A combustion system such as a furnace or boiler includes a perforated reaction holder configured to hold a combustion reaction that produces very low oxides of nitrogen (NOx).

A system includes a gas turbine engine configured to combust an oxidant and a fuel to generate an exhaust gas, a catalyst bed configured to treat a portion of the exhaust gas from the gas turbine engine to generate a treated exhaust gas, a differential temperature monitor configured to monitor a differential temperature between a first temperature of the portion of exhaust gas upstream of the catalyst bed and a second temperature of the treated exhaust gas downstream of the catalyst bed, and an oxidant-to-fuel ratio system configured to adjust a parameter to maintain an efficacy of the catalyst bed based at least in part on the differential temperature in order to maintain a target equivalence ratio.

A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a speed different than the turbine section such that both the turbine section and the fan section can rotate at closer to optimal speeds providing increased performance attributes and performance by desirable combinations of the disclosed features of the various components of the described and disclosed gas turbine engine.

Methods and systems for a full-scale vertical takeoff and landing manned or unmanned aircraft, having an all-electric, low-emission or zero-emission lift and propulsion system, an integrated ‘highway in the sky’ avionics system for navigation and guidance, a tablet-based motion command, or mission planning system to provide the operator with drive-by-wire style direction control, and automatic on-board-capability to provide traffic awareness, weather display and collision avoidance. Automatic computer monitoring by a programmed triple-redundant digital autopilot computer controls each motor-controller and motor to produce pitch, bank, yaw and elevation, while simultaneously restricting the flight regime that the pilot can command, to protect the pilot from inadvertent potentially harmful acts that might lead to loss of control or loss of vehicle stability. By using the results of the state measurements to inform motor control commands, the methods and systems contribute to the operational simplicity, reliability and safety of the vehicle.

A carrier structure for an epicyclic gear drive is provided. The carrier structure includes carrier elements connected with at least one planet gear and the first carrier element is connected with the second carrier element through at least two struts with the at least two struts having an inclination angle of more than 20° in the direction of a rotation around a rotation axis of the carrier structure.

The invention relates to a wheel of a turbine engine comprising a plurality of radially extending vanes, one radially internal or external end of which is connected to an annular platform carrying annular lips (42, 44) extending from said platform in a direction opposite the vane in order to sealingly cooperate with a radially facing abradable material (28). According to the invention, the wheel comprises at least one lip (42, 44) having a concave curved upstream face and a convex curved downstream face or having a convex curved upstream face and a concave curved downstream face.

A flexible metal foil can be fixed on the inside part of a variable pitch vane control ring of a turbojet compressor, so as to close all through holes in which lever pins and their surrounding bushes are housed. As a result, the foil can retain the shank of the bush if the bush breaks. The use of such foil does not impose the development of a new model of control ring and its impact on the mass is small enough so that it does not affect engine performances. Therefore it avoids problems related to the breakage of bushes without having to make major changes to the existing system.

In accordance with some embodiments of the present disclosure, a pressure recovery axial compressor blade is provided. The blade may comprise a high pressure surface and a low pressure surface connected at a leading edge and a trailing edge of the blade. Both the high and low pressure surfaces extend span wise from a first end to a second end. At least one of the high and low pressure surfaces has a finite discontinuity in curvature at an intermediate position along the chord of the blade.

The present invention is directed to in situ methods for maintaining turbine assemblies. One such method includes: disposing a maintenance apparatus on the rotor; positioning the maintenance apparatus proximate to the damaged region by rotating the rotor; and repairing the damaged region by operating a repair tool disposed on the apparatus. Another method includes: disposing a maintenance apparatus on the stator; positioning the damaged region proximate to the maintenance apparatus by rotating the rotor; and repairing the damaged region by operating a repair tool disposed on the apparatus.

An aircraft having a vertical takeoff and landing fight mode and a forward flight mode. The aircraft includes an airframe and a versatile propulsion system attached to the airframe. The versatile propulsion system includes a plurality of propulsion assemblies. A flight control system is operable to independently control the propulsion assemblies. The propulsion assemblies are interchangeably attachable to the airframe such that the aircraft has a liquid fuel flight mode and an electric flight mode. In the liquid fuel flight mode, energy is provided to each of the propulsion assemblies from a liquid fuel. In the electric flight mode, energy is provided to each of the propulsion assemblies from an electric power source.