Method and apparatus for quieting a turbojet engine
OwnerAllen E. Paulsoninventor
Life of this patent
Estimating the term…
Abstract
A noise suppressor for attachment to the aft end of an existing turbojet engine. The noise suppressor includes a free-running turbofan wheel which includes a turbine section mounted for reaction to the exhaust gas from the jet engine, and a concentric outer fan section extending within an air duct concentric with the turbofan wheel. The jet exhaust from normal operation of the jet engine spins the free-running turbofan wheel, and the fan section of that wheel produces a flow of compressed air through the duct to surround and mix with the jet exhaust, thereby reducing the noise emission of the jet engine. A thrust reverser and an afterburner are optional for use with the noise suppressor.
Claims11
Apparatus for reducing the noise emitted by the exhaust from the outlet at the aft end of a jet propulsion engine, comprising:
- a housing configured for location at the outlet of the engine and having a portion spaced outwardly from the engine adjacent the aft end to define a duct having an air inlet, the duct also having an outlet downstream from the aft end of the engine;
- a free turbine mounted for rotation within the housing and driven by the exhaust from the engine outlet so as to rotate independently of rotating elements in the jet engine;
- a fan within the air inlet of the duct and driven by rotation of the free turbine to create an air flow through the duct, such that the air flow substantially surrounds the jet exhaust and thereby reduces the noise of the jet exhaust flowing from the outlet of the duct;
- and
- means for introducing fuel into the exhaust immediately upstream from the free turbine so that the fuel combusts and produces exhaust gas which increases the power available to drive the turbine, thereby driving the fan to produce more thrust for the engine.
A method for reducing the noise emitted from the exhaust from the outlet of a jet propulsion engine, comprising the steps of:
- mounting a free-running turbine aft of the exhuast of the jet engine so that the turbine is driven by the exhaust, thereby reducing the speed of the jet exhaust;
- providing a fan at the circumference of the turbine;
- and
- surrounding the fan with an air bypass duct having an air inlet upstream of the fan so that the fan compresses air which moves aft and mixes with the jet exhaust, so that the reduced speed of the jet exhaust and the mixing of the air from the fan reduces the noise from the jet exhaust;
- and
- selectively redirecting the jet exhaust upstream of the free-running turbine so that the exhaust is blocked from driving the turbine and instead has a component of thrust in a forward direction relative to the longitudinal axis of the engine.
Apparatus for reducing the noise emitted by the jet exhaust from the aft end of a jet propulsion engine, comprising:
- a nacelle surrounding the engine and having an aft end;
- a housing configured for location at the aft end of the nacelle and having means spaced from the nacelle adjacent the aft end of the engine to define a passage having an air inlet, the passage having an outlet downstream from the aft end of the engine;
- a free turbine mounted for rotation within the housing and driven by the exhaust from the engine outlet so as to rotate independently of rotating elements in the jet engine;
- a fan driven by the free turbine to compress air entering the passage from the air inlet, such that the air flows from the outlet of the passage to substantially surround the jet exhaust and thereby reduce the noise of the jet exhaust from the engine;
- means located forwardly of the free turbine to selectively block the exhaust from flowing to the free turbine and redirect the jet exhaust from to a forward direction in relation to the engine, so that the thrust of the jet exhaust is reversed from the normal aftward direction of thrust;
- and
- door means associated with the nacelle and being normally closed but operative in association with the exhaust blocking means to an open position defining a path for the redirected jet exhaust, so that the redirected jet exhaust exits the engine on a path directed forwardly relative to the normal aftward direction of thrust.
Apparatus for reducing the noise emitted by the jet exhaust from the aft end of a jet propulsion engine, comprising:
- a nacelle surrounding the engine and having an aft end;
- a housing configured for location at the aft end of the nacelle and having means spaced from the nacelle adjacent the aft end of the engine to define a passage having an air inlet, the passage having an outlet downstream from the aft end of the engine;
- a free turbine mounted for rotation within the housing and driven by the exhaust from the engine outlet so as to rotate independently of rotating elements in the jet engine;
- a fan driven by the free turbine to compress air entering the passage from the air inlet, such that the air flows from the outlet of the passage to substantially surround the jet exhaust and thereby reduce the noise of the jet exhaust from the engine;
- and
- means selectively operative to close the air inlet of the passage so that the fan inlet does not receive outside air whenever the air inlet is closed.
Dependencies are inferred from the claim text.