In accordance with at least one aspect of this disclosure, there is provided a fuel system for a gas turbine engine of an aircraft, including a main inlet feed conduit fluidly connected to a primary manifold feed conduit and a secondary manifold feed conduit. A primary manifold fluidly connects the primary manifold feed conduit to a plurality of primary fuel injectors, and a secondary manifold fluidly connects the secondary manifold feed conduit to a plurality of secondary fuel injectors.

A fuel oxygen conversion unit for a vehicle or an engine of the vehicle includes a contactor; a mechanically-driven, first fuel gas separator defining a liquid fuel outlet and a stripping gas outlet, the fuel oxygen conversion unit defining a liquid fuel outlet path in fluid communication with the liquid fuel outlet of the first fuel gas separator; and a second fuel gas separator positioned in fluid communication with the liquid fuel outlet path at a location downstream of the first fuel gas separator.

An aircraft including a fuselage, a wing structure, at least one turbomachine running on hydrogen and generating thrust at a propulsion unit distant from the fuselage, at least one fuel tank positioned in the fuselage and configured to store hydrogen in the cryogenic state, at least one hydrogen supply device connecting the fuel tank and the turbomachine and including at least one pump positioned in the fuselage in the vicinity of the fuel tank, at least one hydrogen heating system positioned in the fuselage in the vicinity of the pump. This solution makes it possible to reduce a length of the complex double-walled pipes configured for carrying the hydrogen in the cryogenic state between the fuel tank and the hydrogen heating system.

Embodiments of system and methods for supplying fuel, enabling communications, and conveying electric power associated with operation of a hydraulic fracturing unit of a plurality of hydraulic fracturing units are disclosed and may include a fuel line connection assembly configured to be connected to the first hydraulic fracturing unit and to supply fuel from a fuel source to a gas turbine engine connected to the hydraulic fracturing unit. A system also may include a communications cable assembly configured to be connected to the hydraulic fracturing unit and to enable data communications between the hydraulic fracturing unit and a data center or another hydraulic fracturing unit. A system further may include a power cable assembly configured to be connected to the hydraulic fracturing unit and to convey electric power between the hydraulic fracturing unit and a remote electrical power source or the plurality of hydraulic fracturing units.

A method of operating a fuel delivery system of an aircraft engine of an aircraft includes operating the aircraft engine in a standby mode by maintaining combustion in a combustor of the aircraft engine by supplying fuel to the combustor via a first set of fuel nozzles of a first fuel manifold while providing a trickle flow of fuel via a second set of fuel nozzles of a second fuel manifold into the combustor during engine operation, the trickle flow being defined as a fuel flow rate selected to prevent flame-out of the combustion while providing one of: substantially no motive power to the aircraft, and no motive power to the aircraft, via the combustion of the trickle flow of fuel. An aircraft gas turbine engine is also described.

A method comprising applying braze to a joint location of two work pieces and applying local heating to the joint location of the two work pieces until braze melting temperature is achieved to melt the braze while maintaining temperature of more remote portions of each work piece. The method includes reducing heating of the braze to form a braze joint joining the joint location of the two work pieces.

A method includes joining a fuel plurality of injection components to a fuel manifold, wherein for each fuel injection component in the plurality of fuel injection components, a metallic joint is formed joining and sealing the fuel injection component to the manifold. A system includes a fuel manifold. A plurality of fuel injection components are connected in fluid communication with the fuel manifold with metallic joints sealing between each of the plurality of fuel injection components and the fuel manifold to prevent leakage from between the manifold and the plurality of fuel injection components.

A fuel manifold adapter for a fuel system of an aircraft engine, the fuel manifold adapter comprising: a body having a body-output interface defining a downstream end of a body passage including a body bore about a bore axis, the body-output interface movably and fluidly connectable to a first component of the fuel system mounted to a first mounting point of the engine, and a body-input interface defining an upstream end of the body passage, the body-input interface rigidly and fluidly connectable to a second component of the fuel system mounted to a second mounting point of the engine, and a transfer tube having an upstream-tube end slidably engaged with the body along the bore axis via the body bore, the transfer tube having a downstream-tube end opposite the upstream-tube end slidably engageable along the bore axis with the first component, the downstream-tube end defining a downstream end of the fuel manifold adapter relative to fuel flow through the fuel manifold adapter.

A multipoint fuel injection system comprises an injection system segment including a circumferentially extending outer support defining a fuel manifold with a plurality of manifold passages extending circumferentially therethrough. A first connector is included at a first circumferential end of the outer support and a second connector is included at a second circumferential end of the outer support opposite the first circumferential end. The first and second connectors are each configured to connect each manifold passage with a manifold passages of a respective outer support of a circumferentially adjacent injection system segment. The system includes a circumferentially extending inner support and a plurality of circumferentially spaced apart feed arms extending radially between the inner support and the outer support. A plurality of outlet openings extend in an axial direction from each feed arm for feeding respective injection nozzles.

An electricity generating system is disclosed. The system includes one or more rotary arms extending from a central hub, a tube or blade with an air passage therein extending from each of the one or more rotary arms, a set of rotary blades operably connected to the tube or blade, an axle or shaft joined or fixed to the central hub, and a generator operably connected to the axle or shaft. The air passage has one or more air inlets at or near an end of the tube or blade connected or joined to a corresponding rotary arm. The set of rotary blades is configured to provide a force that rotates the tube or blade. The axle or shaft is configured to rotate with the central hub. The generator is configured to convert a torque from the axle or shaft to electricity.