CA2215761A1 - Acoustical dampening system - Google Patents
Acoustical dampening system Download PDFInfo
- Publication number
- CA2215761A1 CA2215761A1 CA 2215761 CA2215761A CA2215761A1 CA 2215761 A1 CA2215761 A1 CA 2215761A1 CA 2215761 CA2215761 CA 2215761 CA 2215761 A CA2215761 A CA 2215761A CA 2215761 A1 CA2215761 A1 CA 2215761A1
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- Canada
- Prior art keywords
- noise suppression
- noise
- fan
- inlet
- perforated
- Prior art date
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- Abandoned
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- 230000001629 suppression Effects 0.000 claims abstract description 101
- 238000001816 cooling Methods 0.000 claims abstract description 53
- 238000009413 insulation Methods 0.000 claims description 28
- 239000011800 void material Substances 0.000 claims description 6
- 238000009434 installation Methods 0.000 description 5
- 239000002184 metal Substances 0.000 description 4
- 230000002238 attenuated effect Effects 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
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- 238000010586 diagram Methods 0.000 description 2
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- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
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- 238000005057 refrigeration Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
Classifications
-
- 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
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/62—Insulation or other protection; Elements or use of specified material therefor
- E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
- E04B1/82—Heat, 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
- E04B1/8209—Heat, 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 sound absorbing devices
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/62—Insulation or other protection; Elements or use of specified material therefor
- E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
- E04B1/82—Heat, 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
- E04B1/8218—Heat, 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 soundproof enclosures
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B9/00—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation
- E04B9/001—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation characterised by provisions for heat or sound insulation
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B9/00—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation
- E04B9/02—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation having means for ventilation or vapour discharge
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B9/00—Ceilings; Construction of ceilings, e.g. false ceilings; Ceiling construction with regard to insulation
- E04B9/34—Grid-like or open-work ceilings, e.g. lattice type box-like modules, acoustic baffles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/12—Sound
Abstract
The present invention relates to an apparatus for noise suppression. In particular, the apparatus includes an acoustical dampening system including a planar acoustical panel in spaced relation with a plurality of triangular baffles. The system is effective in noise suppression in a wide range of frequencies. The invention also provides an effective enclosure design for noise suppression in vertical and horizontal cooling systems.
Description
CA 0221~761 1997-09-17 Acoustical Dampening System FIELD OF THE INVENTION
The present invention relates to an apparatus for noise suppression. In particular, the apparatus includes an acoustical dampening system which is effective in noise suppression in a wide range of frequencies. The invention also provides an effective enclosure design for noise suppression in vertical and horizontal cooling systems.
BACKGROUND OF THE INVENTION
Process coolers in the oil, gas, petrochemical and other related industries require substantial cooling of various liquid substances. Typically, hot substances are pumped into a header, which is connected to a series of cooling coils with cooling fins, located within a chamber through which high volumes of air are pumped through by rotating fans. The forced air is drafted past the cooling coils and fins thereby transferring heat from the inside of the pipes. In many installations, the air-flow required for the industrial process is very high and necessitates large diameter fans, often in the range of 13 feet, with air flows in the order of 250,000 cubic feet of air per minute passing through the fan systems.
These cooling systems may produce very high noise levels from the blades of the fan, the air flowing past the coiling cools and fins, belts and/or gears, motors and any noise transmitted through steel structures and/or from fluids flowing through the pipes. Noises generated within a cooling system will escape with both the inflow and outflow portions of the cooling system's air flow and may often exceed 100 dBA, which is well in excess of acceptable noise level standards imposed in many regions. Jurisdictional regulations often require that the average noise level around such a cooling installation does not exceed 40 dBA at night and 50 dBA during the day. Accordingly, there has been a need for acoustical chambers which can effectively attenuate the noise levels while also providing effective operation of the cooling system and, in particular, without creating excessive back pressure on the cooling system.
In the design of an acoustical chamber which is effective in meeting the design goals of CA 0221~761 1997-09-17 noise attenuation while maintaining normal operation of a cooling system, there has been a need to develop an effective acoustical dampening system which can be readily formed into an enclosure. In particular, there has been a need for an acoustical dampening system having a baffle system in which noise in a wide range of frequencies can be effectively attenuated and in particular is effective in attenuation of low frequency sound waves using 1/4 wave clipping functions.
In addition, the application of forced-draft horizontal and~ vertical coiling coil systems varies in the market with such equipment serving a variety of applications, including but not limited to the oil, gas, petrochemical, refrigeration, and air-conditioning industries. In many of these applications, excessive noise levels may be produced in the vicinity of cooling machinery which may be hazardous to workers or above legal limits.
In a typical cooling system, the majority of the noise at either the inlet or outlet of the cooling system is projected either up or outwards. Furthermore, noise is typically generated in a range of frequencies wherein the low frequency bands (16-31.5 Hz) being the most difficult to attenuate.
Accordingly, there has been a need for a design of an acoustical chamber wherein the majority of upwardly or outwardly projected noise is attenuated within a u-shaped trap. As well, there has been a need for a design of acoustical chamber wherein the suppression of specific low frequency noise is designed into the chamber by strategic designing the depth or height of the chamber from the source noise to utilize 1/4 wave clipping functions so that specific noise frequencies cannot be developed. For example, 31 Hz band sound will have a wavelength of 10.7 meters with the 1/4 wave 2.6 meters in length. Accordingly, there has been a need for a system of baffles to weave the low frequency sound wave into a sound trap wherein the full length of sound wave cannot fully develop.
. .
Specifically, there has been a need for an acoustical dampening system having a system of triangular baffles and adjacent planar acoustical panels having exposed acoustical insulation providing an effective trapping system for a wide range of noise frequencies.
CA 0221~761 1997-09-17 A review of the prior art has revealed a number of references related to acoustical dampening but none which specifically teach the structure of the present application, nor the use of same to create an acoustical chamber in and around cooling coils.
For example, US Patent 5,317,113 teaches a wall and triangular baffle system. However, this patent does not teach an acoustical dampening system in which the base surface of the triangular baffle is reflective nor 1/4 wave clipping functionality. Still further, this patent does not teach an acoustical chamber with managed air i~ow through it with noisesuppression.
US Patent 5,332,972 teaches a noise reduction unit for gas compressors which includes a plurality of baffles for reducing noise around the inlet. This patent does not teach a noise suppression system having a triangular baffle system.
Other patents such as US Patent 4,971,850, US Patent 2,659,808, US Patent 5,304,750, US Patent 4,605,088, US Patent 3,068,535 and US Patent 4,298,090 each teach various acoustical dampening systems but none are directed to the concept of managed sound attenuation in conjunction with managed air flow.
SUMMARY OF THE INVENTION
In accordance with the invention, an acoustical dampening system is provided, the acoustical dampening system comprising:
an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation;
a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first~ second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation.
CA 0221~761 1997-09-17 In further embodiments, the first, second and third sides of the triangular baffles have a length, d, which defines a equilateral triangle, each triangular baffle is spaced from the planar surface by a distance of approximately d/2 and/or are spaced from one another by a distance of approximately d. In a further embodiment, the perforated surfaces of the planar surface and second and third surfaces have a void fraction of 33-51%.
The apparatus may further comprise a u-shaped chamber adjacent the ends of the triangular baffles, the u-shaped chamber having a perforated outer surface exposing underlying acoustical insulation.
In a specific application, a noise suppression system is provided in a horizontal cooling system having a fan rotating about a vertical axis for suppressing noise around the horizontal cooling system, the noise suppression system comprising:
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight beneath the fan, the first inlet noise suppression medium including vertical acoustical panels outside and below the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight above and outside the fan, the second inlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, eachtriangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and below the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical CA 0221~761 1997-09-17 insulation below the fan and outside the first noise suppression medium.
In a further embodiment, an outlet noise suppression system is also provided including a first outlet noise suppression medium for suppressing noise in direct line-of-sight above the fan, the first outlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generallyparallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a second outlet noise suppression medium for suppressing noise including at least one u-shaped chamber adjacent and outside the triangular baffles; and, a third outlet noise suppression medium for a third inlet noise suppression medium for suppressing noise below the second outlet noise suppression medium, the third outlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
An inlet and o'utlet noise suppression system may also be provided for vertical cooling systems.
CA 0221~761 1997-09-17 BRIEFDESCRIPTION OF THE DRA WINGS
These and other features of the invention will be more apparent from the following description in which reference is made to the appended drawings wherein:
Figure 1 is a schematic perspective diagram of an acoustical dampening system inaccordance with the invention; ~
Figurc 2 is a schematic perspective diagram of a triangular baffle in accordance with the mventlon;
Figure 3 is an end view of a horizontal cooling system and acoustical dampening system in accordance with the invention;
Figure 4 is a partial cross-sectional view of an inlet noise suppression system for a horizontal cooling system in accordance with the invention;
Figure 5 is a schematic side view of the inlet and outlet noise suppression systems of a horizontal cooling system in accordance with the invention;
Figure 6 is a plan view of an inlet noise suppression systems of a vertical cooling system in accordance with the invention;
Figure 7 is a side view of an outlet noise suppression systems of a vertical cooling system in accordance with the invention;
Figure 8 is a side view of a typical vertical cooling system including an inlet noise suppression system and an outlet noise suppression system in accordance with the mventlon.
CA 0221~761 1997-09-17 DETAILED DESCRIPTION OF THE INVENTION
With reference to Figure 1, an acoustical dampening system is described. The system 10 generally includes a flat planar surface 12 and a plurality of acoustical baffles 14 adjacent the planar surface 12. As a result of the design of the planar surface 12 and baffles 14, their relative dimensions and materials of construction, the combination is particularly effective in attenuating or choking noise when installed around noisy industrial machinery having large fans. Furthermore, the construction the acoustical dampening system 10 has a high level of structural strength thus enhancing the installation of the acoustical dampening system 10 as a modular component of a noise dampening enclosure.
The planar surface 12 includes an outer surface 12a which partially exposes an underlying layer of acoustical insulation 12b. Thus, the outer surface 12 is preferably fabricated with a plurality of evenly spaced openings 12c, as shown partially in Figure 1. The evenly spaced openings 12c are typically circular and define a void fraction. The void fraction of the planar surface is preferably in the order of 33-51%. The outer or back surface is also preferably fabricated from a rigid and sound-reflective material such as galvanized sheet metal to also provide structural integrity to the planar surface 12.
Each triangular baffle 14 of the plurality of triangular baffles is also fabricated to have sufficient structural strength to span typical construction distances. Each baffle 14 has a cross-section of an equilateral triangle with the base surface 14a parallel in orientation to the planar su*ace 12. The base surface 14a is non-porous. The two outwardly projecting surfaces 14b and 14c are porous having a void fraction in the range of 33-51% and also expose underlying acoustical insulation 14d as described for the planar surface 12.
In accordance with the invention, it is preferred that the length of each side of the triangular baffle 14 of the acoustical dampening system has a length d, where d is any reasonable length as would be understood for a typical installation. In a typical in~t~ tion, in and around a cooling system, d would be in the range of 1 foot. Each adjacent baffle 14 is spaced from one another by a distance d and the base surface 14a is spaced from the CA 0221~761 1997-09-17 planar surface 12 by a distance d/2.
The outer surfaces of the baffles 14 are preferably fabricated from galvanized sheet metal for its reflective and structural properties as well as for cost considerations.
Suitable acoustical insulation 12b and 14d for the underlying layers of the planar surface 12 and triangular baffles 14 are well known to those skilled in the art and may be chosen, for example, from materials such as FIBREX 1240 (density of 4 pounds per cubic foot) and FIBREX 1280 (density of 8 pounds per cubic foot).
In use, noise which is directed into the noise suppression system 10 will either hit the perforated faces 14b andl4c of the baffle 14, where a proportion of the sound energy will be absorbed and a majority of the rem~ining noise will be reflected against the perforated acoustical surface 12, or it will be driven between the baffles 14 and hit the acoustical surface 12 directly (whereby, again, some of the noise energy will be absorbed). Of the noise hitting the acoustical surface 12, some of the noise energy will be absorbed by the surface 12 with the remainder reflecting. A proportion of the reflected noise will strike the back of the baffle 14a and reflect back to surface 12 in a relentless ricochet pattern.
The acoustical dampening system 10 is particularly effective in dampening noise when forming a component of an enclosure around a cooling system 20 as shown in Figures 3-5.
With reference to Figures 3-5, a horizontal cooling tower includes a horizontal fan 22 which is rotated about a vertical axis for forcing air past cooling tubes 24. The cooling system is elevated above ground level 26 and is supported on a foundation 28. Appropriate structural supports are provided to support and define both an inlet charnber 30 and an outlet chamber 32. The inlet chamber 30 has an inlet noise suppression system and the outlet chamber has an outlet noise suppression system. As shown in Figures 3-5, outside air is drawn into the cooling system 20 through the inlet chamber 30, through the fan 22 and upwardly through the outlet charnber 32.
CA 0221~761 1997-09-17 Within the inlet chamber 30, a first inlet noise suppression system is provided to receive and attenuate noise in direct line of sight below the fan 22. The first inlet noise suppression system includes vertical acoustical panels 30a around and outwardly of the fan 22 (typically 4 walls). The vertical panels 30a are constructed as the planar surface 12 described above, generally including a perforated outer surface of galvanized sheet metal exposing a underlying layer of acoustical insulation on the fan side and plain metal on the outside. The wall height of the vertical panel 3 Oa is flush with the bottom of the fan 22 and defines an inlet u-shaped region 30b by the panels 30a and the floor 30c which is preferably designed to support 1/4 wave clipping functionality. The acoustical walls of the first inlet noise suppression system provide both absorptive and reflective properties for low, medium and high range noise frequencies. If necessary the floor 30c of the u-shaped region 30b may include additional acoustical panels.
A second inlet noise suppression medium is positioned above and outward of the fan 22 and is intended to attenuate noise outwardly and above the fan 22. The second inlet noise suppression system generally includes the acoustical dampening system 10 as described above with the triangular baffles 14 extending from the outer edge of the fan 14 to the outer wall 20a of the cooling system 20 which provides an air flow path which supports the natural air flow with limited restriction. Rem~ining noise and partially suppressed noise seeking to escape the cooling system 20 is driven directly into the baffle system 10.
The second inlet noise suppression medium also serves as a floor/ceiling between the inlet 30 and outlet 32 regions of the cooling system 20 and, accordingly, also serves to prevent recirculation of waste heat within the cooling system 20.
A third inlet noise suppression medium is provided below the second inlet noise suppression medium and outside and below the first inlet noise suppression system. The third inlet noise suppression system includes a plurality of vertically spaced acoustical baffles. Each baffle 34 includes a planar panel having perforations defining a void volume as described above on both sides the panel exposing underlying acoustical insulation. The panels 34 are placed suff1ciently far apart to enable adequate air flow past the baffles 34 for the air flow demands of the fan. Furthermore, the baffles 34 are supported above the CA 0221~761 1997-09-17 ground level 26 at a height sufficient to allow air to enter the system from below. Noise escaping the second inlet noise suppression medium will be forced into a tight, reflective energy consuming pattern between the parallel baffles 34 attenuating rem~ining noise upon each reflection.
Accordingly, air enters the air inlet chamber 30 by flowing upwardly past the vertical baffles 34 whereby it undergoes a 90 degree bend and flows past and parallel to the second inlet noise suppression medium. Air then flows downwa~dly into chamber 30 and then upwardly through the fan 22.
After passing through the fan 22, air flows upwardly past the cooling coils 24 and into the outlet chamber 32. As with the inlet chamber 30, the outlet chamber 32 includes a number of noise suppression media to reduce the noise escaping the enclosure.
A first outlet noise suppression system is provided primarily in direct line of sight above the fan 22, that is along the ceiling of the cooling system 20. As is shown, a horizontal cooling system directs the air flow upwardly and accordingly, the majority of the noise generated will similarly be directed upwardly.
The first outlet noise suppression system includes the acoustical noise suppression system 10 as described above along the inclined ceiling surface of the cooling system 20. As such, the triangular baffles 14 are parallel with respect to the roof line and may be inclined with respect to the horizontal. Accordingly, the majority of noise which reflects off the roof surface will tend towards either the upper or the lower region of the roof. Optional kneewall vertical baffles 32a may be provided in certain buildings if the air outlet remains in line-of-sight with outer areas of the fan 22.
The inclined baffles 14, in conjunction with a u-shaped area 40 (a second outlet noise suppression medium) at the lower region of the roof, provides an acoustical choke for the reflected sound propagating along the underside of the roof. The u-shaped region 40 supports 1/4 wave clipping functionality.
CA 0221~761 1997-09-17 A third outlet noise suppression medium is provided beneath the u-shaped region 40 and includes a plurality of horizontal baffles as vertical baffles 34 described above. The horizontal baffles 42 allow outflowing air to flow along their surfaces and exit the cooling system 20. The third outlet noise suppression medium traps the noise that is reflected from the ceiling and noise which escapes the u-shaped regions 40 by setting up a tight reflective pattern between adjacent panels. A second u-shaped region 40a may be provided in the lower region of the outlet chamber. The vertical spacing, thickness and length of the horizontal baffles is determined by the final noise suppression demands and which also permits adequate air flow for the demands of the fan 22. Floor baffle 44 may be provided for further sound attenuation.
All joints at intersecting walls, floors and ceilings are acoustically sealed as is understood by those skilled in the art.
The length of baffles, the space between baffles, the noise coefficient properties of the acoustical insulation, the reflective properties of the perforated sheeting can all be selected according to the desired noise suppression for a particular installation.
In a vertical cooling system, that is a cooling system having a fan rotating about a horizontal axis, first, second and third inlet noise suppression and first, second and third outlet noise suppression systems are provided to permit adequate air flow and noise suppression in a manner similar to those described above for a horizontal cooling system 20.
Specifically, in a vertical cooling system and as shown in Figures 6 - 8, a vertical cooling system 48 includes an inlet portion 48a as shown in Figure 6 and an outlet portion 48b as shown in Figure 7. A fan 50 is mounted on a horizontal axis and directs air across coiling coils 52. As shown, the inlet noise suppression system includes a first inlet noise suppression medium consisting of a number of parallel spaced baffles 54 which are generally parallel to the flow of air towards the fan, the baffles 54 for attenuating a portion of the noise in a direct line of sight with the fan 50 and to direct the noise directly into the CA 0221~761 1997-09-17 acoustical choke. A second inlet noise suppression medium includes the acoustical dampening system 10 as described above with u-shaped chambers 56 which provide 1/4 wave clipping functionality. A third noise suppression medium includes a plurality of parallel baffles 58 at the entrance to the cooling system 48 at 90 degrees to the first noise suppression medium baffles 54 as is described above.
At the outlet 48b and as shown in Figure 7, an outlet noise suppression system is shown.
In this embodiment, a fan (not shown) is below the outlet noise suppressian system.
Directional baffles 60 direct airflow and noise directly upward into an acoustical choke 12, 14 as described above. Noise which escapes the acoustical choke is attenuated in the outlet baffle system 60.
It is also understood that in the design of an acoustical chamber, knowledge of the existence of a particular noise frequency will assist in the design of the chamber.
Accordingly, the depth or size of an acoustical choke, u-shaped chamber and baffle system can be adjusted to deal with a specific frequency, and specifically to prevent low frequency noise from weaving around baffles to escape suppression.
The terms and expressions which have been employed in this specification are used as terms of description and not of limitations, and there is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims.
The present invention relates to an apparatus for noise suppression. In particular, the apparatus includes an acoustical dampening system which is effective in noise suppression in a wide range of frequencies. The invention also provides an effective enclosure design for noise suppression in vertical and horizontal cooling systems.
BACKGROUND OF THE INVENTION
Process coolers in the oil, gas, petrochemical and other related industries require substantial cooling of various liquid substances. Typically, hot substances are pumped into a header, which is connected to a series of cooling coils with cooling fins, located within a chamber through which high volumes of air are pumped through by rotating fans. The forced air is drafted past the cooling coils and fins thereby transferring heat from the inside of the pipes. In many installations, the air-flow required for the industrial process is very high and necessitates large diameter fans, often in the range of 13 feet, with air flows in the order of 250,000 cubic feet of air per minute passing through the fan systems.
These cooling systems may produce very high noise levels from the blades of the fan, the air flowing past the coiling cools and fins, belts and/or gears, motors and any noise transmitted through steel structures and/or from fluids flowing through the pipes. Noises generated within a cooling system will escape with both the inflow and outflow portions of the cooling system's air flow and may often exceed 100 dBA, which is well in excess of acceptable noise level standards imposed in many regions. Jurisdictional regulations often require that the average noise level around such a cooling installation does not exceed 40 dBA at night and 50 dBA during the day. Accordingly, there has been a need for acoustical chambers which can effectively attenuate the noise levels while also providing effective operation of the cooling system and, in particular, without creating excessive back pressure on the cooling system.
In the design of an acoustical chamber which is effective in meeting the design goals of CA 0221~761 1997-09-17 noise attenuation while maintaining normal operation of a cooling system, there has been a need to develop an effective acoustical dampening system which can be readily formed into an enclosure. In particular, there has been a need for an acoustical dampening system having a baffle system in which noise in a wide range of frequencies can be effectively attenuated and in particular is effective in attenuation of low frequency sound waves using 1/4 wave clipping functions.
In addition, the application of forced-draft horizontal and~ vertical coiling coil systems varies in the market with such equipment serving a variety of applications, including but not limited to the oil, gas, petrochemical, refrigeration, and air-conditioning industries. In many of these applications, excessive noise levels may be produced in the vicinity of cooling machinery which may be hazardous to workers or above legal limits.
In a typical cooling system, the majority of the noise at either the inlet or outlet of the cooling system is projected either up or outwards. Furthermore, noise is typically generated in a range of frequencies wherein the low frequency bands (16-31.5 Hz) being the most difficult to attenuate.
Accordingly, there has been a need for a design of an acoustical chamber wherein the majority of upwardly or outwardly projected noise is attenuated within a u-shaped trap. As well, there has been a need for a design of acoustical chamber wherein the suppression of specific low frequency noise is designed into the chamber by strategic designing the depth or height of the chamber from the source noise to utilize 1/4 wave clipping functions so that specific noise frequencies cannot be developed. For example, 31 Hz band sound will have a wavelength of 10.7 meters with the 1/4 wave 2.6 meters in length. Accordingly, there has been a need for a system of baffles to weave the low frequency sound wave into a sound trap wherein the full length of sound wave cannot fully develop.
. .
Specifically, there has been a need for an acoustical dampening system having a system of triangular baffles and adjacent planar acoustical panels having exposed acoustical insulation providing an effective trapping system for a wide range of noise frequencies.
CA 0221~761 1997-09-17 A review of the prior art has revealed a number of references related to acoustical dampening but none which specifically teach the structure of the present application, nor the use of same to create an acoustical chamber in and around cooling coils.
For example, US Patent 5,317,113 teaches a wall and triangular baffle system. However, this patent does not teach an acoustical dampening system in which the base surface of the triangular baffle is reflective nor 1/4 wave clipping functionality. Still further, this patent does not teach an acoustical chamber with managed air i~ow through it with noisesuppression.
US Patent 5,332,972 teaches a noise reduction unit for gas compressors which includes a plurality of baffles for reducing noise around the inlet. This patent does not teach a noise suppression system having a triangular baffle system.
Other patents such as US Patent 4,971,850, US Patent 2,659,808, US Patent 5,304,750, US Patent 4,605,088, US Patent 3,068,535 and US Patent 4,298,090 each teach various acoustical dampening systems but none are directed to the concept of managed sound attenuation in conjunction with managed air flow.
SUMMARY OF THE INVENTION
In accordance with the invention, an acoustical dampening system is provided, the acoustical dampening system comprising:
an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation;
a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first~ second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation.
CA 0221~761 1997-09-17 In further embodiments, the first, second and third sides of the triangular baffles have a length, d, which defines a equilateral triangle, each triangular baffle is spaced from the planar surface by a distance of approximately d/2 and/or are spaced from one another by a distance of approximately d. In a further embodiment, the perforated surfaces of the planar surface and second and third surfaces have a void fraction of 33-51%.
The apparatus may further comprise a u-shaped chamber adjacent the ends of the triangular baffles, the u-shaped chamber having a perforated outer surface exposing underlying acoustical insulation.
In a specific application, a noise suppression system is provided in a horizontal cooling system having a fan rotating about a vertical axis for suppressing noise around the horizontal cooling system, the noise suppression system comprising:
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight beneath the fan, the first inlet noise suppression medium including vertical acoustical panels outside and below the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight above and outside the fan, the second inlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, eachtriangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and below the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical CA 0221~761 1997-09-17 insulation below the fan and outside the first noise suppression medium.
In a further embodiment, an outlet noise suppression system is also provided including a first outlet noise suppression medium for suppressing noise in direct line-of-sight above the fan, the first outlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generallyparallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a second outlet noise suppression medium for suppressing noise including at least one u-shaped chamber adjacent and outside the triangular baffles; and, a third outlet noise suppression medium for a third inlet noise suppression medium for suppressing noise below the second outlet noise suppression medium, the third outlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
An inlet and o'utlet noise suppression system may also be provided for vertical cooling systems.
CA 0221~761 1997-09-17 BRIEFDESCRIPTION OF THE DRA WINGS
These and other features of the invention will be more apparent from the following description in which reference is made to the appended drawings wherein:
Figure 1 is a schematic perspective diagram of an acoustical dampening system inaccordance with the invention; ~
Figurc 2 is a schematic perspective diagram of a triangular baffle in accordance with the mventlon;
Figure 3 is an end view of a horizontal cooling system and acoustical dampening system in accordance with the invention;
Figure 4 is a partial cross-sectional view of an inlet noise suppression system for a horizontal cooling system in accordance with the invention;
Figure 5 is a schematic side view of the inlet and outlet noise suppression systems of a horizontal cooling system in accordance with the invention;
Figure 6 is a plan view of an inlet noise suppression systems of a vertical cooling system in accordance with the invention;
Figure 7 is a side view of an outlet noise suppression systems of a vertical cooling system in accordance with the invention;
Figure 8 is a side view of a typical vertical cooling system including an inlet noise suppression system and an outlet noise suppression system in accordance with the mventlon.
CA 0221~761 1997-09-17 DETAILED DESCRIPTION OF THE INVENTION
With reference to Figure 1, an acoustical dampening system is described. The system 10 generally includes a flat planar surface 12 and a plurality of acoustical baffles 14 adjacent the planar surface 12. As a result of the design of the planar surface 12 and baffles 14, their relative dimensions and materials of construction, the combination is particularly effective in attenuating or choking noise when installed around noisy industrial machinery having large fans. Furthermore, the construction the acoustical dampening system 10 has a high level of structural strength thus enhancing the installation of the acoustical dampening system 10 as a modular component of a noise dampening enclosure.
The planar surface 12 includes an outer surface 12a which partially exposes an underlying layer of acoustical insulation 12b. Thus, the outer surface 12 is preferably fabricated with a plurality of evenly spaced openings 12c, as shown partially in Figure 1. The evenly spaced openings 12c are typically circular and define a void fraction. The void fraction of the planar surface is preferably in the order of 33-51%. The outer or back surface is also preferably fabricated from a rigid and sound-reflective material such as galvanized sheet metal to also provide structural integrity to the planar surface 12.
Each triangular baffle 14 of the plurality of triangular baffles is also fabricated to have sufficient structural strength to span typical construction distances. Each baffle 14 has a cross-section of an equilateral triangle with the base surface 14a parallel in orientation to the planar su*ace 12. The base surface 14a is non-porous. The two outwardly projecting surfaces 14b and 14c are porous having a void fraction in the range of 33-51% and also expose underlying acoustical insulation 14d as described for the planar surface 12.
In accordance with the invention, it is preferred that the length of each side of the triangular baffle 14 of the acoustical dampening system has a length d, where d is any reasonable length as would be understood for a typical installation. In a typical in~t~ tion, in and around a cooling system, d would be in the range of 1 foot. Each adjacent baffle 14 is spaced from one another by a distance d and the base surface 14a is spaced from the CA 0221~761 1997-09-17 planar surface 12 by a distance d/2.
The outer surfaces of the baffles 14 are preferably fabricated from galvanized sheet metal for its reflective and structural properties as well as for cost considerations.
Suitable acoustical insulation 12b and 14d for the underlying layers of the planar surface 12 and triangular baffles 14 are well known to those skilled in the art and may be chosen, for example, from materials such as FIBREX 1240 (density of 4 pounds per cubic foot) and FIBREX 1280 (density of 8 pounds per cubic foot).
In use, noise which is directed into the noise suppression system 10 will either hit the perforated faces 14b andl4c of the baffle 14, where a proportion of the sound energy will be absorbed and a majority of the rem~ining noise will be reflected against the perforated acoustical surface 12, or it will be driven between the baffles 14 and hit the acoustical surface 12 directly (whereby, again, some of the noise energy will be absorbed). Of the noise hitting the acoustical surface 12, some of the noise energy will be absorbed by the surface 12 with the remainder reflecting. A proportion of the reflected noise will strike the back of the baffle 14a and reflect back to surface 12 in a relentless ricochet pattern.
The acoustical dampening system 10 is particularly effective in dampening noise when forming a component of an enclosure around a cooling system 20 as shown in Figures 3-5.
With reference to Figures 3-5, a horizontal cooling tower includes a horizontal fan 22 which is rotated about a vertical axis for forcing air past cooling tubes 24. The cooling system is elevated above ground level 26 and is supported on a foundation 28. Appropriate structural supports are provided to support and define both an inlet charnber 30 and an outlet chamber 32. The inlet chamber 30 has an inlet noise suppression system and the outlet chamber has an outlet noise suppression system. As shown in Figures 3-5, outside air is drawn into the cooling system 20 through the inlet chamber 30, through the fan 22 and upwardly through the outlet charnber 32.
CA 0221~761 1997-09-17 Within the inlet chamber 30, a first inlet noise suppression system is provided to receive and attenuate noise in direct line of sight below the fan 22. The first inlet noise suppression system includes vertical acoustical panels 30a around and outwardly of the fan 22 (typically 4 walls). The vertical panels 30a are constructed as the planar surface 12 described above, generally including a perforated outer surface of galvanized sheet metal exposing a underlying layer of acoustical insulation on the fan side and plain metal on the outside. The wall height of the vertical panel 3 Oa is flush with the bottom of the fan 22 and defines an inlet u-shaped region 30b by the panels 30a and the floor 30c which is preferably designed to support 1/4 wave clipping functionality. The acoustical walls of the first inlet noise suppression system provide both absorptive and reflective properties for low, medium and high range noise frequencies. If necessary the floor 30c of the u-shaped region 30b may include additional acoustical panels.
A second inlet noise suppression medium is positioned above and outward of the fan 22 and is intended to attenuate noise outwardly and above the fan 22. The second inlet noise suppression system generally includes the acoustical dampening system 10 as described above with the triangular baffles 14 extending from the outer edge of the fan 14 to the outer wall 20a of the cooling system 20 which provides an air flow path which supports the natural air flow with limited restriction. Rem~ining noise and partially suppressed noise seeking to escape the cooling system 20 is driven directly into the baffle system 10.
The second inlet noise suppression medium also serves as a floor/ceiling between the inlet 30 and outlet 32 regions of the cooling system 20 and, accordingly, also serves to prevent recirculation of waste heat within the cooling system 20.
A third inlet noise suppression medium is provided below the second inlet noise suppression medium and outside and below the first inlet noise suppression system. The third inlet noise suppression system includes a plurality of vertically spaced acoustical baffles. Each baffle 34 includes a planar panel having perforations defining a void volume as described above on both sides the panel exposing underlying acoustical insulation. The panels 34 are placed suff1ciently far apart to enable adequate air flow past the baffles 34 for the air flow demands of the fan. Furthermore, the baffles 34 are supported above the CA 0221~761 1997-09-17 ground level 26 at a height sufficient to allow air to enter the system from below. Noise escaping the second inlet noise suppression medium will be forced into a tight, reflective energy consuming pattern between the parallel baffles 34 attenuating rem~ining noise upon each reflection.
Accordingly, air enters the air inlet chamber 30 by flowing upwardly past the vertical baffles 34 whereby it undergoes a 90 degree bend and flows past and parallel to the second inlet noise suppression medium. Air then flows downwa~dly into chamber 30 and then upwardly through the fan 22.
After passing through the fan 22, air flows upwardly past the cooling coils 24 and into the outlet chamber 32. As with the inlet chamber 30, the outlet chamber 32 includes a number of noise suppression media to reduce the noise escaping the enclosure.
A first outlet noise suppression system is provided primarily in direct line of sight above the fan 22, that is along the ceiling of the cooling system 20. As is shown, a horizontal cooling system directs the air flow upwardly and accordingly, the majority of the noise generated will similarly be directed upwardly.
The first outlet noise suppression system includes the acoustical noise suppression system 10 as described above along the inclined ceiling surface of the cooling system 20. As such, the triangular baffles 14 are parallel with respect to the roof line and may be inclined with respect to the horizontal. Accordingly, the majority of noise which reflects off the roof surface will tend towards either the upper or the lower region of the roof. Optional kneewall vertical baffles 32a may be provided in certain buildings if the air outlet remains in line-of-sight with outer areas of the fan 22.
The inclined baffles 14, in conjunction with a u-shaped area 40 (a second outlet noise suppression medium) at the lower region of the roof, provides an acoustical choke for the reflected sound propagating along the underside of the roof. The u-shaped region 40 supports 1/4 wave clipping functionality.
CA 0221~761 1997-09-17 A third outlet noise suppression medium is provided beneath the u-shaped region 40 and includes a plurality of horizontal baffles as vertical baffles 34 described above. The horizontal baffles 42 allow outflowing air to flow along their surfaces and exit the cooling system 20. The third outlet noise suppression medium traps the noise that is reflected from the ceiling and noise which escapes the u-shaped regions 40 by setting up a tight reflective pattern between adjacent panels. A second u-shaped region 40a may be provided in the lower region of the outlet chamber. The vertical spacing, thickness and length of the horizontal baffles is determined by the final noise suppression demands and which also permits adequate air flow for the demands of the fan 22. Floor baffle 44 may be provided for further sound attenuation.
All joints at intersecting walls, floors and ceilings are acoustically sealed as is understood by those skilled in the art.
The length of baffles, the space between baffles, the noise coefficient properties of the acoustical insulation, the reflective properties of the perforated sheeting can all be selected according to the desired noise suppression for a particular installation.
In a vertical cooling system, that is a cooling system having a fan rotating about a horizontal axis, first, second and third inlet noise suppression and first, second and third outlet noise suppression systems are provided to permit adequate air flow and noise suppression in a manner similar to those described above for a horizontal cooling system 20.
Specifically, in a vertical cooling system and as shown in Figures 6 - 8, a vertical cooling system 48 includes an inlet portion 48a as shown in Figure 6 and an outlet portion 48b as shown in Figure 7. A fan 50 is mounted on a horizontal axis and directs air across coiling coils 52. As shown, the inlet noise suppression system includes a first inlet noise suppression medium consisting of a number of parallel spaced baffles 54 which are generally parallel to the flow of air towards the fan, the baffles 54 for attenuating a portion of the noise in a direct line of sight with the fan 50 and to direct the noise directly into the CA 0221~761 1997-09-17 acoustical choke. A second inlet noise suppression medium includes the acoustical dampening system 10 as described above with u-shaped chambers 56 which provide 1/4 wave clipping functionality. A third noise suppression medium includes a plurality of parallel baffles 58 at the entrance to the cooling system 48 at 90 degrees to the first noise suppression medium baffles 54 as is described above.
At the outlet 48b and as shown in Figure 7, an outlet noise suppression system is shown.
In this embodiment, a fan (not shown) is below the outlet noise suppressian system.
Directional baffles 60 direct airflow and noise directly upward into an acoustical choke 12, 14 as described above. Noise which escapes the acoustical choke is attenuated in the outlet baffle system 60.
It is also understood that in the design of an acoustical chamber, knowledge of the existence of a particular noise frequency will assist in the design of the chamber.
Accordingly, the depth or size of an acoustical choke, u-shaped chamber and baffle system can be adjusted to deal with a specific frequency, and specifically to prevent low frequency noise from weaving around baffles to escape suppression.
The terms and expressions which have been employed in this specification are used as terms of description and not of limitations, and there is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims.
Claims (10)
1. An acoustical dampening system comprising:
an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation;
a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation.
an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation;
a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation.
2. An apparatus as in claim 1 wherein the first, second and third sides of the triangular baffles have a length, d, which defines a equilateral triangle.
3. An apparatus as in claim 2 wherein each triangular baffle is spaced from the planar surface by a distance of approximately d/2.
4. An apparatus as in claim 3 wherein adjacent triangular baffles are spaced from one another by a distance of approximately d.
5. An apparatus as in claim 1 wherein the perforated surfaces of the planar surface and second and third surfaces have a void fraction of 33-51%.
6. An apparatus as in claim 1 further comprising a u-shaped chamber adjacent the ends of the triangular baffles, the u-shaped chamber having a perforated outer surface exposing underlying acoustical insulation, the u-shaped chamber having dimensions to support 1/4 wave clipping functionality.
7. In a horizontal cooling system having a fan rotating about a vertical axis, a noise suppression system for suppressing noise around the horizontal cooling tower, the noise suppression system comprising:
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight beneath the fan, the first inlet noise suppression medium including vertical acoustical panels outside and below the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight above and outside the fan, the second inlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, eachtriangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and below the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation below the fan and outside the first noise suppression medium.
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight beneath the fan, the first inlet noise suppression medium including vertical acoustical panels outside and below the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight above and outside the fan, the second inlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, eachtriangular baffle having first, second and third sides, wherein the first side is generally parallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and below the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation below the fan and outside the first noise suppression medium.
8. In a horizontal cooling system as in claim 7, the noise suppression system further comprising an outlet noise suppression system including a first outlet noise suppression medium for suppressing noise in direct line-of-sight above the fan, the first outlet noise suppression medium including an acoustically dampening planar surface including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generallyparallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a second outlet noise suppression medium for suppressing noise including at least one u-shaped chamber adjacent and outside the triangular baffles; and, a third outlet noise suppression medium for a third inlet noise suppression medium for suppressing noise below the second outlet noise suppression medium, the third outlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
a second outlet noise suppression medium for suppressing noise including at least one u-shaped chamber adjacent and outside the triangular baffles; and, a third outlet noise suppression medium for a third inlet noise suppression medium for suppressing noise below the second outlet noise suppression medium, the third outlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
9. In a vertical cooling system having a fan rotating about a horizontal axis, a noise suppression system for suppressing noise around the vertical cooling system, the noise suppression system comprising:
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight adjacent the fan, the first inlet noise suppression medium including vertical acoustical panels adjacent and outside the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight outside the fan and first inlet noise suppression medium, the second inlet noise suppression medium including an acoustically dampening planar surface generally parallel to the fan and including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generallyparallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and outside the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
an inlet noise suppression system including a first inlet noise suppression medium for suppressing noise in direct line-of sight adjacent the fan, the first inlet noise suppression medium including vertical acoustical panels adjacent and outside the fan;
a second inlet noise suppression medium for suppressing noise in direct line-of-sight outside the fan and first inlet noise suppression medium, the second inlet noise suppression medium including an acoustically dampening planar surface generally parallel to the fan and including a perforated and sound-reflective outer surface exposing underlying acoustical insulation and a plurality of triangular baffles in spaced relation from the planar surface, each triangular baffle having first, second and third sides, wherein the first side is generallyparallel to the planar surface and is sound reflective and the second and third surfaces are perforated and expose underlying acoustical insulation;
a third inlet noise suppression medium for suppressing noise outside the first noise suppression medium and outside the fan, the third inlet noise suppression medium including a plurality of vertical and parallel acoustical panels including a perforated and sound-reflective outer surface exposing underlying acoustical insulation.
10. In a vertical cooling system as in claim 7, the noise suppression system further comprising an outlet noise suppression system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2215761 CA2215761A1 (en) | 1997-09-17 | 1997-09-17 | Acoustical dampening system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2215761 CA2215761A1 (en) | 1997-09-17 | 1997-09-17 | Acoustical dampening system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2215761A1 true CA2215761A1 (en) | 1999-03-17 |
Family
ID=29275024
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2215761 Abandoned CA2215761A1 (en) | 1997-09-17 | 1997-09-17 | Acoustical dampening system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2215761A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013114076A1 (en) * | 2012-02-03 | 2013-08-08 | Icopal Limited | Building construction panels |
| FR3094566A1 (en) * | 2019-03-29 | 2020-10-02 | Sbs Synovate | Ventilation device for acoustic enclosure, acoustic enclosure and corresponding method |
| CN114735203A (en) * | 2022-06-13 | 2022-07-12 | 中国空气动力研究与发展中心高速空气动力研究所 | Noise suppression device for triangular prism-shaped aircraft weapons cabin |
-
1997
- 1997-09-17 CA CA 2215761 patent/CA2215761A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013114076A1 (en) * | 2012-02-03 | 2013-08-08 | Icopal Limited | Building construction panels |
| FR3094566A1 (en) * | 2019-03-29 | 2020-10-02 | Sbs Synovate | Ventilation device for acoustic enclosure, acoustic enclosure and corresponding method |
| CN114735203A (en) * | 2022-06-13 | 2022-07-12 | 中国空气动力研究与发展中心高速空气动力研究所 | Noise suppression device for triangular prism-shaped aircraft weapons cabin |
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