Abstract: A constant density heat exchanger is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid held at constant density within the chamber by the first and second control devices.

Abstract: A method, apparatus, and program for additive manufacturing. In one aspect, the method comprises: forming an at least partially solidified portion within a first scan region (801), wherein the solidified portion within the first scan region (801) is formed by irradiating a build material along a first irradiation path (811). A second portion of a build material may be irradiated along a second irradiation path (813), wherein the second scan region (803) is offset with respect to the first scan region (801) thereby defining an offset region (802). The offset region (802) is at least partially solidified by the first irradiation path (811) and the second irradiation path (813) and a reference line (819) intersects the first irradiation path (811) and the second irradiation path (813) within the offset region (802), wherein the reference line (819) is substantially parallel to a side (810) of the first scan region (801).

Abstract: A hybrid-electric propulsion system includes a turbomachine and an electric machine coupled to the turbomachine. A method for operating the hybrid-electric propulsion system includes receiving information indicative of an operability parameter of the turbomachine; determining the turbomachine is operating within a predetermined operability range based at least in part of the received information indicative of the operability parameter of the turbomachine; and operating the hybrid electric propulsion system in an electric generation mode to generate electric power with the electric machine in response to determining the turbomachine is operating within the predetermined operability range.

Abstract: A system including a closed cycle engine having a piston body defining a hot side and a cold side and having a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly. A control system includes one or more sensors operable to detect a piston movement characteristic of the piston assembly movable within the piston body. A controller is communicatively coupled with the one or more sensors and a controllable device. The controller is configured to determine a control command based at least in part on data received from the one or more sensors. The control command is selected based at least in part to cause the electric machine operatively coupled with the piston assembly to generate a preselected electrical power output. The controller provides the determined control command to the controllable device. The controllable device is operable to control an input to an engine working fluid disposed within the piston body.

Abstract: A hybrid-electric propulsion system includes a turbomachine and an electrical system, the electrical system including an electric machine coupled to the turbomachine. A method for operating the propulsion system includes receiving, by one or more computing devices, a command to accelerate the turbomachine to provide a desired thrust output; receiving, by the one or more computing devices, data indicative of a temperature parameter approaching or exceeding an upper threshold; and providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine to provide, or assist with providing, the desired thrust output in response to receiving the command to accelerate the turbomachine and receiving the data indicative of the temperature parameter approaching or exceeding the upper threshold.

Abstract: Systems and methods for converting energy are provided. In one aspect, the system includes a closed cycle engine having a piston body and a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly and operable to generate electrical power. An electrical device is in communication with the electric machine. The system includes a control system having sensors, a controllable device, and a controller. The controller is configured to determine whether a load change on the electric machine is anticipated based at least in part on received data indicative of a load state of the electrical device; in response to whether the load change is anticipated, determine a control command for adjusting an output of at least one of the engine and the electric machine; and cause the controllable device to adjust the output based at least in part on the control command.

Abstract: A constant density heat exchanger and system for energy conversion is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid as the first flow control device and the second flow control device hold the volume of working fluid at constant density within the chamber.

Abstract: A monolithic engine assembly may include an engine body that includes a regenerator body. The engine body and the regenerator body may respectively define at least a portion of a monolithic body, or the engine body may define at least a portion of a first monolithic body-segment and the regenerator body may define at least a portion of a second monolithic body-segment operably coupled or operably couplable to the first monolithic body-segment. The regenerator body may include a regenerator conduit, and a plurality of fin arrays adjacently disposed within the regenerator conduit and respectively supported by the regenerator conduit in spaced relation to one another. The spaced relation of the plurality of fin arrays may define a gap longitudinally separating adjacent ones of the plurality of fin arrays.

Abstract: An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly, that includes a first heater body and a first engine body. The first heater body may define a first portion of a first monolithic body or at least a portion of a first monolithic body-segment. The first engine body may define a second portion of the first monolithic body or at least a portion of a second monolithic body-segment operably coupled or operably couplable to the first heater body. The engine assembly may include a second heater body and/or a second engine body. The second heater body may define a portion of a second monolithic body or a third monolithic body-segment. The second engine body may define a portion of the second monolithic body or a fourth monolithic body-segment operably coupled or operably couplable to the second heater body and/or the first engine body.

Abstract: A system including a closed cycle engine having a piston body defining a hot side and a cold side and having a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly. A control system includes one or more sensors operable to detect a piston movement characteristic of the piston assembly movable within the piston body. A controller is communicatively coupled with the one or more sensors and a controllable device. The controller is configured to determine a control command based at least in part on data received from the one or more sensors. The control command is selected based at least in part to cause the electric machine operatively coupled with the piston assembly to generate a preselected electrical power output. The controller provides the determined control command to the controllable device. The controllable device is operable to control an input to an engine working fluid disposed within the piston body.

Abstract: A propulsion system for an includes a combustion engine, a propulsor, and an electric machine configured to either be driven by the combustion engine or configured to drive the propulsor. The electric machine defines an axis. The electric machine includes a rotor extending along and rotatable about the axis, and a stator having a plurality of winding assemblies, the plurality of winding assemblies spaced along the axis of the electric machine, each winding assembly operable with the rotor independently of an adjacent winding assembly during operation of the electric machine.

Abstract: A hybrid-electric propulsion system for an aircraft is provided herein that can include a propulsor and a turbomachine comprising a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. An auxiliary power unit can be operably coupled with a starter motor. An electrical system can comprise a first electric machine coupled to the turbomachine. The first electric machine can be separate from the starter motor. A controller can be configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

Abstract: Systems and methods for converting energy are provided. In one aspect, the system includes a closed cycle engine having a piston body and a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly and operable to generate electrical power. An electrical device is in communication with the electric machine. The system includes a control system having sensors, a controllable device, and a controller. The controller is configured to determine whether a load change on the electric machine is anticipated based at least in part on received data indicative of a load state of the electrical device; in response to whether the load change is anticipated, determine a control command for adjusting an output of at least one of the engine and the electric machine; and cause the controllable device to adjust the output based at least in part on the control command.

Abstract: A computer-implemented method of assessing a health of a gas turbine engine of a hybrid-electric propulsion system for an aircraft includes receiving, by one or more computing devices, data indicative of an amount of electrical power provided to, or extracted from, an electric machine. The method also includes receiving, by the one or more computing devices, data indicative of an operating parameter of the hybrid-electric propulsion system. The method also includes assessing, by the one or more computing devices, a health of the gas turbine engine based at least in part on the received data indicative of the amount of electrical power provided to, or extracted from, the electric machine and the received data indicative of the operating parameter of the hybrid electric propulsion system. The method also includes providing, by the one or more computing devices, information to a user indicative of the health of the gas turbine engine.

Abstract: An additive manufacturing machine (910) includes a build unit (920) comprising a powder dispenser (906) including a hopper (1004) for receiving a volume of additive powder (1006). A powder supply system (1000) includes a powder supply source (1010) for providing additive powder (1006) into the hopper (1004) during a refill process. A powder reclamation system (1002) includes a vacuum pump (1030) coupled to a vacuum duct (1034, 1036) defining a suction inlet (1040) positioned for collecting misdirected additive powder (1006) dispensed during the refill process. A return duct (1038) includes a filter mechanism (1050) may filter and return the collected additive powder (1006) back to the powder supply source (1010) for reuse.

Abstract: A hybrid-electric propulsion system includes a propulsor, a turbomachine, and an electrical system, the electrical system including an electric machine coupled to the turbomachine. A method for operating the propulsion system includes operating, by one or more computing devices, the turbomachine in a steady-state flight operating condition, the turbomachine rotating the propulsor when operated in the steady-state flight operating condition; receiving, by the one or more computing devices, a command to accelerate the turbomachine while operating the turbomachine in the steady-state flight operating condition; and providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine, the propulsor, or both in response to the received command to accelerate the turbomachine.

Abstract: An aspect of the present disclosure is directed to a system for energy conversion. The system includes a closed cycle engine containing a volume of working fluid. The engine includes an expansion chamber and a compression chamber each separated by a piston attached to a connection member of a piston assembly. The engine further includes a plurality of heater conduits extended from the expansion chamber. The engine includes a plurality of chiller conduits extended from the compression chamber. The expansion chamber and heater conduits are fluidly connected to the compression chamber and chiller conduits via a walled conduit.

Abstract: A hybrid-electric propulsion system includes a propulsor, a turbomachine, and an electrical system, the electrical system including an electric machine coupled to the turbomachine. A method for operating the propulsion system includes operating, by one or more computing devices, the turbomachine such that the turbomachine rotates the propulsor; receiving, by the one or more computing devices, a command to accelerate the turbomachine while operating the turbomachine; and providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine, the propulsor, or both in response to the received command to accelerate the turbomachine.

Abstract: A hybrid-electric propulsion system for an aircraft includes a propulsor and a turbomachine. The turbomachine includes a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. The hybrid electric propulsion system further includes an electrical system including a first electric machine, a second electric machine, and an electric energy storage unit electrically connectable to the first and second electric machines. The first electric machine is coupled to the high pressure spool of the turbomachine and the second electric machine is coupled to the propulsor for driving the propulsor to provide a propulsive benefit for the aircraft. The hybrid electric propulsion system also includes a controller configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

Abstract: A method of operating a hybrid-electric propulsion system for an aircraft includes determining a flight phase parameter for the aircraft is equal to a first value, and operating the hybrid-electric propulsion system in an electric charge mode in response to determining the flight phase parameter for the aircraft is equal to the first value. The method also includes determining the flight phase parameter for the aircraft is equal to a second value different from the first value, and operating the hybrid-electric propulsion system in an electric discharge mode in response to determining the flight phase parameter for the aircraft is equal to the second value.