US5386689A — Active gas turbine (jet) engine noise suppression

Claim 1

Independent Claim 144 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said actuator means comprises an air modulator-based acoustic source that receives a flow of compressed air derived from compression stages of one or more of said engines.

Claim 2

Independent Claim 144 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said actuator means comprises an air modulator-based acoustic source that receives a flow of compressed air derived from compression stages of one or more of said engines.

Claim 3

Independent Claim 156 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said engines have external far and near acoustic radiation fields and said sensor means comprise first error sensors located inside the engine, and second error sensors located in the far and near external acoustic radiation fields of the engine.

Claim 4

Independent Claim 156 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said engines have external far and near acoustic radiation fields and said sensor means comprise first error sensors located inside the engine, and second error sensors located in the far and near external acoustic radiation fields of the engine.

Claim 5

Independent Claim 146 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said controller means receives signals from a plurality of said sensors and comprises means to control a plurality of actuator means simultaneously to suppress acoustic noise from multiple engines.

Claim 6

Independent Claim 146 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said controller means receives signals from a plurality of said sensors and comprises means to control a plurality of actuator means simultaneously to suppress acoustic noise from multiple engines.

Claim 7

Independent Claim 199 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said engines provide signals to keyphasor or tachometer means and said controller receives rotational cycle reference signals from the keyphasor or tachometer means, wherein said engines provide a rotational cycle reference signal and said sensor means provide signals to said controller and said system further comprises means to convert signals from the sensors to digital samples, said means to convert operating at a sampling rate, and rotational speed synchronization means to synchronize the sampling rate to the engines rotational cycle reference signal.

Claim 8

Independent Claim 199 words

A system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of a jet aircraft having an aircraft fuselage, wings, nacelles, tail, and stabilizer structures, said system comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising microphone means located in and around the engines, and on a plurality of aircraft structures selected from among the aircraft fuselage, wings, nacelles, tail, and stabilizer structures, one or more controller means to control said actuators to generate sound in order to effect the reduction of the internal and external sound field as measured by the plurality of sensors wherein said engines provide signals to keyphasor or tachometer means and said controller receives rotational cycle reference signals from the keyphasor or tachometer means, wherein said engines provide a rotational cycle reference signal and said sensor means provide signals to said controller and said system further comprises means to convert signals from the sensors to digital samples, said means to convert operating at a sampling rate, and rotational speed synchronization means to synchronize the sampling rate to the engines rotational cycle reference signal.

Claim 9

Dependent Claim 353 words

A jet aircraft having an active system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of the jet aircraft comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising one or more controller means for controlling said actuators to radiate acoustic energy to cancel acoustic levels measured by said sensor means, said jet engine having a nacelle comprising a cowl, an inlet duct, engine and cowl panels, a bypass duct, an exhaust duct that comprises a tailpipe extension, thrust reverser, and tailpipe, said nacelle having zones containing noise source sensors, internal error sensors, external error sensors, and canceling actuators, said aircraft having forward and rearward ends, wherein said nacelle has an inlet end and comprises a nose cowl having an inlet duct at the inlet end of said nacelle, an engine and cowl panel having a bypass duct immediately behind said nose cowl, a tail pipe extension behind said engine and cowl panel, said tailpipe extension having an exhaust duct and a thrust reverser and tail pipe behind said tail pipe extension, wherein said zones comprising noise source sensors comprise a first noise source sensor zone in the forward end of said engine and cowl panel, a second noise source sensor zone in the forward end of said tail pipe extension and wherein said zones comprising error sensors comprise a first error sensor zone in the forward end of said nose cowl, a second error sensor zone in the rearward end of said engine and cowl panel, and a third error sensor zone in said thrust reverser and tail pipe, actuator zones comprising a first actuator zone in the inlet duct of said nose cowl aft of said first error sensor zone, a second actuator zone in the bypass duct of said engine and cowl panel between said first noise source sensor zone and said second error sensor zone, and a third actuator zone located in the exhaust duct of said tailpipe extension located aft of said second noise source sensor zone.

Claim 10

Dependent Claim 353 words

A jet aircraft having an active system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of the jet aircraft comprising a plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising one or more controller means for controlling said actuators to radiate acoustic energy to cancel acoustic levels measured by said sensor means, said jet engine having a nacelle comprising a cowl, an inlet duct, engine and cowl panels, a bypass duct, an exhaust duct that comprises a tailpipe extension, thrust reverser, and tailpipe, said nacelle having zones containing noise source sensors, internal error sensors, external error sensors, and canceling actuators, said aircraft having forward and rearward ends, wherein said nacelle has an inlet end and comprises a nose cowl having an inlet duct at the inlet end of said nacelle, an engine and cowl panel having a bypass duct immediately behind said nose cowl, a tail pipe extension behind said engine and cowl panel, said tailpipe extension having an exhaust duct and a thrust reverser and tail pipe behind said tail pipe extension, wherein said zones comprising noise source sensors comprise a first noise source sensor zone in the forward end of said engine and cowl panel, a second noise source sensor zone in the forward end of said tail pipe extension and wherein said zones comprising error sensors comprise a first error sensor zone in the forward end of said nose cowl, a second error sensor zone in the rearward end of said engine and cowl panel, and a third error sensor zone in said thrust reverser and tail pipe, actuator zones comprising a first actuator zone in the inlet duct of said nose cowl aft of said first error sensor zone, a second actuator zone in the bypass duct of said engine and cowl panel between said first noise source sensor zone and said second error sensor zone, and a third actuator zone located in the exhaust duct of said tailpipe extension located aft of said second noise source sensor zone.

Claim 11

Dependent Claim 26 words

The jet aircraft of claim 5 wherein the actuators located in one or more of said first, second and third actuator zones comprise air stream modulators.

Claim 12

Dependent Claim 25 words

The jet aircraft of claim 5 wherein the actuators located in one or more of said first, second and third actuator zones comprise piezoceramic actuators.

Claim 13

Dependent Claim 63 words

The jet aircraft of claim 6 wherein one or more of said air stream modulators comprises an air modulator actuator horn having a mouth opening into an ambient bypass air flow, said horn comprising throat means to provide impedance loading to enhance performance, and horn section means to match the impedance of the ambient bypass air flow at the mouth of the horn.

Claim 14

Dependent Claim 38 words

The jet aircraft of claim 8 wherein said horn comprises a mouth having a flange attached to an entry hole in an engine bypass duct wall, a plenum, and a pipe manifold attached to a source of air.

Claim 15

Dependent Claim 35 words

The jet aircraft of claim 9 wherein said engine comprises compressor stages and bleed ports on the engine's compressor stages, and wherein said pipe manifold is adapted to receive compressed air from said bleed ports.

Claim 16

Dependent Claim 42 words

The jet aircraft of claim 10 wherein said throat means of said horn provides an exit from the plenum, and said mouth of said horn provides an entrance back into a bypass duct, each engine having a plurality of air modulator actuators.

Claim 17

Dependent Claim 12 words

The jet aircraft of claim 11 wherein said horn comprises driver means.

Claim 18

Dependent Claim 15 words

The jet aircraft of claim 12 wherein said driver means comprises a stiffness-controlled, electrodynamic actuator.

Claim 19

Dependent Claim 145 words

A jet aircraft having an active system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of the jet aircraft comprising plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising one or more controller means for controlling said actuators to radiate acoustic energy to cancel acoustic levels measured by said sensor means, said jet engine having a nacelle comprising a cowl, an inlet duct, engine and cowl panels, a bypass duct. an exhaust duct that comprises a tailpipe extension, thrust reverser, and tailpipe, said nacelle having zones containing noise source sensors, internal error sensors, external error sensors, and canceling actuators wherein said actuator means comprise acoustic loudspeakers located in one or more of the inlet duct, a bypass duct and the forward end of the tailpipe.

Claim 20

Dependent Claim 145 words

A jet aircraft having an active system for reducing the acoustic levels of internal and external sound fields generated by gas turbine engines of the jet aircraft comprising plurality of actuator means to generate sound, a plurality of sensor means to measure said acoustic levels, said sensor means comprising one or more controller means for controlling said actuators to radiate acoustic energy to cancel acoustic levels measured by said sensor means, said jet engine having a nacelle comprising a cowl, an inlet duct, engine and cowl panels, a bypass duct. an exhaust duct that comprises a tailpipe extension, thrust reverser, and tailpipe, said nacelle having zones containing noise source sensors, internal error sensors, external error sensors, and canceling actuators wherein said actuator means comprise acoustic loudspeakers located in one or more of the inlet duct, a bypass duct and the forward end of the tailpipe.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-02-06	1998-08-08	1999-02-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-02-06	2002-08-08	2003-02-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-02-06	2006-08-08	2007-02-07	$7700.00	Window Closed / Lapsed

Active gas turbine (jet) engine noise suppression

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