# US 2013/0152601 A1 · Controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0152601 A1 - Document ID: US20130152601A1 - Status: Published application - Kind: A1 - Application number: 13/682,122 - Filed: 2012-11-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Assignees: ROLLS-ROYCE plc - Inventors: Marko BACIC - Web page: https://patentgrep.com/patent/US20130152601A1 ## CPC - F01D 11/24: by selectively cooling-heating stator or rotor components - F01D 5/081: {Cooling fluid being directed on the side of the rotor disc or at the roots of the blades (F01D5/087 takes precedence)} - F01D 17/02: Arrangement of sensing elements - F01D 17/085: {to temperature} - F01D 25/14: Casings modified therefor (double casings F01D25/26) - F02C 3/13: having variable working fluid interconnections between turbines or compressors or stages of different rotors {(controlling flow ratio between different flows of multi-flow jet-propulsion plant, e.g. ducted fan F02K3/075)} - F02C 6/08: the gas being bled from the gas-turbine compressor - F02C 7/18: the medium being gaseous, e.g. air {(F02C7/125 takes precedence)} - F02C 7/185: {Cooling means for reducing the temperature of the cooling air or gas} - F02C 9/18: by bleeding, bypassing or acting on variable working fluid interconnections between turbines or compressors or their stages {(F02C3/113 takes precedence)} - F05D 2260/205: Cooling fluid recirculation, i.e. after cooling one or more components is the cooling fluid recovered and used elsewhere for other purposes - F05D 2270/303: Temperature - F05D 2270/305: Tolerances - F05D 2270/44: active, predictive, or anticipative - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A gas turbine engine has, in flow series, a compressor section, a combustor, and a turbine section. The gas turbine engine further has a system for cooling the turbine section and providing tip clearance control between turbine blades and circumferentially distributed segments forming an annular shroud surrounding the blades outer tips. The turbine section cooling sub-system diverts a first cooling air flow, regulated by a first valve arrangement, from the compressor section to a heat exchanger and then to the turbine section to cool its components. The tip clearance control sub-system supplies a second cooling air flow, regulated by a second valve arrangement, to an engine case where the segments are mounted, which regulates thermal expansion of the case and controls the clearance between the segments and outer tips. The system further includes a closed-loop controller which issues demand signals to the first and second valve arrangements. ## Claims ### Claim 1 A gas turbine engine having, in flow series, a compressor section, a combustor, and a turbine section, and further having a system (i) for cooling the turbine section and (ii) for providing tip clearance control between turbine blades of the turbine section and a plurality of circumferentially distributed segments which form an annular shroud surrounding the outer tips of the turbine blades, the system including: a turbine section cooling sub-system which diverts a first cooling air flow received from the compressor section to a heat exchanger and then to the turbine section to cool components thereof, the first cooling air flow by-passing the combustor and being cooled in the heat exchanger, and the turbine section cooling subsystem having a first valve arrangement which regulates the first cooling air flow; a tip clearance control sub-system which supplies a second cooling air flow to an engine case to which the segments are mounted, the second cooling air flow regulating thermal expansion of the case and thereby controlling the clearance between the segments and the outer tips, and the tip clearance control sub-system having a second valve arrangement which regulates the second cooling air flow; and a closed-loop controller which issues first and second demand signals to respectively the first and the second valve arrangements, each of the first and second demand signals being determined on the basis of: (i) a value of the first demand signal at a previous time step, and a measurement or estimate of a turbine section component temperature, and (ii) a value of the second demand signal at a previous time step, and a measurement or estimate of tip clearance. ### Claim 2 (depends on 1) A gas turbine engine according to claim 1, wherein the controller includes (a) a control unit which calculates each of the first and the second demand signals from a plurality of error variables received by the control unit, from the value of the first demand signal at the previous time step, and from the value of the second demand signal at the previous time step, (b) an observer unit which measures or estimates the turbine section component temperature, measures or estimates the tip clearance, and provides observer variables based on the measurements or estimates, and (c) a comparator unit which compares the observer variables with corresponding target variables to determine the error variables, which are then issued to the control unit. ### Claim 3 (depends on 2) A gas turbine engine according to claim 2, wherein one of the observer variables provided by the observer unit is a turbine section component temperature, and the corresponding target variable is a target turbine section component temperature. ### Claim 4 (depends on 2) A gas turbine engine according to claim 2, wherein one of the observer variables provided by the observer unit is a tip clearance, and the corresponding target variable is a target tip clearance. ### Claim 5 (depends on 2) A gas turbine engine according to claims 2, wherein the observer unit includes a turbine section component temperature model and/or a tip clearance model, and the observer variables determined by the observer unit include a plurality of engine state variables, the corresponding target control values being target engine state variables. ### Claim 6 (depends on 1) A gas turbine engine according to claim 1, wherein the first valve arrangement includes one or more switched vortex valves. ### Claim 7 (depends on 1) A gas turbine engine according to claim 1, wherein the heat exchanger is located in a bypass air stream of the engine. ### Claim 8 The closed-loop controller configured to issue first and second demand signals to respective first and the second valve arrangements, each of the first and second demand signals being determined on the basis of: (i) a value of the first demand signal at a first time step, and a measurement or estimate of a turbine section component temperature, and (ii) a value of the second demand signal at the first time step, and a measurement or estimate of tip clearance. ### Claim 9 A method of operating a gas turbine engine having, in flow series, a compressor section, a combustor, and a turbine section, the method including the steps of: diverting a first cooling air flow received from the compressor section to a heat exchanger and then to the turbine section to cool components thereof, the first cooling air flow by-passing the combustor and being cooled in the heat exchanger; supplying a second cooling air flow to an engine case to which a plurality of circumferentially distributed segments are mounted, the segments forming an annular shroud around the outer tips of turbine blades of the turbine section, and the second cooling air flow regulating thermal expansion of the case and thereby controlling a tip clearance between the segments and the outer tips; and issuing first and second demand signals to respectively first and second valve arrangements, the first valve arrangement regulating the first cooling air flow and the second valve arrangement regulating the second cooling air flow, each of the first and second demand signals being determined on the basis of: (i) a value of the first demand signal at a previous time step, and a measurement or estimate of turbine section component temperature, and (ii) a value of the second demand signal at a previous time step, and a measurement or estimate of tip clearance. ### Claim 10 (depends on 9) A method according to claim 9, wherein the issuing step includes the sub-steps of: measuring or estimating the turbine section component temperature, measuring or estimating the tip clearance, providing observer variables based on the measurements or estimates, comparing the observer variables with corresponding target variables to determine a plurality of error variables, calculating each of the first and the second demand signals from the error variables, from the value of the first demand signal at the previous time step, and from the value of the second demand signal at the previous time step, and issuing the first and second demand signals to respectively the first and second valve arrangements.