An engine can utilize a combustor to combust fuel to drive the engine. A fuel nozzle assembly can supply fuel to the combustor for combustion or ignition of the fuel. The fuel nozzle assembly can include a swirler and a fuel nozzle to supply a mixture of fuel and air for combustion. Varying the geometry of the swirler can provide for improved supply of air, which can improve efficiency and flame control.

A combustion staging system for fuel injectors of a multi-stage combustor of a gas turbine engine. The system includes plural fuel injectors, each having respective pilot and mains injection stages. It further includes a splitting unit which, to perform staging control of the combustor, receives a metered fuel flow and, for pilot and mains operation, controllably splits the received fuel flow into a pilot flow for injecting at the pilot stages of the injectors and a mains flow for injecting at the mains stages of the injectors, and for pilot-only operation, controllably splits the received fuel flow into a first part of the pilot flow for injecting at the pilot stages of a first portion of the injectors and a second part of the pilot flow for injecting at the pilot stages of a second portion of the injectors.

A combustion staging system for fuel injectors of a multi-stage combustor of a gas turbine engine. The system includes plural fuel injectors, each having respective pilot and mains injection stages. It further includes a splitting unit which, to perform staging control of the combustor, receives a metered fuel flow and, for pilot and mains operation, controllably splits the received fuel flow into a pilot flow for injecting at the pilot stages of the injectors and a mains flow for injecting at the mains stages of the injectors, and for pilot-only operation, controllably splits the received fuel flow into a first part of the pilot flow for injecting at the pilot stages of a first portion of the injectors and a second part of the pilot flow for injecting at the pilot stages of a second portion of the injectors.

Systems and methods include a plurality of fuel cell stacks extended around a combustion chamber. The plurality of fuel cell stacks are distributed along a length of the combustion chamber in the axial direction. The fuel cell stacks are configured to provide output products to the combustion chamber to achieve at least one of late lean injection and a desired combustor gas concentration distribution.

Systems and methods include a plurality of fuel cell stacks extended around a combustion chamber. The plurality of fuel cell stacks are distributed along a length of the combustion chamber in the axial direction. The fuel cell stacks are configured to provide output products to the combustion chamber to achieve at least one of late lean injection and a desired combustor gas concentration distribution.

A fuel injection system for a gas turbine engine includes a first plurality of fuel nozzles arrayed in a circular pattern. Each of the nozzles in the first plurality of fuel nozzles includes a first airflow area defined therethrough. A second plurality of fuel nozzles radially inward from the first plurality of fuel nozzles. Each of the nozzles in the second plurality of fuel nozzles includes a second airflow area defined therethrough. The first airflow area is larger than the second airflow area. A third plurality of fuel nozzles can be radially inward from the second plurality of fuel nozzles. Each of the nozzles in the third plurality of fuel nozzles can include a third airflow area defined therethrough. The second airflow area can be larger than the third airflow area.

A fuel injection system for a gas turbine engine includes a first plurality of fuel nozzles arrayed in a circular pattern. Each of the nozzles in the first plurality of fuel nozzles includes a first airflow area defined therethrough. A second plurality of fuel nozzles radially inward from the first plurality of fuel nozzles. Each of the nozzles in the second plurality of fuel nozzles includes a second airflow area defined therethrough. The first airflow area is larger than the second airflow area. A third plurality of fuel nozzles can be radially inward from the second plurality of fuel nozzles. Each of the nozzles in the third plurality of fuel nozzles can include a third airflow area defined therethrough. The second airflow area can be larger than the third airflow area.

Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifold and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and supplying pressurized air to the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.

An impending bypass switch includes a housing having a fluid inlet for admitting fluid into an interior of the housing. A piston is displaceable in the interior of the housing in response to a pressure variation of the fluid in the interior. A magnetic sensor is configured to receive a current and is fixedly mounted to the housing. A magnet is mounted to the piston to be displaced with the piston. Displacement of the magnet relative to the magnetic sensor causes a change in the current through the magnetic sensor. The change in the current is indicative of an impending bypass of a component.

In accordance with at least one aspect of this disclosure, there is provided a system for an aircraft engine. In embodiments, the system includes an accessory box and a fuel accessory located in an interior space within the accessory box, where a vent is defined through a wall of the accessory box. In embodiments, the vent includes a plurality of holes or slots in an outer wall of the accessory box for passage of gaseous fuel from the interior space. In embodiments, the vent is configured for passive ventilation of the interior space.