RU2648098C1 - Method of sound absorption with resonant inserts - Google Patents

Method of sound absorption with resonant inserts Download PDF

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Publication number
RU2648098C1
RU2648098C1 RU2017107044A RU2017107044A RU2648098C1 RU 2648098 C1 RU2648098 C1 RU 2648098C1 RU 2017107044 A RU2017107044 A RU 2017107044A RU 2017107044 A RU2017107044 A RU 2017107044A RU 2648098 C1 RU2648098 C1 RU 2648098C1
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Prior art keywords
sound
perforated
absorbing
resonant
sections
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RU2017107044A
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Russian (ru)
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Олег Савельевич Кочетов
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Олег Савельевич Кочетов
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    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84Sound-absorbing elements
    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10KSOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00Methods 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
    • G10K11/16Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84Sound-absorbing elements
    • E04B2001/8423Tray or frame type panels or blocks, with or without acoustical filling
    • E04B2001/8433Tray or frame type panels or blocks, with or without acoustical filling with holes in their face
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82Heat, sound or noise insulation, absorption, or reflection . Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84Sound-absorbing elements
    • E04B2001/8457Solid slabs or blocks
    • E04B2001/8476Solid slabs or blocks with acoustical cavities, with or without acoustical filling
    • E04B2001/848Solid slabs or blocks with acoustical cavities, with or without acoustical filling the cavities opening onto the face of the element
    • E04B2001/8485Solid slabs or blocks with acoustical cavities, with or without acoustical filling the cavities opening onto the face of the element the opening being restricted, e.g. forming Helmoltz resonators

Abstract

FIELD: acoustics.
SUBSTANCE: invention relates to industrial acoustics and can be used for machine drive noise reduction, lining of manufacturing facilities and in other sound-absorbing structures. In the method of sound absorption with resonant inserts between the smooth and perforated surfaces of the sound-absorbing element, a layer of sound-absorbing material of complex shape is placed. Layer of complex shape is made in the form of alternating solid sections and hollow sections, the hollow sections is in the form of prismatic surfaces having, in the section parallel to drawing plane, parallelogram shape, and the inner surfaces are made in the form of a toothed structure. Tops of the teeth face the prismatic surfaces, and the edges of the prismatic surfaces are fixed respectively on the smooth and perforated surfaces. Cavities of the hollow sections, formed by prismatic surfaces, are filled with a sound absorber, and between the smooth surface and continuous sections of the layer of sound-absorbing material of complex shape, as well as between the perforated surface and solid sections, there are resonant plates with resonant inserts performing the functions of the neck of Helmholtz resonators. Resonance plate with resonant inserts placed between the perforated surface and the solid sections of the layer of sound absorbing material of complex shape, are box-shaped, the upper surface of which is adjacent to the solid sections of the layer of sound-absorbing material, and the angles of the side faces are fixed to the perforated surface. Its lower surface facing the perforated surface is set in relation to it with a gap necessary for placing resonant inserts that perform the functions of throats of the Helmholtz resonators. Parameters of the resonant inserts are calculated by certain mathematical dependencies.
EFFECT: technical result consists in increasing the efficiency of sound attenuation and the reliability of the structure as a whole.
1 cl, 1 dwg

Description

The invention relates to industrial acoustics and can be used to reduce the noise of the drive machines, facing industrial premises and other sound-absorbing structures.
The closest technical solution to the technical nature and the achieved result is a sound-absorbing element used as a facing of industrial premises, known from the RF patent No. 2463412 (prototype).
The disadvantage of the technical solution adopted as a prototype is the relatively low noise reduction due to the presence of voids between the layers, where there is no sound absorption between the layers of the sound absorber.
The technical result is an increase in the efficiency of sound attenuation and reliability of the structure as a whole.
This is achieved by the fact that in the method of sound absorption with resonant inserts, which consists in the fact that between the smooth and perforated surfaces of the sound-absorbing element there is a layer of sound-absorbing material of complex shape, the layer of complex shape is made in the form of alternating solid sections and hollow sections, and hollow sections are made in the form prismatic surfaces having a section parallel to the plane of the drawing, the shape of a parallelogram, and the inner surfaces are in the form of a gear structure, with in this case, the tooth peaks are turned inside the prismatic surfaces, and the edges of the prismatic surfaces are fixed respectively on the smooth and perforated surfaces, the cavities of the hollow sections formed by the prismatic surfaces are filled with a sound absorber, and between the smooth surface and the solid sections of the layer of sound-absorbing material of complex shape, and also between the perforated surface and solid sections have resonant plates with resonant inserts that perform the functions of the necks Helmholtz resonators.
The drawing shows a diagram of a sound-absorbing element with resonant inserts for implementing the sound absorption method.
The sound-absorbing element for implementing the sound absorption method with resonant inserts contains a smooth 1 and perforated 2 surfaces, between which there is a layer of sound-absorbing material of complex shape, which is an alternation of solid sections 3 and hollow sections 5, and the hollow sections 5 are formed by prismatic surfaces having a parallel section in cross section the plane of the drawing, the shape of a parallelogram, the inner surfaces of which have a gear structure 6, or wavy, or a surface with a spherical eskimi surfaces (not shown in the drawing). The cavities 4 formed by the smooth 1 and perforated 2 surfaces, between which a layer of sound-absorbing material of complex shape is located, are filled with a sound absorber. In this case, the tops of the teeth face the inside of the prismatic surfaces, and the edges of the prismatic surfaces are fixed respectively on a smooth 1 and perforated 2 surfaces. The cavities 7 of the hollow sections 5 formed by prismatic surfaces are filled with construction foam. Between a smooth 1 surface and solid sections 3 of a layer of sound-absorbing material of complex shape, as well as between a perforated 2 surface and solid sections 3, there are resonant plates 8 and 9 with resonant inserts 10 that serve as the neck of the Helmholtz resonators.
As a sound-absorbing material of the first, more rigid layer, a material based on aluminum-containing alloys was used, followed by filling them with titanium hydride or air with a density in the range of 0.5 ... 0.9 kg / m 3 with the following strength properties: compressive strength in the range of 5 ... 10 MPa, bending strength in the range of 10 ... 20 MPa, for example foam aluminum.
As a sound-absorbing material of the second, softer layer, rockwool-type mineral wool or URSA-type mineral wool, or P-75-type basalt wool, or glass wool with glass-fiber lining, or foamed polymer, such as polyethylene or polypropylene.
The material of the perforated surface is made of solid, decorative vibration-damping materials, for example, agate, antivibrate, and shvim plastic compounds, and the inner surface of the perforated surface facing the sound-absorbing structure is lined with an acoustically transparent material, for example, fiberglass type EZ- 100 or polymer type "Poviden."
Sound-absorbing element for implementing the method of sound absorption with resonant inserts works as follows.
Sound energy, passing through a layer of perforated surface 2 and a combined sound-absorbing layer of complex shape, decreases, since the transition of sound energy into thermal energy (dissipation, energy dissipation) occurs, i.e. in the pores of the sound absorber, representing the Helmholtz resonator model, there are energy losses due to friction, which fluctuates with the excitation frequency of the mass of air in the mouth of the resonator, against the wall of the neck itself, which has the form of a branched network of micropores of the sound absorber. Between a smooth 1 surface and solid sections 3 of a layer of sound-absorbing material of complex shape, as well as between a perforated 2 surface and solid sections 3 there are resonant plates 8 and 9 with resonant inserts 10, which serve as the neck of Helmholtz resonators.
Resonance holes 10 (inserts) located in the resonant plates 8 and 9, serve as the neck of the Helmholtz resonators, the frequency band of the damping of sound energy of which is determined by the diameter and number of resonant holes 10.
It is possible that the resonance plate 9 with resonant inserts 12, 13, 14, located between the perforated surface 2 and the continuous sections 3 of the layer of sound-absorbing material of complex shape, is made box-shaped, the upper surface of which is adjacent to the solid sections 3 of the layer of sound-absorbing material, side faces are attached corners 11 to the perforated surface 2, and its lower surface, facing the side of the perforated surface 2, is set relative to it with a gap necessary to accommodate p resonant inserts 12, 13, 14, performing the functions of the necks of the Helmholtz resonators.
Observations showed that the noise spectrum of a conventional fan has a pronounced tonal character, and the noise level in this case exceeds the sanitary standards by about 5-9 dB, i.e. a conventional active-type muffler cannot cope with a high-frequency pulse of sound, while the noise spectrum has a pronounced tonal character. To solve the problem of increasing the efficiency of an aerodynamic noise silencer, a circuit of a resonant silencer integrated in a sound-absorbing element is proposed.
The physical effect of the operation of such a silencer is based on the fact that, when the natural and exciting frequencies coincide resonantly, the amplitude of the air velocity in the mouth of the resonator is significant and, in the presence of friction, the energy loss of the incident sound wave increases, and the Helmholtz resonator effect is realized.
The resonance plate 9 with resonant inserts 12, 13, 14, built into the sound-absorbing element, located between the perforated surface 2 and the continuous sections 3 of the layer of sound-absorbing material of complex shape and made box-shaped, is a materialized object of the Helmholtz resonator.
The sound absorption method with resonant inserts is as follows.
Between the smooth and perforated surfaces of the sound-absorbing element, there is a layer of sound-absorbing material of complex shape, which is made in the form of alternating solid sections and hollow sections, and the hollow sections are made in the form of prismatic surfaces having a parallelogram shape in cross section parallel to the drawing plane, and the inner surfaces are in the form of a gear structure, with the tops of the teeth facing the inside of the prismatic surfaces, and fixing the edges of the prismatic surfaces respectively, on smooth and perforated surfaces, the cavities of the hollow sections formed by the prismatic surfaces are filled with a sound absorber, and between the smooth surface and the solid sections of the layer of sound-absorbing material of complex shape, as well as between the perforated surface and the solid sections there are resonant plates with resonant inserts that perform the functions the neck of the Helmholtz resonators.
The maximum energy absorption for a single resonator will be observed at the resonant frequency:
Figure 00000001
where k p is the conductivity of the holes in the resonant inserts 12, 13, 14 connecting them to the resonant plate 9 having an analog resonator chamber with a volume of V p (m 3 ); V p is the volume of the resonator chamber (m 3 ); s - the speed of sound in air, taken in the calculations equal to 340 m / s.
Figure 00000002
where n is the number of holes in the insert; S o - the area of one hole with a diameter of do, m 2 ;
l of holes - hole depth, m.
Given the volume Vp of the resonator cavity, according to the dimensions of the resonant plate 9, as well as the resonant frequency f p of the "blade" pulsed noise source, for example a fan, we determine the conductivity of the holes:
Figure 00000003
and their number
Figure 00000004
The noise reduction efficiency of this muffler will be determined by the formula:
Figure 00000005
where F is the cross-sectional area of the resonance plate 9, m 2 ; f, f p - exciting and natural frequencies of the Helmholtz resonator.

Claims (12)

  1. A method of sound absorption with resonant inserts, namely, that between the smooth and perforated surfaces of the sound absorbing element there is a layer of sound-absorbing material of complex shape, the layer of complex shape is made in the form of alternating solid sections and hollow sections, and hollow sections are made in the form of prismatic surfaces having a section parallel to the plane of the drawing, the shape of the parallelogram, and the inner surfaces are in the form of a gear structure, with the tops of the teeth facing inside the prismatic surfaces, and the edges of the prismatic surfaces are fixed respectively on smooth and perforated surfaces, and the cavities of the hollow sections formed by the prismatic surfaces are filled with a sound absorber, and between a smooth surface and continuous sections of a layer of sound-absorbing material of complex shape, as well as between a perforated surface and continuous sections have resonant plates with resonant inserts that serve as the neck of the Helmholtz resonators characterized in that the resonant plate with resonant inserts located between the perforated surface and the solid sections of the layer of sound-absorbing material of complex shape, perform box-shaped, the upper surface of which is adjacent to the solid sections of the layer of sound-absorbing material, and the side faces are attached with corners to the perforated surface, while its lower surface, facing the perforated surface, is set in relation to it with a gap necessary to accommodate the resonance antenna inserts that serve as the neck of the Helmholtz resonators, and the parameters of the resonant inserts are calculated according to the following relationships:
  2. the maximum energy absorption for a single resonator will be observed at the resonant frequency:
  3. Figure 00000006
  4. where k p is the conductivity of the holes in the resonant inserts 12, 13, 14 connecting them to the resonant plate 9 having an analog resonator chamber with a volume of Vp (m 3 ); V p is the volume of the resonator chamber (m 3 ); s is the speed of sound in air, taken in the calculations equal to 340 m / s,
  5. Figure 00000007
  6. where n is the number of holes in the insert; S o - the area of one hole with a diameter of do, m 2 ; l of holes - hole depth, m,
  7. setting the volume volume V p of the resonator cavity, according to the overall dimensions of the resonance plate 9, as well as the resonant frequency f p of the "blade" pulse noise source, for example a fan, determine the conductivity of the holes:
  8. Figure 00000008
  9. Figure 00000009
    ,
  10. the noise reduction efficiency of this muffler will be determined by the formula:
  11. Figure 00000010
  12. where F is the cross-sectional area of the resonance plate 9, m 2 ; f, f p - exciting and natural frequencies of the Helmholtz resonator.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3337090A1 (en) * 1983-10-12 1985-05-02 Martin Holzlehner Suspension element for sliding ceilings
RU2463412C2 (en) * 2010-08-20 2012-10-10 Олег Савельевич Кочетов Sound-absorbing structure of production room
RU2531152C1 (en) * 2013-08-19 2014-10-20 Олег Савельевич Кочетов Kochstar type single-piece sound absorber
RU2561389C1 (en) * 2014-02-17 2015-08-27 Олег Савельевич Кочетов Sound-absorbing structure
RU2613061C1 (en) * 2016-01-18 2017-03-15 Олег Савельевич Кочетов Sound-absorbing element of kochetov with resonant inserts

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3337090A1 (en) * 1983-10-12 1985-05-02 Martin Holzlehner Suspension element for sliding ceilings
RU2463412C2 (en) * 2010-08-20 2012-10-10 Олег Савельевич Кочетов Sound-absorbing structure of production room
RU2531152C1 (en) * 2013-08-19 2014-10-20 Олег Савельевич Кочетов Kochstar type single-piece sound absorber
RU2561389C1 (en) * 2014-02-17 2015-08-27 Олег Савельевич Кочетов Sound-absorbing structure
RU2613061C1 (en) * 2016-01-18 2017-03-15 Олег Савельевич Кочетов Sound-absorbing element of kochetov with resonant inserts

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
БОГОЛЕПОВ И.И. Промышленная звукоизоляция. Л.: Судостроение, 1986, всего 368 с., с.290-309. *

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