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  • 1
    Electronic Resource
    Electronic Resource
    A New Rational Approach to Jet Noise Reduction (1998)
    Springer
    Theoretical and computational fluid dynamics 10 (1998), S. 373-383 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract: This paper offers a new rational approach to jet noise suppression methodology. The tools required to implement such an approach are discussed. These involve the use of global velocimetry to measure those Lighthill turbulent stress tensor terms thought most important to noise generation. The framework of the dynamic systems model as it applies to the development of a noise suppression model is discussed, as well as the latest results on the development of an actuator for control input. The dynamic systems model offers a unique opportunity to study the influence of a concept noise reduction scheme on noise reduction through appropriate algorithms that relate turbulent jet processes to noise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001620050070
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    Paper (German National Licenses)
    Fulltext
  • 2
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    A New Rational Approach to Jet Noise Reduction (1998)
    Springer
    Details
    Publication Date: 1998-01-01
    Print ISSN: 0935-4964
    Electronic ISSN: 1432-2250
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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    PAPER CURRENT
  • 3
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    Mach wave emission from a high-temperature supersonic jet (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The paper considers the compressible Rayleigh equation as a model for the Mach wave emission mechanism associated with high-temperature supersonic jets. Solutions to the compressible Rayleigh equation reveal the existence of several families of supersonically convecting instability waves. These waves directly radiate noise to the jet far field. The predicted noise characteristics are compared to previously acquired experimental data for an axisymmetric Mach 2 fully pressure balanced jet operating over a range of jet total temperatures from ambient to 1370 K. The results of this comparison show that the first-order supersonic instability wave and the Kelvin-Hemlhlotz first-, second-, and third-order modes have directional radiation characteristics that are in agreement with observed data. The assumption of equal initial amplitudes for all of the waves leads to the conclusion that the flapping mode of instability dominates the noise radiatio process of supersonic jets. At a jet temperature of 1370 K, supersonic instability waves are predicted to dominate the noise radiated at high frequency at narrow angles to the jet axis.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 32; 12; p. 2345-2350
    Format: text
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  • 4
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    Fluid dynamics and noise emission associated with supersonic jets (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Methods have long been sought to find an efficient means for reduction of jet noise using either active or passive turbulence control measures. Progress in this area is limited by unclear understanding of the physical supersonic jet noise source mechanisms as they relate to the jet plume turbulence structure. These mechanisms have been extensively studied using round jets. This paper shows that jets with nonround jet exit geometry can provide beneficial noise reduction relative to round jets. Both the fluid dynamic structure and noise of several nonround jets are examined in the paper.
    Keywords: ACOUSTICS
    Type: In: Studies in turbulence (A94-12376 02-34); p. 297-323.
    Format: text
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  • 5
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    The effects of temperature on supersonic jet noise emission (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.
    Keywords: ACOUSTICS
    Type: In: DGLR(AIAA Aeroacoustics Conference, 14th, Aachen, Germany, May 11-14, 1992, Proceedings. Vol. 1 (A93-19126 05-71); p. 295-307.
    Format: text
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  • 6
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    A wind tunnel application of large-field focusing schlieren (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A large-field focusing schlieren apparatus was installed in the NASA Lewis Research Center 9 by 15 foot wind tunnel in an attempt to determine the density gradient flow field of a free jet issuing from a supersonic nozzle configuration. The nozzle exit geometry was designed to reduce acoustic emissions from the jet by enhancing plume mixing. Thus, the flow exhibited a complex three-dimensional structure which warranted utilizing the sharp focusing capability of this type of schlieren method. Design considerations concerning tunnel limitations, high-speed photography, and video tape recording are presented in the paper.
    Keywords: ACOUSTICS
    Type: In: DGLR(AIAA Aeroacoustics Conference, 14th, Aachen, Germany, May 11-14, 1992, Proceedings. Vol. 1 (A93-19126 05-71); p. 169-176.
    Format: text
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  • 7
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    Application Focused Schlieren to Nozzle Ejector Flowfields (1999)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The motivation of the testing was to reduce noise generated by eddy Mach wave emission via enhanced mixing in the jet plume. This was to be accomplished through the use of an ejector shroud, which would bring in cooler ambient fluid to mix with the hotter jet flow. In addition, the contour of the mixer, with its chutes and lobes, would accentuate the merging of the outer and inner flows. The objective of the focused schlieren work was to characterize the mixing performance inside of the ejector. Using flow visualization allowed this to be accomplished in a non-intrusive manner.
    Keywords: Aircraft Propulsion and Power
    Type: First NASA/Industry High Speed Research Program Nozzle Symposium; 15-1 - 15-14; NASA/CP-1999-209423
    Format: application/pdf
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  • 8
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    NASA/LaRC jet plume research (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The following provides a summary for research being conducted by NASA/LaRC and its contractors and grantees to develop jet engine noise suppression technology under the NASA High Speed Research (HSR) program for the High Speed Civil Transport (HSCT). The objective of this effort is to explore new innovative concepts for reducing noise to Federally mandated guidelines with minimum compromise on engine performance both in take-off and cruise. The research program is divided into four major technical areas: (1) jet noise research on advanced nozzles; (2) plume prediction and validation; (3) passive and active control; and (4) methodology for noise prediction.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: First Annual High-Speed Research Workshop, Part 2; p 609-644
    Format: application/pdf
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  • 9
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    Dynamic pressure loads associated with twin supersonic plume resonance (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA Journal (ISSN 0001-1452); 26; 954-960
    Format: text
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  • 10
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    Prediction, Measurement, and Suppression of High Temperature Supersonic Jet Noise (1999)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The photograph in figure 1 displays a water cooled round convergent-divergent supersonic nozzle operating slightly overexpanded near 2460 F. The nozzle is designed to produce shock free flow near this temperature at Mach 2. The exit diameter of this nozzle is 3.5 inches. This nozzle is used in the present study to establish properties of the sound field associated with high temperature supersonic jets operating fully pressure balanced (i.e. shock free) and to evaluate capability of the compressible Rayleigh model to account for principle physical features of the observed sound emission. The experiment is conducted statically (i.e. M(sub f) = 0.) in the NASA/LaRC Jet Noise Laboratory. Both aerodynamic and acoustic measurements are obtained in this study along with numerical plume simulation and theoretical prediction of jet noise. Detailed results from this study are reported previously by Seiner, Ponton, Jansen, and Lagen.
    Keywords: Acoustics
    Type: First NASA/Industry High Speed Research Program Nozzle Symposium; 27-1 - 27-34; NASA/CP-1999-209423
    Format: application/pdf
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