Abstract: A method and apparatus for dumping surge bleed air into a primary nozzle of a free gas turbine engine. The surge bleed air is introduced into gas turbine exhaust flow within the primary nozzle to create a mixed flow which may be used as a combined driver flow to compensate for reduced engine exhaust flow during periods when operation of the turbine engine may be exclusively dedicated to only electric load operation. The surge bleed air may not be the educted flow or the secondary driven flow, while cooling air passing through an oil cooler may be an educted flow. Surge bleed air may flow through, for example, mixer lobes, hollow struts, or the center body before mixing with the gas turbine exhaust flow.

Abstract: An inlet door assembly and method for reducing noise from an auxiliary power unit (APU) contained within an aircraft housing is provided. The inlet assembly includes an inlet duct, an actuator, and a door. The inlet duct is configured to extend from the auxiliary power unit to the aircraft housing and has a sidewall that defines a flow passage through which APU noise propagates. The actuator is disposed at least partially within the inlet duct. The door coupled to the actuator. The actuator is also configured to selectively rotate the door between at least a first position, in which at least a portion of the door deflects APU noise in a first direction, and a second position, in which at least a portion of the door deflects the APU noise in a second direction.

Abstract: A tortuous path quiet exhaust eductor system may be mounted to a gas turbine engine, such as commercial aircraft APU. The system includes an oil cooler, eductor primary nozzle, oil cooler air nozzle, and surge air dump nozzle. The primary nozzle, oil cooler air nozzle, and surge air dump nozzle direct exhaust flow to entrain APU compartment cooling air, oil cooling air and surge air in a direction having both radial and axial components with respect to the APU centerline axis. The exhaust flow is directed into an eductor mixing duct angled away from the centerline axis and then is turned to enter an exit duct angled toward the centerline axis so that direct line of sight acoustic paths from the tail pipe exit to the turbine exit are blocked, suppressing core noise. The tail pipe ducts may be acoustically treated, further enhancing noise suppression.

Abstract: A swirl generator for creating bulk swirl in a compressor plenum in the opposite direction to the direction of rotation of the compressor rotor. The generator includes a continuous flow passageway formed by an inlet duct and a compressor forming an angle in the range of about 0°-180° to one another. A non-uniform velocity gradient is created by forming an area of non-uniform cross-sectional area within the flow passageway. The non-uniform area may comprise a ramp with a tapered end line, a rounded line of intersection, a fillet or by lengthening one side wall of the inlet duct relative to the opposite side wall. Preferably, the non-uniform cross sectional area uniformly tapers from ones sidewall of the flow passageway to the opposite sidewall.

Abstract: A tortuous path quiet exhaust eductor system may be mounted to a gas turbine engine, such as commercial aircraft APU. The system includes an oil cooler, eductor primary nozzle, oil cooler air nozzle, and surge air dump nozzle. The primary nozzle, oil cooler air nozzle, and surge air dump nozzle direct exhaust flow to entrain APU compartment cooling air, oil cooling air and surge air in a direction having both radial and axial components with respect to the APU centerline axis. The exhaust flow is directed into an eductor mixing duct angled away from the centerline axis and then is turned to enter an exit duct angled toward the centerline axis so that direct line of sight acoustic paths from the tail pipe exit to the turbine exit are blocked, suppressing core noise. The tail pipe ducts may be acoustically treated, further enhancing noise suppression.

Abstract: A swirl generator for creating bulk swirl in a compressor plenum in the opposite direction to the direction of rotation of the compressor rotor. The generator includes a continuous flow passageway formed by an inlet duct and a compressor forming an angle in the range of about 0°-180° to one another. A non-uniform velocity gradient is created by forming an area of non-uniform cross-sectional area within the flow passageway. The non-uniform area may comprise a ramp with a tapered end line, a rounded line of intersection, a fillet or by lengthening one side wall of the inlet duct relative to the opposite side wall. Preferably, the non-uniform cross sectional area uniformly tapers from ones sidewall of the flow passageway to the opposite sidewall.

Abstract: An air inlet assembly for bringing air to an auxiliary power unit mounted in the compartment of an aircraft. The assembly includes a duct extending from an intake contoured to conform to the to the aircraft fuselage to an exit coupled to the inlet plenum of the auxiliary power unit. A first door hingeably mounted to the aft side of said intake and moveable from an open position to a closed position where said first door lies flush against intake, said first door having a closing wall and two side walls and a second door hingeably mounted to the forward end of said intake, said second door having a plate with two inwardly extending walls, each of said inwardly extending walls hinged to one of said side walls so that the second door rotates with said first door. During ground operation air that would have swirled around the side walls of the first door thus generating inlet corner vortices are now blocked by the side walls of the second door.

Abstract: A method and apparatus for cooling the heat generated by a gas turbine engine mounted in a compartment is provided. The apparatus comprises a novel eductor that incorporates a mixer nozzle to entrain sufficient air flow through the compartment to provide all the necessary cooling. The engine's oil cooler is mounted to the eductor so that the entrained air flow passes through it and cools the engine's oil. The novel eductor also has means for receiving a flow of high velocity air from the engine and injecting this air downstream of the mixer nozzle to enhance the entraining of the cooling flow.