Techniques for Supersonic Turbojet Noise Reduction

2012 ◽  
Author(s):  
David Munday ◽  
Dan Cuppoletti ◽  
Michael Perrino ◽  
Ephraim Gutmark ◽  
Markus O. Burak ◽  
...  
Keyword(s):  
Mach Number ◽  
Noise Reduction ◽  
Secondary Flow ◽  
High Performance ◽  
Supersonic Jet ◽  
Military Aircraft ◽  
Mach Numbers

Observations and simulations are presented of a supersonic jet from a nozzle representative of high-performance military aircraft such as the Saab Gripen. The nozzle has a design Mach number of 1.56 and is examined at its design condition with a surrounding secondary flow at Mach numbers of 0.0, 0.1 and 0.3. Chevrons and internal fluidic injection by microjets each reduce the noise generated by the main jet.

Acoustics measurements of military-style supersonic beveled nozzle jets with interior corrugations

2016 ◽  
Vol 16 (1-2) ◽  
pp. 21-43 ◽  
Author(s):  
Russell W Powers ◽  
Dennis K McLaughlin
Keyword(s):  
Noise Reduction ◽  
Acoustic Field ◽  
High Speed ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Operating Conditions ◽  
Military Aircraft ◽  
Azimuthal Dependence ◽  
Penn State ◽  
Mixing Noise

Increasingly powerful and noisy military aircraft have generated the need for research leading to the development of supersonic jet noise reduction devices. The hot, high speed supersonic jets exhausting from military aircraft during takeoff present a most challenging problem. The present study extends prior research on two methods of noise reduction. The first is the internal nozzle corrugations pioneered by Seiner et al. and the second is the beveled exit plane explored most recently by Viswanathan. A novel research idea of creating fluidic corrugations similar to the nozzle corrugations has been initiated by Penn State. To further the understanding and analysis of the fluidic corrugations, the present study focuses on the flow field and acoustic field of nozzles with two, three, and six conventional, hardwalled corrugations. The effect of the combination of the internal corrugations with a beveled nozzle is explored. The results show that significant noise reductions of over 3 dB of the mixing noise and the broadband shock-associated noise can be achieved. The combination of the beveled nozzle and the internal nozzle corrugations showed that there is less azimuthal dependence of the acoustic field than for the purely beveled nozzle. The combination nozzle was shown to reduce the noise over a wider range of polar angles and operating conditions than either the purely beveled nozzle or the purely corrugated nozzle.

The Impingement of a Uniform, Axisymmetric, Supersonic Jet on a Perpendicular Flat Plate

1971 ◽  
Vol 22 (4) ◽  
pp. 403-420 ◽  
Author(s):  
J. H. Gummer ◽  
B. L. Hunt
Keyword(s):  
Mach Number ◽  
Flat Plate ◽  
Supersonic Jet ◽  
Theoretical Description ◽  
Alternative Methods ◽  
Number Range ◽  
Sonic Line ◽  
Pressure Distributions ◽  
Experimental Shock ◽  
Mach Numbers

SummaryThe impingement region produced by directing a uniform, axisymmetric, supersonic jet of air normally onto a large, flat plate has been investigated experimentally and theoretically for four jets in the Mach number range 1·64 to 2·77. A qualitative theoretical description of the flow in the neighbourhood of the sonic line is given. A single-strip version of the method of Polynomial Approximation and Integral Relations (PIR) is applied to the flow, using two alternative methods of determining the centre-line shock height. The PIR predictions are compared to experimental shock shapes and pressure distributions. It is found that a PIR method in which the sonic line is assumed to intersect the shock at the jet edge leads to very good agreement with experiment at the higher jet Mach numbers, but accuracy is much reduced at the lower Mach numbers, the shock height being in error by about 62 per cent at a jet Mach number of 1·64. A change in flow pattern at small nozzle-to-plate distances is reported.

scholarly journals Effect of fluid injection on turbulence and noise reduction of a supersonic jet

2019 ◽  
Vol 377 (2159) ◽  
pp. 20190082 ◽  
Author(s):  
Chitrarth Prasad ◽  
Philip Morris
Keyword(s):  
Noise Reduction ◽  
High Performance ◽  
Large Scale ◽  
Near Field ◽  
Supersonic Jet ◽  
Acoustic Mode ◽  
Turbulent Structures ◽  
Direct Cross ◽  
Cross Correlations ◽  
Convection Speed

Supersonic jets, such as the ones used in high-performance military aircraft, have both downstream and upstream noise components due to the large-scale turbulent structures and the presence of shock cells in the jet plume. The fluid insert technology is a noise reduction method that has been shown to effectively reduce both these noise components. This paper analyses the unsteady flow changes associated with different fluid insert configurations with a goal of helping to understand the detailed noise reduction mechanisms. Using direct cross-correlations of the near-field data with the far-field microphone signals, it is found that even the use of a single injector as a fluid insert helps break up the large-scale structures of the flow. However, a more azimuthally distributed blowing is required to reduce the upstream broadband shock-associated noise (BBSAN). Addition of upstream injectors at each azimuthal location further enhances the BBSAN reduction. Decomposition of the jet flow-field into hydrodynamic and acoustic modes shows that fluid insert nozzles reduce the amplitude and convection speed of the coherent acoustic mode in the plane of highest noise reduction. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.

Heat Transfer in Rotating Serpentine Coolant Passage With Ribbed Walls at Low Mach Numbers

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Low Mach Number ◽  
Heat Transfer Coefficients ◽  
Rotation Numbers ◽  
Wide Range ◽  
Mach Numbers

This paper experimentally investigates the effect of rotation on heat transfer in typical turbine blade serpentine coolant passage with ribbed walls at low Mach numbers. To achieve the low Mach number (around 0.01) condition, pressurized Freon R-134a vapor is utilized as the working fluid. The flow in the first passage is radial outward, after the 180 deg tip turn the flow is radial inward to the second passage, and after the 180 deg hub turn the flow is radial outward to the third passage. The effects of rotation on the heat transfer coefficients were investigated at rotation numbers up to 0.6 and Reynolds numbers from 30,000 to 70,000. Heat transfer coefficients were measured using the thermocouples-copper-plate-heater regional average method. Heat transfer results are obtained over a wide range of Reynolds numbers and rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Regional heat transfer coefficients are correlated with Reynolds numbers for nonrotation and with rotation numbers for rotating condition, respectively. The results can be useful for understanding real rotor blade coolant passage heat transfer under low Mach number, medium–high Reynolds number, and high rotation number conditions.

Effect of Axial Location of Micro Vortex Generators on Supersonic Jet Noise Reduction

2022 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim J. Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise ◽  
Axial Location

Supersonic Jet Noise Reduction Using Micro Vortex Generators

2021 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise

Effect of Mach number on the acoustic field of 2:1 elliptic-slot jet

2001 ◽  
Vol 105 (1043) ◽  
pp. 9-16 ◽  
Author(s):  
S. B. Verma ◽  
E. Rathakrishnan
Keyword(s):  
Mach Number ◽  
Fundamental Frequency ◽  
Acoustic Field ◽  
Major Axis ◽  
Shock Structure ◽  
Minor Axis ◽  
Noise Levels ◽  
Underexpanded Jets ◽  
Barrel Shock ◽  
Mach Numbers

Abstract The shock-structure and the related acoustic field of underexpanded jets undergoes significant changes as the Mach number Mj is increased. The present investigation is carried out to study the effect of Mach number on an underexpanded 2:1 elliptic-slot jet. Experimental data are presented for fully expanded Mach numbers ranging from 1.3 to 2.0. It is observed that the ‘cross-over’ point at the end of the first cell at low Mach numbers gets replaced by a normal shock at a highly underexpanded condition resulting in the formation of a ‘barrel’ shock along the minor-axis side with a ‘bulb’ shock formed along the major-axis side. The above change in shock structure is accompanied by a related change in the acoustic field. The amplitude of fundamental frequency along the minor-axis side grows with Mj but falls beyond Mj = 1.75. Along the major-axis side, however, the fundamental frequency does not exist at low Mach numbers. It appears at Mj = 1.75 but then falls at Mj = 2.0. The related azimuthal directivity of overall noise levels (OASPL) shows significant changes with Mj.

Aeroelastic Problems in connection with High-Speed Flight

1956 ◽  
Vol 60 (547) ◽  
pp. 459-475 ◽  
Author(s):  
E. G. Broadbent
Keyword(s):  
Mach Number ◽  
High Speed ◽  
The Other ◽  
Control Surface ◽  
The Past ◽  
Other Hand ◽  
Aerodynamic Derivatives ◽  
Mach Numbers ◽  
The One

SummaryA review is given of developments in the field of aeroelasticity during the past ten years. The effect of steadily increasing Mach number has been two-fold: on the one hand the aerodynamic derivatives have changed, and in some cases brought new problems, and on the other hand the design for higher Mach numbers has led to thinner aerofoils and more slender fuselages for which the required stiffness is more difficult to provide. Both these aspects are discussed, and various methods of attack on the problems are considered. The relative merits of stiffness, damping and massbalance for the prevention of control surface flutter are discussed. A brief mention is made of the recent problems of damage from jet efflux and of the possible aeroelastic effects of kinetic heating.

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