# US 2017/0284296 A1 · Secondary airflow passage for adjusting airflow distortion in gas turbine engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0284296 A1 - Document ID: US20170284296A1 - Status: Published application - Kind: A1 - Application number: 15/084,966 - Filed: 2016-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-03-30 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Brian Francis Nestico; Brian K. Kestner; Brandon Wayne Miller - Web page: https://patentgrep.com/patent/US20170284296A1 ## CPC - F02C 7/042: having variable geometry - B64D 27/10: of gas-turbine type (jet aircraft B64D27/16) - B64D 31/06: actuated automatically - F02C 3/06: the compressor comprising only axial stages (F02C3/10 takes precedence) - F02C 3/14: characterised by the arrangement of the combustion chamber in the plant (combustion chambers per se F23R; F02C3/205 takes precedence) - F02C 7/057: Control or regulation (conjointly with fuel supply control F02C9/50, with nozzle area control F02K1/16) - F05D 2210/44: bidirectional, i.e. in opposite, alternating directions - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2270/101: Compressor surge or stall - F05D 2270/102: caused by working fluid flow velocity profile distortion - F05D 2270/3011: Inlet pressure - F05D 2270/44: active, predictive, or anticipative - F05D 2270/54: by electronic means, e.g. electronic tubes, transistors or IC's within an electronic circuit - 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) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract Systems and methods for adjusting airflow distortion in a gas turbine engine using a secondary airflow passage assembly are disclosed. A gas turbine engine can include a compressor section, a combustion section, and a turbine section in series flow and defining at least in part an engine airflow path. A casing can enclose the gas turbine engine and be at least partially exposed to a bypass airflow. The gas turbine engine can further include a secondary airflow passage assembly comprising a door and a duct, the duct defining an inlet located on the casing, the duct defining an outlet in airflow communication with the engine airflow path, the duct comprising an airflow passage extending between the inlet and outlet. The door can be moveable between an open and closed position to allow a portion of the bypass airflow to flow through the airflow passage to adjust airflow distortion. ## Claims ### Claim 1 A core engine of a gas turbine engine, comprising: a compressor section, a combustion section, and a turbine section in series flow, the compressor section, combustion section, and turbine section defining at least in part an engine airflow path for the gas turbine engine; a casing at least partially enclosing the compressor section, combustion section, and turbine section of the core engine, the casing at least partially exposed to a bypass airflow; and a secondary airflow passage assembly, comprising a duct, the duct defining an inlet located on the casing, the duct defining an outlet in airflow communication with the engine airflow path, the duct defining an airflow passage extending between the inlet and outlet, and; a door moveable between an open position and a closed position, the door allowing at least a portion of the bypass airflow to flow through the airflow passage when in the open position, the door restricting substantially all airflow through the airflow passage when in the closed position. ### Claim 2 (depends on 1) The core engine of claim 1, wherein the door is configured to be controlled based at least in part on an airflow distortion in the engine airflow path. ### Claim 3 (depends on 2) The core engine of claim 2, further comprising: one or more pressure sensor devices located at least partially in the engine airflow path for obtaining one or more measurements associated with airflow distortion. ### Claim 4 (depends on 1) The core engine of claim 1, wherein the core engine comprises a plurality of secondary airflow passage assemblies. ### Claim 5 (depends on 4) The core engine of claim 4, wherein the core engine comprises a plurality of pressure sensor devices, wherein each secondary airflow passage assembly is associated with a pressure sensor device configured to obtain one or more measurements associated with the secondary airflow passage assembly. ### Claim 6 (depends on 4) The core engine of claim 4, wherein the core engine defines a circumferential direction, wherein the plurality of secondary airflow passage assemblies is spaced about the circumferential direction of the core engine. ### Claim 7 (depends on 1) The core engine of claim 1, wherein the core engine defines an axial direction, wherein the door is movable at least partially along the axial direction between the open and closed positions. ### Claim 8 (depends on 1) The core engine of claim 1, wherein the door extends at least partially into the bypass airflow in the open position to direct a portion of the bypass airflow into the airflow passage. ### Claim 9 (depends on 1) The core engine of claim 1, wherein the door is additionally movable to an intermediate position between the open and closed positions, wherein the portion of airflow in the intermediate position is less than the portion of airflow in the open position and more than the portion of airflow in the closed position. ### Claim 10 (depends on 9) The core engine of claim 9, wherein the door is movable between the open, closed, and intermediate positions based on signals from a controller to adjust an airflow distortion in the engine airflow path. ### Claim 11 (depends on 9) The core engine of claim 9, wherein the secondary airflow passage assembly comprises one or more actuators operable for moving the door between the open, closed, and intermediate positions. ### Claim 12 A method for adjusting airflow distortion in a gas turbine engine on an aircraft, the gas turbine engine comprising a compressor section, a combustion section, and a turbine section in series flow, the compressor section, combustion section, and turbine section defining at least in part an engine airflow path, the compressor section, combustion section, and turbine section at least partially enclosed in a casing, the casing at least partially exposed to a bypass airflow, the method comprising: determining, by one or more control devices, an airflow distortion condition associated with the engine airflow path; and controlling, by the one or more control devices, a door of a secondary airflow passage to adjust the airflow distortion condition of the gas turbine engine, the secondary airflow passage assembly comprising a duct, the duct defining an inlet located on the casing, the duct defining an outlet in airflow communication with the engine airflow path, the duct defining an airflow passage extending between the inlet and outlet, the door allowing at least a portion of the bypass airflow to flow through the airflow passage when in the open position, the door restricting substantially all airflow through the airflow passage when in the closed position. ### Claim 13 (depends on 12) The method of claim 12, wherein the door is additionally movable to an intermediate position between the open and closed position, wherein the portion of airflow in the intermediate position is less than the portion of airflow in the open position and more than the portion of airflow in the closed position. ### Claim 14 (depends on 13) The method of claim 13, wherein controlling the door of the secondary airflow passage assembly comprises moving the door between the open, closed, and intermediate positions. ### Claim 15 (depends on 12) The method of claim 12, wherein controlling the door of a secondary airflow passage assembly to adjust the airflow distortion condition comprises controlling the door of a secondary airflow passage assembly to reduce the airflow distortion condition. ### Claim 16 (depends on 12) The method of claim 12, wherein determining the airflow distortion condition associated with the engine airflow path comprises obtaining one or more measurements using one or more pressure sensor devices. ### Claim 17 (depends on 12) The method of claim 12, wherein controlling the door comprises sending a control signal to one or more actuators operable for moving the door. ### Claim 18 A gas turbine engine system for an aircraft comprising: a compressor section, a combustion section, and a turbine section in series flow and defining at least in part an engine airflow path, a casing at least partially enclosing the compressor section, combustion section, and turbine section, the casing at least partially exposed to a bypass airflow; a secondary airflow passage assembly, comprising a duct and a door, the duct defining an inlet located on the casing, the duct defining an outlet in airflow communication with the engine airflow path, the duct defining an airflow passage extending between the inlet and outlet, the door moveable between an open position and a closed position, the door allowing at least a portion of the bypass airflow to flow through the airflow passage when in the open position, the door restricting substantially all airflow through the airflow passage when in the closed position; and a controller operably connected to the door of the secondary airflow passage assembly, the controller comprising one or more processors and one or more memory devices located on an aircraft, the one or more memory devices storing instructions that when executed by the one or more processors cause the one or more processors to perform operations, the operations comprising: determine an airflow distortion condition within the engine airflow path; and control the door to adjust an airflow through the airflow passage to adjust the determined airflow distortion condition. ### Claim 19 (depends on 18) The gas turbine engine system of claim 18, wherein the core engine comprises one or more pressure sensor devices located at least partially in the engine airflow path for obtaining one or more measurements for determining the airflow distortion condition. ### Claim 20 (depends on 17) The gas turbine engine system of claim 17, wherein the door is additionally movable to an intermediate position between the open and closed position, wherein the portion of airflow in the intermediate position is less than the portion of airflow in the open position and more than the portion of airflow in the closed position.