Turbofan engine with reduced noise
First Claim
1. A noise-reduced turbofan engine comprising:
- a) a core engine having axial flow fans, multi-stage compressors and multi-stage reaction turbines and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow;
b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; and
c) a material layer located in a spacing between a tip of blades for at least some of the fans and a duct for the fans, thereby to reduce a normal clearance between the tip of blades for the fan and the duct.
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Accused Products
Abstract
A noise reduction kit for modifying a two (2) spool axial flow turbofan engine with multi-stage compressors and fan driven by multi-stage reaction turbines, and a thrust of at least about 18,000 lbs. at sea level. There is a fan at the upstream end of the core engine for generating axial fan air flow through bypass ducts terminating at a common nozzle, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches. A material layer is located in a spacing between a tip of blades for at least some of the fans and a duct for the fans, thereby to reduce a normal clearance between the tip of blades for the fan and the duct. Mixing means for radially diverting fan air and permitting radially outward expansion of exhaust gas is provided coaxially downstream to the core engine. An acoustically dampened light bulb-shaped nose cone is provided for coaxial attachment to an upstream end of the core engine. There is an inlet pressure sensing probe housed in an inlet bullet forwardly of the fans. Alternatively, there is an inlet pressure sensing probe housed at a location of an inlet guide vane forwardly of the fans, the probe being shaped for aerodynamic location in the inlet guide vane. The axial flow front fan is axially separated from the inlet guide vane is extended relatively forwardly.
56 Citations
19 Claims
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1. A noise-reduced turbofan engine comprising:
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a) a core engine having axial flow fans, multi-stage compressors and multi-stage reaction turbines and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow; b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; and c) a material layer located in a spacing between a tip of blades for at least some of the fans and a duct for the fans, thereby to reduce a normal clearance between the tip of blades for the fan and the duct. - View Dependent Claims (2, 3, 4, 9, 10, 11, 13)
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5. A noise-reduced turbofan engine comprising:
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a) a core engine having axial flow fans, multi-stage compressors and multi-stage reaction turbines and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow; b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; and c) an inlet pressure sensing probe housed in an inlet bullet forwardly of the fans. - View Dependent Claims (12)
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6. A noise-reduced turbofan engine comprising:
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a) a core engine having axial flow fans, multi-stage compressors and multi-stage reaction turbines and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow; b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; and c) an inlet pressure sensing probe housed at a location of an inlet guide vane forwardly of the fans, the probe being located in the inlet guide vane. - View Dependent Claims (7)
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8. A noise-reduced turbofan engine comprising:
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a) a core engine having axial flow fans, multi-stage compressors and multi-stage reaction turbines and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow; b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; and c) a material layer located about the inside wall of the duct in a spacing between a tip of blades for at least some of the fans and a duct for the fans, thereby to reduce a normal clearance between the tip of blades for the fan and the duct, the thickness of the layer being between about 0.050 to about 0.090 of an inch.
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14. A noise-reduced turbofan engine comprising:
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a) a core engine having axial flow fans, multistage compressors and multistage reaction turbines, and a thrust of at least about 18,000 lbs. at sea level, the fans being at an upstream end of the core engine for generating axial fan air flow; b) bypass ducts for receiving at least portion of the axial fan air flow from the fans, the ducts terminating at a common nozzle located at the outlet for exhaust gas from the engine, the common nozzle having a mixing plane area for each of the fan air flow and for the exhaust gas in a range between 700 and 800 square inches; c) a mixer in the common nozzle disposed axially to receive and exhaust the exhaust gas and fan air, said mixer having an upstream end and an annular mixer wall axially extending downstream therefrom, the wall being formed into a plurality of circumferentially alternating radially inward and radially outward lobes, the radially inward lobes defining cold chutes for radially inwardly diverting fan air and outward lobes defining hot chutes for permitting radially outward expansion of exhaust gas; and d) a material layer located in a spacing between a tip of blades for at least some of the fans and a duct for the fans, thereby to reduce a normal clearance between the tip of blades for the fan and the duct. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification