Abstract: A system for controlling a start sequence of a gas turbine engine includes an electronic engine control system, a thermal model, memory, a model for determining a time period (tmotoring), and a controller. The thermal model synthesizes a heat state of the gas turbine engine. The memory records the current heat state at shutdown and a shutdown time of the gas turbine engine. The model for determining the time period is for motoring the gas turbine engine at a predetermined speed Ntarget that is less than a speed to start the gas turbine engine, where tmotoring is a function of the heat state recorded at engine shutdown and an elapsed time of an engine start request relative to a previous shutdown time. The controller modulates a starter valve to maintain the gas turbine engine within a predetermined speed range of NtargetMin to NtargetMax for homogenizing engine temperatures.

Abstract: A system for controlling blade tip clearances in a gas turbine engine may comprise an active clearance control system and a controller in operable communication with the active clearance control system. The controller may be configured to identify a cruise condition, reduce a thrust limit of the gas turbine engine to a de-rated maximum climb thrust, determine a first target tip clearance based on the de-rated maximum climb thrust, and send a command signal correlating to the first target tip clearance to the active clearance control system.

Abstract: A variable-geometry system for a gas turbine engine can be used to improve operations in various inclement weather conditions. This may be achieved by varying the orientation of an element in a gas turbine engine flowpath in response to a comparison between sensor-gathered parameter data and stored parameter values and ranges using a pre-programmed algorithm. The orientation of the element may be infinitely variable within a range of orientations.

Abstract: A dual-use air turbine system for a gas turbine engine of an aircraft is provided. The dual-use air turbine system includes a variable area air turbine mechanically linked to a spool of the gas turbine engine through a multi-speed gear set. The dual-use air turbine system also includes a plurality of valves in pneumatic ducting operable to direct an engine start air flow through an inlet of the variable area air turbine and drive rotation of the spool during an engine start mode of operation. The valves are further operable to direct an engine bleed air flow from a compressor section of the gas turbine engine through the inlet of the variable area air turbine and drive rotation of the spool during an environmental control system active mode of operation.

Abstract: A compressor section for use in a gas turbine engine comprises a compressor rotor having a hub and a plurality of blades extending radially outwardly from the hub and an outer housing surrounding an outer periphery of the blades. A tap taps air at a radially outer first location, passing the tapped air through a heat exchanger, and returning the tapped air to an outlet at a second location which is radially inward of the first location, to provide cooling air adjacent to the hub. A gas turbine engine is also disclosed.

Abstract: A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a control unit to command the gas turbine engine to perform one of a rolling takeoff procedure and an unrestricted takeoff procedure. The control unit is configured command the gas turbine engine to perform the rolling takeoff procedure when information required to determine whether the unrestricted takeoff procedure can be performed is unavailable to the control unit.

Abstract: A system and a method for adjusting an angle of at least one stator vane of a low pressure compressor (LPC) of a two spool gas turbine engine is disclosed. Variable stator vanes are rotatably coupled to a stationary case in one of the stages of the LPC. An actuator is coupled to at least one of the variable stator vanes for imparting rotation of the stator vane about a radius of the case. Various coupling or linkage arrangements may be made so that rotation of one vane results in rotation of the other vanes disposed along the case. The controller includes the stored constraints, the ability to estimate operating condition, and the ability to estimate optimum targets.

Abstract: A system for starting a gas turbine engine of an aircraft is provided. The system includes a pneumatic starter motor, a discrete starter valve switchable between an on-state and an off-state, and a controller operable to perform a starting sequence for the gas turbine engine. The starting sequence includes alternating on and off commands to an electromechanical device coupled to the discrete starter valve to achieve a partially open position of the discrete starter valve to control a flow from a starter air supply to the pneumatic starter motor to drive rotation of a starting spool of the gas turbine engine below an engine idle speed, where the controller modulates a duty cycle of the discrete starter valve via pulse width modulation.

Abstract: A bowed rotor start mitigation system for a gas turbine engine is provided. The bowed rotor start mitigation system includes a variable position starter valve and a controller. The controller is operable to dynamically adjust the variable position starter valve to deliver a starter air supply to a starter to drive rotation of a starting spool of the gas turbine engine according to a dry motoring profile that continuously varies a rotor speed of the starting spool up to a point below a critical rotor speed.

Abstract: A gas turbine engine comprises a housing having an inlet leading to a fan rotor. A bypass door is mounted upstream of the inlet to the fan rotor, and is moveable away from a non-bypass position to a bypass position to selectively bypass boundary layer air vertically beneath the engine. An aircraft is also disclosed.

Abstract: A system for controlling a start sequence of a gas turbine engine includes an electronic engine control system, a thermal model, memory, a model for determining a time period (fmotoring), and a controller. The thermal model synthesizes a heat state of the gas turbine engine. The memory records the current heat state at shutdown and a shutdown time of the gas turbine engine. The model for determining the time period is for motoring the gas turbine engine at a predetermined speed Ntarget that is less than a speed to start the gas turbine engine, where tmotoring is a function of the heat state recorded at engine shutdown and an elapsed time of an engine start request relative to a previous shutdown time. The controller modulates a starter valve to maintain the gas turbine engine within a predetermined speed range of NtargetMin to NtargetMax for homogenizing engine temperatures.

Abstract: A total air temperature (TAT) sensor assembly is disclosed. The assembly includes a housing that accommodates a temperature sensor. The assembly also includes a first airfoil that includes a leading end and a trailing end and a second airfoil that includes a leading end and a trailing end. The first and second airfoils are disposed in a spaced-apart fashion that defines a curved passageway so incoming air can flow between the first and second airfoils before engaging the housing and the temperature sensor. The trailing ends of the airfoils are disposed on opposite sides of the housing and spaced apart from the housing to permit air flowing through the curved passageway to pass the housing.

Abstract: A system for starting a gas turbine engine of an aircraft is provided. The system includes a pneumatic starter motor, a discrete starter valve switchable between an on-state and an off-state, and a controller operable to perform a starting sequence for the gas turbine engine. The starting sequence includes alternating on and off commands to an electromechanical device coupled to the discrete starter valve to achieve a partially open position of the discrete starter valve to control a flow from a starter air supply to the pneumatic starter motor to drive rotation of a starting spool of the gas turbine engine below an engine idle speed.

Abstract: A compressor of a gas turbine engine includes at least one rotor, and at least one stator, wherein the at least one stator includes a water channel wall located on a surface of the stator, wherein the water channel wall is configured to direct water away from a center line of the turbine engine and is located an offset distance from an outside wall of the compressor, wherein the offset distance is zero percent to twenty percent of the span of the stator.

Abstract: A compressor section of a gas turbine engine includes a bleed port having a flow splitter therein so as to define a downstream bleed channel having a downstream inlet and an upstream bleed channel having an upstream inlet that is positioned radially outward from the downstream inlet.

Abstract: A gas turbine engine includes an engine core includes at least one compressor, a combustor downstream of the compressor, and at least one turbine downstream of the combustor. A primary flowpath fluidly connects each of the compressor, the combustor, and the turbine. At least one particle extraction duct has an extraction duct inlet connected to the primary flowpath fore of the compressor and an extraction duct outlet connected to a bypass flowpath.

Abstract: A gas turbine engine including a compressor, a combustor fluidly connected to the compressor via a primary flowpath, a turbine fluidly connected to the combustor via the primary flowpath, an engine controller communicatively coupled to at least one sensor in the gas turbine engine, the controller including a non-transitory memory and a processor, and the at least one sensor including an inlet temperature and/or pressure sensor, wherein the sensor is disposed aft of a fan.

Abstract: A dual-use air turbine system for a gas turbine engine of an aircraft is provided. The dual-use air turbine system includes a variable area air turbine mechanically linked to a spool of the gas turbine engine through a multi-speed gear set. The dual-use air turbine system also includes a plurality of valves in pneumatic ducting operable to direct an engine start air flow through an inlet of the variable area air turbine and drive rotation of the spool during an engine start mode of operation. The valves are further operable to direct an engine bleed air flow from a compressor section of the gas turbine engine through the inlet of the variable area air turbine and drive rotation of the spool during an environmental control system active mode of operation.

Abstract: A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a control unit to command the gas turbine engine to perform one of a rolling takeoff procedure and an unrestricted takeoff procedure. The control unit is configured command the gas turbine engine to perform the rolling takeoff procedure when information required to determine whether the unrestricted takeoff procedure can be performed is unavailable to the control unit.

Abstract: A bleed air system for an aircraft includes a turbocompressor including a turbine portion coupled to drive a compressor portion. The compressor portion includes a compressor inlet and a compressor air discharge. The turbine portion includes a turbine inlet and a turbine discharge. A passage delivers air to the compressor inlet from one or more locations of an engine. A passage delivers air to the turbine inlet from at least one or more locations of the engine. A passage receives air from the compressor discharge selectively delivered to one or more locations of the engine. An outlet passage receives air from the turbine discharge communicating airflow to an aircraft system. A controller directs inlet and discharge airflow of the compressor portion and the turbine portion to control operation of the turbocompressor. A gas turbine engine and a method are also disclosed.