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Author : C. Kannepalli
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Analysis of Supersonic Jet Noise Reduction Concepts written by C. Kannepalli and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Lockheed-Georgia Company
Publisher :
ISBN 13 :
Total Pages : 270 pages
Book Rating : 4.F/5 ( download)
Download or read book The Generation and Radiation of Supersonic Jet Noise written by Lockheed-Georgia Company and published by . This book was released on 1972 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : W. C. Sperry
Publisher :
ISBN 13 :
Total Pages : 150 pages
Book Rating : 4.3/5 (91 download)
Download or read book Fundamental Study of Jet Noise Generation and Suppression written by W. C. Sperry and published by . This book was released on 1961 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : K. K. Ahuja
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book An Evaluation of Various Concepts of Reducing Supersonic Jet Noise written by K. K. Ahuja and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Generation and Radiation of Supersonic Jet Noise: Summary of supersonic jet noise studies written by and published by . This book was released on 1972 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Lockheed-Georgia Company
Publisher :
ISBN 13 :
Total Pages : 322 pages
Book Rating : 4.F/5 ( download)
Download or read book The Generation and Radiation of Supersonic Jet Noise: Jet flow measurement and analysis with special emphasis on remote sensing devices written by Lockheed-Georgia Company and published by . This book was released on 1972 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781723430411
Total Pages : 184 pages
Book Rating : 4.4/5 (34 download)
Download or read book The Aeroacoustics of Supersonic Coaxial Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-23 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Instability waves have been established as the dominant source of mixing noise radiating into the downstream arc of a supersonic jet when the waves have phase velocities that are supersonic relative to ambient conditions. Recent theories for supersonic jet noise have used the concepts of growing and decaying linear instability waves for predicting radiated noise. This analysis is extended to the prediction of noise radiation from supersonic coaxial jets. Since the analysis requires a known mean flow and the coaxial jet mean flow is not described easily in terms of analytic functions, a numerical prediction is made for its development. The Reynolds averaged, compressible, boundary layer equations are solved using a mixing length turbulence model. Empirical correlations are developed for the effects of velocity and temperature ratios and Mach number. Both normal and inverted velocity profile coaxial jets are considered. Comparisons with measurements for both single and coaxial jets show good agreement. The results from mean flow and stability calculations are used to predict the noise radiation from coaxial jets with different operating conditions. Comparisons are made between different coaxial jets and a single equivalent jet with the same total thrust, mass flow, and exit area. Results indicate that normal velocity profile jets can have noise reductions compared to the single equivalent jet. No noise reductions are found for inverted velocity profile jets operated at the minimum noise condition compared to the single equivalent jet. However, it is inferred that changes in area ratio may provide noise reduction benefits for inverted velocity profile jets. Dahl, Milo D. Glenn Research Center AEROACOUSTICS; COAXIAL FLOW; GAS JETS; JET AIRCRAFT NOISE; NOISE PREDICTION (AIRCRAFT); NOISE REDUCTION; SUPERSONIC JET FLOW; COMPUTATIONAL FLUID DYNAMICS; FLOW STABILITY; MACH NUMBER; MIXING LENGTH FLOW THEORY; TEMPERATURE RATIO; VELOCITY DISTRIBUTION...
Author : Venkata Rajeshwar Majety
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (18 download)
Download or read book An Analysis of Noise Reduction in Supersonic Jets by Fluid Insert Nozzles written by Venkata Rajeshwar Majety and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research is to analyze the noise reduction obtained with the use of fluid insert nozzles in heated supersonic jets. In this regard, the far-field pressure data of two types of nozzles (baseline and fluid inserts) are used to investigate and validate the spatiotemporal characteristics of the radiation field, and to determine the sound reduction obtained. Further, to gain a better understanding of the noise radiated, the polar correlation technique is used to determine the location and relative strengths of the noise sources. The results of this research can be summarized as follows: the fluid insert nozzles reduce the overall sound radiated by a maximum amount of 10 dB and 4 dB respectively in the downstream and upstream directions of the jet flow. The highest levels of sound are radiated in the downstream directions of the jet flow for all the nozzle cases. The greatest amount of noise reduction is obtained in the 60 azimuthal plane. Irrespective of the nozzle type, significant noise source strength is located within ten nozzle diameters downstream from the nozzle exit. As the frequency increases, the highest peak of the noise source strength distribution moves closer to the nozzle exit.
Download or read book The Generation and Radiation of Supersonic Jet Noise: Future studies for definition of supersonic jet noise generation and reduction mechanisms written by and published by . This book was released on 1972 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (227 download)
Download or read book Evaluation of Some Recent Jet Noise Reduction Concepts written by and published by . This book was released on 2003 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses RANS based numerical simulations of a 1/10th scale over-expanded supersonic plume (resembling that of an F-18 aircraft) with chevrons used as passive noise reduction devices. Three variant designs of the chevrons mounted in specified azimuthal arrangements around the baseline nozzle exit are evaluated. A major effect of the chevrons is to amplify the Mach disc size and move it closer to the nozzle exit. For these over-expanded exhausts, the chevrons must extend sufficiently deep into the plume core stream to reduce jet noise levels. Results from our simulations are in nominal accord with the experimental observations (primarily noise measurements) as ascertained by examining the flow structure, and via using jet noise prediction codes. Evaluation of the thrust loss produced by these devices is found to be minimal except for the one chevron configuration that provided maximum noise reduction. Our studies indicate that noise reduction devices which work for laboratory model jets may have to be revised to have them work for the real engine due to complexities in the internal mixing which cannot be replicated at laboratory scale. We discuss issues related to these differences and with real aircraft effects such as plume/plume interactions and installation effects, and we present a complete aircraft/dual engine plume simulation using innovative multi-element unstructured gridding.
Author : Brenda Henderson
Publisher : BiblioGov
ISBN 13 : 9781289088347
Total Pages : 32 pages
Book Rating : 4.0/5 (883 download)
Download or read book Update on Supersonic Jet Noise Research at Nasa written by Brenda Henderson and published by BiblioGov. This book was released on 2013-06 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: An update on jet noise research conducted in the Fundamental Aeronautics and Integrated Systems Research Programs was presented. Highlighted research projects included those focused on the development of prediction tools, diagnostic tools, and noise reduction concepts.
Author : Haukur Elvar Hafsteinsson
Publisher :
ISBN 13 : 9789175970868
Total Pages : pages
Book Rating : 4.9/5 (78 download)
Download or read book Study of Supersonic Jet Noise Reduction Using LES written by Haukur Elvar Hafsteinsson and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (317 download)
Download or read book Supersonic Jet Noise Reductions Predicted with Increased Jet Spreading Rate written by and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Brenda Henderson
Publisher : BiblioGov
ISBN 13 : 9781289066277
Total Pages : 26 pages
Book Rating : 4.0/5 (662 download)
Download or read book Jet Noise Reduction Potential from Emerging Variable Cycle Technologies written by Brenda Henderson and published by BiblioGov. This book was released on 2013-06 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic and flow-field experiments were conducted on exhaust concepts for the next generation supersonic, commercial aircraft. The concepts were developed by Lockheed Martin (LM), Rolls-Royce Liberty Works (RRLW), and General Electric Global Research (GEGR) as part of an N+2 (next generation forward) aircraft system study initiated by the Supersonics Project in NASA s Fundamental Aeronautics Program. The experiments were conducted in the Aero-Acoustic Propulsion Laboratory at the NASA Glenn Research Center. The exhaust concepts utilized ejectors, inverted velocity profiles, and fluidic shields. One of the ejector concepts was found to produce stagnant flow within the ejector and the other ejector concept produced discrete-frequency tones that degraded the acoustic performance of the model. The concept incorporating an inverted velocity profile and fluid shield produced overall-sound-pressure-level reductions of 6 dB relative to a single stream nozzle at the peak jet noise angle for some nozzle pressure ratios. Flow separations in the nozzle degraded the acoustic performance of the inverted velocity profile model at low nozzle pressure ratios.
Author : Chitrarth Prasad
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (113 download)
Download or read book Simulation of Supersonic Jet Noise Reduction Using Fluid Inserts for Low Bypass Ratio Turbofans written by Chitrarth Prasad and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design constraints on jet engines for high performance supersonic military aircraft require lower bypass ratios and supersonic exhaust velocities, which result in very high noise levels. This is a great concern to the US Navy as the noise generated from the jet exhaust of high performance supersonic military aircraft can affect the hearing and performance of personnel working in close proximity of the aircraft. There have been reports about the US Department of Veteran Affairs spending over hundreds of millions of dollars in disability payments for hearing loss compensation to former Navy personnel. In addition to this, jet noise is also a source of annoyance in communities in the vicinity of airbases and military training routes.Over the years, several noise reduction methods have been proposed with varying levels of success. The most effective noise reduction strategies include the installation of chevrons, and the use of corrugated seals, among many others. One primary disadvantage of these technologies is that they are passive technologies and cannot be switched off or modified after take-off and hence may reduce overall aircraft performance. An active, though steady, noise reduction technology is the use of fluid inserts in the divergent section of a converging-diverging nozzle. The fluid inserts consist of rows of injectors that inject a small amount of bypass air into the diverging section of the nozzle. It has been shown that by altering the configuration and operating conditions of the fluid inserts, noise reduction for both mixing and shock noise can be achieved. Since this blowing can be controlled, the fluid inserts can be switched off or modified after take-off to minimize any performance penalty to the aircraft.Although considerable experimental research has been performed to explore the effects of fluid inserts on the jet exhaust, the available data have been found to be insufficient to correlate the noise reduction with changes in the flow-field due to the noise reduction device. The present study is an extension to the previousresearch on fluid inserts that uses Large Eddy Simulation (LES) with the Ffowcs Williams-Hawkings (FWH) analogy for farfield noise prediction. The simulations are carried out using a commercially available CFD package, STAR-CCM+. The project aims to simulate and analyze the unsteady flow changes associated withthe noise reduction device to help understand the detailed mechanisms for the observed noise reductions.Different fluid insert configurations are used to analyze the effect of individual injector placement in a fluid insert on noise generation. It is observed that the changes in upstream noise correlate extremely well with the shock structure of the fluid insert jets downstream of the nozzle exit. Further insight into the noisereduction patterns is obtained by using two-point space time correlations and the use of the modal techniques such as Proper Orthogonal Decomposition on the near-field data on the FWH surface, which show that fluid inserts reduce the amplitude of the noise radiating coherent structures. Using Doaks Momentum Potential Theory, it is observed that the changes associated with fluid insertson the hydrodynamic and acoustic modes correlate well with the far-field noise reduction.
Author :
Publisher :
ISBN 13 :
Total Pages : 30 pages
Book Rating : 4.:/5 (317 download)
Download or read book Results from an Exploratory Study of Airframe Noise on a Small-scale Model of a Supersonic Transport Concept written by and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Seyyed Saman Salehian
Publisher :
ISBN 13 :
Total Pages : 536 pages
Book Rating : 4.:/5 (119 download)
Download or read book Aeroacoustics of Supersonic Jet Interacting with Solid Surfaces and Its Suppression written by Seyyed Saman Salehian and published by . This book was released on 2020 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The noise generated by supersonic jet is of primary interest in the high-speed flight. In several flight conditions jet exhaust of the propulsion system interacts with solid surfaces. For example, jet impingement on ground for a rocket lift-off, or interactions influenced by the integration of the engine with the airframe. Such complex applications require consideration of the role of acoustic-surface interactions on the noise generation of the jet and its radiation. Numerical analysis of supersonic jet noise involved in these scenarios is investigated by employing Hybrid Large Eddy Simulation - Unsteady Reynolds Averaged Simulation approach to model turbulence. First, the supersonic impinging jet noise reduction using aqueous injectors is investigated. The technique employed to suppress impingement noise, involves injecting liquid water from the ground surface. The Volume of Fluid model is adopted to simulate the two phase flow. The flow field and acoustic results agree well with the existing experimental data. The possible mechanisms of noise reduction by water injection are investigated. Second, supersonic jet noise reduction by employing the shielding effect of a flat plate parallel to the jet is investigated. The numerical simulations model the shielding effect of the flat plate on the acoustics of supersonic jet, and results agree with the corresponding experimental data. The physical mechanisms involved in the flow-surface interactions are investigated. With understanding these mechanisms, a slightly wavy plate is proposed including theoretical background to determine the parameters needed for the way wall to provide acoustic reduction efficiently. Results show that the proposed wavy shield can effectively reduce both the level and extent of the jet noise source as compared to that of a flat shield."--Abstract.
