# US 2020/0400076 A1 · Active device for attenuating acoustic emissions for a turbojet engine including controlled turbines

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- Number: US 2020/0400076 A1
- Document ID: US20200400076A1
- Status: Published application
- Kind: A1
- Application number: 17/014,527
- Filed: 2020-09-08
- Published: 2020-12-24
- Earliest claimed: 2018-03-08
- Assignees: Safran Nacelles
- Applicants: Safran Nacelles
- Inventors: Jean-Paul RAMI; Hervé HURLIN; Jean-Baptiste GOULARD; Marc VERSAEVEL; Philippe MICHEAU; Julien DRANT; Ambre ALLARD; Alain BERRY; Raymond ROBERT
- Web page: https://patentgrep.com/patent/US20200400076A1

## CPC

- F02C 7/24: Heat or noise insulation (air intakes having provisions for noise suppression F02C7/045; turbine exhaust heads, chambers, or the like F01D25/30; silencing nozzles of jet-propulsion plants F02K1/00)
- B64D 33/02: of combustion air intakes
- F02C 7/045: having provisions for noise suppression
- F02C 7/32: Arrangement, mounting, or driving, of auxiliaries
- F02K 1/34: for attenuating noise
- F02K 1/827: {Sound absorbing structures or liners}
- F16K 31/041: {for rotating valves (F16K31/055 takes precedence)}
- G10K 11/161: {in systems with fluid flow (G10K11/162 takes precedence; gas flow silencers or exhaust apparatus for machines or engines in general or for internal combustion engine F01N, noise absorbers in pipes or pipe systems F16L55/02; noise absorption in air conditioning and ventilation F24F13/24; silencing exhaust or propulsion jets in aircraft B64D33/06)}
- G10K 11/178: by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K 11/17857: {Geometric disposition, e.g. placement of microphones}
- B64C 2220/00: Active noise reduction systems
- B64D 2033/0206: {comprising noise reduction means, e.g. acoustic liners}
- F05D 2220/326: to drive shrouded, low solidity propeller
- F05D 2220/327: to drive shrouded, high solidity propeller
- F05D 2260/962: by means of "anti-noise"
- F05D 2270/304: Spool rotational speed
- F05D 2270/333: Noise or sound levels
- G10K 2210/121: Rotating machines, e.g. engines, turbines, motors; Periodic or quasi-periodic signals in general
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)
- F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)}
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- B64C: AEROPLANES; HELICOPTERS
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

## Claims

### Claim 1

An active device for attenuating tonal acoustic emissions of a nacelle of an aircraft turbojet engine, the active device comprising:
a circulation conduit for supplying controlled pressurized air flow; and
a rotary element receiving the supplied controlled pressurized air flow, wherein the rotary element comprises a chopping system for pulsating the flow of delivered air, wherein the rotary element is controlled in speed and in angular position, wherein the rotary element delivers to a diffuser at an outlet of the device a pulsed air flow rate with a pulsation having an adjusted frequency, phase, and amplitude so as to reduce acoustic power radiated out of the nacelle, wherein
the rotary element comprises an outlet sleeve, wherein the outlet sleeve has an adjustable passage geometry for the output air flow rate.

### Claim 2 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1, further comprising a plurality of sensors to monitor acoustic waves in the nacelle in order to calculate, in real time, the control of the rotary element.

### Claim 3 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1, further comprising a controller configured to obtain information regarding the angle of rotation of the motorization of the turbojet engine.

### Claim 4 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1, wherein the rotary element is formed by a rotor comprising windows for passage of the output air flow rate of the rotary element.

### Claim 5 (depends on 4)

The active device for attenuating tonal acoustic emissions according to claim 4, wherein the rotor forms a drum rotating along its axis and having a transverse face equipped with air inlet holes in the drum, the windows being distributed over a cylindrical contour of the drum.

### Claim 6 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1, wherein the rotary element is driven by an electric motor or a pneumatic motor and further includes an electromagnetic speed regulation brake.

### Claim 7 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1, wherein the active device includes a plurality of flow rate control valves arranged upstream of the rotary element.

### Claim 8 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1 further comprising a diffuser at a pulsed flowing outlet downstream of the rotor element, wherein the diffuser is secured to a wall of the aircraft turbojet engine to diffuse the attenuating air flow rate in front of the wall.

### Claim 9 (depends on 1)

The active device for attenuating tonal acoustic emissions according to claim 1 further comprising an air flow rate control valve.

### Claim 10 (depends on 1)

An aircraft turbojet nacelle having the active device for attenuating tonal acoustic emissions according to claim 1.

### Claim 11 (depends on 10)

The aircraft turbojet nacelle according to claim 10, wherein the circulation conduit comprises an air inlet taken from a primary flow of the motorization of the turbojet engine.

### Claim 12 (depends on 10)

The aircraft turbojet nacelle according to claim 10, wherein the circulation conduit comprises an air inlet taken on a secondary flow given by a fan of a bypass turbojet engine.

### Claim 13 (depends on 10)

The aircraft turbojet nacelle according to claim 10, wherein the circulation conduit comprises an air inlet taken on a source comprising a compressor, a booster, or a compressed air accumulator.

### Claim 14 (depends on 10)

The aircraft turbojet nacelle according to claim 10, further comprising a plurality of active devices for attenuating tonal acoustic emissions disposed in a ring.