Abstract: A seal assembly includes a first feather seal with a first cooling hole extending through the first feather seal. The seal assembly also includes a second feather seal adjacent to the first feather seal. The second feather seal includes a second cooling hole extending through the second feather seal. The first cooling hole is positioned over at least a portion of the second cooling hole.

Abstract: A control system for limiting a power turbine torque of a gas turbine engine is disclosed. In various embodiments, the control system includes an engine control module configured to output an effector command signal to a gas generator of the gas turbine engine; a power turbine governor module configured to output to the engine control module a power turbine torque request signal; and a power turbine torque limiter module configured to output to the power turbine governor module a power turbine speed rate signal to limit a power turbine speed overshoot of the gas turbine engine.

Abstract: An after-fan system for an engine may comprise an after-fan turbine an electrical generator operationally coupled to the after-fan turbine, and an electric motor electrically coupled to the electrical generator. The electrical generator may be configured to generate an electrical current in response to rotation of the after-fan turbine. The electric motor may be configured to generate torque.

Abstract: A nacelle assembly of a gas turbine engine includes an annular structure defining a central axis, and having a radially inward surface and a radially outward surface, the radially inward surface at least partially defining a bypass duct. An aft portion of the radially inward surface at least partially defines an axially extending convergent-divergent exit nozzle. A secondary nozzle flap is radially spaced from the aft portion of the radially inward surface. The secondary nozzle flap and the aft portion of the radially inward surface define a secondary bypass duct therebetween. The secondary nozzle flap is operably connected to the annular structure such that the secondary nozzle flap is selectably movable relative to the aft portion of the radially inward surface, thereby changing a cross-sectional area of a secondary bypass duct exit.

Abstract: A gas turbine engine includes an engine spool with a turbine section, a propeller, a motor, and a variable drive arrangement. The variable drive arrangement mechanically couples the engine spool to the propeller, and includes a first gear connection rotationally coupled to the propeller, a second gear connection rotationally coupled to the engine spool, and a sprag clutch rotationally coupled to the first gear connection. The sprag clutch is configured to passively decouple the motor from the first gear connection when a torque input from the engine spool exceeds a torque input from the motor, and is configured to passively couple the motor to the first gear connection when the torque input from motor exceeds a torque input from the engine spool.

Abstract: A vane arm connection system for a gas turbine engine includes a vane stem having a head with flat contact surfaces; a vane arm having a claw, the claw having opposed arms having inwardly facing surfaces engaging the flat contact surfaces of the head; and a torque transfer member having a body defining an opening for engaging the flat contact surfaces of the head of the vane stem, and at least one arm extending from the body to contact the claw, whereby load from torque is transferred away from the inwardly facing surfaces.

Abstract: A nickel-phosphorus alloy coating comprising a substrate having a surface; a nickel phosphorus alloy coating plated to the surface, the nickel phosphorus alloy consisting of phosphorus from 15.0 wt. percent to 20.9 wt. percent.

Abstract: A rotor disk assembly for a gas turbine engine includes a rotor disk that defines an axis, the rotor disk comprising a slot within a rim of the disk and a spacer within the slot, the spacer having a clearance feature sized to permit rotation of a rotor blade from an insertion position to an installed position.

Abstract: A surge control system includes a rotor system with at least one compressor section and at least one turbine section operably coupled to a shaft. The surge control system also includes sensors configured to collect sensor data from the rotor system, an electric motor operably coupled to the rotor system, and a controller. The controller is operable to detect surge event from the sensor data, determine an amount of power to apply to the rotor system, and increase the amount of power provided to the rotor system to recover from the surge event.

Abstract: A rotor disk assembly for a gas turbine engine includes a rotor disk that defines an axis; and a damper pivot support that extends from a rim of the rotor disk, the damper pivot support comprising an aperture that defines a pivot axis parallel to the axis. A method to dampen a rotor blade of a gas turbine engine, includes independently pivoting a first damper and a second damper of a damper assembly about the pivot axis to respectively contact a first blade and a second blade in response to centrifugal force below a platform of the respective first blade and second blade.

Abstract: A rotor blade for a gas turbine engine including an inner ply layer group that at least partially defines a base of a root region; a platform around the inner ply layer group that at least partially defines the base; and a platform over-wrap around the platform, the platform over-wrap at least partially defines the base.

Abstract: An engine control device may comprise a processor and a memory. The engine control device may be configured to modify a fuel flow based on a density of the fuel proximate a fuel nozzle. The engine control device may include a densimeter embedded in, or disposed proximate, the engine control device. The engine control device may include a temperature sensor embedded in, or disposed proximate, the engine control device. The engine control device may be electrically coupled to a fuel valve and/or configured to modulate the fuel valve based on a density of the fuel at the fuel valve.

Abstract: A cooling system for a plurality of conductive cables in a gas turbine engine includes a cooling source and an electric motor disposed in a tail cone. The cooling source may comprise an electric fan or an oil pump. The cooling source may be configured for active cooling of the plurality of conductive cables. The electric fan may be in fluid communication with ambient air during operation of the gas turbine engine.

Abstract: A hybrid electric gas turbine engine includes a fan section having a fan, a turbine section having a turbine drivably connected to the fan through a main shaft that extends along a central longitudinal axis, a gas generating core extending along a first axis that is radially offset from the central longitudinal axis, a first electric motor drivably connected to the main shaft, wherein the electric motor is colinear with the main shaft, and an electric compressor extending along a second axis that is radially offset from the central longitudinal axis, the electric compressor in fluid communication with the second turbine section.

Abstract: An inkjet chip including a substrate, a plurality of control elements, an insulating layer, a plurality of first conductive patterns, a plurality of second conductive patterns and a plurality of heaters is provided. The insulating layer is disposed on the control element and has a plurality of openings. The openings each have a first length in a first direction. Each first conductive pattern has a first sidewall overlapping one of the openings and is electrically connected between one of the control elements and one of the heaters. Each second conductive pattern has a second sidewall overlapping the one of the openings and is electrically connected to one of the heaters. A distance in the first direction is included between the first sidewall and the second sidewall opposing to each other. The distance is less than the first length. A thermal bubble inkjet printhead adopting the inkjet chip is also provided.

Abstract: A rotor stack for a gas turbine engine includes a first rotor disk with a first rotor spacer arm, the first rotor spacer arm having a first flange with an outboard flange surface and an inboard flange surface, a first hole along an axis through the first flange, the first hole having a counterbore in the outboard flange surface; a second rotor disk with a web having a second hole along the axis; a third rotor disk with a third rotor spacer arm, the third rotor spacer arm having a third flange with an outboard flange surface and an inboard flange surface, a third hole along the axis through the third flange, the third hole having a counterbore in the inboard flange surface; and a bushing with a tubular body and a flange that extends therefrom, the tubular body comprising at least one axial groove along an outer diameter thereof, the bushing extends through the first hole, the second hole and partially into the counterbore in the inboard flange surface of the third hole.

Abstract: A thermal bubble inkjet printhead including a substrate, a plurality of control elements, a plurality of heaters, an ink barrier and a nozzle plate is provided. The control elements are disposed on the substrate. The heaters are electrically connected to the control elements. The material of the heaters is a transparent conductive material. The ink barrier is disposed on the heater and has a plurality of ink chambers. Each of the ink chambers overlaps one of the heaters. The nozzle plate is disposed on the ink barrier and has a plurality of nozzles. Each nozzle overlaps one of the ink chambers.

Abstract: A method for producing a metal boride powder includes producing a bonding gas stream from a first powder in a first fluidizing bed reactor, delivering the bonding gas stream to a second fluidized bed reactor through a conduit fluidly connecting the first and second fluidized bed reactors, fluidizing a second powder in the second fluidized bed reactor, mixing the second powder with the bonding gas stream such that a metal boride or boron-doped powder is formed.

Abstract: A diffuser may comprise an inlet and an outlet. The inlet may comprise an arcuate shape. The outlet may comprise an annular shape. The diffuser may transition from the arcuate shape at the inlet to the annular shape at the outlet. The diffuser may comprise a radially inner wall and a radially outer wall disposed opposite the radially inner wall. The radially inner wall and the radially outer wall may partially define a duct.

Abstract: A vane ring for a gas turbine engine includes a contoured stop that extends from the static flowpath wall, the contoured stop being of an airfoil shape such that a first side of the contoured stop matches a portion of a first side of the first variable vane along a chord length when the first variable vane is pivoted about the longitudinal axis to a first position.