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: A gas turbine engine includes a rotatable first shaft, a first disk connected to the first shaft, a second disk connected to the first shaft, a combustor radially outward from the first disk and the second disk, and a heat exchanger connected to the combustor aft of the second disk. The first disk includes a row of low pressure compressor blades and a row of high pressure turbine blades connected to a radially outer end of the row of low pressure compressor blades. The second disk includes a row of high pressure compressor blades and a row of low pressure turbine blades connected to a radially outer end of the row of high pressure compressor blades.

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: A hybrid propulsion system includes a gas turbine engine having a low speed spool, a high speed spool, and a combustor. The low speed spool includes a low pressure compressor and a low pressure turbine, and the high speed spool includes a high pressure compressor and a high pressure turbine. The hybrid propulsion system also includes a motor configured to augment rotational power of the high speed spool, a flow modulation device configured to control a combustor bypass air flow around the combustor to the turbine section, and a controller. The controller is operable to determine a mode of operation, apply supplemental power to the high speed spool using the motor, modulate the combustor bypass air flow using the flow modulation device, and adjust a fuel-air ratio at the combustor based on modulation of the combustor bypass air flow and the supplemental power applied to the high speed spool.

Abstract: A gas turbine engine includes a rotatable first shaft, a first disk connected to the first shaft, a second disk connected to the first shaft, a combustor radially outward from the first disk and the second disk, and a heat exchanger connected to the combustor aft of the second disk. The first disk includes a row of low pressure compressor blades and a row of high pressure turbine blades connected to a radially outer end of the row of low pressure compressor blades. The second disk includes a row of high pressure compressor blades and a row of low pressure turbine blades connected to a radially outer end of the row of high pressure compressor blades.

Abstract: A system for light-off detection in a gas turbine engine according to an example of the present disclosure includes, among other things, a computing device that has memory and a processor. The computing device is configured to execute a data module and a comparison module. The data module is programmed to access data that corresponds to a present rotational speed of a gas turbine engine component. The comparison module is programmed to cause an indicator to be generated in response to determining that an acceleration rate relating to the present rotational speed meets at least one predetermined acceleration threshold, the indicator relating to an engine light-off condition.

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: 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: A gas turbine engine inlet door control system includes an actuator, an engine controller and a door controller. The actuator opens and closes an inlet door of a gas turbine engine. The engine controller determines an intermediate door position based upon one or more engine start factors. The door controller operates the actuator to open the inlet door to the intermediate door position based on the one or more engine start factors.

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: A system and method are provided for determining the health of an engine. The method includes a plurality of standard noise spectra collected from engines with known defects. A noise spectrum of the engine being monitored is sensed and compared to the plurality of standard noise spectra from the engines with known defects. From the comparison, a type and a degree of defect is identified based upon the comparison.

Abstract: An embodiment of the present invention is a gas turbine engine including a compressor, a turbine, an annular combustor, an exhaust duct, a first engine shaft bearing, and a second engine shaft bearing. The turbine has an axial flow direction toward the compressor. The combustor has an axial flow direction away from the compressor. The exhaust duct is disposed between the compressor and the combustor. The first engine shaft bearing is disposed on an axial side of the compressor opposite the turbine. The second engine shaft bearing is disposed on an axial side of the turbine opposite the compressor.

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: A load compressor includes an air inlet and an outlet, and a surge control valve positioned on the outlet. The surge control valve serves to selectively pass air to a downstream use, or to be dumped to atmosphere. A control for the compressor and the surge control valve is also included. The control is provided with a variable indicative of the operation of the load compressor, the variable being indicative of a movement to transient operation of the compressor. The control is provided with a low surge control limit for steady state operation. The control is also provided with a higher surge control limit, and switches to use of the higher surge control limit if the variable being monitored is seen to change beyond a particular threshold. The low and higher surge control limits are utilized to control the opening of the surge control valve. An aircraft air supply system and a method are also disclosed.

Abstract: A system and method are provided for determining the health of an engine. The method includes a plurality of standard noise spectra collected from engines with known defects. A noise spectrum of the engine being monitored is sensed and compared to the plurality of standard noise spectra from the engines with known defects. From the comparison, a type and a degree of defect is identified based upon the comparison.

Abstract: A compressor impeller includes a hub and a plurality of blades. The hub is formed of first forged portion and a second forged portion that are bonded together. The first forged portion is comprised of a first alloy and the second forged portion is comprised of a second alloy that has lower fracture toughness than the first alloy. The blades are integral with and extend from the hub and are formed from the first forged portion. The hub is formed from both the first forged portion and the second forged portion.