Abstract: According to an aspect, a gas turbine engine includes a turbine section with a turbine case and a plurality of turbine blades within the turbine case. The gas turbine engine also includes an active clearance control system with an active clearance control cooling air supply, a valve pneumatically coupled to the active clearance control cooling air supply, and a controller. The controller is configured to determine an active cooling control schedule adjustment based on a condition of the gas turbine engine, operate the active clearance control system according to an active cooling control schedule as modified by the active cooling control schedule adjustment, apply a decay function to the active cooling control schedule adjustment to reduce an effect on the active cooling control schedule adjustment, and resume operating the active clearance control system according to the active cooling control schedule based on an active cooling control condition being met.

Abstract: A method of operating a gas turbine engine includes commanding an acceleration of the gas turbine engine and moving a variable pitch high pressure compressor vane toward an open position thereby reducing an acceleration rate of a high pressure turbine rotor thereby reducing a change in a clearance gap between the high pressure turbine rotor and a blade outer airseal. An active clearance control system of a gas turbine engine includes an engine control system configured to command an acceleration of the gas turbine engine and move a variable pitch high pressure compressor vane toward an open position thereby slowing an acceleration rate of a high pressure turbine rotor thereby reducing a change in a clearance gap between the high pressure turbine rotor and a blade outer airseal located radially outboard of the high pressure turbine rotor.

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.

Abstract: A method of operating a gas turbine engine includes commanding an acceleration of the gas turbine engine and moving a variable pitch high pressure compressor vane toward an open position thereby reducing an acceleration rate of a high pressure turbine rotor thereby reducing a change in a clearance gap between the high pressure turbine rotor and a blade outer airseal. An active clearance control system of a gas turbine engine includes an engine control system configured to command an acceleration of the gas turbine engine and move a variable pitch high pressure compressor vane toward an open position thereby slowing an acceleration rate of a high pressure turbine rotor thereby reducing a change in a clearance gap between the high pressure turbine rotor and a blade outer airseal located radially outboard of the high pressure turbine rotor.

Abstract: A gas turbine engine blade includes a blade portion having a leading edge and a trailing edge. A first surface connects the leading edge to the trailing edge and a second surface connects the leading edge to the trailing edge. A tip section is located at a first end of the blade portion and includes a pocket protruding into the tip section from an outermost end of the tip section. The pocket has a first side wall adjacent the first surface and a second side wall adjacent the second surface. At least one of the first side wall and the second side wall have a curve distinct from a curve of the corresponding adjacent surface.

Abstract: A blade outer air seal for a gas turbine engine having a surface that is eccentric with respect to the engine rotation centerline, and a method for creating same, are disclosed. Also, a method for grinding a work piece having nominal curvature defined by a work piece curvature centerline is disclosed, comprising the steps of: a) determining a desired surface profile for the work piece; b) providing a rotating grinding surface having a grinding rotation centerline; c) offsetting the grinding rotation centerline from the work piece curvature centerline; and d) applying the rotating grinding surface to the work piece while rotating the rotating grinding surface about the grinding rotation centerline to create the desired surface profile.

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.

Abstract: Disclosed is an active tip clearance control system (ATCCS) for a gas turbine engine, having an electronically controlled regulating valve directing cooling airflow to a turbine case, and an engine electronic control (EEC), controlling the electronically controlled regulating valve, wherein the EEC controls the electronically controlled regulating valve to regulate cooling airflow according to a selected target blade tip clearance schedule, and wherein the selected target blade tip clearance schedule is selected before or after an engine cycle, from of a plurality of target blade tip clearance schedules, each correlating to one of a plurality of thrust rating applications for the engine.

Abstract: Aspects of the disclosure are directed to systems and methods for receiving operating state parameters associated with an operative state of an aircraft, determining a clearance value between a first structure of the engine and a second structure of the engine, where the clearance value is determined based on the operating state parameters and a passive clearance model that includes a specification of an uncertainty in the clearance value, determining that the clearance value deviates from a clearance target in an amount that is greater than a threshold, and engaging an active clearance control (ACC) mechanism based on the deviation.

Abstract: Disclosed is an active tip clearance control system (ATCCS) for a gas turbine engine, having an electronically controlled regulating valve directing cooling airflow to a turbine case, and an engine electronic control (EEC), controlling the electronically controlled regulating valve, wherein the EEC controls the electronically controlled regulating valve to regulate cooling airflow according to a selected target blade tip clearance schedule, and wherein the selected target blade tip clearance schedule is selected before or after an engine cycle, from of a plurality of target blade tip clearance schedules, each correlating to one of a plurality of thrust rating applications for the engine.

Abstract: A blade outer air seal for a gas turbine engine having a surface that is eccentric with respect to the engine rotation centerline, and a method for creating same, are disclosed. Also, a method for grinding a work piece having nominal curvature defined by a work piece curvature centerline is disclosed, comprising the steps of: a) determining a desired surface profile for the work piece; b) providing a rotating grinding surface having a grinding rotation centerline; c) offsetting the grinding rotation centerline from the work piece curvature centerline; and d) applying the rotating grinding surface to the work piece while rotating the rotating grinding surface about the grinding rotation centerline to create the desired surface profile.

Abstract: A gas turbine engine blade includes a blade portion having a leading edge and a trailing edge. A first surface connects the leading edge to the trailing edge and a second surface connects the leading edge to the trailing edge. A tip section is located at a first end of the blade portion and includes a pocket protruding into the tip section from an outermost end of the tip section. The pocket has a first side wall adjacent the first surface and a second side wall adjacent the second surface. At least one of the first side wall and the second side wall have a curve distinct from a curve of the corresponding adjacent surface.

Abstract: A blade outer air seal for a gas turbine engine having a surface that is eccentric with respect to the engine rotation centerline, and a method for creating same, are disclosed. Also, a method for grinding a work piece having nominal curvature defined by a work piece curvature centerline is disclosed, comprising the steps of: a) determining a desired surface profile for the work piece; b) providing a rotating grinding surface having a grinding rotation centerline; c) offsetting the grinding rotation centerline from the work piece curvature centerline; and d) applying the rotating grinding surface to the work piece while rotating the rotating grinding surface about the grinding rotation centerline to create the desired surface profile.

Abstract: A method is provided for calibrating an active clearance control system for a plurality of turbine engines. During this method, a squeeze test is performed between a tip of a rotor blade and a shroud. Results of the squeeze test are applied to adjust a gap between the tip and the shroud. The performance of the squeeze test and the application of the results may be individually performed for each of the turbine engines.

Abstract: Aspects of the disclosure are directed to systems and methods for receiving operating state parameters associated with an operative state of an aircraft, determining a clearance value between a first structure of the engine and a second structure of the engine, where the clearance value is determined based on the operating state parameters and a passive clearance model that includes a specification of an uncertainty in the clearance value, determining that the clearance value deviates from a clearance target in an amount that is greater than a threshold, and engaging an active clearance control (ACC) mechanism based on the deviation.

Abstract: A process for machining a turbine engine blade outer air seal in situ, the process comprising replacing a blade with a cutting tool assembly proximate a blade outer air seal, wherein the blade outer air seal is assembled in a gas turbine engine case. The process includes coupling a blower to the blade outer air seal. The blade outer air seal comprises at least one flow path. The process includes creating a purge air stream with the blower through the blade outer air seal. The process includes machining the blade outer air seal, wherein particulate is formed from the machining. The process includes preventing the particulate from blocking the at least one flow path of the blade outer air seal.

Abstract: A process for machining a turbine engine blade outer air seal in situ, the process comprising replacing a blade with a cutting tool assembly proximate a blade outer air seal, wherein the blade outer air seal is assembled in a gas turbine engine case. The process includes coupling a blower to the blade outer air seal. The blade outer air seal comprises at least one flow path. The process includes creating a purge air stream with the blower through the blade outer air seal. The process includes machining the blade outer air seal, wherein particulate is formed from the machining. The process includes preventing the particulate from blocking the at least one flow path of the blade outer air seal.

Abstract: A method is provided for calibrating an active clearance control system for a plurality of turbine engines. During this method, a squeeze test is performed between a tip of a rotor blade and a shroud. Results of the squeeze test are applied to adjust a gap between the tip and the shroud. The performance of the squeeze test and the application of the results may be individually performed for each of the turbine engines.

Abstract: A blade outer air seal for a gas turbine engine having a surface that is eccentric with respect to the engine rotation centerline, and a method for creating same, are disclosed. Also, a method for grinding a work piece having nominal curvature defined by a work piece curvature centerline is disclosed, comprising the steps of: a) determining a desired surface profile for the work piece; b) providing a rotating grinding surface having a grinding rotation centerline; c) offsetting the grinding rotation centerline from the work piece curvature centerline; and d) applying the rotating grinding surface to the work piece while rotating the rotating grinding surface about the grinding rotation centerline to create the desired surface profile.