According to one embodiment, a noise reduction apparatus includes a speaker, a generator and a controller. The speaker outputs control sound. The generator generates self-excited sound. The controller controls a phase and an amplitude of the control sound to reduce noise generated from a noise source, based on the control sound and the self-excited sound that is synchronized with the control sound.

An aerofoil component (10) defining an in use leading edge (16) and a trailing edge (18), the leading edge (16) comprising at least one serration (22) defining a sawtooth profile projecting in a generally upstream direction, each serration (22) comprising a plurality of rectangular-wave projections (26) extending in an upstream chordwise direction from the sawtooth profile.

A silencer duct that may be part of, for example, a turbomachine inlet and may include a duct body, and a silencer element extending axially through the duct body. A first portion of a coupler may extend axially from a first side of the duct body. A second portion of a coupler may extend axially from a second side of the duct body. At least one of the first portion of the coupler and the second portion of the coupler are configured to couple to at least one of an adjacent silencer duct and an inlet.

A fan blade includes a blade body and a shape memory alloy actuator. The blade body has a pressure side disposed opposite a suction side. Each of the pressure side and the suction side extends radially from a root towards a tip and extends axially from a leading edge towards a trailing edge. The blade body defines a passageway that is disposed between the pressure side and the suction side. The shape memory alloy actuator is received within the passageway and is operatively connected to the blade body.

According to one embodiment, a rotor-stator blade interference noise reduction system includes a plurality of rotor blades rotating around a center axis, a plurality of stator blades facing the plurality of rotor blades and being equal in number to the plurality of rotor blades, a plurality of speakers installed approximately along a rotor blade plane defined by the plurality of rotor blades rotating and generating control sound, and an evaluation microphone, in which a distance from the evaluation microphone to one of the plurality of speakers, a distance from the evaluation microphone to another of the plurality of speakers, and a distance from the evaluation microphone to the center axis, are approximately equal.

According to one embodiment, a noise reduction apparatus includes a speaker, a generator and a controller. The speaker outputs control sound. The generator generates self-excited sound. The controller controls a phase and an amplitude of the control sound to reduce noise generated from a noise source, based on the control sound and the self-excited sound that is synchronized with the control sound.

According to one embodiment, a rotor-stator blade interference noise reduction system includes a plurality of rotor blades rotating around a center axis, a plurality of stator blades facing the plurality of rotor blades and being equal in number to the plurality of rotor blades, a plurality of speakers installed approximately along a rotor blade plane defined by the plurality of rotor blades rotating and generating control sound, and an evaluation microphone, in which a distance from the evaluation microphone to one of the plurality of speakers, a distance from the evaluation microphone to another of the plurality of speakers, and a distance from the evaluation microphone to the center axis, are approximately equal.

For example, a controller of an Active Acoustic Control (AAC) system may be configured to process input information including AAC configuration information, and a plurality of noise inputs representing acoustic noise at a plurality of noise sensing locations. For example, the controller may be configured to process the input information to determine a sound control pattern to control sound within a sound control zone based on the plurality of noise inputs. For example, the controller may include a Neural-Network (NN) trained to generate an NN output based on an NN input, wherein the NN input is based on the AAC configuration information. For example, the controller may be configured to generate the sound control pattern based on the NN output, and to output the sound control pattern to one or more acoustic transducers.

In one embodiment, a method for reducing noise generated by inlet guide vane (IGV) wake and rotor interaction in a turbine engine, the noise having acoustic energy substantially dominating at one or two frequencies, comprises altering noise frequencies to distribute the acoustic energy into a broadband frequency spectrum by ejecting fluid flows from holes located on a side near a trailing edge of at least one of a plurality of inlet guide vanes (IGVs), toward a rotor downstream of the IGVs to merge with an air flow guided by the side of the at least one of the IGVs for interfering with said IGV wake and rotor interaction.

A piezo-actuated valve, system, and method of exciting gas turbine turbomachinery are provided. The piezo-actuated valve includes a valve body extending along a first axis between a first and second end, the valve body defining a first opening near the first end, a second opening near the second end, a third opening centrally located on the valve body, and a valve cavity between the first opening and the second opening, a tube connected to the third opening and extending from the valve body along a second axis transverse to the first axis, a shuttle valve assembly slidably disposed within the valve body, wherein the shuttle valve slides between the first end to a first stopper and the second end to a second stopper, a first piezo injector having an injector tip extending through the first opening, and a second piezo injector having an injector tip extending through the second opening.