
Nozzle Pressure

Abstract Mean velocity and first order turbulence measurements were obtained from a three-dimensional upwash fountain flow generated by the impingement of two compressible axisymmetric turbulent jets onto a normal plane. The jet impingement area and fountain formation regions were examined with data obtained through the use of particle image velocimetry. Seven configurations with different nozzle pressure ratios were considered to ascertain the influence of jet compressibility on the fountain development. Results indicate that the mixing of the fountain is dependent on the nozzle pressure ratio, leading to an increase in the fountain spreading rate with increase in nozzle pressure ratio.

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.

Screech Tone Suppression in Non Circular Twin Jet

2010 ◽  
Author(s):  
V. Boopathi sabareesh ◽  
K. Srinivasan ◽  
T. Sundararajan
Keyword(s):  
Flow Visualization ◽  
Pressure Ratio ◽  
Jet Flow ◽  
Directivity Pattern ◽  
Nozzle Pressure Ratio ◽  
Acoustic Characteristics ◽  
Screech Tone ◽  
Nozzle Pressure ◽  
Twin Jets ◽  
Single Jet

The acoustic characteristics of twin jet screech tone is studied for various jet configurations such as both square and diamond. The measurement is carried out along the jet direction for various angles at two different planes using a microphone and the jet flow visualization is done by the shadowgraph technique. It is observed that the screech tone suppression is taken place for diamond jet configuration for the small jet spacing S = 0.5. By comparing the directivity pattern of twin jets with single jet, it is found that the twin jet behave as a single jet at higher nozzle pressure ratio.

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.

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