# US 2013/0156541 A1 · Active turbine tip clearance control system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156541 A1 - Document ID: US20130156541A1 - Status: Published application - Kind: A1 - Application number: 13/326,434 - Filed: 2011-12-15 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Pratt & Whitney Canada Corp. - Inventors: Andreas ELEFTHERIOU; Daniel ALECU - Web page: https://patentgrep.com/patent/US20130156541A1 ## CPC - F01D 11/20: Actively adjusting tip-clearance - F01D 11/22: by mechanically actuating the stator or rotor components, e.g. moving shroud sections relative to the rotor - F01D 11/24: by selectively cooling-heating stator or rotor components - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) ## Abstract An active tip clearance control (ATCC) system of a gas turbine engine includes an ejector to selectively drive an air flow passing through the ATCC system. A high pressure air flow as a motive flow of the ejector is controlled by a valve according to engine operation requirements. ## Claims ### Claim 1 An active tip clearance control (ATCC) system of a gas turbine engine comprising an ATCC manifold disposed adjacent a rotor case, the manifold configured for directing air over the rotor case, an inlet passage fluidly connecting the ATCC manifold with an air source, a vent passage in fluid communication with the manifold and the atmosphere for venting air received from the ATCC manifold to the atmosphere, a controllable valve receiving and controlling a high pressure air flow, and an ejector configured to use the controlled high pressure air flow to selectively drive said air through the ATCC manifold. ### Claim 2 (depends on 1) The active tip clearance control (ATCC) system as defined in claim 1 wherein the ejector is mounted on the inlet passage and positioned upstream of the manifold to drive the air through the inlet passage towards the ATCC manifold. ### Claim 3 (depends on 1) The active tip clearance control (ATCC) system as defined in claim 1 wherein the ejector is mounted on the vent passage and positioned downstream of the manifold to drive the air through the vent passage and away from the ATCC manifold. ### Claim 4 (depends on 1) The active tip clearance control (ATCC) system as defined in claim 1 wherein the air source is a fan driven bypass air flow directed through a bypass duct of the engine. ### Claim 5 (depends on 1) The active tip clearance control (ATCC) system as defined in claim 1 wherein the air source is ambient air. ### Claim 6 (depends on 1) The active tip clearance control (ATCC) system as defined in claim 1 wherein the vent passage is in fluid communication with the atmosphere via a bypass duct for directing a fan driven bypass air flow. ### Claim 7 An aircraft turbofan gas turbine engine comprising: an annular outer case surrounding a fan assembly; an annular core case positioned within the outer case and accommodating a compressor assembly, a combustion gas generator assembly and a turbine assembly, the annular outer and core cases defining an annular bypass duct therebetween for directing a bypass air flow driven by the fan assembly to pass therethrough; and an active tip clearance control (ATCC) apparatus including an ATCC manifold mounted to a turbine case for discharging cooling air over the turbine case to cool the same, an inlet passage connecting the ATCC manifold with the bypass duct at a first location of the bypass duct, a vent passage disposed downstream of the ATCC manifold and being in fluid communication with the bypass duct at a second location of the bypass duct downstream of the first location, the ATCC apparatus further including a solenoid valve controlling a high pressure air flow and an ejector using the controlled high pressure air to selectively drive the cooling air through the ATCC manifold. ### Claim 8 (depends on 7) The aircraft turbofan gas turbine engine as defined in claim 7 wherein the ejector is mounted on the inlet passage to drive the cooling air through the inlet passage towards the ATCC manifold. ### Claim 9 (depends on 7) The aircraft turbofan gas turbine engine as defined in claim 7 wherein the ejector is mounted on the vent passage to drive the cooling air through the vent passage and away from the ATCC manifold. ### Claim 10 (depends on 7) The aircraft turbofan gas turbine engine as defined in claim 7 wherein the ejector is formed with a hole defined in a side wall of one of the inlet and vent passages for receiving the controlled high pressure air flow to be injected into said one of the inlet and vent passages. ### Claim 11 (depends on 7) The aircraft turbofan gas turbine engine as defined in claim 7 wherein the high pressure air flow is compressor air of the engine. ### Claim 12 (depends on 7) The aircraft turbofan gas turbine engine as defined in claim 7 wherein a volume of the high pressure air flow is smaller than a volume of the cooling air flow in each time unit. ### Claim 13 A method for controlling an active tip clearance control (ATCC) system of a gas turbine engine, comprising amplifying a control signal for actuating the ATCC system in steps of: a) selectively actuating a solenoid valve using an electric signal as the control signal to control an on/off condition of a high pressure air flow; and b) using the on/off-controlled high pressure air flow to selectively actuate an ejector which drives a cooling air flow through the ATCC system, thereby selectively increasing an energy level of the cooling air flow passing through the ATCC system, resulting in an increased pressure differential over the ATCC system. ### Claim 14 (depends on 13) The method as defined in claim 13 wherein a volume of the high pressure air flow is smaller than a volume of the cooling air flow in each time unit. ### Claim 15 (depends on 13) The method as defined in claim 13 wherein in step (b) the high pressure air flow is injected by the ejector into the cooling air flow in the ATCC system upstream of a turbine case which the ATCC system selectively discharges the cooling air flow to cool, thereby boosting the cooling air flow upstream of the turbine case to a high pressure level. ### Claim 16 (depends on 13) The method as defined in claim 13 wherein in step (b) the high pressure air flow is injected by the ejector into the cooling air flow in the ATCC system, downstream of a turbine casing which the ATCC system selectively discharges the cooling air flow to cool, thereby increasing a momentum of the cooling air flow downstream of the turbine case in order to create a suction effect on the cooling air flow discharged from the ATCC system.