5526432: Ducted axial fan
INVENTORS: Denenberg; Jeffrey N., Trumbull, CT
ASSIGNEES: Noise Cancellation Technologies, Inc., Linthicum, MD
ISSUED: June 11, 1996   FILED: Oct. 11, 1994
SERIAL NUMBER: 335271   MAINT. STATUS:
INTL. CLASS (Ed.  6): G10K 11/16;
U.S. CLASS: 381-071; 415-119;
FIELD OF SEARCH: 381-71,94 ; 415-119 ;
AGENTS: none

ABSTRACT:   A ducted axial fan for large diameter ducts (11) which includes equidistantly spaced sensors (22,23) upstream and downstream of an axial fan and spaced actuators (24, 26) located around the periphery of said duct to cancel tonal noise caused by the air turbulence generated by the rotation of the fan.

U.S. REFERENCES:   (No patents reference this one)
Patent No. Inventor Issued Title
4044203 Swinbanks 8 /1977 Active control of sound waves
4153815 Chaplin et al. 5 /1979 Active attenuation of recurring sounds
4715559 Fuller 12 /1987 Apparatus and method for global noise reduction
5141391 Acton et al. 8 /1992 Active control of unsteady motion phenomena in turbomachinery

EXEMPLARY CLAIM(s): Show all 10 claims

I claim:
  • 1. In a duct having a multi-bladed axially mounted fan means with multiple blades and an intake side and an exhaust side mounted therein creating a rotating sound field, the improvement comprising
    • a first sensor means mounted upstream of said fan means,
    • a second sensor means mounted downstream of said fan means,
    • a series of actuator means mounted around said duct means adjacent said fan means, and
    • a two channel control means operatively connected to said actuator means and said first and second sensor means and adapted to directly cancel the tonal noise generated by said axial fan by canceling the pressure waves generated by said fan's rotation by generating different rotating pressure antiwaves on each side of the blade so that noise propagates from both the exhaust and intake sides of the fan to quiet said rotating sound field.

RELATED U.S. APPLICATIONS:

Patent No. Appl No. Issue Date
64598

FOREIGN APPLICATION PRIORITY DATA: none

FOREIGN REFERENCES:

Document No. Country Date Intl. Class
63-74399 Japan 4 /1988  
3-13998 Japan 1 /1991  
WO92-17936 WIPO 10 /1992  

OTHER REFERENCES: none
PRIMARY/ASSISTANT EXAMINERS: Isen; Forester W.;
ADDED TO DATABASE: Sep. 1 , 1996