A method of fabricating a mixer for a gas turbine engine is provided. The method includes forming a forward end and an aft end of the mixer, and forming an annularly undulating contour that defines a plurality of core immersion lobes and a plurality of bypass immersion lobes between the forward end and the aft end. The plurality of bypass immersion lobes includes a first bypass immersion lobe and a second bypass immersion lobe. The first bypass immersion lobe has a first crown contour line extending from the forward end to the aft end of the mixer, and the second bypass immersion lobe has a second crown contour line extending from the forward end to the aft end of the mixer. The first crown contour line is different than the second crown contour line.

A propulsion system includes a gas turbine engine, an inlet particle separator, an infrared suppression system, and an engine controller. The engine controller may be configured to determine an activation state of the inlet particle separator, adjust one or more engine operating parameters based on the activation state, and control the gas turbine engine based on the adjusted engine operating parameters. The engine operating parameters may be adjusted based on inlet flow, which is determined based on the activation state. The engine controller may be further configured to determine an activation state of the infrared suppression system, adjust one or more engine operating parameters based on the activation state, and control the gas turbine engine based on the adjusted engine operating parameters. The engine operating parameters may be adjusted based on backpressure, which is determined based on the activation state.

An exhaust infrared signature reduction arrangement includes an exhaust duct, a first vane support disposed within the exhaust duct and a second vane support disposed within the exhaust duct downstream from the first vane support. The first vane support and the second vane support are movable between a first configuration and a second configuration.

An airplane including an airframe and a turboprop propulsion system is disclosed in this paper. The turboprop propulsion system includes a propeller mounted for rotation about a propeller axis and a gas turbine coupled to the propeller to drive rotation of the propeller.

Systems and methods for the protection of a surface adjacent to an exhaust system are presented herein. The system may comprise an ejector, an ejector inlet, and a ejector shroud, and a shroud outlet. The ejector may include the exhaust nozzle of an engine. The should outlet is in fluid communication with the atmosphere. The adjacent surface may partially bound a region proximate to and downstream of the shroud outlet. The system may further comprise a plurality of forced mixing lobes that extend from the engine exhaust nozzle in a region spaced apart from the adjacent surface. The distribution of the lobes may be asymmetric in the cross section of the ejector shroud proximate to the shroud outlet.

According to one aspect, an infrared suppression system that utilizes a primary airflow and a secondary air flow for a gas turbine engine is provided. The infrared suppression system includes an exit flap configured to control a flow of exhaust air out of the gas turbine engine and a secondary flow door that is configured to selectively control the secondary air flow into the gas turbine engine. The mixture of the secondary air flow and the primary air flow from the gas turbine engine suppresses an infrared signature produced by the gas turbine engine.

Methods and systems for restricting movement in a flow mixer of an exhaust duct, the flow mixer having a first row of flutes and a second row of flutes generally opposite to the first row of flutes, each flute being elongated and defining an elongated axis. At least two flute ties connect, or couple, together at least two flutes from the first row of flutes and at least two flutes from the second row of flutes. A retainer is coupled to the flute ties and extends generally perpendicularly to the elongated axis of each of the flutes from the first and second rows of flutes. The combination of the retainer and flute ties is configured to generally restrain relative movement between the flutes from the first row and the flutes from the second row.

Systems and methods for power generation for an aircraft are provided. In one example embodiment, a power generation system for an aircraft includes a thermionic generator arranged to receive heat from at least one heat source. The thermionic generator is configured to generate electrical power for one or more aircraft systems based at least in part on the heat received from the at least one heat source. The power generation system further includes a thermoelectric generator arranged to receive waste heat from the thermionic generator. The thermoelectric generator is configured to generate electrical power for one or more aircraft systems based at least in part on the waste heat received from the thermionic generator.

An exhaust infrared signature reduction arrangement includes an exhaust duct having a plurality of holes through a wall of the exhaust duct, and a housing surrounding at least a portion of the exhaust duct defining a cavity between the exhaust duct and the housing.