Abstract: Methods and systems for a gas turbine engine comprising a modulated bleed valve are provided. The gas turbine engine may comprise a turbine nozzle coupled to a controller, a modulated bleed valve in communication with the controller, and a tangible, non-transitory memory providing instructions to the controller to perform operations. The operations may include receiving parameter values from the parameter sensor at various times, determining desired bleed airflows to flow through the modulated bleed valve at various times, and/or commanding the modulated bleed valve to assume an open configuration or a closed configuration at various times. The modulated bleed valve may be configured to allow bleed airflow to bypass a nozzle choke area of the turbine nozzle and join a nozzle airflow.

Abstract: Methods and systems for a gas turbine engine comprising a modulated bleed valve are provided. The gas turbine engine may comprise a turbine nozzle coupled to a controller, a modulated bleed valve in communication with the controller, and a tangible, non-transitory memory providing instructions to the controller to perform operations. The operations may include receiving parameter values from the parameter sensor at various times, determining desired bleed airflows to flow through the modulated bleed valve at various times, and/or commanding the modulated bleed valve to assume an open configuration or a closed configuration at various times. The modulated bleed valve may be configured to allow bleed airflow to bypass a nozzle choke area of the turbine nozzle and join a nozzle airflow.

Abstract: An aircraft system includes a component configured to operate with a minimum power demand. The aircraft system also includes an auxiliary power unit including an engine. The auxiliary power unit is configured to power the component and to operate the engine in a plurality of operating modes including a power mode and a standby mode. The auxiliary power unit generates a first power output at least equal to the minimum power demand during the power mode. The auxiliary power unit generates a second power output less than the minimum power demand during the standby mode.

Abstract: An example auxiliary power unit bracket includes, among other things, a gearbox mounting face and a compartment mounting face, the gearbox mounting face configured to attach to an auxiliary power unit gearbox below a sump level line, the compartment mounting face configured to attach to a portion of an auxiliary power unit compartment above the sump level line.

Abstract: A gas turbine engine has a nose cone with a nose cone upstream end and an inlet housing including a plurality of separate flow paths at a housing upstream end which is downstream of the nose cone upstream end. The inlet housing includes a mixing portion downstream of the housing upstream end which mixes airflow from the separate flow paths, such that the airflow is generally around 360 degrees of a rotational axis of the gas turbine engine. A rotor and a turbine drive a shaft to drive the rotor with the shaft including a bearing mounted at a location downstream of the nose cone upstream end.

Abstract: A turbine wheel is disposed about an axis and has a back face including a plurality of lobes disposed about a periphery of the back face. The lobes define scalloped areas therebetween. The scalloped areas are further defined by a radius BR2 that blends into a first lobe and into a radius BR1 that also blends into a flat area.

Abstract: An aircraft system includes a component configured to operate with a minimum power demand. The aircraft system also includes an auxiliary power unit including an engine. The auxiliary power unit is configured to power the component and to operate the engine in a plurality of operating modes including a power mode and a standby mode. The auxiliary power unit generates a first power output at least equal to the minimum power demand during the power mode. The auxiliary power unit generates a second power output less than the minimum power demand during the standby mode.

Abstract: Systems and methods for controlling an auxiliary power unit (APU) are provided. The systems and methods may comprise detecting an operating condition of the APU, determining an optimal APU frequency in response to the operating condition, and setting an angular velocity of the APU to the optimal APU frequency.

Abstract: An exhaust system for an APU in a gas turbine engine aircraft having a tail cone in which exhaust noise is reduced. An APU exhaust liner is attached to the APU and extending to an oval cutout at the tail cone The liner has a first constant cross section from the APU to a point proximate the tail cone, and a second, increasing cross section from the point proximate the tail cone to the liner cutout. The liner is turned toward the side of the tail. The liner cutout is further enlarged with at least one larger cutout.

Abstract: Systems and methods for controlling an auxiliary power unit (APU) are provided. The systems and methods may comprise detecting an operating condition of the APU, determining an optimal APU frequency in response to the operating condition, and setting an angular velocity of the APU to the optimal APU frequency.

Abstract: A supercharge compound configuration of a forced induction intake and/or breather system for an internal combustion engine is provided. The system may be configured to improve the power output of an internal combustion engine when considered against similar internal combustion engines with conventional forced induction systems. The supercharge compound configuration may comprise a turbine that may be driven by the exhaust of the internal combustion engine. The turbine may also be operatively and/or directly coupled to a gearbox and/or a compressor.

Abstract: An example method of sealing an interface within a gas turbine engine includes holding a sealing ring arrangement relative to a turbine nozzle using a flange extending from a combustor liner. The method further includes urging the sealing ring arrangement toward a sealed relationship with the turbine nozzle.

Abstract: An exhaust duct through which an exhaust gas jet from a gas turbine engine flows comprises a duct wall, an inlet, an outlet and an eductor. The inlet, through which the exhaust gas jet enters the exhaust duct, is positioned at an upstream end of the exhaust duct. The outlet, through which the exhaust gas jet exits the exhaust duct, is positioned at a downstream end of the exhaust duct. The eductor is positioned proximate the downstream end. In one embodiment, the eductor comprises a perforated wall segment of the duct wall through which ambient air from outside of the duct wall is permitted to enter the exhaust duct. In yet another embodiment, the eductor is diverging.

Abstract: An exemplary pressure influencing assembly for an aircraft auxiliary system an inlet opening to an aircraft auxiliary system and an exhaust opening from the aircraft auxiliary system. Both the inlet opening and the exhaust opening face at least partially radially away from an axis. At least some of the inlet opening is circumferentially aligned with at least some of the exhaust opening relative to the axis.

Abstract: A gas turbine engine has a nose cone with a nose cone upstream end and an inlet housing including a plurality of separate flow paths at a housing upstream end which is downstream of the nose cone upstream end. The inlet housing includes a mixing portion downstream of the housing upstream end which mixes airflow from the separate flow paths, such that the airflow is generally around 360 degrees of a rotational axis of the gas turbine engine. A rotor and a turbine drive a shaft to drive the rotor with the shaft including a bearing mounted at a location downstream of the nose cone upstream end.

Abstract: An auxiliary power unit bracket, according to an exemplary aspect of the present disclosure includes, among other things, a gearbox mounting face and a compartment mounting face, the gearbox mounting face configured to attach to an auxiliary power unit gearbox below a sump level line, the compartment mounting face configured to attach to a portion of an auxiliary power unit compartment above the sump level line.

Abstract: An exhaust system for an APU in a gas turbine engine aircraft having a tail cone in which exhaust noise is reduced. An APU exhaust liner is attached to the APU and extending to an oval cutout at the tail cone The liner has a first constant cross section from the APU to a point proximate the tail cone, and a second, increasing cross section from the point proximate the tail cone to the liner cutout. The liner is turned toward the side of the tail. The liner cutout is further enlarged with at least one larger cutout.

Abstract: A turbine wheel is disposed about an axis and has a back having a separator disposed thereon, an inner undercut disposed between the separator and the axis, and an outer undercut disposed between the separator and an outer periphery of the back face. The inner undercut is defined by a first radius blending toward the axis and into a first flat section, and further defined by a second radius blending into the first flat section and into the separator.

Abstract: A turbine blade comprises an airfoil having a pressure side and a suction side, and extending from a leading edge to a trailing edge. The airfoil has a tip remote from a mounting root, and a pocket extending inwardly of the tip. The pocket has spaced walls with one wall associated with the pressure side of the airfoil, and an opposed wall associated with the suction side. A pin extends across the pocket and connects the opposed walls. A slot is formed in the pin at a location intermediate ends of the pin which connect to the opposed walls. A method for identifying a location for the pin along a distance between a leading edge and a trailing edge of the pocket utilizes a modal analysis, and seeks to find a location where both a reaction force and a moment are lower than they might be at other locations.

Abstract: An exemplary diffuser includes a plurality of air flow channels defined by a corresponding plurality of vanes. The vanes extend from a first side of the diffuser and define a width of the air flow channel between the corresponding plurality of vanes. The first side has at least one tapered surface extending from an inner radial position to an outer radial position. The distance between a tapered surface and a top side of the plurality of the vanes defines a depth of the air flow channel. The width of the air flow channel varies relative to the depth of the air flow channel along the length of the air flow channel.