US3791483A - Sound absorber - Google Patents

Sound absorber Download PDF

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Publication number
US3791483A
US3791483A US00264209A US3791483DA US3791483A US 3791483 A US3791483 A US 3791483A US 00264209 A US00264209 A US 00264209A US 3791483D A US3791483D A US 3791483DA US 3791483 A US3791483 A US 3791483A
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Prior art keywords
housing
sound
sound absorber
partition members
throughflow
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Expired - Lifetime
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US00264209A
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English (en)
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C Vasiljevic
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Individual
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    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/24—Means for preventing or suppressing noise

Definitions

  • ABSTRACT A sound absorber, especially for aerodynamic installations, comprising a tubular-like housing closed at each end by a cover member, each said cover member leaving free a central throughpassage opening.
  • Two dampening systems are housed within the housing, one such dampening system extending as a longitudinal dampening device over the housing inner wall, the other dampening system being formed by partition walls located perpendicular to the throughflow direction and distributed over the length of the housing. These partition walls only cover a part of the internal compartment of the housing left free by the longitudinal dampening device.
  • the present invention relates to a new and improved construction of sound absorber or sound dampening device, especially for aerodynamic installations, and comprises a tubular-like housing closed at each end by a cover member which in each case leaves free a central throughflow opening.
  • Sound absorbers for aerodynamic installations must be designed in consideration of their free throughflow cross-section such that the flow velocity and pressure drop are as small as possible.
  • the effective dampening region should begin at approximately 200 Hz and should be very wide-band.
  • the sheet metal spiral is effective at the high-frequency region, namely by impeding the so-called sound radiation.
  • it has the'additional drawback that with respect to the air throughflow there is produced a superimposed spin flow and a considerable additional pressure loss.
  • Another and more specific object of the present invention relates to a new and improved construction of sound absorber which avoids the drawbacks of the prior art sound absorbers and, in particular, aims at the provision of special installations for the interior of the sound absorber which are capable of realizing up to the middle-frequency range, that is up to the third octave band a high sound dampening action independent of the dampening devices along the periphery and extensively independent of the parameter U/F.
  • Yet a further significant object of the present invention relates to a novel construction of sound absorber, the frequency range of which encompasses higher sound absorption of at least five octaves.
  • the invention contemplates accomodating two dampening systems internally of the sound absorber housing.
  • One of the dampening systems extends in the form of a longitudinal dampening device over the inner wall of the housing and the other dampening system is formed by partition walls arranged perpendicular to the direction of throughflow and distributed over the length of the housing.- The partition walls only cover a portion of the internal compartment of the housing which is left free by the longitudinal dampening device.
  • both dampening systems are constructed according to the principle of a resona tor.
  • the partition walls distributed .over the length of the housing are arranged at the same spacing y from one another.
  • the housing cross-section which is left free by the partition walls approximately corresponds to the throughflow surface of the connection opening of the sound absorber at the housing covers.
  • the partition walls can be in the form of ring-shaped or annular discs mounted in the housing and which in each instance exhibit an inner throughflow opening, or these partition walls are in the form of surface discs which are arranged at the central axis of the housing and fixed relative to the housing and fixed relative to the housing wall by supports.
  • the partition walls can be interconnected or supported by supports extending through the lengthwise axis of the housing. For each meter of sound absorber at least five such type partition walls can be advantageously employed.
  • partition walls are constructed as ring-shaped discs then there is realized a preferred constructional manifestation of the sound absorber which acoustically strives for a low-pass like resonator dampening action and aerodynamically realizes a very favorable pressure loss.
  • the partition walls are designed as surface discs arranged at the center of the housing, then, the outer diameter thereof should correspond approximately to the inner diameter of the connection openings at the covers; the outer diameter can be however somewhat smaller.
  • partition walls are covered with a sound-absorbing material, for instance mineral wool, foamed plastic, just to mention a few suitable materials.
  • sound-absorbing material for instance mineral wool, foamed plastic, just to mention a few suitable materials.
  • an appropriately arranged inflow lining ' which is located at the forwardmost partition wall.
  • the partition walls can be molded components formed of metal, plastic, especially formed plastics or the like.
  • a further advantage of the invention is realized in that for the construction of the dampening system there are formed resonator inserts fabricated from plastic and which exhibit the shape of a box open at one side with throughpassage openings at the bottom or floor. These resonator inserts are advantageously arranged such that their open side confronts the housing inner wall and the partition walls.
  • a particularly advantageous construction of sound absorber can be realized if the housing inner wall is covered with resonator inserts arranged in a row closely following one another and which are directed inwardly by means of their perforated floor. Moreover, the resonator inserts are covered by a continuous layer of sound-absorbing material (mineral wool) which is retained by a rigid grid, sieve or the like.
  • sound-absorbing material mineral wool
  • the inner dampening system can either consist of partition walls formed or ring-shaped discs and covered with a mineral wool layer, the partition walls merging with the longitudinal dampening device, or there can be used partition walls in the form of circular discs located at the central axis of the sound absorber housing and which, in turn, together with the sound-absorbing'material arranged thereon or therebetween are enclosed by a sieve, grid or the like and supported in the center of the housing by suitable supports, struts or the like.
  • a particularly good effect also can be then realized if the resonator inserts are covered at their open side confronting the inner wall of the housing by a plastic foil or the like. Fabrication of the inventive sound absorber is simplitied in that both dampening systems are manufactured as pre-fabricat'ed units and each for itself or conjointly can be inserted from the head'end into the tubular-like housing.
  • FIG. 6 is a cross-sectional view of the arrangement of FIG. 5, taken substantially along the line VIVI thereof;
  • FIG. 7 is a perspective view of a resonator insert
  • FIG. 8 is a cross-sectional view of the arrangement of FIG. 7, taken substantially along the line VIII-VIII thereof;
  • FIG. 9 is a cross-sectional view of the arrangement of FIG. 7, taken substantially along the line IX-IX thereof;
  • FIG. 10 is a graph explaining the mode of operation of the sound absorber.
  • the inventive sound absorbers or sound-dampening devices generally possess a tubular-like or pipe-like housing 1 which may possess a round, oval or quadrangular cross-section and closed at its ends by the covers or cover members 2 which, in turn, each possess a central throughflow opening 3.
  • Each such throughflow opening 3 can be advantageously provided with a flange 3a for connection to other pipe conduits.
  • a longitudinal dampening device 4 Internally of the housing 1 there is provided a longitudinal dampening device 4 which can be constructed either according to the absorptionprinciple, but most preferably according to the resonator principle.
  • the longitudinal dampening device 4 is covered and supported in the housing 1 at the inside by means of a sieve cylinder or by means of a grid, perforated sheet metal or the like, as generally indicated by reference numeral 5.
  • partition walls 6 are distributively arranged at a uniform spacing from one another throughout the length of housing 1.
  • Each of. these parti tion walls 6 exhibits a central throughflow opening 7 which is approximately equal in surface area to the connection openings 3 at the housing covers 2.
  • the illustrated ring-shaped discs forming such partition walls 6 are provided with flexed or bent portions 8 disposed in the direction of throughflow.
  • the partition walls 6 are covered with a sound-absorbing material 9, for instance mineral wool, at the region of the hollow compartment bounded by the flexed portions 8.
  • the partition walls 6 are advantageously fixedly seated at the sieve or perforated sheet metal member 5. They form together with the longitudinal dampening device 4 an-insert unit which can be pushed into the housing 1 from the head end thereof.
  • What is decisive for the magnitude of the upper boundary frequency of the low-pass like dampening is the magnitude of the partial hollow compartment H between the partition walls in relation to the square of the radius of the throughpassage opening 7.
  • the partition walls are formed by circular discs 11 which are coaxially arranged at the same spacing from one another at the interior of the housing 1 lined with the longitudinal dampening device 4, 5.
  • the discs 11 have marginal flexed portions 13 and are covered with a sound-absorbing material, for instance mineral wool 14, at the side confronting the outlet pr exit, as shown.
  • the discs 11 are retained by means of struts 10 piercingly inserted through the housing 1 and supported at the lateral covers 2.
  • the forwardmost strut 11 is provided with an inflow lining 12 for reducing the pressure loss.
  • the partition walls 6 are covered and connected with one another at the inside by means of a sieve, grid, perforated sheet metal or the like, as generally indicated by the reference character 15.
  • the space between the partition walls 6 can be also filled with a suitable sound-absorbing material 16.
  • resonator inserts 17 In order to ensure for a good dampening action for the longitudinal dampening system there are employed resonator inserts 17, as such have been illustrated in detail in FIGS. 7 to 9.
  • These inserts 17 entirely consist of foamed plastic, such as for instance styropor. They essentially possess a box-like configuration, and compartments are formed by transverse walls 18 and longitudinally extending walls 19 and wherein the floor 21 has a somewhat larger thickness and is equipped with a multiplicity of openings 22 arranged in rows behind and adjacent one another.
  • the resonator inserts 17 are mounted in the housing 1 behind and neighboring one another with their open side facing towards the outside.
  • a cover foil 25 covers the resonator compartments 20 at their open side.
  • the resonator inserts introduced as a lining into the housing 1 are finally covered with a sound-absorbing layer 26 formed of mineral wool or the like and retained by the cylindrical sieve, grid or equivalent structure, generally indicated by reference character 5.
  • FIGS. 5 and 6 there is illustrated an improved version of sound absorber of the type shown in FIG. 2.
  • the longitudinal dampening system is formed by resonator inserts.
  • the inner dampening device consists of ce'ntrally'arranged circular discs 1 1 forming the partition walls, as such have already been used for the embodiment of sound absorber of FIG. 2.
  • the inner sound absorber is enclosed as a unit by a sieve cylinder 27 and is retained by means of the discs 28 at the housing, and specifically at the sieve jacket 15.
  • the inventive constructions of sound absorbers there is realized, among other things, the advantage that with the internally arranged resonator sound can be effectively dampened in a low-pass like manner at least up to the third octave region, that is into the middle-frequency region. Furthermore, by virtue thereof there is realized the very notable advantage that the thickness of the longitudinal dampening device can be generally considerably less than is usually the case. With the special constructional embodiment which contemplates the internal arrangement of the surface discs there is realized the additional advantage that the so-called sound radiation can be almost completely suppressed without additional manufacturing expenditure. As a result there is produced a sound absorber with the important acoustical advantage that in a frequency range of five to six octaves high dampening with approximately constant frequency course of the dampening can be realized.
  • the inner resonator arrangement is designed as an independent insert unit.
  • the graph depicted in FIG. 10 illustrates the throughput dampening mass Db plotted over the frequency f for a tested sound absorber designed according to the invention.
  • a sound absorber especially for aerodynamic installations, comprising a housing having a tubular wall defining a flow passage there-through, said housing including an inlet end and an outlet end, each of said ends being partially closed by covers having throughflow openings defined therein, an outer dampening system defined by a plurality of resonator inserts arranged tightly in a row behind one another and extending longitudinally over the inner surface of said tubular wall, said resonator inserts having an open side and a perforated floor, said open sides facing the inner surface of said wall and said perforated floors facing inwardly of said housing and covered by a continuous layer of sound absorbing material, an inner dampening system disposed coaxially with said other dampening system and partially obstructing said flow passage, said inner dampening system including a plurality of partition members distributed over the length of said housing and having side walls extending transversely of said flow passage and facing said inlet and outlet ends, and sound absorbing material covering said side wall of each of said partition members which faces said outlet
  • each cover has an opening defining a connection opening forming a throughflow area, and wherein the crosssection area of the flow passage left unobstructed by the partition members approximately corresponds to the throughflow area of the connection opening at the housing covers.
  • partition members comprise a number of ringshaped discs inserted into the housing, each of said ring-shaped discs having an internal throughflow open- 4.
  • partition members comprises surface discs which are arranged at the central axis of the housing, and support means for supporting such surface discs relative to the wall of the housing.
  • partition members form circular discs lowherein the partition members are in the form of ringcated substantially at the axial center of the sound absorber housing, means for enclosing said circular discs together with the sound-absorbing material, and support means for securing the circular discs at the center of the housing.
  • both dampening systems are constructed as pre-fabricated units each of which can be individually or collectively inserted from one end of the housing into such housing.
  • each of said resonator inserts is defined by a box, and wherein said open side and said perforated floor comprise opposite sides of said bort.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Exhaust Silencers (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
US00264209A 1971-06-24 1972-06-19 Sound absorber Expired - Lifetime US3791483A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2131410A DE2131410C3 (de) 1971-06-24 1971-06-24 Schalldämpfer, insbesondere für lufttechnische Anlagen

Publications (1)

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US3791483A true US3791483A (en) 1974-02-12

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US00264209A Expired - Lifetime US3791483A (en) 1971-06-24 1972-06-19 Sound absorber

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US (1) US3791483A (enrdf_load_stackoverflow)
AT (1) AT320223B (enrdf_load_stackoverflow)
CH (1) CH550964A (enrdf_load_stackoverflow)
DE (1) DE2131410C3 (enrdf_load_stackoverflow)
FR (1) FR2143276B1 (enrdf_load_stackoverflow)
GB (1) GB1373292A (enrdf_load_stackoverflow)
IT (1) IT956565B (enrdf_load_stackoverflow)
NL (1) NL7208711A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955643A (en) * 1974-07-03 1976-05-11 Brunswick Corporation Free flow sound attenuating device and method of making
US5356264A (en) * 1991-12-26 1994-10-18 General Electric Company Viscoelastic vibration damper for engine struts
US20040163887A1 (en) * 2003-02-25 2004-08-26 Ziehl John C. Exhaust silencer system
EP1580494A1 (en) * 2004-03-24 2005-09-28 Uponor Innovation Ab Silencer for ventilating duct
US20060157295A1 (en) * 2005-01-14 2006-07-20 Ziehl John C Combination muffler and spark arrester
US20060180388A1 (en) * 2005-02-14 2006-08-17 Honeywell International, Inc. Eccentric exhaust muffler for use with auxiliary power units
US20070256889A1 (en) * 2006-05-03 2007-11-08 Jia Yu Sound-absorbing exhaust nozzle center plug
US20080080977A1 (en) * 2006-09-29 2008-04-03 Laurent Bonnet Wind turbine rotor blade with acoustic lining
US20110186378A1 (en) * 2008-09-22 2011-08-04 Stebro Psd Ltd. Open chamber exhaust mufflers and related methods of manufacture and use
US8931591B2 (en) * 2012-09-28 2015-01-13 Fisher Controls International Llc Simplified modal attenuator
US9376946B1 (en) 2015-04-02 2016-06-28 Fisher Controls International Llc Modal attenuator
US20190120414A1 (en) * 2017-10-23 2019-04-25 Hamilton Sundstrand Corporation Duct assembly having internal noise reduction features, thermal insulation and leak detection
US20210080151A1 (en) * 2017-10-11 2021-03-18 Carrier Corporation Muffler with metallic meshed rings
CN113160785A (zh) * 2020-01-07 2021-07-23 尤姆弗泰克有限公司 用于降低空气传声和固体传声的设备

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2498793A1 (fr) * 1981-01-29 1982-07-30 Snecma Garniture insonorisante pour conduit de gaz notamment pour veine de soufflante de turboreacteur et outillage pour sa fabrication
DE9317376U1 (de) * 1993-11-12 1994-02-03 Wilms, Peter, 45731 Waltrop Vorrichtung zur Schalldämpfung an einem Silofahrzeug
AT408676B (de) * 1999-12-07 2002-02-25 Kamleithner Maly Uta Mag Ing Lüftungsrohr, insbesondere zuluftrohr

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1909511A (en) * 1929-11-01 1933-05-16 Gen Motors Res Corp Muffler
FR782848A (fr) * 1934-03-03 1935-06-12 Bronzavia Sa Silencieux pour moteurs à explosions et autres applications
US2326612A (en) * 1940-11-25 1943-08-10 Maxim Silencer Co Silencer
US2514996A (en) * 1948-07-28 1950-07-11 Jr Charles H Faust Flash eliminator and silencer for firearms
US2989136A (en) * 1959-04-14 1961-06-20 Wohlberg George Sound attenuation
US3132717A (en) * 1955-05-27 1964-05-12 Bolt Beranek & Newman Acoustically absorbent conduit
US3141520A (en) * 1960-01-14 1964-07-21 Grunzweig And Hartmann A G Sound absorber for gas conduits
US3142354A (en) * 1960-08-09 1964-07-28 Gutehoffnungshuette Sterkrade Sound absorption device and method of manufacture

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1909511A (en) * 1929-11-01 1933-05-16 Gen Motors Res Corp Muffler
FR782848A (fr) * 1934-03-03 1935-06-12 Bronzavia Sa Silencieux pour moteurs à explosions et autres applications
US2326612A (en) * 1940-11-25 1943-08-10 Maxim Silencer Co Silencer
US2514996A (en) * 1948-07-28 1950-07-11 Jr Charles H Faust Flash eliminator and silencer for firearms
US3132717A (en) * 1955-05-27 1964-05-12 Bolt Beranek & Newman Acoustically absorbent conduit
US2989136A (en) * 1959-04-14 1961-06-20 Wohlberg George Sound attenuation
US3141520A (en) * 1960-01-14 1964-07-21 Grunzweig And Hartmann A G Sound absorber for gas conduits
US3142354A (en) * 1960-08-09 1964-07-28 Gutehoffnungshuette Sterkrade Sound absorption device and method of manufacture

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955643A (en) * 1974-07-03 1976-05-11 Brunswick Corporation Free flow sound attenuating device and method of making
US5356264A (en) * 1991-12-26 1994-10-18 General Electric Company Viscoelastic vibration damper for engine struts
US20040163887A1 (en) * 2003-02-25 2004-08-26 Ziehl John C. Exhaust silencer system
US6868939B2 (en) 2003-02-25 2005-03-22 Vicious Cycle Performance, Inc. Exhaust silencer system
EP1580494A1 (en) * 2004-03-24 2005-09-28 Uponor Innovation Ab Silencer for ventilating duct
US20060157295A1 (en) * 2005-01-14 2006-07-20 Ziehl John C Combination muffler and spark arrester
US7367424B2 (en) * 2005-02-14 2008-05-06 Honeywell International, Inc. Eccentric exhaust muffler for use with auxiliary power units
US20060180388A1 (en) * 2005-02-14 2006-08-17 Honeywell International, Inc. Eccentric exhaust muffler for use with auxiliary power units
US7784283B2 (en) * 2006-05-03 2010-08-31 Rohr, Inc. Sound-absorbing exhaust nozzle center plug
US20070256889A1 (en) * 2006-05-03 2007-11-08 Jia Yu Sound-absorbing exhaust nozzle center plug
US20080080977A1 (en) * 2006-09-29 2008-04-03 Laurent Bonnet Wind turbine rotor blade with acoustic lining
US7959412B2 (en) * 2006-09-29 2011-06-14 General Electric Company Wind turbine rotor blade with acoustic lining
CN101153578B (zh) * 2006-09-29 2013-03-27 通用电气公司 具有声学衬垫的风轮机转子叶片
US20110186378A1 (en) * 2008-09-22 2011-08-04 Stebro Psd Ltd. Open chamber exhaust mufflers and related methods of manufacture and use
US8931591B2 (en) * 2012-09-28 2015-01-13 Fisher Controls International Llc Simplified modal attenuator
US9376946B1 (en) 2015-04-02 2016-06-28 Fisher Controls International Llc Modal attenuator
US20210080151A1 (en) * 2017-10-11 2021-03-18 Carrier Corporation Muffler with metallic meshed rings
US11808490B2 (en) * 2017-10-11 2023-11-07 Carrier Corporation Muffler with metallic meshed rings
US12050032B2 (en) 2017-10-11 2024-07-30 Carrier Corporation Muffler with metallic meshed rings
US20190120414A1 (en) * 2017-10-23 2019-04-25 Hamilton Sundstrand Corporation Duct assembly having internal noise reduction features, thermal insulation and leak detection
CN113160785A (zh) * 2020-01-07 2021-07-23 尤姆弗泰克有限公司 用于降低空气传声和固体传声的设备
US11727911B2 (en) 2020-01-07 2023-08-15 Umfotec Gmbh Device for reducing airborne and structure-borne sound
CN113160785B (zh) * 2020-01-07 2024-02-23 尤姆弗泰克有限公司 用于降低空气传声和固体传声的设备

Also Published As

Publication number Publication date
AT320223B (de) 1975-01-27
CH550964A (de) 1974-06-28
FR2143276A1 (enrdf_load_stackoverflow) 1973-02-02
DE2131410C3 (de) 1975-04-30
GB1373292A (en) 1974-11-06
IT956565B (it) 1973-10-10
DE2131410A1 (de) 1973-01-11
FR2143276B1 (enrdf_load_stackoverflow) 1973-07-13
NL7208711A (enrdf_load_stackoverflow) 1972-12-28
DE2131410B2 (de) 1974-09-12

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