US20130323052A1

US20130323052A1 - Retaining ring

Info

Publication number: US20130323052A1
Application number: US13/485,098
Authority: US
Inventors: Qingxuan Michael Zhang; Theresa Ann Brown
Original assignee: Solar Turbines Inc
Current assignee: Solar Turbines Inc
Priority date: 2012-05-31
Filing date: 2012-05-31
Publication date: 2013-12-05

Abstract

A retaining ring assembly for a gas turbine engine. The retaining ring assembly may include a discontinuous ring member having first and second portions of reduced cross-sectional area. The second portion may be configured to overlap the first portion. Further, the first and second portions may each include a transition portion configured to transition from a main portion of the ring member to a respective one of the first and second portions. Also, each transition portion may include a rounded fillet extending along the length of the transition portion.

Description

TECHNICAL FIELD

The present disclosure relates generally to a turbine engine, and more particularly, to a retaining ring for maintaining axial alignment of components within an engine.

BACKGROUND

Gas turbine engines (GTEs) produce power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed air. In general, GTEs have an upstream air compressor coupled to a downstream turbine with a combustion chamber (combustor) in between. Energy is produced when a mixture of compressed air and fuel is burned in the combustor, and the resulting hot gases are used to spin blades of a turbine. In typical GTEs, a main rotary shaft extends along an engine axis and couples rotational movement of various components of the GTE about the engine axis.
During combustion, internal components of GTEs are often subjected to intense temperatures and reaction forces caused by the release of energy during ignition of fuel. These high temperatures and reaction forces often result in thermal expansion of various components and improper displacement of components, such as the blades of a turbine, within a GTE. Such expansion and displacement of internal components of a GTE may lead to increased wear, and GTE down time in order to repair damaged components.
U.S. Pat. No. 5,338,154 to Meade et al. (the '154 patent) discloses a retaining ring for retaining an interstage seal of a gas turbine engine. According to the '154 patent, the retaining ring includes a split ring having overlapping ends for preventing axial movement of a seal located between two stages of a gas turbine engine.

SUMMARY

Embodiments of the present disclosure may be directed to a retaining ring assembly for a gas turbine engine. The retaining ring assembly may include a discontinuous ring member having first and second portions of reduced cross-sectional area. The second portion may be configured to overlap the first portion. Further, the first and second portions may each include a transition portion configured to transition from a main portion of the ring member to a respective one of the first and second portions. Also, each transition portion may include a rounded fillet extending along the length of the transition portion.
In further embodiments, the present disclosure may include a turbine engine assembly. The turbine engine assembly may include a rotary shaft. Further, the turbine engine assembly may include a plurality of turbine blades having a corresponding plurality of axially extending arms including retention portions. Also, the turbine engine assembly may include a retaining ring configured for receipt within the retention portion of each of the plurality of turbine blades. The retaining ring may include a discontinuous ring member having first and second portions of reduced cross-sectional area. The second portion may be configured to overlap the first portion. Further, the first and second portions may each include a transition portion configured to transition from a main portion of the ring member to a respective one of the first and second portions. Also, each transition portion may include a rounded fillet.
In further embodiments, the present disclosure may be directed to a method of reducing stress concentration of a retaining ring within a gas turbine engine. The method may include operating a gas turbine engine. Additionally, the method may include radially compressing and positioning a retaining ring within the gas turbine engine. The retaining ring may include a discontinuous ring member having a pair of rounded fillets. Further, the method may include releasing the radially compressed retaining ring within the gas turbine engine and decreasing a stress concentration in the retaining ring at a location adjacent to each of the pair of rounded fillets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a GTE;

FIG. 2 is a cross-sectional illustration of the GTE of FIG. 1 having an exemplary retaining ring;

FIG. 3 is a cross-sectional illustration of the exemplary retaining ring of FIG. 2;

FIG. 4 is an enlarged view of the construction of the exemplary retaining ring of FIG. 3;

FIG. 5 is an enlarged isometric view of a fillet of the exemplary retaining ring of FIG. 3;

FIG. 6 is an enlarged side view of a fillet of the exemplary retaining ring of FIG. 3; and

FIG. 7 is an exemplary method of reducing a stress concentration of the exemplary retaining ring of FIGS. 3-6 within a GTE.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary schematic gas turbine engine (GTE) 5 having a compressor system 10, a combustor system 20, and a turbine system 30 arranged lengthwise along an engine axis 15 on a rotary shaft 40. The compressor system 10 is configured to compress air and deliver the compressed air to the combustor system 20. The compressor system 10 may include a plurality of stationary blades or nozzles and a plurality of rotary blades configured to cooperate with one another to compress air. Additionally, the turbine system 30 may include a plurality of turbine blades 50 and/or nozzles (not identified in FIG. 1). Hot gases emitted from the combustor system 20 may be directed to the turbine blades 50 so as to impart rotational movement to the turbine blades 50. The thus imparted rotational movement may be utilized to drive one or more machines and or components (not shown) intended to be driven by the GTE 5.
As shown in FIG. 2, each of the plurality of turbine blades 50 may include a geometry configured to interact with hot gases emitted from the combustor system 20. That is, each turbine blade 50 may be shaped so as to cooperate with and be moved by a stream of hot gas flowing past turbine blades 50 in a direction parallel to engine axis 15. For example, each turbine blade 50 may include an airfoil shape, as is known in the art, such that flowing hot gases may drive turbine blades 50 to rotate, thereby rotating rotary shaft 40. Indeed, each turbine blade 50 may include a concave surface on a first side (pressure side), and an oppositely arranged convex surface on a second side (suction side). That is, the concave surface of each turbine blade 50 may directly face the convex surface of each adjacent turbine blade 50. In this manner, a gas flow passage is created between adjacent turbine blades 50.
Additionally, each turbine blade 50 may include a base or platform 60, an insert or root 70, and an arm 80. For example, as shown in FIG. 2, each turbine blade 50 may have a base 60 defining a radially inward end of turbine blade 50. Each base 60 may be positioned proximate to and spaced from a base 60 of an adjacent turbine blade 50. For example, as shown in FIG. 2, bases 60 of adjacent turbine blades 50 may be positioned alongside one another with a gap 65 therebetween. Gap 65 may be used to introduce cooling fluid flow along turbine blades 50 as is known in the art. Additionally, one or more bases 60 of turbine blades 50 may include cooling fluid passages (not shown) extending therethrough, and configured for passing cooling fluid adjacent to turbine blades 50, as is known in the art. Further, a damper (not shown) may be located between the bases 60 of adjacent turbine blades 50. Such dampers may be utilized in order to dampen vibration imparted on turbine blades 50 during operation of the GTE 5, as is known in the art.
As shown in FIG. 2, each turbine blade 50 may be positioned about rotary shaft 40. That is, each turbine blade 50 may be connected to rotary shaft 40 so that upon interaction with hot gasses emitted from the combustor system 20, turbine blades 50 may rotate about engine axis 15, thereby causing rotation of rotary shaft 40. In one exemplary embodiment, rotary shaft 40 may include a plurality of slots 75 spaced circumferentially about rotary shaft 40. Each slot 75 of the plurality of slots 75 may be configured to receive a corresponding insert 70 of the plurality of turbine blades 50. For example, as noted above, each turbine blade 50 may include an insert 70 extending radially inwardly of the base 60. Each insert 70 may be configured to slide, snap, attach, or otherwise connect the turbine blade 50 to the rotary shaft 40.
Insert 70 and slot 75 may each include any appropriate corresponding shapes. In one exemplary embodiment, for example, slot 75 may be configured so as to have a shape matching, or similar to a shape of insert 70. That is, slot 75 and insert 70 may include complimentary mating surfaces such that insert 70 may be received within slot 75. For example, as shown in FIG. 2, each of slot 75 and insert 70 may include an amorphous or irregular shape, such as a fir-tree shape. Alternatively, slot 75 and insert 70 may include any other of a variety of complimentary shapes such as, for example, triangular, rectangular, circular, square, and/or any other shapes sufficient to retain insert 70 within slot 75.
During operation of GTE 5, turbine blades 50 may be subject to intense forces and vibrations. That is, as hot gases emitted from the combustor system 20 impact turbine blades 50, turbine blades 50 may be pushed (i.e. jostled or moved) out of place. Indeed, turbine blades 50 may slide axially along engine axis 15 within slots 75. Such movement may cause axial misalignment of turbine blades 50, leading to increased wear.
In order to maintain proper positioning of turbine blades 50 within rotary shaft 40, each turbine blade 50 may include an arm 80. Arm 80 may extend from turbine blade 50 axially parallel to engine axis 15, toward a downstream end of GTE 5. As shown in FIG. 2, arm 80 may include a c-shaped retaining portion 85. Alternatively, retaining portion 85 may include any other configuration, such as, for example, a u-shape.
Retaining portion 85 may be configured to receive a retaining ring or member 90 as will be described in further detail below. Indeed, retaining portion 85 and retaining ring 90 may cooperate so as to maintain each turbine blade 50 at a desired axial position within GTE 5. Specifically, retaining portion 85 and retaining ring 90 may cooperate so as to prevent each turbine blade 50 from moving axially parallel to engine axis 15. That is, retaining ring 90 and retaining portion 85 may inhibit movement of inserts 70 from axially sliding within slots 75 of rotary shaft 40. As such, each turbine blade 50 may be maintained in proper alignment within GTE 5.
As shown in FIG. 3, retaining ring 90 may be in the form of a split ring. That is, retaining ring 90 may be ring or circle shaped having a cut or split portion 100 as shown in FIG. 4, and as will be described in further detail below. In one exemplary embodiment, retaining ring 90 may be comprised of an alloy. In particular, retaining ring 90 may be comprised of Waspaloy® (a super alloy including nickel, chromium, cobalt, molybdenum, titanium, and aluminum). As such, retaining ring 90 may exhibit improved material strength and stability as will be described in further detail below.
FIG. 4 is an enlarged view of the exemplary retaining ring 90, having the split portion 100 of FIG. 3. As shown, split portion 100 may be comprised of a cut through the thickness of retaining ring 90. That is, split portion 100 may include a discontinuous length of retaining ring 90. Split portion 100 may be comprised of a first member 110 and a second member 120.
Each of first member 110 and second member 120 may include a reduced thickness portion of retaining ring 90. That is, each of first member 110 and second member 120 may include a reduced cross-sectional area. For example, retaining ring 90 may include a main portion 95 having a first cross-sectional area. Main portion 95 may include any appropriate cross-sectional shape, such as, for example, a circular, square, or rectangular cross-sectional shape. As shown in FIG. 4, each of first member 110 and second member 120 may include a reduced or smaller cross-sectional area. In other words, the cross-sectional area of retaining ring 90 may be reduced from main portion 95 to first and second members 110 and 120. Additionally, each of first and second members 110 and 120 may include a cross-sectional shape similar to that of main portion 95. For example, each of first and second members may include any appropriate cross-sectional shape, such as, for example, a circular, square, or rectangular cross-sectional shape. It is understood that the cross-sectional shape of first and second members 110 and 120 may be different than the cross-sectional shape of main portion 95.
As shown in FIGS. 3 and 4, first member 110 and second member 120 may be arranged in an overlapping configuration. That is, first member 110 may be configured to nest underneath second member 120, or vice versa. Such an overlapping arrangement allows retaining ring 90 to expand and contract under varying thermal conditions, as will be explained in further detail below. Further, due to the reduced cross-sectional area of first and second members 110 and 120 relative to main portion 95, retaining ring 90 may maintain a substantially circular shape. That is, since each of first and second members 110 and 120 include reduced cross-sectional areas, retaining ring 90 may maintain a substantially circular shape when first and second members 110 and 120 overlap, as shown in FIG. 3.
Additionally, due to the construction of retaining ring 90 having overlapping first and second members 110 and 120, retaining ring 90 may be biased in use. Indeed, retaining ring 90 may be sized such that, upon insertion into retaining portion 85 of arm 80, retaining ring 90 applies radially outward spring force against arm 85. Such spring force may assist in maintaining turbine blades 50 in proper alignment.
Retaining ring 90 may include a first transition portion 130 and a second transition portion 140. Each of the first transition portion 130 and the second transition portion 140 may include a region configured to reduce stress concentrations. Indeed, each of first transition portion 130 and second transition portion 140 include a rounded fillet 150. Fillet 150 may include a radius of curvature 160 configured for stress concentration reduction in the area of first transition portion 130 and second transition portion 140. In an exemplary embodiment, the radius of curvature 160 of each fillet 150 may be greater than about 0.400 inches (1.02 cm). Indeed, in another exemplary embodiment, the radius of curvature 160 of each fillet 150 may be about 0.500 inches (1.27 cm)±five hundredths of an inch (1.27 mm). As discussed in further detail below, such an arrangement, including fillets 150, may provide improved life.
FIG. 5 depicts an enlarged isometric view of fillet 150 and FIG. 6 depicts an enlarged side view of fillet 150. As shown, fillet 150 includes a radius of curvature 160 as discussed above. Fillet 150 comprises a smooth, rounded transition from main portion 95 to a respective one of each of first and second members 110 and 120. For example, as shown in FIG. 5, fillet 150 comprises a first transition portion 130 between main portion 95 of retaining ring 90 and first member 110. That is, fillet 150 continuously, and without any sharp notches or angled tapers, reduces the cross-sectional area of retaining ring 90 from a first point, for example point 170, on main portion 95, to a second point, for example, point 180, on a corresponding one of first and second members 110 and 120. Said differently, fillet 150 comprises a continuous curve along the length of the transition portions 130 and 140. Indeed, each of first and second transition portion 130 and 140 comprise a continuously round (i.e. never flat) transition between the main portion 95 and a respective one of the first and second members 110 and 120. In such a manner, fillet 150 reduces stress concentrations within retaining ring 90, including those within first transition portion 130 and second transition portion 140.
Retaining ring 90 may be produced in any appropriate manner, such as, for example, stamping a ring shaped member. As noted above, in an exemplary embodiment, the ring shaped member may be stamped (or otherwise manufactured) from Waspaloy® and processed (i.e. cut) to form split portion 100 defining first and second members 110 and 120 of reduced thickness, each having a fillet 150.

INDUSTRIAL APPLICABILITY

The disclosed retaining ring 90 may be applicable to any GTE 5. In particular, the disclosed retaining ring 90 may be applicable to any GTE 5 for maintaining the axial position of turbine blades 50.
As shown in FIG. 7, a method 200 of reducing a stress concentration of retaining ring 90 within GTE 5 is illustrated. The method 200 may include operating the GTE 5 at step 210. At step 220, the method may further include radially compressing and positioning the retaining ring 90 within the GTE 5. That is, retaining ring 90 may be positioned about rotary shaft 40 and adjacent turbine blades 50. For example, retaining ring 90 may be slid onto rotary shaft 40 from an end of rotary shaft 40. Alternatively, retaining ring 90, having split portion 100, may be expanded (i.e. radially spread open) and positioned about rotary shaft 40. Once retaining ring 90 is positioned about rotary shaft 40, retaining ring 90 may be radially compressed.
At step 230, retaining ring 90 may be deployed into GTE 5. That is, retaining ring 90, being biased radially outward, may be released such that retaining ring 90 expands. Upon expansion, retaining ring 90 may be received within and urge retaining portion portions 85 of turbine blades 50 radially outward. Such radially exerted force assists in maintaining retaining ring 90 in position and turbine blades 50 axially in place. That is, as retaining ring 90 pushes against retaining portion 85 of turbine blades 50 having inserts 70 axially slidable into slots 75, the thus imparted outward radial spring force provided by retaining ring 90 assists in preventing turbine blades 50 from becoming misaligned. Indeed, the outwardly applied radial force imparted on the turbine blades 50 may prevent or inhibit turbine blades 50 from sliding axially along rotary shaft 40.
At step 240, stress concentration in the retaining ring 90 may be reduced during operation of GTE 5. That is, retaining ring 90, including rounded fillets 150 may reduce a stress concentration adjacent to each of the fillets 150. Indeed, due to the rounded shape of fillets 150, localized stress concentrations encountered during operation of the GTE 5 may be reduced.
The presently disclosed retaining ring 90 and method for reducing a stress concentration of retaining ring 90 within GTE 5, have numerous features. As noted above, turbine blades 50 and retaining ring 90 may be exposed to a harsh environment within GTE 5. In particular, turbine blades 50 may be subject to intense forces and vibrations. That is, hot gases emitted from the combustor system 20 impact turbine blades 50 and urge turbine blades 50 to slide axially parallel to engine axis 15 within slots 75.
Additionally, extreme temperature fluctuations and operating temperatures may often result in failure of components within a GTE. The presently disclosed retaining ring 90, however, helps avoid such component failure. Indeed, rather than including a transition portion having a sharp notch or taper structure as is common in prior art retaining rings, the presently disclosed retaining ring 90 includes a smoothly rounded fillet 150. That is, while prior art retaining rings 90 include notches or tapers leading to localized stress concentrations, the presently disclosed retaining ring 90 reduces stress concentrations by including continuously rounded fillets 150. As such, the presently disclosed retaining ring 90 exhibits improved resistance to the harsh environment within the GTE 5.
Further, the presently disclosed retaining ring 90, being comprised of Waspaloy®, exhibits reduced amounts of plastic deformation, especially adjacent arms 80. That is, contrary to prior art retaining rings in which plastic deformation restricts free movement (i.e. radial expansion and contraction) and induces stress, the presently disclosed retaining ring 90 may exhibit a higher yield strength, decrease the amount of plastic deformation induced, and reduce overall stress in retaining ring 90. Such characteristics improve the life of the retaining ring 90.
Additionally, as noted above, prior art retaining rings include sharp notches or tapers within transition portions. That is, prior art retaining rings include a sharp angled taper or notch to transition between a first portion and a reduced thickness portion on overlapping members of a split retain ring. Such sharp tapers or notches were previously thought to be required so as to allow for adequate spacing between an end of one overlapping member and the beginning of a transition portion of another overlapping member. That is, due to thermal expansion and contraction, it was commonly thought that an elongated transition portion, such as the presently disclosed fillet 150 would interfere with operation of a retaining ring. Contrary to the prior art, it has been found that an elongated rounded fillet, such as fillet 150 will not interfere with retaining ring 90 operation. That is, unlike sharp angled transition regions between an end of one overlapping member and the beginning of a transition portion of another overlapping member (that provide an increased space for relative movement of the overlapping members), the presently disclosed retaining ring 90 employs a round fillet 150 having an elongated radius of curvature. It has been found that such a construction does not interfere with operation of the GTE 5 because friction or other forces dictate that less space is required between an end of one overlapping member and the beginning of a transition portion of another overlapping member.
The disclosed rounded fillet 150 improves stress rupture life of the disclosed retaining ring 90. Indeed, sharp notches or tapers may result in increased stress concentration resulting in creep rupture and overloading. On the other hand, the smooth fillet 150 of the presently disclosed retaining ring 90 improves strength, durability, and life of the retaining ring, even while exposed to extreme temperatures within the GTE 5 environment.
Further, the presently disclosed retaining ring reduces the space between an end of first member 110 and fillet 150 on second member 120. Indeed, the presently disclosed retaining ring 90 takes into account friction induced between first member 110 and second member 120 as they slide relative to one another during thermal expansion or contraction of retaining ring 90. That is, the induced friction enables the space between an end of first member 110 and fillet 150 on second member 120 to be reduced.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed retaining and method of installing it within GTE 5. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

What is claimed is:

1. A retaining ring assembly for a gas turbine engine, comprising:

a discontinuous ring member having first and second portions of reduced cross-sectional area, the second portion being configured to overlap the first portion;

wherein the first and second portions each include a transition portion configured to transition from a main portion of the ring member to a respective one of the first and second portions; and

wherein each transition portion includes a rounded fillet extending along the length of the transition portion.

2. The retaining ring assembly of claim 1, wherein each of the rounded fillets includes a radius of curvature greater than about 0.400 inches.

3. The retaining ring assembly of claim 2, wherein each of the rounded fillets includes a radius of curvature of about 0.500 inches.

4. The retaining ring assembly of claim 1, wherein the rounded fillet is continuously curved and devoid of any angle or taper.

5. The retaining ring assembly of claim 1, wherein the ring member is biased radially outward when positioned within the gas turbine engine.

6. The retaining ring assembly of claim 1, wherein the ring member is comprised of a material configured to thermally expand and contract.

7. The retaining ring assembly of claim 6, wherein the material includes Waspaloy®.

8. The retaining ring assembly of claim 1, wherein each of the first and second portions are configured to move relative to one another.

9. A turbine engine assembly, comprising:

a rotary shaft;

a plurality of turbine blades including a corresponding plurality of axially extending arms having retention portions; and

a retaining ring configured for receipt within the retention portion of each of the plurality of turbine blades, the retaining ring including:

wherein each transition portion includes a rounded fillet.

10. The assembly of claim 9, wherein each of the rounded fillets includes a radius of curvature greater than about 0.400 inches.

11. The assembly of claim 10, wherein each of the rounded fillets includes a radius of curvature of about 0.500 inches.

12. The assembly of claim 9, wherein the ring member is biased radially outward when positioned in the turbine engine.

13. The assembly of claim 9, wherein the ring member is comprised of a material configured to thermally expand and contract.

14. The assembly of claim 13, wherein the material includes Waspaloy®.

15. The assembly of claim 9, wherein the retaining ring and the plurality of arms are configured to cooperate so as to maintain an alignment of the plurality of turbine blades within the rotary shaft.

16. The assembly of claim 9, wherein each of the plurality of turbine blades includes an insert configured to slide axially within a correspondingly shaped slot of a plurality of slots on the rotary shaft.

17. The assembly of claim 9, wherein each of the first and second portions are configured to move relative to one another.

18. A method of reducing stress concentration of a retaining ring within a gas turbine engine, comprising:

operating a gas turbine engine;

radially compressing and positioning a retaining ring within the gas turbine engine, the retaining ring including a discontinuous ring member having a pair of rounded fillets;

releasing the radially compressed retaining ring within the gas turbine engine; and

decreasing a stress concentration in the retaining ring at a location adjacent to each of the pair of rounded fillets.

19. The method of claim 18, further including:

applying radially outward spring pressure to a plurality of turbine blades so as to maintain an axial alignment of the plurality of turbine blades.

20. The method of claim 18, wherein each of the rounded fillets includes a radius of curvature of about 0.500 inches.