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.

FIELD

The present disclosure relates generally to gas turbine engines, and more specifically, to aerated squeeze-film dampers for gas turbine engines.

BACKGROUND

Gas turbine engines typically comprise bearings which support rotating shafts. The bearings may comprise an inner race which rotates with the shaft, and a plurality of rollers between the inner race and an outer race, which does not rotate. The shaft may whirl and deflect from the engine centerline. Squeeze-film dampers may be used to damp the whirling. In a squeeze-film damper, a thin annulus of oil is typically retained between the outer race and/or a bearing support structure and a bearing housing. Oil may be fed into the annulus to form the squeeze-film damper which damps whirling of the shaft. Typically, the annulus is sealed to prevent air from reaching the squeeze-film damper and to allow the squeeze-film damper to achieve higher levels of dynamic pressure.

SUMMARY

In various embodiments, a bearing assembly is disclosed. The bearing assembly may comprise an inner race coupled to the shaft; an outer race disposed around the inner race; a bearing support structure coupled to the outer race; a housing disposed around the bearing support structure, wherein the housing and the bearing support structure define a squeeze-film damper annulus configured to contain an aerated damping fluid; and an air supply port in fluid communication with the squeeze-film damper annulus. The air supply port may be configured to supply an airflow to aerate a damping oil and generate the aerated damping fluid.

In various embodiments, the bearing assembly may comprise a fluid pump in fluid communication with the squeeze-film damper annulus, wherein the fluid pump is configured to supply the damping oil. The fluid pump may comprise a positive-displacement pump. In various embodiments, the bearing assembly may comprise an orifice plate in fluid communication with the air supply port, wherein the orifice plate is configured to control a flow of the supplied airflow. In various embodiments, the air supply port may be configured to supply the airflow to aerate the damping oil upstream from an inlet of the fluid pump. In other embodiments, the air supply port may be configured to supply the airflow to aerate the damping oil downstream from an outlet of the fluid pump. In various embodiments, the bearing assembly may comprise a first seal and a second seal disposed between the outer race and the housing, wherein the first seal and the second seal define an axial boundary of the squeeze-film damper annulus.

In various embodiments, a squeeze film damper may comprise an outer race having an annular geometry; a bearing support structure coupled to the outer race; a housing disposed about the bearing support structure; a first seal and a second seal between the bearing support structure and the housing, wherein the housing, the bearing support structure, the first seal, and the second seal define a squeeze-film damper annulus; and an aerated damping fluid contained within the squeeze-film damper annulus.

In various embodiments, the squeeze-film damper may comprise a fluid pump in fluid communication with the squeeze-film damper annulus, wherein the fluid pump is configured to supply a damping fluid. In various embodiments, the squeeze-film damper may comprise an air supply port in fluid communication with the fluid pump, wherein the air supply port is configured to supply an airflow to aerate the damping fluid and generate the aerated damping fluid. In various embodiments, the squeeze-film damper may comprise an orifice plate in fluid communication with the air supply port, wherein the orifice plate is configured to control a flow of the supplied airflow. The air supply port may be configured to supply the airflow to aerate the damping fluid upstream from an inlet of the fluid pump. The air supply port may also be configured to supply the airflow to aerate the damping fluid downstream from an outlet of the fluid pump.

In various embodiments, a gas turbine engine is disclosed. The gas turbine engine may comprise a shaft; an inner bearing race coupled to the shaft; an outer bearing race disposed around the inner bearing race, wherein the shaft and the inner bearing race are configured to rotate within the outer bearing race; a bearing support structure coupled to the outer bearing race; a housing surrounding the bearing support structure, wherein the outer bearing race is configured to whirl within the housing, and wherein a squeeze-film damper annulus is defined between the bearing support structure and the housing. The squeeze-film annulus may be configured to contain an aerated damping fluid.

In various embodiments, the gas turbine engine may comprise a fluid pump in fluid communication with the squeeze-film damper annulus, wherein the fluid pump is configured to supply a damping oil. In various embodiments, the gas turbine engine may comprise an air supply port in fluid communication with the fluid pump, wherein the air supply port is configured to supply an airflow to aerate the damping oil and generate the aerated damping fluid. The gas turbine engine may comprise an orifice plate in fluid communication with the air supply port, wherein the orifice plate is configured to control a flow of the supplied airflow. The air supply port may be configured to supply the airflow to aerate the damping oil upstream from an inlet of the fluid pump. The air supply port may also be configured to supply the airflow to aerate the damping oil downstream from an outlet of the fluid pump. In various embodiments, the gas turbine engine may also comprise a first seal and a second seal disposed between the outer race and the housing, wherein the first seal and the second seal define an axial boundary of the squeeze-film damper annulus.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosures, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation.

The scope of the disclosure is defined by the appended claims and their legal equivalents rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, coupled, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

As used herein, “aft” refers to the direction associated with a tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of gas turbine engine100. As used herein, “forward” refers to the direction associated with a nose (e.g., the front end) of the aircraft, or generally, to the direction of flight or motion. As utilized herein, radially inward refers to the negative R direction and radially outward refers to the R direction. An A-R-C axis is shown throughout the figures to illustrate the relative position of various components.

In various embodiments, and with reference toFIG. 1, a gas turbine engine100(such as a turbofan gas turbine engine) is depicted. Gas turbine engine100is disposed about engine centerline120, which may also be referred to as axis of rotation120. Gas turbine engine100may comprise a fan140, compressor sections150and160, a combustion section180including a combustor, and turbine sections190,191. Air compressed in the compressor sections150,160may be mixed with fuel and burned in combustion section180and expanded across the turbine sections190,191. The turbine sections190,191may include high pressure rotors192and low pressure rotors194, which rotate in response to the expansion. The turbine sections190,191may comprise alternating rows of rotary airfoils or blades196and static airfoils or vanes198. Cooling air may be supplied to the combustor and turbine sections190,191from the compressor sections150,160. A plurality of bearings115may support spools in the gas turbine engine100.FIG. 1provides a general understanding of the sections in a gas turbine engine, and is not intended to limit the disclosure. The present disclosure may extend to all types of rotating machinery, turbomachinery, and pumps, including turbofan gas turbine engines and turbojet engines, for all types of applications. This may also extend when used in combination with other bearing types in said applications including journal type bearings.

The forward-aft positions of gas turbine engine100lie along axis of rotation120. For example, fan140may be referred to as forward of turbine section190and turbine section190may be referred to as aft of fan140. Typically, during operation of gas turbine engine100, air flows from forward to aft, for example, from fan140to turbine section190. As air flows from fan140to the more aft components of gas turbine engine100, axis of rotation120may also generally define the direction of the air stream flow.

With reference toFIG. 2, an exemplary bearing assembly200with an aerated squeeze-film damper is shown in cross section, in accordance with various embodiments. Bearing assembly200may include a shaft202configured to rotate about engine centerline120. Although an engine is used for exemplary purposes, squeeze-film dampers of the present disclosure may be used in various embodiments where damping is desired. Shaft202may engage an inner race206of a bearing204, which also rotates about engine centerline120. Bearing204may be defined by inner race206(e.g., an inner bearing race), an outer race210(e.g., an outer bearing race), and a rolling element208(e.g., spherical balls, cylindrical rollers, and/or the like) disposed between outer race210and inner race106. Outer race210may be rotationally stationary about engine centerline120. In that regard, inner race106rotates while outer race210remains stationary. Rolling elements208may rotate and decrease friction between inner race206and outer race210as inner race106rotates relative to outer race210. Outer race210may comprise an annular geometry.

In various embodiments, bearing assembly200may comprise a squeeze-film damper201. Squeeze-film damper201may be configured to attenuate periodic deflection relative to axis of rotation120, as discussed further herein. Squeeze-film damper201may include a bearing support structure212. In various embodiments, bearing support structure212may be coupled to outer race210and may be configured to engage seal216. Seal216may also be configured to engage a housing218. A squeeze-film damper annulus214may be defined between bearing support structure212and housing218with seals216(e.g., a first seal and a second seal) defining the axial boundaries of squeeze-film damper annulus214. Squeeze-film damper annulus214may be at least partially sealed by seals216. Seals216may comprise any suitable seal capable of at least partially sealing squeeze-film damper annulus214, such as, for example, a piston-ring seal, an O-ring seal, and/or the like. Squeeze-film damper annulus214may be configured to retain a damping fluid such as, for example, oil and/or an aerated damping fluid234, as discussed further herein. The damping fluid may be delivered through passage220into squeeze-film damper annulus214. A portion of the damping fluid, heated by the shearing of the damping fluid in squeeze-film damper annulus214, may leak by seals216in an axial direction, and additional, cooler damping fluid may be supplied to squeeze-film damper annulus214via passage220. A static structure222may be disposed radially outward from bearing assembly200and configured to retain bearing assembly200in a radial direction. A damper centering spring224may be disposed forward and/or aft of bearing support structure212, and may be configured to retain bearing assembly200in an axial direction. A radial stiffness of damper centering spring224may be established based on the structural dynamics of the gas turbine engine100and/or various subsystems, and the effectiveness of squeeze-film damper201.

In various embodiments, bearing assembly200may comprise a variety of components configured to generate an aerated damping fluid234, and provide the aerated damping fluid234to squeeze-film damper201. Aerated damping fluid234may comprise an aerated fluid, such as, for example aerated oil. For example, aerated damping fluid234may be created by combining a damping fluid (e.g., oil) with an airflow via a Venturi effect, by introducing the airflow at a higher pressure relative to the pressure of the damping fluid, and/or any other suitable method of interspersing airflow into the damping fluid, allowing the airflow to aerate the damping fluid.

As discussed further herein, and in various embodiments, aerated damping fluid234may increase damping performance (e.g., damping and stiffness, rotor and case response) in squeeze-film damper201of bearing assembly200compared to the use of only damping fluid. By tailoring the introduction of the airflow into the damping fluid, a pressure profile of aerated damping fluid234may be changed and controlled. In that respect, varying the introduction of the airflow over an operating range of the gas turbine engine may provide a mechanism for varying and controlling stiffness and damping properties of aerated damping fluid234. Aerated damping fluid234may better control rotor resonance in order to reduce response amplitude and transmissibility of rotor response to the engine structure.

For example, and in various embodiments, bearing assembly200may comprise a fluid pump230. Fluid pump230may be in fluid communication with squeeze-film damper annulus214, via passage220. Fluid pump230may be configured to pressurize and/or supply a damping fluid (e.g., oil). Fluid pump230may comprise any suitable pump capable of pressurizing and/or supplying the damping fluid. For example, fluid pump230may comprise a positive-displacement pump, such as, for example, a rotary vane pump, a gear pump, and/or the like. Fluid pump230may receive the damping fluid from a fluid source235(e.g., an oil supply system, an oil tank, etc.).

In various embodiments, bearing assembly200may also comprise an air supply port240. Air supply port240may be configured to provide an air flow to bearing assembly200to aerate the damping fluid. Air supply port240may comprise a solenoid valve, and/or any other suitable valve, configured to control the flow of air. Air supply port240may also comprise a fixed port, adjustable port, and/or the like configured to introduce air. Air supply port240may receive the airflow from an air source245(e.g., an air tank, ambient air, etc.). Air supply port240may be in fluid communication with an orifice plate242. Orifice plate242may be configured to meter and/or control the airflow from air supply port240. For example, orifice plate242may be in electronic communication with a processor, a controller, and/or the like, configured to communicate with orifice plate242to control the release of airflow. In that respect, the ratio of air to damping fluid may be controlled to generate aerated damping fluid234having tailored damping and stiffness characteristics.

In various embodiments, fluid pump230and air supply port240may be in fluid communication with passage220via an aerated fluid passage236. In that regard, the damping fluid provided by fluid pump230and the airflow provided by air supply port240, via orifice plate242, may be combined in aerated fluid passage236to generate aerated damping fluid234. For example, the damping fluid may be combined with the airflow in aerated fluid passage236via a Venturi effect, by introducing the airflow at a higher pressure relative to the pressure of the damping fluid, and/or the like, allowing the airflow to aerate the damping fluid.

In various embodiments, air supply port240and orifice plate242may be located in any suitable location relative to fluid pump230. For example, and as depicted inFIG. 2, air supply port240and/or orifice plate242may be located downstream of fluid pump230, and may be in fluid communication with a discharge (or an outlet) of fluid pump230. In that respect, the damping fluid from fluid source235may be aerated by the airflow released from orifice plate242, via air supply port240and air source245, after the damping fluid is pumped through fluid pump230.

In various embodiments, and with reference toFIG. 3, an air supply port340and/or an orifice plate342may also be located upstream of fluid pump330, and may be in fluid communication with a suction (or an inlet) of fluid pump330. In that respect, the damping fluid from fluid source335may be aerated by the airflow released from orifice plate342, via air supply port340and air source245, before reaching fluid pump330. In various embodiments, the damping fluid may also be aerated using any other suitable method, and/or with any other suitable lubrication system configuration.