# US 10,119,403 B2 · Mistuned concentric airfoil assembly and method of mistuning same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,403 B2 - Document ID: US10119403B2 - Status: Granted - Kind: B2 - Application number: 14/618,478 - Filed: 2015-02-10 - Published: 2017-06-08 - Granted: 2018-11-06 - Earliest claimed: 2014-02-13 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Richard K. Hayford; Steven J. Ford - Web page: https://patentgrep.com/patent/US10119403B2 ## CPC - F01D 5/146: {of blades with tandem configuration, split blades or slotted blades} - F01D 5/022: {with concentric rows of axial blades} - F01D 5/225: {by shrouding} - F01D 25/06: for preventing blade vibration (means on blade-carrying members or blades F01D5/00) - F05D 2260/961: by mistuning rotor blades or stator vanes with irregular interblade spacing, airfoil shape - 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 An example method of reducing a vibratory response of airfoils that support a shroud includes circumferentially misaligning some of the airfoils in a radially inner array of airfoils with all airfoils of a radially outer array of airfoils, and circumferentially aligning at least one of the airfoils in the radially inner array of airfoils with all airfoils of the radially outer array of airfoils. ## Claims ### Claim 1 An airfoil assembly for a gas turbine engine, comprising: an annular shroud having a radially inner face and a radially outer face opposing the radially inner face; a radially inner array of airfoils extending from the radially inner face; a radially outer array of airfoils extending from the radially outer face; wherein the radially inner array of airfoils are configured to guide flow within a radially inner bypass flow passage, the radially inner bypass flow passage bypassing and being radially outward of a compressor section; and wherein one airfoil of the radially inner array of airfoils is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils at a twelve o'clock position, and the remaining airfoils in the radially inner array of airfoils are circumferentially misaligned with the airfoils of the radially outer array of airfoils. ### Claim 2 An airfoil assembly for a gas turbine engine, comprising: an annular shroud having a radially inner face and a radially outer face opposing the radially inner face; a radially inner array of airfoils extending from the radially inner face; a radially outer array of airfoils extending from the radially outer face, wherein at least one airfoil of the radially inner array of airfoils is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils, and at least one airfoil of the radially inner array of airfoils is circumferentially misaligned with the airfoils of the radially outer array of airfoils; wherein the radially inner array of airfoils are configured to guide flow within a radially inner bypass flow passage, the radially inner bypass flow passage bypassing and being radially outward of a compressor section; and wherein each of the radially inner array of airfoils at or above a horizontal midline of the assembly is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils when is in an installed position. ### Claim 3 (depends on 2) The assembly of claim 2, wherein the annular shroud, the radially inner array of airfoils, and the radially outer array of airfoils are cast together as a single unitary structure. ### Claim 4 An airfoil assembly for a gas turbine engine, comprising: a shroud having a radially inner face and a radially outer face opposing the inner face; a radially inner array of airfoils extending from the radially inner face; and a radially outer array of airfoils extending from the radially outer face, wherein a distance between circumferentially adjacent airfoils of the radially inner array of airfoils or circumferentially adjacent airfoils in the radially outer array of airfoils varies; wherein a total number of airfoils in the radially inner array of airfoils is greater than a total number of airfoils in the radially outer array of airfoils; and wherein one airfoil of the radially inner array of airfoils is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils at a twelve o'clock position, and the remaining airfoils of the radially inner array of airfoils are circumferentially misaligned with all airfoils in the radially outer array of airfoils. ### Claim 5 (depends on 4) The assembly of claim 4, wherein the shroud is an annular shroud. ### Claim 6 (depends on 4) The assembly of claim 4, wherein the shroud, the radially inner array of airfoils, and the radially outer array of airfoils are cast together as a single unitary structure. ### Claim 7 (depends on 4) The assembly of claim 4, wherein the shroud is a middle shroud and further comprising a radially inner shroud and a radially outer shroud, the radially inner array of airfoils extending from the middle shroud to the radially inner shroud, the radially outer array of airfoils extending from the middle shroud to the radially outer shroud. ### Claim 8 (depends on 4) The assembly of claim 4, wherein the radially inner array of airfoils are configured to guide flow within a radially inner bypass flow passage. ### Claim 9 (depends on 8) The assembly of claim 8, wherein the radially outer array of airfoils are configured to guide flow within a radially outer bypass flow passage. ### Claim 10 (depends on 9) The assembly of claim 9, wherein the radially inner bypass flow passage and the radially outer bypass flow passage are both radially outside a core flow passage. ### Claim 11 (depends on 10) The assembly of claim 10, wherein: the radially inner bypass flow passage and the radially outer bypass flow passage both bypass and are radially outward of the core flow passage; and the core flow passage extends through the compressor section, the combustor section and the turbine section. ### Claim 12 A method of reducing a vibratory response of airfoils that support a shroud for a gas turbine engine, comprising: circumferentially aligning an airfoil of a radially inner array of airfoils and an airfoil of a radially outer array of airfoils at a twelve o'clock position; and circumferentially misaligning the remaining airfoils of the radially inner array of airfoils with all the airfoils of the radially outer array; and guiding flow through a radially inner bypass flow passage using the radially inner array of airfoils, the radially inner bypass flow passage bypassing and being radially outward of a core flow passage. ### Claim 13 (depends on 12) The method of claim 12, further comprising guiding flow through a radially outer bypass flow passage using the radially outer array of airfoils. ### Claim 14 (depends on 13) The method of claim 13, further comprising moving core flow through the core flow passage that is radially inside the radially inner bypass flow passage. ### Claim 15 An airfoil assembly for a gas turbine engine, comprising: an annular shroud having a radially inner face and a radially outer face opposing the radially inner face; a radially inner array of airfoils extending from the radially inner face; a radially outer array of airfoils extending from the radially outer face, wherein at least one airfoil of the radially inner array of airfoils is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils, and at least on airfoil of the radially inner array of airfoils is circumferentially misaligned with the airfoils of the radially outer array of airfoils; wherein the radially inner array of the airfoils are configured to guide flow within a radially inner bypass flow passage, the radially inner bypass flow passage bypassing and being radially outward of a compressor section; wherein the radially outer array of airfoils are configured to guide flow within a radially outer bypass flow passage; wherein the radially inner bypass flow passage and the radially outer bypass flow passage are both radially outside a core flow passage; wherein a distance between circumferentially adjacent airfoils of the radially inner array of airfoils or circumferentially adjacent airfoils in the radially outer array of airfoils varies; wherein the core flow passage extends through the compressor section, a combustor section and a turbine section; wherein each of the radially inner array of airfoils at or above a horizontal midline of the assembly is circumferentially aligned with a corresponding airfoil in the radially outer array of airfoils when is in an installed position, the horizontal midline extending through an opposed pair of the radially inner array of airfoils and extending through an opposed pair of the radially outer array of airfoils; and wherein each of the radially inner and radially outer bypass flow passages is free of any rotatable airfoils downstream of the radially inner array of airfoils and downstream of the radially outer array of airfoils.