Acoustics – Sound-modifying means – Sound absorbing panels
Reexamination Certificate
2001-08-14
2003-08-05
Dang, Khanh (Department: 2181)
Acoustics
Sound-modifying means
Sound absorbing panels
C181S286000, C181S292000, C181S293000, C181S213000
Reexamination Certificate
active
06601672
ABSTRACT:
BACKGROUND
This invention relates to an acoustic liner of two layers and a fluid pressurizing device and method utilizing same.
Fluid pressurizing devices, such as centrifugal compressors, are widely used in different industries for a variety of applications involving the compression, or pressurization, of a gas. However, a typical compressor produces a relatively high noise level which is an obvious nuisance to the people in the vicinity of the device. This noise can also cause vibrations and structural failures.
For example, the dominant noise source in a centrifugal compressor is typically generated at the locations of the impeller exit and the diffuser inlet, due to the high velocity of the fluid passing through these regions. The noise level becomes higher when discharge vanes are installed in the diffuser to improve pressure recovery, due to the aerodynamic interaction between the impeller and the diffuser vanes.
Various external noise control measures such as enclosures and wrappings have been used to reduce the relative high noise levels generated by compressors, and similar devices. These external noise reduction techniques can be relatively expensive especially when they are often offered as an add-on product after the device is manufactured.
Also, internal devices, usually in the form of acoustic liners, have been developed which are placed in the compressors, or similar devices, for controlling noise inside the gas flow paths. These liners are often based on the well-known Helmholtz resonator principle according to which the liners dissipate the acoustic energy when the sound waves oscillate through perforations in the liners, and reflect the acoustic energy upstream due to the local impedance mismatch caused by the liner. Examples of Helmholtz resonators are disclosed in U.S. Pat. Nos. 4,100,993; 4,135,603; 4,150,732; 4,189,027; 4,443,751; 4,944,362; and 5,624,518.
A typical Helmholtz array acoustic liner is in the form of a three-piece sandwich structure consisting of honeycomb cells sandwiched between a perforated facing sheet and a back plate. Although these three-piece designs have been successfully applied to suppress noise in aircraft engines, it is questionable whether or not they would work in fluid pressurizing devices, such as centrifugal compressors. This is largely due to the possibility of the perforated facing sheet of the liner breaking off its bond with the honeycomb under extreme operating conditions of the compressor, such as, for example, during rapid depressurization caused by an emergency shut down of the compressor. In the event that the perforated facing sheet becomes loose, it not only makes the acoustic liners no longer functional but also causes excessive aerodynamic losses, and even the possibility of mechanical catastrophic failure, caused by the potential collision between the break-away perforated sheet metal and the spinning impeller.
Therefore what is needed is a system and method for reducing the noise in a fluid pressurizing device utilizing a Hemholtz array acoustic liner while eliminating its disadvantages.
SUMMARY
Accordingly an acoustic liner is provided, as well as a fluid processing device and method incorporating same, according to which the liner attenuates noise and consists of one or more acoustic liners each including a plurality of cells formed in a plate in a manner to form an array of resonators.
REFERENCES:
patent: 1783276 (1930-12-01), Bliss
patent: 1972563 (1934-09-01), Irvin
patent: 3181646 (1965-05-01), Edwards
patent: 3360193 (1967-12-01), Harris et al.
patent: 3948346 (1976-04-01), Schindler
patent: 4135603 (1979-01-01), Dean, III et al.
patent: 4137992 (1979-02-01), Herman
patent: 4150850 (1979-04-01), Doerfling
patent: 4189027 (1980-02-01), Dean, III et al.
patent: 4190131 (1980-02-01), Robinson
patent: 4204586 (1980-05-01), Hani et al.
patent: 4241806 (1980-12-01), Metzger
patent: 4287962 (1981-09-01), Ingard et al.
patent: 4303144 (1981-12-01), Wirt
patent: 4421455 (1983-12-01), Tomren
patent: 4433751 (1984-02-01), Bonneau
patent: 4504188 (1985-03-01), Traver et al.
patent: 4848514 (1989-07-01), Snyder
patent: 4854416 (1989-08-01), Lalikos et al.
patent: 4926963 (1990-05-01), Snyder
patent: 4932835 (1990-06-01), Sorokes
patent: 4944362 (1990-07-01), Motsinger et al.
patent: 4947958 (1990-08-01), Snyder
patent: 5007499 (1991-04-01), Ebbing et al.
patent: 5014815 (1991-05-01), Arcas et al.
patent: 5025888 (1991-06-01), Arcas et al.
patent: 5099566 (1992-03-01), Barrett
patent: 5173020 (1992-12-01), Ebbing et al.
patent: 5173021 (1992-12-01), Grainger et al.
patent: 5249919 (1993-10-01), Sishtla et al.
patent: 5644918 (1997-07-01), Gulati et al.
patent: 5919029 (1999-07-01), Van Nostrand et al.
patent: 5923003 (1999-07-01), Arcas et al.
patent: 5979593 (1999-11-01), Rice et al.
patent: 6135238 (2000-10-01), Arcas et al.
patent: 6309176 (2001-10-01), Periyathamby et al.
International Searching Authority, Patent Cooperation Treaty, Notification of Transmittal of The International Search Report or the Declaration, International Application No. PCT/US01/47515, Apr. 18, 2002, 6 pages.
Dang Khanh
Dresser-Rand Company
Haynes and Boone, LLP.
LandOfFree
Double layer acoustic liner and a fluid pressurizing device... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Double layer acoustic liner and a fluid pressurizing device..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Double layer acoustic liner and a fluid pressurizing device... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3124936