Active control of tone noise in engine ducts
AssigneeThe Boeing Company
InventorAnders O. Andersson
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Abstract
The application of active noise control to influence the fan-noise components in engine ducts. The fan is used as a source of counter noise by introducing flow distortions upstream or downstream of the fan. Microphone arrays sense the noise and produce a control output signal for controlling a distortion producer. The control output signal for the distortion producer comes from a control algorithm utilizing the output of the microphone signals sampled at a defined rate based on the fan blade passing frequency.
Claims12
A method for control of the fan-generated component of noise emanating from ducts of jet engines, comprising the steps of:
- a) providing devices for introducing flow distortions in the form of wakes;
- b) collecting sensor signals harmonically related to rotor blade-passing frequency for controlling the wake-producing devices;
- and,
- c) providing means for absorbing the broad-band sound generated by said wake-producing devices.
A system for control of the fan generated component of noise emanating from ducts of jet engines, comprising in combination:
- a) a plurality of devices for introducing wakes to the fan;
- b) said control means responsive to a plurality of signals sampled at a predetermined rate related to the fan blade passing frequency;
- and,
- c) means for absorbing the broad-band sound generated by said wake-producing devices.
Dependencies are inferred from the claim text.