# US 2013/0156583 A1 · Airfoils including tip profile for noise reduction and method for fabricating same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156583 A1 - Document ID: US20130156583A1 - Status: Published application - Kind: A1 - Application number: 13/330,766 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: General Electric Company - Inventors: Trevor Howard Wood - Web page: https://patentgrep.com/patent/US20130156583A1 ## CPC - F01D 5/141: {Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147)} - B64C 11/18: Aerodynamic features - B64C 11/48: Units of two or more coaxial propellers - F01D 5/145: {Means for influencing boundary layers or secondary circulations (for compressors F04D29/68)} - F01D 5/20: Specially-shaped blade tips to seal space between tips and stator {(F01D5/225 takes precedence)} - F04D 19/024: {with contrarotating parts} - F04D 29/164: {of an axial flow wheel} - F04D 29/324: {Blades} - F04D 29/681: {especially adapted for elastic fluid pumps} - B64D 2027/005: {Aircraft with an unducted turbofan comprising contra-rotating rotors, e.g. contra-rotating open rotors [CROR]} - F01D 1/26: traversed by the working-fluid substantially axially - F05D 2220/36: specially adapted for the fan of turbofan engines - F05D 2240/307: related to the tip of a rotor blade - F05D 2250/712: concave - Y02E 10/72: Wind turbines with rotation axis in wind direction - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - Y10T 29/49336: Blade making - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - B64C: AEROPLANES; HELICOPTERS - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An airfoil, a fan assembly and an unducted contra-rotating fan engine include fabricating at least one airfoil including a suction and a pressure side coupled together at a leading and a trailing edge and extending therebetween. The airfoil includes a plurality of chord sections having a chord length. The airfoil including a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length. The tip profile is configured to reduce the high unsteady pressure near the tip portion of the airfoil. ## Claims ### Claim 1 An airfoil comprising: a root portion and a tip portion, wherein the tip portion is configured extending radially outward from the root portion; a suction side and a pressure side coupled together at a leading edge and a trailing edge spaced chord-wise and downstream from the leading edge; a plurality of chord sections having a chord length and extending in a chord-wise direction between the leading edge and the trailing edge of the airfoil and spaced apart along a length of the airfoil in a span-wise direction between the root portion and the tip portion; and a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length, wherein the tip profile is configured to reduce high unsteady pressure near the tip portion of the airfoil. ### Claim 2 (depends on 1) An airfoil in accordance with claim 1, further including a tip profile defining a first portion having a first reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length and at least one additional portion having a reducing slope extending from the first portion toward the trailing edge along at least a portion of the chord length, wherein the first reducing slope is greater than the reducing slope of the at least one additional portion. ### Claim 3 (depends on 2) An airfoil in accordance with claim 2, wherein the first portion having a first reducing slope extends from the tip portion at the leading edge in a chord-wise direction at least 25% of the chord length of the airfoil. ### Claim 4 (depends on 2) An airfoil in accordance with claim 2, wherein the first portion having a first reducing slope extends from the tip portion at the leading edge in a chord-wise direction less than 25% of the chord length of the airfoil. ### Claim 5 (depends on 2) An airfoil in accordance with claim 2, further including a tip profile defining a first portion having a first reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length and a second portion having a second reducing slope extending from the first portion to the trailing edge along at least a portion of the chord length, wherein the first reducing slope is greater than the second reducing slope. ### Claim 6 (depends on 1) An airfoil in accordance with claim 1, wherein the airfoil is one of a ducted or unducted fan blade, rotor blade, wind turbine blade, or an aircraft aerodynamic surface. ### Claim 7 (depends on 6) An airfoil in accordance with claim 6, wherein the airfoil is a fan blade of an aft positioned bladerow of an unducted fan engine. ### Claim 8 (depends on 6) An airfoil in accordance with claim 6, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine. ### Claim 9 (depends on 6) An airfoil in accordance with claim 6, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine and an aft positioned bladerow of an unducted fan engine. ### Claim 10 A fan assembly comprising: a disk; and a plurality of fan blades coupled to the disk, each blade of the plurality of fan blades comprising: an airfoil comprising a root portion, a tip portion, a suction side and a pressure side coupled together at a leading edge and at a trailing edge spaced chord-wise and downstream from the leading edge; a plurality of chord sections having a chord length and extending in a chord-wise direction between the leading edge and the trailing edge of the airfoil and spaced apart along a length of the airfoil in a span-wise direction between the root portion and the tip portion; and a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length, wherein the tip profile is configured to reduce high unsteady pressure near the tip portion of the airfoil. ### Claim 11 (depends on 10) A fan assembly in accordance with claim 10, wherein the airfoil is configured to facilitate a reduction in noise associated with gust/tip vortex interaction. ### Claim 12 (depends on 10) A fan assembly in accordance with claim 10, further including a tip profile defining a first portion having a first reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length and at least one additional portion having a reducing slope extending from the first portion toward the trailing edge along at least a portion of the chord length, wherein the first slope is greater than the reducing slope of the at least one additional portion. ### Claim 13 (depends on 12) A fan assembly in accordance with claim 12, wherein the first portion having a first reducing slope extends from the tip portion at the leading edge in a chord-wise direction at least 25% of the chord length of the airfoil. ### Claim 14 (depends on 12) A fan assembly in accordance with claim 12, wherein the first portion having a first reducing slope extends from the tip portion at the leading edge in a chord-wise direction less than 25% of the chord length of the airfoil. ### Claim 15 (depends on 12) A fan assembly in accordance with claim 12, further including a tip profile defining a first portion having a first reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length and a second portion having a second reducing slope extending from the first portion to the trailing edge along at least a portion of the chord length, wherein the first reducing slope is greater than reducing slope of the second portion. ### Claim 16 (depends on 10) A fan assembly in accordance with claim 10, wherein the airfoil is one of a ducted or unducted fan blade, a wind turbine blade, or an aircraft aerodynamic surface. ### Claim 17 (depends on 16) A fan assembly in accordance with claim 16, wherein the airfoil is a fan blade of an aft positioned bladerow of an unducted fan engine. ### Claim 18 (depends on 16) A fan assembly in accordance with claim 16, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine. ### Claim 19 (depends on 16) A fan assembly in accordance with claim 16, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine and an aft positioned bladerow of an unducted fan engine. ### Claim 20 An unducted contra-rotating fan engine comprising: an unducted fan section including a first fan blade row and a second fan blade row axially spaced aftward from the first fan blade row, the second fan blade row including a plurality of airfoils, each airfoil comprising: a root portion and a tip portion, wherein the tip portion is configured extending radially outward from the root portion; a suction side and a pressure side coupled together at a leading edge and a trailing edge spaced chord-wise and downstream from the leading edge; a plurality of chord sections having a chord length and extending in a chord-wise direction between the leading edge and the trailing edge of the airfoil and spaced apart along a length of the airfoil in a span-wise direction between the root portion and the tip portion; and a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length, wherein the tip profile is configured to reduce high unsteady pressure near the tip portion of the airfoil. ### Claim 21 (depends on 20) An unducted contra-rotating fan engine in accordance with claim 20, wherein the airfoil is a fan blade of an aft positioned bladerow of an unducted fan engine. ### Claim 22 (depends on 20) An unducted contra-rotating fan engine in accordance with claim 20, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine. ### Claim 23 (depends on 20) An unducted contra-rotating fan engine in accordance with claim 20, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine and an aft positioned bladerow of an unducted fan engine. ### Claim 24 (depends on 20) An unducted contra-rotating fan engine in accordance with claim 20, wherein the airfoil is configured to facilitate a reduction in an unsteady response of the airfoil to its own vortex, pulsating and oscillating in response to an incident flow disturbance from upstream. ### Claim 25 A method of fabricating an airfoil, said method comprising: fabricating at least one airfoil including a root portion, a tip portion, a suction side and a pressure side coupled together at a leading edge and a trailing edge spaced chord-wise and downstream from the leading edge; wherein the airfoil includes a plurality of chord sections having a chord length and extending in a chord-wise direction between the leading edge and the trailing edge of the airfoil and spaced apart along a length of the airfoil in a span-wise direction between the root portion and the tip portion, said tip portion comprises: a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length, wherein the tip profile is configured to reduce high unsteady pressure near the tip portion of the airfoil. ### Claim 26 (depends on 25) A method of fabricating an airfoil in accordance with claim 25, wherein the airfoil is one of a ducted and unducted fan blade, wind turbine blade, or an aircraft aerodynamic surfaces. ### Claim 27 (depends on 26) A method of fabricating an airfoil in accordance with claim 26, wherein the airfoil is a fan blade of an aft positioned bladerow of an unducted fan engine. ### Claim 28 (depends on 26) A method of fabricating an airfoil in accordance with claim 26, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine. ### Claim 29 (depends on 26) A method of fabricating an airfoil in accordance with claim 26, wherein the airfoil is a fan blade of a forward positioned bladerow of an unducted fan engine and an aft positioned bladerow of an unducted fan engine.