Patent Application
20200308986
The present disclosure relates generally to a turbine casing. More particularly, the present disclosure relates to ballistic structures of a turbine casing for a starter.
Structures designed for dealing with ballistic events, such as high energy debris released from a damaged turbine wheel, are typically constrained by the mechanical properties of the materials used in the structures. In such an event, the released particle must be contained so as not to puncture through the turbine outer case. In addition, after a failure event the turbine case must retain its structural integrity while the engine shuts down in order to prevent further potentially catastrophic damage. Despite these significant ballistic requirements on the turbine case, the turbine case contributes to the overall weight of the engine. Among the many challenges faced by a person of skill in the art is how to balance the ballistic requirements of the turbine case with the competing weight constraint.
A turbine containment arrangement includes a turbine rotor rotatable about a turbine axis and a casing. The casing extends radially outward of the turbine rotor and includes an outer ring, an inner ring, and a plurality of fins. The inner ring is disposed radially inward from and co-axially with the outer ring and the turbine axis. The outer ring and the inner ring form an annular gap extending therebetween. The plurality of fins is disposed between the outer ring and the inner ring and extends at least partially circumferentially and radially therebetween. The plurality of fins is monolithically formed with the inner and outer rings.
A method of forming a casing for a turbine containment arrangement includes building the casing with a layer-by-layer additive manufacturing process. The casing includes an outer ring, an inner ring, and a plurality of fins. The inner ring is disposed radially inward from and co-axially with the outer ring. The outer ring and the inner ring form an annular gap extending therebetween. The plurality of fins is disposed between the outer ring and the inner ring and extends at least partially circumferentially and radially therebetween. The outer ring, the inner ring, and the fins are integrally formed together as a single piece of material with a layer-by-layer additive manufacturing process.
The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims, and accompanying figures.
While the above-identified figures set forth one or more embodiments of the present disclosure, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings.
Existing debris containment methods utilized in a turbine casing for turbine engine starters incorporate a carved out hollow area with ridges that requires a multi-piece assembly involving costly (and heavy) brazing, welding, and re-machining. Proposed herein is a casing formed by layer-by-layer additive manufacturing that includes built-in spiral fins extending between the inner wall and the outer wall of the casing so as to provide resilient ballistic functionality, weight reduction, and manufacturing simplicity of the casing.
Starter 10 is a starter unit for a turbine engine. Turbine containment arrangement 12 includes turbine rotor 16 with blades 18 and casing 20 with outer ring 22, inner ring 24, and fins 28. Flowpath 14 is a flow path of air passing through turbine containment arrangement 12. Turbine rotor 16 is a hub or disk that includes blades 18 and is configured to rotate about centerline axis ACL. Centerline axis ACL is an axis extending through a centerpoint of turbine rotor 16. Direction of rotation DR is a direction of rotation of turbine rotor 16. Blades 18 are airfoils.
Casing 20 includes outer ring 22, inner rings 24, and fins 28. Outer ring 22 and inner ring 24 are annular bands of solid material (e.g., metallic material). Radius ROR is a radius of outer ring 22. Annular gap 26 is an annular shaped space. In this example, fins 28 are curved ribbons of solid material. In other examples, fins 28 can be flat planar pieces of solid material. Fin axis AF is an axis about which a single fin 28 is rotated about to form its curvature. For example, each fin of fins 28 has its own respective fin axis AF. Curvature radius RC is a radius of curvature of one fin of the fins 28.
In this non-limiting embodiment, starter 10 is connected to an engine of an aircraft via a gear train with a drive shaft. Turbine containment arrangement 12 is mounted within a portion of starter 10. Flowpath 14 passes through a portion of starter 10 and flows across blades 18 of turbine rotor 16. Turbine rotor 16 is disposed within and rotates relative to inner ring 24 of casing 20. Centerline axis ACL extends perpendicular to a radial direction of turbine rotor 16. Direction of rotation DR is shown as counter-clockwise in this example. Blades 18 are connected to and extend radially outward from a center disk of turbine rotor 16. Blades 18 are disposed in casing 20 such that flowpath 14 flows across blades 18.
Casing 20 is disposed about and extends around turbine rotor 16. Outer ring 22 and inner ring 24 are connected to fins 28. In some embodiments, casing 20 can be built/formed with layer-by-layer additive manufacturing such that outer ring 22, inner ring 24, and fins 28 are integrally formed together as a single piece of material (e.g., monolithic) with a layer-by-layer additive manufacturing process. In one non-limiting embodiment, a selective laser sintering process is used to form casing 20. In other examples, casing 20 with outer ring 22, inner ring 24, and fins 28 can be formed with titanium, an alloy of nickel containing chromium and iron, or other metals including superalloys with resistance to high temperatures. Annular gap 26 extends between outer ring 22 and inner ring 24 in a radial direction relative to turbine rotor 16.
Each fin 28 is connected to and extends between outer ring 22 and inner ring 24. In this non-limiting embodiment, each fin of fins 28 is curved in a direction that is opposite to direction of rotation DR of turbine rotor 16. For example, each fin of fins 28 is shown to include a curved shape that includes both a radially outward component and a tangential component that is opposite to direction of rotation DR of turbine rotor 16 such that each fin is concave inwards towards an inside of turbine rotor 16. In another non-limiting embodiment, fins 28 can be oriented in different manners. For example, fins 28 can be disposed such that fins 28 are convex in a radially outward direction. Additionally, fins 28 can be curved in a same direction as direction of rotation DR of turbine rotor 16.
In the illustrated embodiment, fins 28 are shown as including a single set of fins 28 that are all rotated in the same direction and are uniformly spaced. In other non-limiting embodiments, there can be multiple sets of fins 28 defined by differing amounts of curvature as well as frequency. In other non-limiting embodiments, however, there can be more than one set of fins 28, such that separate sets of fins can be oppositely oriented from another with regards to curvature. For example, a second set of fins 28 could be situated in casing 20 such that the curvature of the second set of fins ran in an opposite direction to fins 28 shown in
In this example, curvature radius RC of fins 28 is less than radius ROR of outer ring 22. In this non-limiting embodiment, the spaces between adjacent fins 28 are occupied with air at standard temperature and pressure (e.g., ambient). In another non-limiting embodiment, the spaces between fins 28 can be occupied in whole or in part by a high-temperature, soft spongy material such as plastic, rubber, and/or metallic foam. In this example, fin axis AF is offset from and parallel to centerline axis ACL of turbine rotor 16.
Turbine containment arrangement 12 of starter 10 functions to spool up the aircraft engine by blowing air with flowpath 14 across blades 18 to rotate turbine rotor 16 that drives a gear train that eventually drives the engine. For example, as the air from flowpath 14 flows across blades 18, the airfoil shape of blades 18 creates a pressure differential causing turbine rotor 16 to rotate about centerline axis ACL. Casing 20 houses rotor turbine 16 and contains the air of flow path 14. Outer ring 22 provides an exterior layer of casing 20 that prevents particles from exiting out of casing 20. Outer ring 22 also acts to stop any particles that come into contact with outer ring 22 from the inside of outer ring 22 thereby preventing the particles from exiting casing 20. Inner ring 24 provides containment of flow path 14 through casing 20. Inner ring 24 also acts to reduce the kinetic energy (e.g., speed) of any particles that puncture through inner ring 24. Annular gap 26 provides spacing between inner ring 24 and outer ring 22, and allows for multiple fins 28 to slow down particles that puncture through inner ring 24.
In the event of a particle puncturing through inner ring 24 and entering gap 26, the particle comes into contact with fins 28. As the particle comes into contact with one of fins 28, the fin 28 absorbs a portion of the kinetic energy of the particle to reduce the velocity of the particle. Additionally, the layered configuration of fins 28 allows for a particle moving through gap 26 to come into contact with multiple fins 28 that sequentially reduce the kinetic energy of the particle. Also, the amount of curvature and angle between each of fins 28 and inner ring 24 deflect such a particle in tangential and radially inward component vectors, which encourages entrapment of the particle within outer ring 22. For example, as a particle punctures through inner ring 24 and enters gap 26, the particle is likely to have a tangential component velocity perpendicular to a radial direction of turbine rotor 16. The angled/curved configuration of fins 28 counteracts this tangential component by situating the surfaces of fins 28 to be closer to perpendicular to such a tangential vector of the particle's motion. Also in this way, the particle will come into contact with multiple of fins 28 as the particle punctures through successive fins 28.
In some embodiments contemplated in view of the present disclosure, fin axis AF and/or curvature radius RC can be moved and/or adjusted (e.g., reduced or increased) to provide different configurations, locations, and curvature amounts for fins 28.
By way of utilizing layer-by-layer additive manufacturing, relatively thin fins 28 can be formed to create armor and cushions to absorb kinetic energy of particles that puncture through inner ring 24. Due to forming casing with additive manufacturing, flow path 14 is uninterrupted throughout turbine containment arrangement 12 and the manufacturing process does not require any additional pieces, assembly, or re-machining. The spiral configuration of fins 28 allows for multiple barriers for particles to pass through while reducing the overall weight of the housing due to the relatively small thickness of fins 28.
Casing 120 includes outer ring 122, inner rings 124, and fins 128. Here, centerline axis ACL is shown as an axis extending through an axial centerpoint of casing 120. Outer ring 122 and inner ring 124 are annular bands of solid material (e.g., metallic material). Annular gap 126 is a space extending between outer gap 122 and inner gap 124. In this example, fins 128 are circular or ring-shaped ribbons of solid material. Fin axis AF is an axis about which each of fins 128 is centered.
In
The concentric arrangement of fins 128 causes particles entering into gap 126 to come into contact with fins 128 and be deflected in a tangential direction. If the particle punctures through one or more of fins 128, each consecutive fins 128 would further absorb kinetic energy from the particle and deflect the particle further in a tangential direction. The quantity of fins 128 and sizes can be varied depending on the weight requirements of casing 120. In another non-limiting embodiment, fins 28 and fins 128 can both be combined to form a mixed set of fins including both spiral and circular configurations.
A turbine containment arrangement includes a turbine rotor rotatable about a turbine axis and a casing. The casing extends radially outward of the turbine rotor and includes an outer ring, an inner ring, and a plurality of fins. The inner ring is disposed radially inward from and co-axially with the outer ring and the turbine axis. The outer ring and the inner ring form an annular gap extending therebetween. The plurality of fins is disposed between the outer ring and the inner ring and extends at least partially circumferentially and radially therebetween. The plurality of fins is monolithically formed with the inner and outer rings.
The arrangement of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components.
Each of the plurality of fins can extend from the inner ring to the outer ring.
Each of the plurality of fins can be curved about a respective fin axis that can be offset from and/or parallel to the axis of the turbine rotor.
The outer ring can include a first radius, wherein each of the plurality of fins can comprise a radius of curvature that can be less than the first radius.
Each of the plurality of fins can spiral outward in a direction that can be opposite to a direction of rotation of the turbine wheel.
Each of the plurality of fins can include a circular shape and/or can be coaxial with the axis of the turbine rotor.
A method of forming a casing for a turbine containment arrangement includes building the casing with a layer-by-layer additive manufacturing process. The casing includes an outer ring, an inner ring, and a plurality of fins. The inner ring is disposed radially inward from and co-axially with the outer ring. The outer ring and the inner ring form an annular gap extending therebetween. The plurality of fins is disposed between the outer ring and the inner ring and extends at least partially circumferentially and radially therebetween. The outer ring, the inner ring, and the fins are integrally formed together as a single piece of material with a layer-by-layer additive manufacturing process.
The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following steps, features, configurations and/or additional components.
The layer-by-layer additive manufacturing process can comprise a selective laser sintering process.
Each of the plurality of fins can be curved about a respective fin axis that can be offset from and/or parallel to the axis of the turbine rotor.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
