Abstract: A gas turbine engine includes a variable area nozzle having a plurality of flaps. The flaps are actuated by a plurality of actuating mechanisms driven by shape memory alloy (SMA) actuators to vary fan exist nozzle area. The SMA actuator has a deformed shape in its martensitic state and a parent shape in its austenitic state. The SMA actuator is heated to transform from martensitic state to austenitic state generating a force output to actuate the flaps. The variable area nozzle also includes a plurality of return mechanisms deforming the SMA actuator when the SMA actuator is in its martensitic state.

Abstract: A method and apparatus for suppressing jet noise in a gas turbine engine powerplant 10 is disclosed. Various construction details are developed for providing sound suppression at sea level take-off operative conditions and not providing sound suppression at cruise operative conditions. In one embodiment, the powerplant 10 has a lobed mixer 152 between a primary flowpath 44 and a second flowpath 46, a diffusion region downstream of the lobed mixer region (first mixing region 76), and a deployable ejector/mixer 176 in the diffusion region which forms a second mixing region 78 having a diffusion flowpath 72 downstream of the ejector/mixer and sound absorbing structure 18 bounding the flowpath throughout the diffusion region. The method includes deploying the ejector/mixer 176 at take-off and stowing the ejector/mixer at cruise.

Abstract: An exhaust nozzle extends from an engine nacelle and has an opening disposed at an acute angle such that the exhaust stream is blown over a length of the propeller blade. The opening has a plurality of guide vanes disposed therein to shape the exhaust stream most effectively. By spreading the exhaust stream over the length of a propeller, mixing of the exhaust stream with ambient air is maximized, thereby lowering the temperature of the exhaust stream to tolerable levels.

Abstract: A nacelle structure (14) for a gas turbine engine (4) extends upstream from the engine air inlet (10) and includes an external surface (18) and an internal surface (16). The external surface (18) is concentric about a linear centerline (22) which is disposed parallel to the free airflow stream (6) encountered by the nacelle (14) in flight. The internal surface (16) is concentric about a curved centerline (30), the curved centerline (30) being parallel to the free airflow stream (6) at the nacelle inlet (12) and parallel to the engine centerline (26) at the engine air inlet (10) for smoothly directing the internal airflow stream (32) into the engine air inlet (10).

Abstract: A fairing added to the upstream end of the lobe of conventional lobed mixers or inverters for a gas turbine engine redirects the boundary layer so as to improve engine performance.

Abstract: A cooperating flap moveable axially and radially and a collapsible plug in a two-dimensional nozzle for aircraft powered by a gas turbine engine serves to maximize nozzle performance for subsonic, supersonic and speeds therebetween.

Abstract: The ducting extending a substantial axial length of a gas turbine engine is faired to transition the annular flows of the core engine and fan to a rectangular separate flow in a pair of two-dimensional exhaust nozzles so as to control each flow individually. Each flow is judiciously located to achieve noise control and infrared suppression.

Abstract: A compartmentized muffler plug for the tail pipe of a jet engine is disclosed where the compartments are formed by conically shaped axially disposed partitions whose base bears against the wall of the plug and is in compression to accommodate radial growth and the sound suppression openings to the grazing flow are disposed to face the slanted walls of the partition to enhance sound suppression.

Abstract: The lobe-type mixer on a turbine type power plant is improved upon by "scalloping" the side walls for enhancing mixing of two flow streams to obtain improved noise suppression and/or engine performance. The improved lober mixer also minimizes pressure losses.