# US 11,111,809 B2 · Electric heating for turbomachinery clearance control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,111,809 B2 - Document ID: US11111809B2 - Status: Granted - Kind: B2 - Application number: 15/979,085 - Filed: 2018-05-14 - Published: 2019-11-14 - Granted: 2021-09-07 - Earliest claimed: 2018-05-14 - Assignees: Raytheon Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Neil Terwilliger; Christopher J. Hanlon; Patrick D Couture; Coy Bruce Wood - Web page: https://patentgrep.com/patent/US11111809B2 ## CPC - F01D 11/24: by selectively cooling-heating stator or rotor components - F01D 11/18: using stator or rotor components with predetermined thermal response, e.g. selective insulation, thermal inertia, differential expansion - F01D 25/10: Heating, e.g. warming-up before starting - F05D 2240/24: for turbines - F05D 2240/55: Seals - F05D 2260/201: by impingement of a fluid - F05D 2270/62: Electrical actuators - 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 clearance control system for a gas turbine engine may comprise a rotor blade, an outer structure disposed radially outward from the rotor blade, and a heating element configured to cause the outer structure to be heated in response to electric current being supplied to the heating element, wherein a gap between the rotor blade and the outer structure is at least one of increased, decreased, and maintained in response to the outer structure being heated. ## Claims ### Claim 1 A gas turbine engine, comprising: an engine case; a rotor blade disposed within the engine case, the rotor blade configured to rotate about an engine centerline axis; an outer structure disposed radially outward from the rotor blade, wherein the outer structure comprises an outer air seal; at least one case support associated with the engine case, wherein the at least one case support extends radially inward from the engine case; a clearance control ring positioned adjacent the at least one case support to form an internal cavity between the engine case and the clearance control ring, and wherein the at least one case support provides support for the clearance control ring; and a heating element operatively coupled to the clearance control ring; wherein the clearance control ring is mounted to the outer air seal such that the clearance control ring can move independently of the engine case; in response to electric current being supplied to the heating element, the heating element causes the clearance control ring to be heated and, in response to the clearance control ring being heated, the clearance control ring and the outer air seal move together in a first direction with respect to the engine case and the at least one case support; and a volume of the internal cavity varies in response to the clearance control ring moving with respect to the engine case. ### Claim 2 (depends on 1) The gas turbine engine of claim 1, further comprising an injection nozzle configured to deliver a cooling air flow to the clearance control ring to cause the clearance control ring to move in a second direction. ### Claim 3 (depends on 1) The gas turbine engine of claim 1, further comprising: an electric power supply configured to supply the electric current to the heating element; and a controller configured to regulate the electric current being supplied to the heating element. ### Claim 4 (depends on 1) The gas turbine engine of claim 1, wherein the clearance control ring comprises a thermal expansion coefficient that is greater than that of the engine case. ### Claim 5 (depends on 1) The gas turbine engine of claim 1, wherein the at least one case support comprises: a first radial wall extending radially inward from the engine case; and a second radial wall extending radially inward from the engine case, wherein the clearance control ring is positioned axially between the first radial wall and the second radial wall. ### Claim 6 (depends on 1) The gas turbine engine of claim 1, wherein the heating element is coupled to an outer surface of the clearance control ring. ### Claim 7 (depends on 1) The gas turbine engine of claim 1, wherein the heating element is embedded in the clearance control ring. ### Claim 8 (depends on 1) The gas turbine engine of claim 1, wherein the clearance control ring is supported by the engine case such that the clearance control ring moves freely with respect to the engine case in at least the first direction. ### Claim 9 A method for controlling blade tip clearance for a gas turbine engine, comprising: detecting, by a controller, a condition of the gas turbine engine; sending, by the controller, electric current to a heating element; heating, by the heating element, a clearance control ring, wherein the clearance control ring is positioned adjacent at least one case support to form an internal cavity between an engine case and the clearance control ring, and wherein the clearance control ring is mounted to an outer air seal such that the clearance control ring can move independently of the engine case; and moving the clearance control ring together with the outer air seal in a first direction with respect to the engine case and the at least one case support to maintain a gap between a rotor blade and the outer air seal, wherein the at least one case support extends radially inward from the engine case, and the at least one case support provides support for the clearance control ring. ### Claim 10 (depends on 9) The method of claim 9, wherein the detecting the condition of the gas turbine engine comprises detecting an engine shutdown of the gas turbine engine. ### Claim 11 (depends on 9) The method of claim 9, wherein the detecting the condition of the gas turbine engine comprises detecting an increase in throttle of the gas turbine engine. ### Claim 12 (depends on 9) The method of claim 9, wherein the at least one case support comprises: a first radial wall extending radially inward from the engine case; and a second radial wall extending radially inward from the engine case, wherein the clearance control ring is positioned axially between the first radial wall and the second radial wall. ### Claim 13 (depends on 9) The method of claim 9, wherein the heating element is coupled to an outer surface of the clearance control ring. ### Claim 14 (depends on 9) The method of claim 9, wherein the heating element is embedded in the clearance control ring. ### Claim 15 (depends on 9) The method of claim 9, wherein the clearance control ring is supported by the engine case such that the clearance control ring moves freely with respect to the engine case in at least the first direction.