Abstract: An engine includes an inlet tube introducing air to a combustion process and a first plurality of fuel injectors disposed in the inlet tube and used for scram-jet engine operation. The engine includes a second plurality of fuel injectors used for ram-jet engine operation. The second plurality of fuel injectors is upstream from the first plurality of fuel injectors and is disposed in the inlet tube. The engine includes a combustor swirl zone downstream of and adjacent to the first plurality of fuel injectors.

Abstract: A bidirectional gas discharge tube (GDT) includes a discharge chamber, first and second cathodes, a gas disposed within the discharge chamber, and a control grid. The first and second cathodes are disposed within the discharge chamber and include first and second faces, respectively. The first face and the second face are plane-parallel. The gas is configured to insulate the first cathode from the second cathode. The control grid is disposed between the first and second cathodes within the discharge chamber. The control grid is configured to generate an electric field to initiate establishment of a conductive plasma between the first and second cathodes to close a conduction path extending between the first and second cathodes.

Abstract: An engine includes an inlet tube introducing air to a combustion process and a first plurality of fuel injectors disposed in the inlet tube and used for scram-jet engine operation. The engine includes a second plurality of fuel injectors used for ram-jet engine operation. The second plurality of fuel injectors is upstream from the first plurality of fuel injectors and is disposed in the inlet tube. The engine includes a combustor swirl zone downstream of and adjacent to the first plurality of fuel injectors.

Abstract: A hypersonic aircraft includes one or more leading edge assemblies that are designed to cool the leading edge of certain portions of the hypersonic aircraft that are exposed to high thermal loads, such as extremely high temperatures and/or thermal gradients. Specifically, the leading edge assemblies may include an outer wall tapered to a leading edge or stagnation point. A coolant supply may be in fluid communication with at least one fluid passageway that passes through the outer wall to deliver a flow of cooling fluid, such as liquid metal, to the stagnation point. The liquid metal vaporizes when the leading edge experiences a high heat load, thereby transpiration cooling the leading edge and/or facilitating a magnetohydrodynamic process for generating thrust or electricity.

Abstract: A hypersonic aircraft includes one or more leading edge assemblies that are designed to cool the leading edge of certain portions of the hypersonic aircraft that are exposed to high thermal loads, such as extremely high temperatures and/or thermal gradients. Specifically, the leading edge assemblies may include an outer wall tapered to a leading edge or stagnation point. A coolant supply provides a flow of cooling fluid to a porous tip that is joined to the forward end of the outer wall and defines variable porosity and/or internal barriers to direct a flow of cooling fluid to the regions of the leading edge experiencing the highest thermal loading.

Abstract: A DC circuit breaker includes a gas discharge tube (GDT) coupled in parallel with an extinguishing path. The GDT conducts and interrupts a load current through a normal current path. The GDT includes a thermionic cathode, an anode, and a control grid. The control grid is configured to regulate opening and closing of the normal current path. The extinguishing path is configured to lengthen a break time for the DC circuit breaker.

Abstract: A DC circuit breaker includes a gas discharge tube (GDT) coupled in parallel with an extinguishing path. The GDT conducts and interrupts a load current through a normal current path. The GDT includes a thermionic cathode, an anode, and a control grid. The control grid is configured to regulate opening and closing of the normal current path. The extinguishing path is configured to lengthen a break time for the DC circuit breaker.

Abstract: A bidirectional gas discharge tube (GDT) includes a discharge chamber, first and second cathodes, a gas disposed within the discharge chamber, and a control grid. The first and second cathodes are disposed within the discharge chamber and include first and second faces, respectively. The first face and the second face are plane-parallel. The gas is configured to insulate the first cathode from the second cathode. The control grid is disposed between the first and second cathodes within the discharge chamber. The control grid is configured to generate an electric field to initiate establishment of a conductive plasma between the first and second cathodes to close a conduction path extending between the first and second cathodes.

Abstract: A hypersonic aircraft includes one or more leading edge assemblies that are designed to cool the leading edge of certain portions of the hypersonic aircraft that are exposed to high thermal loads, such as extremely high temperatures and/or thermal gradients. Specifically, the leading edge assemblies may include an outer wall tapered to a leading edge or stagnation point. A coolant supply provides a flow of cooling fluid to a porous tip that is joined to the forward end of the outer wall and defines variable porosity and/or internal barriers to direct a flow of cooling fluid to the regions of the leading edge experiencing the highest thermal loading.

Abstract: A hypersonic aircraft includes one or more leading edge assemblies that are designed to cool the leading edge of certain portions of the hypersonic aircraft that are exposed to high thermal loads, such as extremely high temperatures and/or thermal gradients. Specifically, the leading edge assemblies may include an outer wall tapered to a leading edge or stagnation point. A coolant supply may be in fluid communication with at least one fluid passageway that passes through the outer wall to deliver a flow of cooling fluid, such as liquid metal, to the stagnation point. The liquid metal vaporizes when the leading edge experiences a high heat load, thereby transpiration cooling the leading edge and/or facilitating a magnetohydrodynamic process for generating thrust or electricity.

Abstract: The present disclosure relates to gas turbine engine operation in which an igniter assembly is provided with an electrical energy input (e.g., an electrical waveform) that is configured to increase a likelihood of igniting a fuel-air mixture surrounding the igniter assembly. In certain embodiments, the igniter assembly is supplied with an augmented electrical waveform that may reduce a quantity of sparks generated by the igniter assembly before successful light-off (e.g., ignition) of the fuel-air mixture is achieved (e.g., as compared to a quantity of sparks generated to achieve ignition by an igniter assembly that receives an electrical energy input in the form of a conventional electrical waveform). Accordingly, the augmented electrical waveform may reduce wear (e.g., via oxidation) on electrodes of the igniter assembly, such as a primary electrode (e.g., a center electrode) and a secondary electrode (e.g., an outer shell electrode) disposed about the primary electrode.

Abstract: Embodiments of the present disclosure relate to a spark gap device that includes a first electrode having a first surface and a second electrode having a second surface offset from and facing the first surface. The spark gap device also includes a light source configured to emit light toward at least the first surface such that photons emitted by the light source when the spark gap is operated are incident on the first surface and cause electron emission from the first surface. The light source includes a discharge probe having a third electrode sealed in a tube filled with an inert gas. The spark gap device may not include a radioactive component.

Abstract: A fuel oxygen reduction unit for an aeronautical engine is provided. The fuel oxygen reduction unit includes a stripping gas line that provides a stripping gas flow and a plasma reactor in fluid communication with the stripping gas line. The plasma reactor includes a plasma reactor gas inlet that receives the stripping gas flow from the stripping gas line and a plasma reactor gas outlet that provides the stripping gas flow back to the stripping gas line, the plasma reactor configured to reduce a free oxygen content of the stripping gas flow such that an outlet free oxygen content of the stripping gas flow that exits the plasma reactor gas outlet is lower than an inlet free oxygen content of the stripping gas flow that enters the plasma reactor gas inlet.

Abstract: A hypersonic propulsion engine includes: a turbine engine including a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbine engine defining a turbine engine inlet upstream of the compressor section and a turbine engine exhaust downstream of the turbine section; a ducting assembly defining a bypass duct having a substantially annular shape and extending around the turbine engine, an afterburning chamber located downstream of the bypass duct and at least partially aft of the turbine engine exhaust, and an inlet section located at least partially forward of the bypass duct and the turbine engine inlet; and an inlet precooler positioned at least partially within the inlet section of the ducting assembly and upstream of the turbine engine inlet, the bypass duct, or both for cooling an airflow provided through the inlet section of the ducting assembly to the turbine engine inlet, the bypass duct, or both.

Abstract: A high voltage gas switch includes a gas-tight housing containing an ionizable gas at a preselected gas pressure. The gas switch includes a gas-tight housing containing an ionizable gas at a gas pressure selected based upon a Paschen curve for the ionizable gas, where the Paschen curve plots breakdown voltages of the ionizable gas as a function of gas pressure multiplied by grid-to-anode distance, and where values of gas pressure multiplied by grid-to-anode distance increase over at least a portion of the Paschen curve in conjunction with increasing breakdown voltages. The gas switch also includes an anode disposed within the gas-tight housing, a cathode disposed within the gas-tight housing, and a control grid positioned between the anode and the cathode, where the control grid is spaced apart from the anode by a grid-to-anode distance selected based upon a desired operating voltage.

Abstract: A cold-cathode switching device is presented. The cold-cathode switching device includes a housing defining a chamber; an ionizable gas disposed in the chamber; and a plurality of electrodes disposed in the chamber. The plurality of electrodes includes a cathode and an anode defining a discharge gap, and wherein at least one of the cathode and anode comprises a material that is liquid at an operating temperature of the cathode or the anode.

Abstract: The present disclosure relates to gas turbine engine operation in which an igniter assembly is provided with an electrical energy input (e.g., an electrical waveform) that is configured to increase a likelihood of igniting a fuel-air mixture surrounding the igniter assembly. In certain embodiments, the igniter assembly is supplied with an augmented electrical waveform that may reduce a quantity of sparks generated by the igniter assembly before successful light-off (e.g., ignition) of the fuel-air mixture is achieved (e.g., as compared to a quantity of sparks generated to achieve ignition by an igniter assembly that receives an electrical energy input in the form of a conventional electrical waveform). Accordingly, the augmented electrical waveform may reduce wear (e.g., via oxidation) on electrodes of the igniter assembly, such as a primary electrode (e.g., a center electrode) and a secondary electrode (e.g., an outer shell electrode) disposed about the primary electrode.

Abstract: An engine includes an inlet tube introducing air to a combustion process and a first plurality of fuel injectors disposed in the inlet tube and used for scram-jet engine operation. The engine includes a second plurality of fuel injectors used for ram-jet engine operation. The second plurality of fuel injectors is upstream from the first plurality of fuel injectors and is disposed in the inlet tube. The engine includes a combustor swirl zone downstream of and adjacent to the first plurality of fuel injectors.

Abstract: A gas switch includes a gas-tight housing containing an ionizable gas, an anode disposed within the gas-tight housing, and a cathode disposed within the gas-tight housing, where the cathode includes a conduction surface. The gas switch also includes a control grid positioned between the anode and the cathode, where the control grid is arranged to receive a bias voltage to establish a conducting plasma between the anode and the cathode. In addition, the gas switch includes a plurality of magnets selectively arranged to generate a magnetic field proximate the conduction surface that reduces the kinetic energy of charged particles striking the conduction surface and raises the conduction current density at the cathode surface to technically useful levels.

Abstract: A gas switch includes a gas-tight housing containing an ionizable gas, an anode disposed within the gas-tight housing, and a cathode disposed within the gas-tight housing, where the cathode includes a conduction surface. The gas switch also includes a control grid positioned between the anode and the cathode, where the control grid is arranged to receive a bias voltage to establish a conducting plasma between the anode and the cathode. In addition, the gas switch includes a plurality of magnets selectively arranged to generate a magnetic field proximate the conduction surface that reduces the kinetic energy of charged particles striking the conduction surface and raises the conduction current density at the cathode surface to technically useful levels.