# US 11,078,799 B2 · Turbomachine rotor blade with an airfoil having a variable elliptical trailing edge > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,799 B2 - Document ID: US11078799B2 - Status: Granted - Kind: B2 - Application number: 16/695,256 - Filed: 2019-11-26 - Published: 2021-05-27 - Granted: 2021-08-03 - Earliest claimed: 2019-11-26 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Marios Karakasis; Robert Piotr Bujnicki; Adam John Fredmonski - Web page: https://patentgrep.com/patent/US11078799B2 ## CPC - F01D 5/141: {Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147)} - F01D 5/30: Fixing blades to rotors; Blade roots {; Blade spacers} - F01D 5/12: Blades ({specially adapted for radial flow machines or engines F01D5/04}; blade roots F01D5/30; rotors with blades adjustable in operation F01D7/00; stator blades F01D9/02) - F05D 2220/32: in gas turbines - F05D 2240/122: related to the trailing edge of a stator vane - F05D 2240/303: related to the leading edge of a rotor blade - F05D 2240/304: related to the trailing edge of a rotor blade - F05D 2240/305: related to the pressure side of a rotor blade - F05D 2240/306: related to the suction side of a rotor blade - F05D 2250/14: elliptical - F05D 2250/141: circular - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A rotor blade of a turbomachine includes an airfoil. The airfoil includes a root and a tip which define a span of the airfoil therebetween. The airfoil also includes a leading edge and a trailing edge downstream of the leading edge along a flow direction. The leading edge and the trailing edge each extend across the span of the airfoil from the root to the tip. The airfoil further includes a pressure side surface and a suction side surface. The pressure side surface and the suction side surface are continuous about the trailing edge and collectively define an arc centered on the trailing edge. The arc has a semi-major axis and a semi-minor axis. The semi-major axis and the semi-minor axis of the arc define an axis ratio, and the axis ratio varies over the span of the airfoil. ## Claims ### Claim 1 An airfoil of a rotor blade for a turbomachine, the airfoil comprising: a root; a tip spaced radially outward from the root, the root and the tip defining a span of the airfoil therebetween; a leading edge extending across the span of the airfoil from the root to the tip; a trailing edge downstream of the leading edge along a flow direction, the trailing edge extending across the span of the airfoil from the root to the tip; a pressure side surface extending between the root and the tip and extending between the leading edge and the trailing edge; a suction side surface extending between the root and the tip and extending between the leading edge and the trailing edge, the suction side surface opposing the pressure side surface, the pressure side surface and the suction side surface continuous about the trailing edge; and an arc centered on the trailing edge and collectively defined by a portion of the pressure side surface and a portion of the suction side surface, the arc having a semi-major axis and a semi-minor axis; wherein the semi-major axis and the semi-minor axis of the arc define an axis ratio, and the axis ratio varies over the span of the airfoil, wherein the arc is generally circularly shaped at the root and the tip of the airfoil, and wherein the arc is elliptically shaped between the root and the tip of the airfoil. ### Claim 2 (depends on 1) The airfoil of claim 1, wherein the axis ratio is greater at a midpoint of the span than at the root or the tip. ### Claim 3 (depends on 1) The airfoil of claim 1, wherein the axis ratio varies symmetrically across the span. ### Claim 4 (depends on 1) The airfoil of claim 1, wherein the axis ratio is constant over a mid-span portion of the airfoil. ### Claim 5 (depends on 4) The airfoil of claim 4, wherein the mid-span portion of the airfoil comprises about two thirds of the span of the airfoil. ### Claim 6 (depends on 1) The airfoil of claim 1, wherein the axis ratio is greatest in a mid-span portion of the airfoil. ### Claim 7 (depends on 6) The airfoil of claim 6, wherein the axis ratio is constant over the mid-span portion of the airfoil. ### Claim 8 (depends on 7) The airfoil of claim 7, wherein the mid-span portion of the airfoil comprises about two thirds of the span of the airfoil. ### Claim 9 (depends on 6) The airfoil of claim 6, wherein the semi-major axis is about three times the semi-minor axis in the mid-span portion of the airfoil. ### Claim 10 (depends on 1) The airfoil of claim 1, wherein the axis ratio is about one to one (1:1) at the root and at the tip of the airfoil, and wherein the axis ratio is up to about four to one (4:1) between the root and the tip of the airfoil. ### Claim 11 A turbomachine, comprising; a compressor; a combustor disposed downstream from the compressor; and a turbine disposed downstream from the combustor, the turbine including a rotor shaft extending along an axial direction through the turbine and a rotor blade connected to the rotor shaft, an airfoil of the rotor blade comprising: a root; a tip spaced radially outward from the root, the root and the tip defining a span of the airfoil therebetween; a leading edge extending across the span of the airfoil from the root to the tip; a trailing edge downstream of the leading edge along a flow direction, the trailing edge extending across the span of the airfoil from the root to the tip; a pressure side surface extending between the root and the tip and extending between the leading edge and the trailing edge; a suction side surface extending between the root and the tip and extending between the leading edge and the trailing edge, the suction side surface opposing the pressure side surface, the pressure side surface and the suction side surface continuous about the trailing edge; and an arc centered on the trailing edge and collectively defined by a portion of the pressure side surface and a portion of the suction side surface, the arc having a semi-major axis and a semi-minor axis; wherein the semi-major axis and the semi-minor axis of the arc define an axis ratio and the axis ratio varies over the span of the airfoil, wherein the arc is generally circularly shaped at the root and the tip of the airfoil, and wherein the arc is elliptically shaped between the root and the tip of the airfoil. ### Claim 12 (depends on 11) The turbomachine of claim 11, wherein the axis ratio is greater at a midpoint of the span than at the root or the tip. ### Claim 13 (depends on 11) The turbomachine of claim 11, wherein the axis ratio varies symmetrically across the span. ### Claim 14 (depends on 11) The turbomachine of claim 11, wherein the axis ratio is constant over a mid-span portion of the airfoil. ### Claim 15 (depends on 14) The turbomachine of claim 14, wherein the mid-span portion of the airfoil comprises about two thirds of the span of the airfoil. ### Claim 16 (depends on 11) The turbomachine of claim 11, wherein the axis ratio is greatest in a mid-span portion of the airfoil. ### Claim 17 (depends on 16) The turbomachine of claim 16, wherein the axis ratio is constant over the mid-span portion of the airfoil. ### Claim 18 (depends on 17) The turbomachine of claim 17, wherein the mid-span portion of the airfoil comprises about two thirds of the span of the airfoil. ### Claim 19 (depends on 16) The turbomachine of claim 16, wherein the semi-major axis is about three times the semi-minor axis in the mid-span portion of the airfoil. ### Claim 20 (depends on 11) The turbomachine of claim 11, wherein the axis ratio is about one to one (1:1) at the root and at the tip of the airfoil, and wherein the axis ratio is up to about four to one (4:1) between the root and the tip of the airfoil.