US3738448A - Sound silencing method and apparatus - Google Patents

Sound silencing method and apparatus Download PDF

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Publication number
US3738448A
US3738448A US00207008A US3738448DA US3738448A US 3738448 A US3738448 A US 3738448A US 00207008 A US00207008 A US 00207008A US 3738448D A US3738448D A US 3738448DA US 3738448 A US3738448 A US 3738448A
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US
United States
Prior art keywords
duct
sound
flow
transversely
baffle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00207008A
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English (en)
Inventor
I Ver
U Kurze
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Bolt Beranek and Newman Inc
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Bolt Beranek and Newman Inc
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/78—Other construction of jet pipes
    • F02K1/82—Jet pipe walls, e.g. liners
    • F02K1/827—Sound absorbing structures or liners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • F16L55/033—Noise absorbers
    • F16L55/0336—Noise absorbers by means of sound-absorbing materials

Definitions

  • This disclosure deals with a novel sound muffler for 181/48, 59,35 R, 33 HB, 33 HE gas turbine engines and the like employing in the same duct section both longitudinal baffles and outward] versely extending side-branch cavities.
  • the present invention relates to acoustic muffling or silencing methods and apparatus being more particularly directed to novel structures and techniques for silencing gas turbine engines and similar noise-producing systems.
  • the airspace behind the flow-resistive lining permits the gas or other fluid medium particles carrying the acoustical energy to oscillate in the flow-resistive material and surrender part of their energy due to friction loss. It is well understood that optimal sound attenuation is achieved in narrow ducts by a relatively low flow resistance of the facing material which is less than the characteristic impedance of the gas.
  • both the lowand high-frequency sounds must be silenced, accordingly, combinations of the above-mentioned techniques have been employed; such as employing the longitudinal baffling in one section of the duct to silence the high frequencies, serially or successively followed by side branches faced with the acoustically resistant material to attenuate the low frequencies.
  • this composite treatment may require relatively long ducts in order to accommodate the successive silencing sections, and, in addition, does not enable synergistic or cooperative effects to take place between the silencing sections of different effective frequency range.
  • the mechanism of this interaction is that the reduction of wave speed due to the structure factor of the parallel baffles increases the attenuation performance of the side-branch mufflers and that an equivalent structure factor of the side branches increases the attenuation of the parallel baffles resulting in increased sound attenuation at both lowand highfrequencies.
  • the baffles may be disposed in a plane substantially parallel to the facing layer of the side branch.
  • the flow resistance of the baffles should be small to permit sound transmission from the center of the duct to the side branch resonators.
  • the baffles may be disposed in a plane substantially perpendicular to the facing layer of the side branches. In this case, the additional low-frequency attenuation is achieved by the propagation of the low-frequency sound energy toward the side branches in the narrow channels formed by the parallel baffles.
  • the flow resistance of the baffles is not confined to small values.
  • the combination of the lowand high-frequency sections may result in considerable economy of size of the required duct. It is important to point out that in applications where the gas flow carries high-intensity, low-frequency sound, and duct walls are required to have a large mass per unit area or high stiffness in order to prevent acoustic transmission; so that the savings in the necessary length dimensions of the duct achievable by the present invention may constitute a very appreciable advantage.
  • a further object of the invention is to provide a novel acoustic silencing structure and method of more general application as well.
  • FIG. 1 of which is a longitudinal section of an acoustical silencing duct constructed in accordance with a preferred embodiment of the invention
  • FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1 looking in the direction of the arrows;
  • FIGS. 3 and 4 views, respectively, like FIGS. 1 and 2, of a modification, with FIG. 4 being a section taken along the line 4-4 of FIG. 3, looking in the direction of the arrows.
  • FIG. 1 a gas or other fluid medium containing or carrying low and high-frequency sounds, such as those produced by a gas turbine, for example, is shown entering a duct housing, chamber, or enclosure I, at an inlet region 1, and passing through a novel combined low and high-frequency muffling section, emerging or exiting with the sounds attenuated at the outlet II.
  • a gas or other fluid medium containing or carrying low and high-frequency sounds such as those produced by a gas turbine, for example, is shown entering a duct housing, chamber, or enclosure I, at an inlet region 1, and passing through a novel combined low and high-frequency muffling section, emerging or exiting with the sounds attenuated at the outlet II.
  • the high-frequency sounds are primarily absorbed as the result of the use of a plurality of longitudinally extending, substantially parallel absorbing baffles 3 (as of sound attenuation materials described in the above-mentioned articles and patents), spaced transversely at distances small compared with the sound wave lengths involved in the medium so as to provide longitudinal fluid flow paths; but the baffles are long compared to such wave lengths.
  • the sides or walls of the duct I opposite the baffles 3 are rather provided with flow resistive layers 5 that, in turn, face side branches or cavities 7 extending transversely outward of the duct I and preferably provided with soundimpervious transverse-separating septa 9 that prevent propagation of the low-frequency sounds longitudinally along the cavity and force substantially transverse particle oscillation.
  • the novel location of the lowfrequency section 5-7 juxtaposed to the highfrequency sound energy propagating longitudinally along the duct I, but to absorb, also, low-frequency energy forced to resonate transversely between the cavities 7, as before described.
  • the longitudinally oriented baffle 3 must have some transparency to the acoustic energy; again as distinguished from those prior art baffles that have high flow resistance or impervious separators, septa and similar structures.
  • the high-frequency performance of the silencer with low-flow resistance baffles oriented substantially parallel to the facing of the side branch, as shown in FIG. 1, is somewhat reduced in comparison to a system with high-flow resistance baffles alone. This, however, does not impair the overall performance of the silencer for typical gas turbine engines and other noises producing systems with similar spectra, because standard parallel baffle silencers usually provide unbalanced attenuation in favor of higher frequencies. In those special cases where stronger high-frequency attenuation is required, on the other hand, the configuration shown in FIGS. 3 and 4 may be more advantageously employed.
  • the flow resistance of the parallel baffles 3, which are this time oriented substantially perpendicular to the cavity facing 5 can be optimized so that with the given spacing a balanced highand lowfrequency attenuation is achieved.
  • Apparatus for attenuating sound of relatively low and high frequencies accompanying the flow of a fluid medium having, in combination, longitudinally extending duct means provided with an inlet for receiving the said fluid medium and an outlet for exiting the same, a plurality of substantially parallel longitudinal soundabsorbing baffle means extending along the duct means between the inlet and outlet and transversely spaced from one another between the sides of the duct means so as to provide a plurality of longitudinal fluid flow paths between the inlet and the outlet, the said duct means sides opening into transverse side branches extending transversely outward and longitudinally along the duct means and defining cavity means faced with flow resistive layer means and communicating through the same with the duct means, thecavities having terminating walls spaced from said layer means, and said duct means having transverse fluid flow paths between said sides.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Exhaust Silencers (AREA)
  • Pipe Accessories (AREA)
US00207008A 1971-12-13 1971-12-13 Sound silencing method and apparatus Expired - Lifetime US3738448A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US20700871A 1971-12-13 1971-12-13

Publications (1)

Publication Number Publication Date
US3738448A true US3738448A (en) 1973-06-12

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ID=22768834

Family Applications (1)

Application Number Title Priority Date Filing Date
US00207008A Expired - Lifetime US3738448A (en) 1971-12-13 1971-12-13 Sound silencing method and apparatus

Country Status (7)

Country Link
US (1) US3738448A (fr)
JP (1) JPS4865312A (fr)
CA (1) CA964139A (fr)
DE (1) DE2255428A1 (fr)
FR (1) FR2165436A5 (fr)
GB (1) GB1383354A (fr)
IT (1) IT987575B (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4020900A (en) * 1974-01-31 1977-05-03 Kabushiki Kaisha Komatsu Seisakusho Device for ventilating cooling air of construction
US5276291A (en) * 1992-07-10 1994-01-04 Norris Thomas R Acoustic muffler for high volume fluid flow utilizing Heimholtz resonators with low flow resistance path
US5661272A (en) * 1995-01-27 1997-08-26 Iannetti; Francesco E. Engine noise reduction apparatus
US5962821A (en) * 1995-01-27 1999-10-05 Iannetti; Francesco E. Internal combustion engine noise reduction apparatus
CH691191A5 (de) * 2000-01-06 2001-05-15 Rudolf Ing Htl Gehring Drehverbindung auf Gleitlagerbasis.
US6705428B2 (en) 2000-12-08 2004-03-16 Abb Turbo Systems Ag Exhaust gas system with helmholtz resonator
US20040262077A1 (en) * 2003-05-02 2004-12-30 Huff Norman T. Mufflers with enhanced acoustic performance at low and moderate frequencies
US20110061968A1 (en) * 2008-04-30 2011-03-17 Kalle Helenius Sound Attenuator for Low Frequencies, Method for Manufacturing Sound Attenuator for Low Frequencies and System for Attenuating Low Frequencies for Example In Air-Conditioning Ducts of Paper Mills

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5417681Y2 (fr) * 1973-11-27 1979-07-06
ZA783845B (en) * 1977-07-13 1979-07-25 Carrier Corp Pressure variation absorber
GB2136502B (en) * 1983-03-17 1986-09-03 Chillcotts Ltd Internal combustion engine exhaust silencer
DE3521941C2 (de) * 1985-06-19 1994-02-03 Stahl & Sohn Gmbh & Co Kg Vorrichtung zur Schalldämpfung eines Schwingbrenners
US4747467A (en) * 1986-04-01 1988-05-31 Allied-Signal Inc. Turbine engine noise suppression apparatus and methods
JP4937730B2 (ja) * 2006-09-22 2012-05-23 株式会社キングジム 綴込具及びファイリング用具
JP5215735B2 (ja) * 2008-05-30 2013-06-19 三菱重工業株式会社 ガスタービン排気設備

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2051515A (en) * 1935-10-07 1936-08-18 Maxim Silencer Co Sound attenuating device
GB733329A (en) * 1952-11-12 1955-07-06 Lothar Cremer Improvements in or relating to ducts having sound-absorbing walls for the conductionof gaseous fluids
GB783055A (en) * 1955-03-01 1957-09-18 Werner Genest Ges Fuer Isolier Improvements in or relating to sound absorbers for induction and exhaust ducts of power unit and compressor testing stations
DE1095504B (de) * 1955-03-18 1960-12-22 Nordwestdeutscher Rundfunk Absorptionsdaempfer fuer Klima- oder Belueftungsanlagen
US2989136A (en) * 1959-04-14 1961-06-20 Wohlberg George Sound attenuation
AT226480B (de) * 1960-01-14 1963-03-25 Gruenzweig & Hartmann Schalldämpfer
DE1200007B (de) * 1964-07-24 1965-09-02 Gerber Schall Schwingungstech Schalldaempfer mit einer Kulisse zur Daempfung von aus einer Wandoeffnung od. dgl. ausstrahlenden Geraeuschen
US3353626A (en) * 1963-12-09 1967-11-21 Cremer Lothar Sound absorbing ventilation conduit with side branch chambers

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2051515A (en) * 1935-10-07 1936-08-18 Maxim Silencer Co Sound attenuating device
GB733329A (en) * 1952-11-12 1955-07-06 Lothar Cremer Improvements in or relating to ducts having sound-absorbing walls for the conductionof gaseous fluids
GB783055A (en) * 1955-03-01 1957-09-18 Werner Genest Ges Fuer Isolier Improvements in or relating to sound absorbers for induction and exhaust ducts of power unit and compressor testing stations
DE1095504B (de) * 1955-03-18 1960-12-22 Nordwestdeutscher Rundfunk Absorptionsdaempfer fuer Klima- oder Belueftungsanlagen
US2989136A (en) * 1959-04-14 1961-06-20 Wohlberg George Sound attenuation
AT226480B (de) * 1960-01-14 1963-03-25 Gruenzweig & Hartmann Schalldämpfer
US3353626A (en) * 1963-12-09 1967-11-21 Cremer Lothar Sound absorbing ventilation conduit with side branch chambers
DE1200007B (de) * 1964-07-24 1965-09-02 Gerber Schall Schwingungstech Schalldaempfer mit einer Kulisse zur Daempfung von aus einer Wandoeffnung od. dgl. ausstrahlenden Geraeuschen

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4020900A (en) * 1974-01-31 1977-05-03 Kabushiki Kaisha Komatsu Seisakusho Device for ventilating cooling air of construction
US5276291A (en) * 1992-07-10 1994-01-04 Norris Thomas R Acoustic muffler for high volume fluid flow utilizing Heimholtz resonators with low flow resistance path
US5661272A (en) * 1995-01-27 1997-08-26 Iannetti; Francesco E. Engine noise reduction apparatus
US5962821A (en) * 1995-01-27 1999-10-05 Iannetti; Francesco E. Internal combustion engine noise reduction apparatus
CH691191A5 (de) * 2000-01-06 2001-05-15 Rudolf Ing Htl Gehring Drehverbindung auf Gleitlagerbasis.
US6705428B2 (en) 2000-12-08 2004-03-16 Abb Turbo Systems Ag Exhaust gas system with helmholtz resonator
US20040262077A1 (en) * 2003-05-02 2004-12-30 Huff Norman T. Mufflers with enhanced acoustic performance at low and moderate frequencies
US7281605B2 (en) 2003-05-02 2007-10-16 Owens-Corning Fiberglas Technology Ii, Llc Mufflers with enhanced acoustic performance at low and moderate frequencies
US20110061968A1 (en) * 2008-04-30 2011-03-17 Kalle Helenius Sound Attenuator for Low Frequencies, Method for Manufacturing Sound Attenuator for Low Frequencies and System for Attenuating Low Frequencies for Example In Air-Conditioning Ducts of Paper Mills
US8272475B2 (en) * 2008-04-30 2012-09-25 Metso Paper, Inc. Sound attenuator for low frequencies, method for manufacturing sound attenuator for low frequencies and system for attenuating low frequencies for example in air-conditioning ducts of paper mills

Also Published As

Publication number Publication date
FR2165436A5 (fr) 1973-08-03
JPS4865312A (fr) 1973-09-08
GB1383354A (en) 1974-02-12
DE2255428A1 (de) 1973-06-28
CA964139A (en) 1975-03-11
IT987575B (it) 1975-03-20

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