|5526432: Ducted axial
||Denenberg; Jeffrey N.,
||Noise Cancellation Technologies, Inc.,
||June 11, 1996
||Oct. 11, 1994
|INTL. CLASS (Ed.
|FIELD OF SEARCH:
||381-71,94 ; 415-119 ;
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.
||Active control of sound waves
||Chaplin et al.
||Active attenuation of recurring sounds
||Apparatus and method for global noise reduction
||Acton et al.
||Active control of unsteady motion phenomena in
CLAIM(s): Show all 10
- 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
- a first sensor means mounted upstream of said fan means,
- a second sensor means mounted downstream of said fan
- 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.
APPLICATION PRIORITY DATA: none
Isen; Forester W.;
ADDED TO DATABASE:
Sep. 1 , 1996