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Tuesday, July 21, 2020 | History

3 edition of Jet noise suppression by porous plug nozzles found in the catalog.

Jet noise suppression by porous plug nozzles

Jet noise suppression by porous plug nozzles

  • 9 Want to read
  • 23 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch in [Washington, D.C.?] .
Written in English

    Subjects:
  • Jet plane sounds,
  • Jet planes -- Noise,
  • Noise control -- United States

  • Edition Notes

    StatementA.B. Bauer, V. Kibens and R.W. Wlezien ; prepared for Langley Research Center
    SeriesNASA contractor report -- 3613
    ContributionsKibens, V, Wlezien, R. W, Langley Research Center, United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch, Douglas Aircraft Company
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL14931065M

    For both convergent and convergent-divergent nozzles, the relative importance of shock noise with respect to jet-mixing noise is found to be maximum near the pressure ratio at which a Mach disk Jet noise reduction by microjets- A parametric study. the porous nozzles are shown to suppress the pairing of vortices and enhance the flow mixing, and therefore, the development of shear

    Get this from a library! Aeroacoustics of supersonic jet flows from contoured and solid-porous conical plug-nozzles. [Darshan Singh Dosanjh; Indu S Das; Langley Research Center.] After 18 months of testing on mixed surfaces, we tested the top vacuums on hardwood. The best vacuum for hardwood floors is the Shark - Apex, with its revolutionary soft roller. The Best Flip Chair. The Best Tower Fan. Seville Classics - UltraSlimline. The Best Window Air Conditioner. Frigidaire - FFREU1. The Best Portable Air ://

    Abstract. The noise of supersonic jets issued from choked or convergent-divergent nozzles is a subject of considerable current interest. When these jets are operated at off-design pressure ratios, measured noise spectra invariably show that they are made up of discrete and broadband ://   O ur collective experience as professional musicians, frequent travelers and avid music fans who have worn countless earplugs over the years informed our tests and ratings to determine the best earplugs for the casual consumer. We tested the 12 top plugs on the market over the course of three weeks, putting each pair through a series of critical tests, and determined that Moldex – Pura-Fit


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Jet noise suppression by porous plug nozzles Download PDF EPUB FB2

Jet Noise Suppression by Porous s A. Bauer Douglas Aircraft Company Long Beach, California V. Kibens and R. Wlezien McDonnell Douglas Research Laboratories St. Louis, Missouri Prepared for Langley Research Center under Contract NAS l- 84 National Aeronautics and Space Administration   Jet noise suppression data presented earlier by Maestrello for porous plug nozzles have been supplemented by the testing of a family of nozzles having an equivalent throat diameter of cm.

Two circular reference nozzles and eight plug nozzles having radius ratios of either or were tested at total pressure ratios of to Get this from a library.

Jet noise suppression by porous plug nozzles. [A B Bauer; V Kibens; R W Wlezien; Langley Research Center.; United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch.; Douglas Aircraft Company.] Jet noise suppression data presented earlier by Maestrello for porous plug nozzles were supplemented by the testing of a family of nozzles having an equivalent throat diameter of cm.

Two circular reference nozzles and eight plug nozzles having radius ratios of either or were tested at total pressure ratios of to Jet noise suppression data presented earlier by Maestrello for porous plug nozzles have been supplemented by the testing of a family of nozzles having an equivalent throat diameter of cm.

Two circular reference nozzles and eight plug nozzles having radius ratios of either or were tested at total pressure ratios of to   An experimental study on porous plug jet noise suppressor. MAESTRELLO; L. MAESTRELLO. NASA, Langley Research Center, Hampton, Va.

NOISE SUPPRESSION OP SUPERSONIC JETS BY CONTOURED AND POROUS CONICAL ://   As part of a continuing study of possible methods of jet noise reduction, some tests have been made on a porous plug type noise suppressor. Very little information exists on the aeroacoustic performance of jet nozzles having porous elements designed to eliminate the shock wave in the exhaust stream and by so doing to eliminate the shock associated noise and :// Noise suppression using image averaging relies on three basic assumptions: (1) that a relatively large number of input images is available, (2) that each input image has been corrupted by the same type of additive noise, and (3) that the additive noise is random with zero mean value and independent of the image.

When these assumptions hold, it may be advantageous to acquire multiple images   Modelling of noise reduction in complex multistream jets - Volume - Dimitri Papamoschou you will be asked to authorise Cambridge Core to connect with your account. Jet noise suppression by porous plug nozzles.

NASA CR Brès, G. A., Ham, F. E., Nichols, J. & Lele, S. Unstructured large-eddy   MaestrelloS9d has shown that the porous plug nozzle suppressor does indicate a cancellation of the shock noise component with an additional reduction in the jet mixing noise.

the acoustic performance r.f a much shorter porous plug nozzle suppressor than was used in See “Initial Results of a Porous Plug Nozzle for Supersonic Jet Noise Suppression”, by Maestrello, NASA TM,and “Jet Noise Suppression by Porous Plug Nozzles” by Bauer, Kibens, and Wlezian, NASA Contractor reportMoreover, a contoured plug-nozzle operated at its design pressure ratio provides baseline acoustic data for a shock-free plug-nozzle supersonic jet flow and, as such, this is an ideal to be approached when the objective is to achieve the suppression of shock noise in improperly expanded jet flows issuing from uncontoured or conical ://   Aeroacoustics of supersonic jet flows from a contoured plug-nozzle.

Short conical solid/perforated plug-nozzle as supersonic jet noise supressor. Journal of Sound and Vibration, Vol. No. NOISE SUPPRESSION OP SUPERSONIC JETS BY CONTOURED AND POROUS CONICAL :// Experimental investigations are carried out with an objective of reducing impingement jet noise using coaxial swirl jets.

Two nozzle-to-plate distances have been considered and the Mach number values ranged from to Apparatus and method for jet noise suppression: Authors: Maestrello, L.

A method and apparatus for jet noise suppression through control of the static pressure of the jet and control of the rate of entrainment of ambient fluid into the jet downstream of the exhaust nozzle is disclosed.porous nozzle plug centerbody which may be   Several high radius plug (HRP) nozzles were also considered.

Previous noise tests have shown an improvement using HRP nozzles, as described by Bauer, Kibens and Wleizen 6. Porous plugs proved to be effective in reducing screech noise when shock cells where present.

A family of HRP nozzles was tested, including axisymmetric and non-symmetric The JT8D turbofan engine, widely used in short and medium range transport aircraft, contributes substantially to airport community noise.

The jet noise is predominant in the JT8D engine and may be reduced in a modified engine, without loss of thrust, by increasing the airflow to reduce jet ://?and[]=subject:"NOISE+REDUCTION".

A scaling law for predicting the overall flyover noise of a single stream circular jet from static experiments [A. Michalke and U. Michel, J. Sound Vibrat – ()] is extended to the prediction of spectra. The theory is based on the Lighthill approach to jet noise.

The density terms are retained to include the effects of jet ://   Past experimental work established the potential for high radius plug nozzles to reduce jet noise with relatively modest reductions in thrust efficiency.

See “Initial Results of a Porous Plug Nozzle for Supersonic Jet Noise Suppression”, by Maestrello, NASA TM,and “Jet Noise Suppression by Porous Plug Nozzles” by Bauer   Actually, there were similar tricks used on Boeing aircraft before to reduce jet noise.

The Rolls-Royce Conway (as used on the Boeing ) had a scalloped exhaust which improved jet mixing and reduced exhaust noise. Since the Conway was also the first operational bypass engine, the lower exhaust speed of this design helped to reduce noise ://.

these noise components is a strong function of the direction of observation. Many devices such as nozzle with tabs, slotted tubes, chuted nozzle, lobed nozzle, multi-tube nozzle etc. are used for suppressing the jet noise. Contoured and porous plug nozzles are also commonly used for reducing the jet noise.

However, in most cases   chuted nozzles, lobed nozzles, multi-tube nozzles, etc., are used for suppressing jet noise. Contoured and porous plug nozzles are also commonly used. 7 However, in most cases the attachment of a noise-reducing device incurs undesirable ef-fects, such as increasing dead weight and reducing thrust.

Supersonic jet-noise suppression achieved   Free Online Library: Technologies for jet noise reduction in turbofan engines.(Report) by "Aviation"; Transportation industry Jet airplane noise Control Jet airplanes Usage Jet plane sounds Jet planes Noise Jet transports Noise control Research Turbofan engines Maintenance and repair+for+jet+noise+reduction+in+turbofan.