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US 6,505,706 B2Granted
Exhaust flow guide for jet noise reduction
AssigneePratt & Whitney Canada Corp.
InventorMan-Chun Tse
Life of this patent
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AssigneePratt & Whitney Canada Corp.
InventorMan-Chun Tse
Estimating the term…
A gas turbine engine includes an exhaust flow guide attached to the engine exhaust end. The exhaust flow guide is made of a piece of sheet metal curved about the central longitudinal axis of the engine to form a partial portion of a nozzle having curved leading and trailing edges, and side edges. The exhaust flow guide asymmetrically affects the downstream jet noise contribution volume of the exhaust gases discharged from the engine exhaust end to change the jet noise directivity and reduce its power level. The exhaust flow guide can further include additional features such as perforations, corrugated surfaces, reinforcing strips and irregularly shaped trailing edges to further improve the mixing of exhaust gas flow with surrounding fluid flow to further reduce the downstream jet noise contribution volume, thereby resulting in jet noise reduction. The exhaust flow guide according to the present invention also improves attenuation of engine noise generated in the engine and emitted from the engine exhaust end. The present invention provides a jet noise reduction device which is simple and economical to manufacture and maintain, and is applicable to both short and long cowl nacelle gas turbine engines.
A gas engine exhaust jet noise reduction device for a gas turbine engine having an exhaust end, the device comprising an exhaust flow guide adapted to be attached to the exhaust end, the exhaust flow guide having a piece of sheet metal curved to form a partial portion of a nozzle having curved leading and trailing edges, and side edges, the curved leading edge having a circumferential length greater than a circumferential length of the curved trailing edge, a distance from a central point of the curved leading edge to an imaginary straight line extending between two circumferentially opposed extremities of the curved leading edge being greater than one quarter of a diameter of an inner periphery of the exhaust end, thereby asymmetrically guiding an exhaust flow to change a jet noise directivity and reduce jet noise power level.
A gas turbine engine for aircraft including an engine exhaust end, the gas turbine engine comprising an exhaust flow guide made of a piece of sheet metal attached to and extending rearwards from the engine exhaust end, the sheet metal being curved about a central longitudinal axis of the engine to form a partial portion of a nozzle having curved leading and trailing edges, and side edges, the curved leading edge having a circumferential length greater than a circumferential length of the trailing edge, a distance from a central point of the curved leading edge to an imaginary straight line extending between two circumferentially opposed extremities of the curved leading edge being greater than one quarter of a diameter of an inner periphery of the exhaust end, thereby asymmetrically guiding exhaust flow to change a jet noise directivity and reduce jet noise power level.
A method for reducing jet noise of gas turbine engines comprising a step of changing jet noise directivity and reducing jet noise power levels using an exhaust flow guide made of a curved sheet metal attached to an engine exhaust end to form a partial portion of a nozzle to asymmetrically affect viscous shearing of rapidly moving exhaust gases into a relative quiescent surrounding fluid flow at the boundary between the exhaust gases and the surrounding fluid flow.
Dependencies are inferred from the claim text.