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Tuesday, August 4, 2020 | History

4 edition of Exact solutions for sound radiation from a circular duct found in the catalog.

Exact solutions for sound radiation from a circular duct

Exact solutions for sound radiation from a circular duct

  • 369 Want to read
  • 10 Currently reading

Published by National Aeronautics and Space Administration, Ames Research Center, National Technical Information Service, distributor in Moffett Field, Calif, [Springfield, Va .
Written in English

    Subjects:
  • Wiener Hopf equations,
  • Ducts,
  • Circular waveguides,
  • Acoustic properties,
  • Sound waves

  • Edition Notes

    StatementY.C. Cho and K. Uno Ingard.
    SeriesNASA technical memorandum -- 112200.
    ContributionsIngard, K. Uno., Ames Research Center.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17838517M
    OCLC/WorldCa40962670

    Introduction. The assessment of the complex reflection coefficient R at the open end of ducts is an important procedure in order to predict the acoustical behaviour of these systems in terms of their resonance frequencies and their capability of radiating sound.. For cylindrical ducts and normal acoustic modes, exact solutions have been proposed for a thin unflanged pipe situation (Levine and. assumed to exist within a building space. Sound radiation from a duct wall has been modelled in three ways: analytically as a "nite-length line source [7}9], as a "nite-length cylindrical (or equivalent cylindrical) radiator [9] or numerically by using "nite element.

    ACOUSTIC RADIATION PATTERNS FOR A SOURCE IN A HARD-WALLED UNFLANGED CIRCULAR DUCT By Raymond G. Holm and William E. Zorumski Langley Research Center SUMMARY Acoustic radiation patterns are measured for a source in a hard-walled unflanged circular duct.   The first edition of Sound and Structural Vibration was written in the early s. Since then, two major developments have taken place in the field of vibroacoustics. Powerful computational methods and procedures for the numerical analysis of structural vibration, acoustical fields and acoustical interactions between fluids and structures have been developed and these are now universally Reviews: 2.

      The book considers sources such as jet noise, flow-induced tones and self-excited vibration, dipole sound from rigid and flexible acoustically compact surfaces, random vibration of flow-excited plates and cylindrical shells, cavitation noise, acoustic transmission characteristics and sound radiation from bubbly liquids, splash noise, throttling Book Edition: 1.   The influence of bifurcations in an aeroengine bypass duct on noise radiation was investigated through high-orderaccurate three-dimensional numerical simulations. The physical process was described by a set of acoustic perturbation equations. Four bifurcation arrangements with an airfoil cross section were regularly placed in />circumferential by:


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Exact solutions for sound radiation from a circular duct Download PDF EPUB FB2

INTRODUCTION Sound radiation from circular ducts is a classical acoustics problem. Exact solutions were previously reported: the Wiener-Hopf technique was used for radiation of propagating modes from a circular duct with negligibly thin duct wall (refs.

Sound radiation from a circular duct is a classic problem. Exact solutions were previously reported for the case of a negligibly thin duct wall, using the Wiener–Hopf technique. Despite the elegance of its closed‐form solutions, the numerical presentations have been limited to Author: Y.

Cho. Get this from a library. Exact solutions for sound radiation from a circular duct. [Y C Cho; K Uno Ingard; Ames Research Center.]. This paper presents a method of evaluation of Wiener-Hopf technique solutions for sound radiation from an unflanged circular duct with infinitely thin duct wall, including mean flows Topics: AcousticsAuthor: Uno K.

Ingard and Y. Cho. This paper presents a method of evaluation of Wiener-Hopf technique solutions for sound radiation from an unflanged circular duct with infinitely thin duct wall, including mean flows Topics: Aeronautics Author: K.

Uno Ingard and Y. Cho. Abstract. The exact solution for radiation from a cylindrical pipe obtained by using the Wiener–Hopf method has been available for over 50 years.

Approximate solutions can be used to simplify the problem, and their accuracy compared with the exact solution. Firstly, the exact solution can be simplified by using the method Cited by: An analytic analysis has been carried out to investigate the effects of temperature on the sound radiation from an unflanged circular duct by using a Wiener-Hopf technique.

The wave equations were solved separately inside and outside the duct and the solutions were matched on the duct by: 5. distribution of sound sources at the base of the smokestack are only very seldom available. The assumption of equi-contribution of radiation modes is thus necessary in the most cases.

However, this assumption must be used with caution. Indeed, in the case of the studied model, with a 5 cm diameter duct, only five modes are to be taken into account.

The current paper describes an analytical model, to predict the sound radiation characteristics like total radiated sound power level, modal radiation efficiency, and directivity of the radiated sound from the duct walls.

The analytical model is developed based on an equivalent plate model of the rectangular by: 1. Simplified expansions for radiation from a baffled circular piston where a is the piston radius and r is the distance from the piston center, an exact solution is given by an series of spherical Hankel functions and Legendre polynomials with explicit, closed-form, “ Acoustic field of a pulsed circular piston,” J.

Sound Cited by:   An analytical model is presented for sound radiation from a semi-infinite unflanged annular duct. The duct carries a jet which issues into a uniform mean flow while an inner cylindrical centre body extends downstream from the duct by: Analytical solutions for the problem of radiation of sound from a duct with flow have been shown to serve as an important first model for acoustic engine-aircraft engineering applications, useful.

sound radiation characteristics of the external sound field are also of great interest. This problem can be investigated by analytical, experimental, and numerical approaches. Levine and Schwinger [1] proposed an analytical model for the dominant mode propagation of sound out of a semi-infinite circular duct in the absence of flow.

Their. The directivity of the sound radiation from panels and openings. If the sound source is situated in the room or duct, the sound absorption coefficient model is used in conjunction with a model Author: John Laurence Davy. As the external Mach number is increased the noise radiation pattern is shifted away from the inlet axis.

The theory is developed using approximations for sound propagation in circular ducts. An exact analysis using Hankel function solutions for the zero Mach number case is given to provide a check of the simpler approximate theory.

An Introduction to Acoustics S.W. Rienstra & A. Hirschberg Eindhoven University of Technology 28 Nov This is an extended and revised edition of IWDE Comments and corrections are gratefully accepted.

This file may be used and printed, but for personal or educational purposes only. c S.W. Rienstra & A. Hirschberg Sound radiation of a circular piston in the outlet of a finite hemispherical cavity of a finite inner impedance.

Exact solutions for sound radiation from a moving monopole above an impedance plane. An analytic Green's function for a lined circular duct containing uniform mean flow. Journal of Sound and Vibration, Vol. No. Sound reflection at a duct open end induces resonant amplification of acoustic energy in the duct and causes high intensity sound radiation.

This phenomenon sometime causes low frequency noise pollution radiation from pipe and some self-sustained acoustic oscillation in machines. In order to reduce such kind of acoustic resonance, acoustic damping should be added to the duct. Idemen, “A new method to obtain exact solutions of vector Wiener-Hopf equations”, ZAMM, vol.

59, pp.zbMATH CrossRef MathSciNet Google Scholar [3] I. Abrahams, “Scattering of sound by two parallel semi-infinite screens”, Wave Motion, vol. 9, pp.zbMATH CrossRef MathSciNet Google ScholarCited by: 8. Propagation and radiation of sound from flanged circular ducts with circumferentially varying wall admittances, II: Finite ducts with sources Exact Wiener-Hopf solution of multi-section duct liners.

KOCH; 16 August The acoustics of aircraft engine-duct by:. Formulas of Acoustics XV Contents J Splitter type silencer with splitters of porous layers covered with a foil J Lined duct corners and junctions J Sound radiation from lined duct orifice J Conical duct transitions; special case: hard walls J Lined conical duct transition, evaluated with stepping duct sections A complete presentation and analysis of the major topics in sound suppression and noise control for the analysis and design of acoustical mufflers, air conditioning and ventilation duct work.

Both fundamentals and the latest technology are discussed, with an emphasis on applications. Deals with reactive mufflers, dissipative silencers, the frequency-domain approach, and the time-domain approach.5/5(1).Exact closed form solutions are obtained for a particular class of converging-diverging circular duct which is here referred to as 'circular cosh duct'.

Numerical results are presentd in terms of the transmission loss for the various duct shapes and frequencies. The results are also applicable to studies of sound radiation from certain.