Abstract: A bearing assembly is provided. The bearing assembly includes an inner race configured to couple to a shaft, an outer race disposed around the inner race, and a housing disposed around the outer race. The housing and the outer race define an annulus and a buffer region, and the buffer region defines an axial boundary of the annulus.

Abstract: A squeeze film damper includes a static member and a whirling member positioned adjacent to the static member. A gap is formed between the static member and the whirling member. A pressurized oil reservoir is formed in the gap between the static member and the whirling member. A first low pressure oil reservoir is formed in a first cavity in the whirling member, wherein the first low pressure oil reservoir is positioned on a first end of the pressurized oil reservoir. A second low pressure oil reservoir is formed in a second cavity in the whirling member, wherein the second low pressure oil reservoir is positioned on a second end of the pressurized oil reservoir. A first primary seal is positioned between the first end of the pressurized oil reservoir and the first low pressure oil reservoir, and a second primary seal is positioned between the second end of the pressurized oil reservoir and the second low pressure oil reservoir.

Abstract: A squeeze film damper includes a static member and a whirling member positioned adjacent to the static member. A gap is formed between the static member and the whirling member. A pressurized oil reservoir is formed in the gap between the static member and the whirling member. A first low pressure oil reservoir is formed in a first cavity in the whirling member, wherein the first low pressure oil reservoir is positioned on a first end of the pressurized oil reservoir. A second low pressure oil reservoir is formed in a second cavity in the whirling member, wherein the second low pressure oil reservoir is positioned on a second end of the pressurized oil reservoir. A first primary seal is positioned between the first end of the pressurized oil reservoir and the first low pressure oil reservoir, and a second primary seal is positioned between the second end of the pressurized oil reservoir and the second low pressure oil reservoir.

Abstract: A film damper for a gas turbine engine includes an annular inner member and an annular outer member located radially outboard of the annular inner member, the annular outer member and the annular inner member defining a damper annulus therebetween. A fluid supply passage delivers a flow of fluid into the damper annulus from the annular outer member, and a backflow prevention device is located at the fluid supply passage to prevent backflow of the flow of fluid from the damper annulus into the fluid supply passage.

Abstract: A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a first turbine, driving a compressor with a second turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, and having a bypass ratio of greater than 10, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

Abstract: A bearing assembly is provided. The bearing assembly may include an inner race configured to couple to a shaft, an outer race disposed around the inner race, a bearing support structure coupled to the outer race, and a housing disposed around the bearing support structure. The housing and the bearing support structure may define a squeeze-film damper annulus configured to receive an aerated damping fluid. The aerated damping fluid may be provided from a fluid pump and an air supply port.

Abstract: A gas turbine engine includes a fan section that has a fan with a plurality of airfoils, a compressor section, a gear train that reduces a rotational speed of the fan relative to a shaft in operation, a turbine section that has a first turbine and a second turbine, and a bypass ratio of greater than 10. The first turbine drives the shaft. A nacelle extends along an engine axis and surrounds the fan. A variable area fan nozzle defines a discharge airflow area. A fan airfoil flutter sensing system has a first sensor that actively and selectively detects a fan airfoil flutter condition in operation, and communicates with a controller programmed to move the variable area fan nozzle and vary the discharge airflow area to mitigate the flutter condition.

Abstract: A gas turbine engine includes a fan section that has a fan. A fan casing surrounds the fan section. A compressor section defines an engine axis. A gear train reduces a rotational speed of the fan relative to a shaft. A low pressure turbine is coupled to the shaft. A nacelle extends along the engine axis and surrounds the fan casing, a bypass ratio of greater than 10. A variable area fan nozzle defines a discharge airflow area. A flutter sensing system includes a controller programmed to move the variable area fan nozzle to vary the discharge airflow area in response to detecting an airfoil flutter condition associated with adjacent airfoils of the fan.

Abstract: A method of developing a suggested blend repair to an airfoil includes the steps of: (a) storing history with regard to a particular airfoil in a particular engine; (b) taking information with regard to new damage to the particular airfoil; (c) reaching an initial blend recommendation based upon step (b); (d) assessing whether the initial blend recommendation of step (c) would be appropriate to repair the new damage based upon a consideration of steps (a)-(c); and (e) reporting a final blend recommendation. An airfoil repair recommendation system is also disclosed.

Abstract: A bearing assembly is provided. The bearing assembly includes an inner race configured to couple to a shaft, an outer race disposed around the inner race, and a housing disposed around the outer race. The housing and the outer race define an annulus and a buffer region, and the buffer region defines an axial boundary of the annulus.

Abstract: A film damper for a gas turbine engine includes an annular inner member and an annular outer member located radially outboard of the annular inner member, the annular outer member and the annular inner member defining a damper annulus therebetween. A fluid supply passage delivers a flow of fluid into the damper annulus from the annular outer member, and a backflow prevention device is located at the fluid supply passage to prevent backflow of the flow of fluid from the damper annulus into the fluid supply passage.

Abstract: A damping treatment is applied to the ligaments of a squirrel cage type bearing support. The damping treatment reduces the vibrations transmitted to the engine casing as the engine passes through various resonance frequencies of the various parts of the gas turbine engine. A squeeze-film damper damps engine vibrations, but the oil in the squeeze-film damper can act as a stiffener during certain operational ranges, which increases the transmission of vibrations to the engine structure. Applying a damping treatment to the ligaments of the squirrel cage provides effective vibration damping.

Abstract: A damping treatment is applied to the ligaments of a squirrel cage type bearing support. The damping treatment reduces the vibrations transmitted to the engine casing as the engine passes through various resonance frequencies of the various parts of the gas turbine engine. A squeeze-film damper damps engine vibrations, but the oil in the squeeze-film damper can act as a stiffener during certain operational ranges, which increases the transmission of vibrations to the engine structure. Applying a damping treatment to the ligaments of the squirrel cage provides effective vibration damping.

Abstract: A gas turbine engine includes a circumferential array of stator vanes that have first and second vanes with different vibrational frequencies than one another. The first vanes are arranged in circumferentially alternating relationship with the second vanes.

Abstract: A gas turbine engine includes a plurality of blades, a sensor configured to detect vibration on one or more of the plurality of blades, and a controller coupled to the sensor and configured to adjust a blade incidence upon an onset of vibration being detected by the sensor wherein the adjustment of the blade incidence reduces the vibration.

Abstract: A hollow blade of a gas turbine engine has a sacrificial elongated damper disposed slideably in a chamber for minimizing modes of vibration during operation. The chamber is defined between two opposing surfaces generally spanning radially outward from an axis of the engine and a face facing radially inward. The damper is constructed and arranged to make loaded contact with the face via a centrifugal force created by rotation of the engine.

Abstract: A novel probabilistic method for analyzing high cycle fatigue (HCF) in a design of a gas turbine engine is disclosed. The method may comprise identifying a component of the gas turbine engine for high cycle fatigue analysis, inputting parametric data of the component over a predetermined parameter space into at least one computer processor, using the at least one computer processor to build a plurality of flexible models of the component based on the parametric data of the component over the predetermined parameter space, using the at least one computer processor to build a plurality of emulators of the component based on the plurality of flexible models, and using the at least one computer processor to predict a probability of HCF based at least in part on the parametric data of the component over the predetermined parameter space and the plurality of emulators.

Abstract: A bearing for a gas turbine engine may comprise a squeeze film damper. A bearing housing may comprise a roughened surface. The roughened surface may increase friction between the bearing housing and the oil in the squeeze film damper. The increased friction may increase the damping force in the squeeze film damper. The increased damping force may prevent oil inertia, and prevent resonant vibrations.

Abstract: A bearing for a gas turbine engine may comprise a squeeze film damper. A bearing housing may comprise a roughened surface. The roughened surface may increase friction between the bearing housing and the oil in the squeeze film damper. The increased friction may increase the damping force in the squeeze film damper. The increased damping force may prevent oil inertia, and prevent resonant vibrations.

Abstract: A rotor assembly for a gas turbine engine includes a rotor defining an outer periphery; and a plurality of blades attached to the outer periphery. The plurality of blades includes a material property different than the other of the plurality of blades to provide mistuning of the rotor.