Abstract: A turbine apparatus comprises a rotor with a hub section defined about a rotational axis and a plurality of blades attached to the hub section. The plurality of blades comprises a first group having a first angular spacing in a first circumferential sector of the rotor, and a second group having a second angular spacing in a second circumferential sector of the rotor. The first angular spacing is different from the second angular spacing, and the rotor blades are asymmetric about the rotational axis.

Abstract: An exhaust silencer assembly includes an exhaust duct and an exhaust silencer. The exhaust silencer is disposed about the exhaust duct and has a plurality of solid baffles and at least one perforated baffle The exhaust silencer assembly is disposed downstream of an auxiliary power unit and at least partially attenuates the downstream noise of the combustion gases that result from operation of the auxiliary power unit. In one embodiment, at least one of the plurality of solid baffles is disposed to extend axially between generally radially extending solid baffles, perforated baffle(s), or partially perforated baffles. The axially extending solid baffle allows for cavity depth variation in the silencer to optimize tuning of particular frequencies from the auxiliary power unit.

Abstract: An inlet plenum for a compressor that suppresses acoustic shock waves generated by the compressor, which inlet plenum has an inlet duct with a wall that surrounds an air flow path between a mouth of the inlet plenum and the compressor, comprises: at least one cavity that penetrates an inner surface of the wall, circumscribes the inner surface generally transversely to the air flow path and has a position along the air flow path that is generally coincident with at least one constructive interference peak of the acoustic shock waves along the inner surface; a width of the cavity along the direction of the air flow that is less than or equal to the wavelength of at least one of the acoustic shock waves; and a depth of the cavity generally perpendicular to the direction of the air flow that approximates a multiple of a quarter wavelength of at least one of the acoustic shock waves.

Abstract: An APU has a gas turbine engine and a starter generator to be selectively driven by the gas turbine engine. A sensor senses windmilling of components associated with the starter generator. A lock feature limits rotation within the starter generator when windmilling is sensed. A method of operation is also disclosed.

Abstract: An example auxiliary power unit air inlet assembly includes a noise attenuating component disposed within a conduit. The conduit is configured to communicate a first flow of fluid to an auxiliary power unit. A second flow of fluid is communicated to the noise attenuating component. The second flow of fluid limits formation of ice in the conduit. The first flow of fluid is different than the second flow of fluid.

Abstract: A heat exchanger has a first passage to be connected to a source of fuel. The heat exchanger has an outlet to communicate the fuel downstream. A second passage connects to a source of air. The air passes adjacent to the first passage to heat fuel in the first passage. A jet pump is positioned downstream of the second passage to receive air from the second passage. The jet pump includes a tap connected to a housing compartment to drain fluid from the compartment. A method is also disclosed.

Abstract: An exhaust eductor for a gas turbine engine comprises: an engine exhaust chamber with an exhaust chamber inlet that receives engine exhaust from the gas turbine engine and an exhaust chamber outlet that discharges the engine exhaust to establish an exhaust gas flow through the engine exhaust chamber; an air chamber with an air inlet that receives ambient air external to the gas turbine engine; and a mixing baffle that couples the air chamber to the engine exhaust chamber, comprising a first side adjacent the air chamber, a second side adjacent the exhaust chamber, multiple apertures through the mixing baffle that extend from the first side to the second side of the mixing baffle, each aperture having a corresponding canopy that extends from an upstream end of the aperture along the second side of the mixing baffle into the exhaust gas flow for at least a portion of the length of the aperture, to establish an air flow from the air inlet of the air chamber into the exhaust gas flow.

Abstract: A door system for an inlet comprises: a first door hinged to face a first direction that covers a portion of the inlet; a second door, adjacent to the first door, hinged to face a second direction opposite the first direction that covers the remainder of the inlet; and an actuator system that operates the doors in selectable door system states comprising: first door closed and second door closed; first door opened and second door closed; first door opened and second door opened; and first door closed and second door opened.

Abstract: An inlet door assembly includes an inlet door rotatable about an axis of rotation.

Abstract: An inlet silencer for an air inlet in a housing, which housing contains a source of high frequency noise radiated by an air intake for the source of high frequency noise, comprises: a plenum that extends longitudinally within the housing that couples the air inlet in an upstream region of the plenum to the air intake for the source of high frequency noise in a downstream region of the plenum; a partition that extends laterally within the plenum between the upstream region of the plenum and the downstream region of the plenum; at least one channel that penetrates longitudinally through the partition that has a gap across its inner surface that approximates one wavelength of at least one fundamental frequency of high frequency noise that the source of high frequency noise generates; and acoustic damping material that lines the inner surface of the channel.

Abstract: An example auxiliary power unit (APU) exhaust silencer includes cooling features to protect the outer skin and other components from heat generated by gases passing through an exhaust duct. Cooling air flow through a cooling air passage in thermal contact with the exhaust silencer carries heat away from other nearby components and the aircraft skin.

Abstract: An exhaust silencer assembly comprising a casing having an exhaust gas entrance opening, an exhaust gas exit opening, and a cooling air inlet opening, and an acoustic-attenuating porous liner disposed within an interior chamber of the casing, thereby dividing the interior chamber into an inner region located between the exhaust gas entrance opening and the exhaust gas exit opening, and an outer region located between the acoustic-attenuating porous liner and the casing, where the cooling air inlet opening is located at the outer region.

Abstract: An inlet door assembly includes an inlet door rotatable about an axis of rotation.

Abstract: A fuel control system uses a fuel pump powered by a variable speed pump motor controlled by a closed loop electronic feedback system that tracks motor speed and corrects fuel pump motor speed so that the fuel pump delivers flow according to a desired flow schedule based on the pressure feedback from the manifold.

Abstract: An exhaust silencer assembly comprising a casing having an exhaust gas entrance opening, an exhaust gas exit opening, and a cooling air inlet opening, and an acoustic-attenuating porous liner disposed within an interior chamber of the casing, thereby dividing the interior chamber into an inner region located between the exhaust gas entrance opening and the exhaust gas exit opening, and an outer region located between the acoustic-attenuating porous liner and the casing, where the cooling air inlet opening is located at the outer region.

Abstract: An exhaust silencer assembly for use with a gas turbine engine, the exhaust silencer assembly comprising an exhaust duct extension disposed downstream from an exhaust diffuser of the gas turbine engine, and an exhaust silencer disposed downstream from the exhaust duct extension. The exhaust duct extension has a length that is at least about 50% of an inner diameter of the exhaust duct extension.

Abstract: An exhaust duct system for a gas turbine engine that mounts within a tail cone of an aircraft, comprises an exhaust exit that exits one side of the tail cone offset from the axial centreline of the tail cone and an exhaust duct that couples the engine to the offset exhaust exit, with a straight section of the exhaust duct extending from the exhaust exit for a length that corresponds to at least one diameter of the exhaust duct.