Turbine blade tip shroud with axially offset cutter teeth and related surface configurations and methods

Abstract

A turbine blade tip shroud having axially offset cutter teeth and associated surface configurations is provided. A tip shroud (220) of a turbine blade (200) has a first cutter tooth (260) extending from the tip rail (250) from one of the upstream (252) and downstream (254) sides of the tip rail (250) and adjacent a leading edge (229) of the body (227). The tip shroud (220) also includes a second cutter tooth (262) extending from the tip rail (250) from the other side of the tip rail (250) at a location axially spaced from the first cutter tooth (260). The cutter teeth (260, 262) are axially offset. The tip shroud (220) can be initially manufactured in this shape or can be modified from a used tip shroud that has cutter teeth on the opposite side near the leading edge of the tip shroud body. Various tip shroud surface shapes expressed in Cartesian coordinates are also provided.

Description

[Technical field]

[0001] The subject matter disclosed herein relates to turbomachines. More particularly, the subject matter disclosed herein relates to a turbine blade tip shroud having axially offset cutter teeth and an associated surface profile for the tip shroud. A method for repairing the tip shroud is also provided. [Background technology]

[0002] Some jet aircraft and simple or combined cycle power plant systems employ turbines, also known as turbomachines, in their construction and operation. Some of these turbines employ airfoils, e.g., turbine nozzles, blades, airfoils, etc., that are exposed to a fluid flow during operation. These airfoils are configured to aerodynamically interact with the fluid flow and generate energy from the fluid flow as part of the generation of electricity. For example, the airfoils can be used to generate thrust, convert kinetic energy to mechanical energy, and / or convert thermal energy to mechanical energy. Additionally, during operation, tip shrouds at the radially outer ends of the airfoils interact with stationary components to channel hot gases to the airfoils. Due to such interactions and associated energy conversions, the aerodynamic characteristics of the tip shrouds can result in losses in the operation, performance, thrust, efficiency, reliability, and power output of the system or turbine. Additionally, interaction between the tip shroud and the stationary components can cause tip shroud imbalances, shortening the blade creep life and exacerbating the problems mentioned above. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2008 / 292466 Summary of the Invention

[0004] All aspects, examples and features described below may be combined in any manner that is technically possible.

[0005] One aspect of the disclosure provides a turbine blade tip shroud including: a body configured to couple to an airfoil at a radially outer end of the airfoil, the body having a leading edge and a trailing edge opposite the leading edge, a tip rail extending radially from the body, the tip rail having an upstream side and a downstream side opposite the upstream side, a first cutter tooth extending from the tip rail from one of the upstream and downstream sides of the tip rail and adjacent a leading edge of the body, and a second cutter tooth extending from the tip rail from the other of the upstream and downstream sides of the tip rail axially spaced from the first cutter tooth.

[0006] Another aspect of the present disclosure includes any of the preceding aspects, wherein the first cutter tooth extends from an upstream side of the tip rail and the second cutter tooth extends from a downstream side of the tip rail.

[0007] Another aspect of the present disclosure includes any of the preceding aspects, wherein the axial distance from the first cutter tooth is within a range of 30% to 50% of an axial length of the tip rail.

[0008] One aspect of the disclosure provides a method of modifying a turbine blade tip shroud, the method including removing first cutter teeth extending from selected upstream and downstream sides of a tip rail of the turbine blade tip shroud, the first cutter teeth being opposite second cutter teeth extending from the tip rail from the other of the upstream and downstream sides of the tip rail, and forming third cutter teeth on the selected upstream and downstream sides of the tip rail axially spaced from the second cutter teeth.

[0009] Another aspect of the present disclosure includes any of the preceding aspects, wherein the first cutter tooth and the second cutter tooth are adjacent a leading edge of the body of the turbine blade tip shroud.

[0010] Another aspect of the present disclosure includes any of the preceding aspects, wherein the second cutter tooth extends from an upstream side of the tip rail and a third cutter tooth extends from a downstream side of the tip rail.

[0011] Another aspect of the present disclosure includes any of the preceding aspects, wherein the location axially away from the second cutter tooth is within a range of 30% to 50% of an axial length of the tip rail.

[0012] Another aspect of the present disclosure includes any of the preceding aspects, wherein the body of the turbine blade tip shroud includes a pair of opposed, axially extending wings, and further includes removing a portion of at least one of the pair of opposed, axially extending wings.

[0013] Another aspect of the present disclosure includes any of the preceding aspects, wherein removing the portion of at least one of the pair of axially opposed wings includes rounding the edge surface from a more straight edge surface shape.

[0014] Another aspect of the present disclosure includes any of the preceding aspects, wherein removing the portion of at least one of the pair of axially opposed wings includes forming a straight end surface.

[0015] One aspect of the disclosure provides a turbine blade tip shroud comprising: a pair of axially oppositely extending wings configured to couple to an airfoil at a radially outer end of the airfoil, the airfoil having a suction side, a pressure side opposite the suction side, a leading edge spanning between the pressure side and the suction side, and a trailing edge opposite the leading edge spanning between the pressure side and the suction side; and a tip rail extending radially from the pair of axially oppositely extending wings, the tip rail having a downstream side, an upstream side opposite the downstream side, and a forward most and a radially outermost origin, wherein the tip rail side has a shape having a nominal profile substantially in accordance with at least a portion of the X and Y Cartesian coordinate values ​​set forth in TABLE I, where the Cartesian coordinate values ​​originating from the forward most and radially outermost points are dimensionless values ​​between 0% and 100% that can be converted to distances by multiplying the X and Y values ​​by the tip rail axial length expressed in distance units, and the X and Y values ​​are connected by lines to define the tip rail side profile.

[0016] Another aspect of the present disclosure includes any of the preceding aspects, wherein the airfoil and the turbine blade tip shroud are components of a third stage blade.

[0017] Another aspect of the disclosure includes any of the preceding aspects, wherein the leading and trailing edge surfaces have a shape having a nominal profile substantially in accordance with at least a portion of the Cartesian coordinate values ​​of X, Y, and Z values ​​defined in TABLE II, originating at a forward-most and radially-outermost point, where the Cartesian coordinate values ​​are dimensionless values ​​between 0% and 100% and can be converted to distances by multiplying the value by the tip rail axial length, and where the X, Y, and Z values ​​are smoothly combined together to form the leading and trailing edge surface shapes.

[0018] One aspect of the disclosure provides a turbine blade tip shroud comprising a pair of opposed, axially extending wings configured to couple to an airfoil at a radially outer end of the airfoil, the airfoil having a pressure side, a suction side opposite the pressure side, a leading edge spanning between the pressure side and the suction side, and a trailing edge opposite the leading edge spanning between the pressure side and the suction side, and a tip rail extending radially from the pair of opposed, axially extending wings, the tip rail having a downstream side, an upstream side opposite the downstream side, and a forward-most and radially outermost origin. and leading and trailing edge surfaces having a shape having a nominal profile substantially in accordance with at least a portion of the Cartesian coordinate values ​​of X, Y, and Z values ​​set forth in TABLE II, originating at a forward-most and radially-outermost point, where the Cartesian coordinate values ​​are dimensionless values ​​between 0% and 100% that can be converted to distances by multiplying by the axial length of the tip rail, and the X, Y, and Z values ​​join smoothly together to form the leading and trailing edge surface profiles.

[0019] Another aspect of the present disclosure includes any of the preceding aspects, wherein the airfoil and the turbine blade tip shroud are parts of a third stage blade.

[0020] Another aspect of the disclosure includes any of the preceding aspects, wherein the tip rail side has a shape having a nominal profile substantially according to at least a portion of the XY Cartesian coordinate values ​​set forth in TABLE I, originating at the forward-most and radially outermost origin, the Cartesian coordinate values ​​being dimensionless values ​​between 0% and 100% and convertible to distance by multiplying the X and Y values ​​by the tip rail axial length expressed in units of distance, and the X and Y values ​​are connected by a line to define the tip rail side profile.

[0021] Two or more aspects described in this disclosure may be combined to form an embodiment not specifically described herein, including those described in the Abstract.

[0022] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0023] These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings illustrating various embodiments of the present disclosure. [Figure 1] 1 illustrates a schematic diagram of an exemplary turbomachine. [Diagram 2] FIG. 2 illustrates a cross-sectional view of an exemplary gas turbine assembly having four stages that may be used with the turbomachine of FIG. 1. [Diagram 3] 1 illustrates a schematic three-dimensional view of an exemplary turbine blade including a tip shroud at a radially outer end of an airfoil in accordance with various embodiments of the present disclosure; [Figure 4] 1 illustrates a top view of a tip shroud according to various embodiments of the present disclosure. [Diagram 5]13 illustrates a top view of a tip shroud according to another embodiment of the present disclosure. [Figure 6] 1 illustrates a top view of a prior art tip shroud that is modified in accordance with various embodiments of the present disclosure. [Figure 7] 1 illustrates a top view of a tip shroud modified by removing cutter teeth and, optionally, a portion of one or more wings of the tip shroud in accordance with an embodiment of the present disclosure. [Figure 8] FIG. 1 illustrates a plan view of a tip shroud with tip rail upstream and downstream surface profile data points in accordance with various embodiments of the present disclosure. [Figure 9] 4 illustrates a plan view of a tip shroud including profile data points for the leading and trailing edge surfaces in accordance with various embodiments of the present disclosure;

[0024] It should be noted that the drawings of the present disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure. In the drawings, like numbers represent like elements between the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] As a first issue, in order to clearly explain the current state of the art, it becomes necessary to select specific terminology when referring to and describing relevant machine components within turbomachinery. Wherever possible, common industry terminology is used and adopted in a manner consistent with its accepted meaning. Unless otherwise specified, such terms should be given a broad interpretation consistent with the context of this application and the scope of the appended claims. Those skilled in the art will appreciate that certain components are often referred to using several different or overlapping terms. What is described herein as being a single part may include and be referred to as being made up of several parts in other contexts. Alternatively, what is described herein as including several components may be referred to as a single part elsewhere.

[0026] Additionally, several descriptive terms are used regularly in this specification, and it will be helpful to define these terms at the beginning of this section. These terms and their definitions are as follows, unless otherwise stated: "Downstream" and "Upstream" as used herein are terms that indicate a direction relative to the flow of a fluid, such as the working fluid through a turbine or by the turbine blades, or, for example, the flow of air through a combustor or the flow of cooling water through one of the turbine's component systems. The term "downstream" corresponds to the direction of the fluid flow, and the term "upstream" refers to the opposite direction to the flow. Components such as blades and shrouds that are located in the flow of fluids through a gas turbine can be described as having a "leading edge", which is the very edge of the component that first encounters the oncoming flow of fluids, and a "trailing edge", which is opposite the leading edge. The terms "forward" and "aft" refer to directions, without further specification, with "forward" referring to the forward or compressor end of the engine and "aft" referring to the aft or turbine end of the engine.

[0027] It is often necessary to describe components located at different radial positions relative to the central axis. The term "radial" refers to movement or position perpendicular to the axis. For example, if a first component is located closer to the axis than a second component, the specification states that the first component is "radially inward" or "inboard" of the second component. On the other hand, if a first component is located farther from the axis than the second component, the specification may state that the first component is "radially outward" or "outboard" of the second component. The term "axial" refers to movement or position parallel to the axis A, e.g., the rotor shaft 110. Finally, the term "circumferential" refers to movement or position around an axis. It will be understood that such terms may also be applied in relation to the central axis of the turbine.

[0028] Furthermore, certain descriptive terms may be used regularly in this specification, as explained below: The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another, and are not intended to imply a position or importance of the individual components.

[0029] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly indicates otherwise. Furthermore, as used herein, it will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes examples in which the event occurs and examples in which it does not occur.

[0030] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly engaged, connected, or coupled to the other element or layer, or there may be intervening elements or layers present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] Various aspects of the disclosure relate to a turbine blade tip shroud having a first cutter tooth extending from the tip rail from one of the upstream and downstream sides of the tip rail and disposed adjacent a leading edge of the body. The tip shroud also includes a second cutter tooth extending from the tip rail from the other of the upstream and downstream sides of the tip rail axially spaced from the first cutter tooth. The tip shroud may be initially manufactured in this shape. Alternatively, according to the modification methods described herein, the tip shroud may be modified to have opposing cutter teeth near the leading edge of the tip shroud body.

[0032] Aspects of the present disclosure may include a tip shroud surface profile expressed in terms of Cartesian coordinates. The tip rail includes a forward-most origin and a radially outermost origin that serve as reference points for the lateral, i.e., upstream and downstream, surface profiles of the tip rail, as well as the leading and trailing edge surface profiles of the tip shroud, as described herein. The surface profiles are described as shapes having a nominal profile that substantially follows at least a portion of the X and Y, and possibly Z, Cartesian coordinate values ​​set forth in the respective tables. The Cartesian coordinates originate at the forward-most and radially outermost origin of the tip rail.

[0033] Cartesian coordinate values ​​are dimensionless values ​​between 0% and 100% that can be converted to distance by multiplying the value by a particular normalization parameter value expressed in units of distance. That is, since the coordinate values ​​in the table are percentages of the normalization parameter, multiplication of the actual desired distance of the normalization parameter renders the actual coordinates of the surface profile for a tip shroud having that actual desired distance of the normalization parameter. As described further herein, the normalization parameter may include the tip rail axial length LTR (FIG. 4). Thus, the actual X, Y, and possibly Z values ​​of the tip rail surface profile can be rendered by multiplying the values ​​in the particular table by the actual desired tip rail axial length LTR (e.g., 5.2 centimeters). In any case, the X, Y, and if provided, Z values ​​are connected by lines and / or arcs to define a smooth surface profile.

[0034] Referring to the drawings, FIG. 1 is a schematic diagram of an exemplary turbomachine 90 in the form of a combustion turbine or gas turbine (GT) system 100 (hereinafter "GT system 100") that may be used for power generation. The GT system 100 includes a compressor 102 and a combustor 104. The combustor 104 includes a combustion region 105 and a fuel nozzle assembly 106. The GT system 100 also includes a turbine 108 and a common rotor compressor / turbine shaft 110 (hereinafter "rotor shaft 110"). In one non-limiting embodiment, the GT system 100 may be a 9F.05 engine sold by General Electric Company, Greenville, SC. ​​The present disclosure is not limited to any particular GT system and may be implemented in connection with other engines including, for example, other HA, F, B, LM, GT, TM and E class engine models from General Electric Company, as well as engine models from other companies. Moreover, the teachings of the present disclosure do not necessarily apply only to GT systems, but may be applied to other types of turbomachines, such as steam turbines, jet engines, compressors, etc.

[0035] FIG. 2 illustrates a cross-sectional view of an example portion of a turbine 108 having four stages L0-L3 that may be used with the GT system 100 of FIG. 1. The four stages are designated L0, L1, L2, and L3. Stage L0 is the first stage and is the smallest (radially) of the four stages. Stage L1 is the second stage, axially adjacent to and next downstream of stage L0. Stage L2 is the third stage, axially adjacent to and next downstream of stage L1. Stage L3 is the fourth and last stage and is the largest (radially). It should be understood that four stages are shown as one non-limiting example only and that each turbine 108 may have more or less than four stages.

[0036] A set of stationary vanes or nozzles 112 cooperate with a set of rotating blades 114 to form each stage L0-L3 of the turbine 108 and define a portion of a flowpath through the turbine 108. Each set of rotating blades 114 is coupled to a respective rotor wheel 116 that circumferentially couples them to the rotor shaft 110. That is, a plurality of rotating blades 114 are circumferentially spaced apart and mechanically coupled to each rotor wheel 116. The stationary nozzle section 115 includes stationary nozzles 112 that are circumferentially spaced apart about the rotor shaft 110. Each nozzle 112 may include at least one endwall (or platform) 120, 122 coupled to an airfoil 130. In the illustrated example, the nozzles 112 include a radially outer endwall 120 and a radially inner endwall 122. A radially outer endwall 120 couples the nozzle 112 to a casing 124 of the turbine 108 .

[0037] 1-2, in operation, air flows through the compressor 102 and the compressed air is delivered to the combustor 104. Specifically, the compressed air is delivered to a fuel nozzle assembly 106 that is integral with the combustor 104. The fuel nozzle assembly 106 is in flow communication with a combustion region 105. The fuel nozzle assembly 106 is also in flow communication with a fuel source (not shown in FIG. 1 ) and channels fuel and air to the combustion region 105. The combustor 104 ignites and burns the fuel. The combustor 104 is in flow communication with a turbine 108 in which thermal energy in the gas stream is converted to mechanical rotational energy. The turbine 108 is rotatably coupled to and driven by a rotor shaft 110. The compressor 102 may also be rotatably coupled to the rotor shaft 110. In the exemplary embodiment, there are multiple combustors 104 and fuel nozzle assemblies 106. In the following discussion, only one of each component will be discussed unless otherwise noted. At least one end of the rotating rotor shaft 110 may extend axially away from either the compressor 102 or the turbine 108 and may be attached to a load or machine (not shown), such as, but not limited to, an electrical generator, a load compressor, and / or another turbine.

[0038] 3 is an enlarged perspective view showing details of an exemplary turbine rotor blade 114 as blade 200. For ease of explanation, a legend may be provided in the drawings in which the X-axis extends generally axially (i.e., extends along axis A of rotor shaft 110 (FIG. 1)), the Y-axis extends generally perpendicular to axis A of rotor shaft 110 (FIG. 1) (representing a circumferential plane), and the Z-axis extends radially relative to axis A of rotor shaft 110 (FIG. 1). In comparison to FIG. 3, the direction of the arrows in the legend indicates the direction of positive coordinate values.

[0039] Blade 200 is a rotatable (dynamic) blade that may be part of a set of turbine rotor blades 114 distributed circumferentially about a rotor shaft 110 ( FIG. 1 ) in a stage of a turbine (e.g., turbine 108). That is, during operation of the turbine, as a working fluid (e.g., gas or steam) is directed across the airfoil of the blade, blade 200 initiates a rotation of the rotor shaft (e.g., rotor shaft 110) and rotates about an axis A defined by the rotor shaft 110. It is understood that blade 200 is configured to couple (mechanically couple via fasteners, welds, slots / grooves, etc.) with a plurality of similar or separate blades (e.g., blade 200 or other blades) to form a set of blades in a stage of a turbine. With reference to FIG. 2 , in various non-limiting embodiments, blade 200 may include a first stage (L0) blade, a second stage (L1) blade, a third stage (L2) blade, or a fourth stage (L3) blade. In certain embodiments, the blades 200 may be third stage (L2) blades. In various embodiments, the turbine 108 may include a set of blades 200 in only the first stage (L0), or only the second stage (L3), or only the third stage (L2), or only the fourth stage (L3) of the turbine 108.

[0040] 3, the blade 200 may include an airfoil 202 having a pressure side 204 (blocked in this view) and a suction side 206 opposite the pressure side 204. The blade 200 may also include a leading edge 208 spanning between the pressure side 204 and the suction side 206, and a trailing edge 210 opposite the leading edge 208 and spanning between the pressure side 204 and the suction side 206. As previously mentioned, the pressure side 204 of the airfoil 202 faces generally upstream and the suction side 206 faces generally downstream.

[0041] As shown, the airfoil 202 of the blade 200 extends from a platform at a root end 212 to a radially outer end 222. The root end 212 may be coupled to the airfoil 202 along a pressure side 204, a suction side 206, a leading edge 208, and a trailing edge 210. More specifically, the blade 200 includes an airfoil 202 coupled at the root end 212 to an endwall 213 and coupled at its tip or radially outer end 222 to a turbine blade tip shroud 220 (hereinafter "tip shroud 220"). The tip shroud 220 is shown as modified in accordance with an embodiment of the present disclosure.

[0042] 3 as including a dovetail 224, endwall 213 may have any suitable configuration for connecting to rotor shaft 110. Root end 212 is configured to mate with a mating slot (e.g., a dovetail slot) in a turbine rotor shaft (e.g., rotor shaft 110) via dovetail 224 to mate with an adjacent component of another blade 200. Root end 212 is located radially inward of airfoil 202 and is intended to be formed in any complementary configuration to the rotor shaft.

[0043] In various embodiments, the blade 200 includes a fillet 214 proximate the radially inner end 226 of the airfoil 202, the fillet 214 connecting the airfoil 202 and the platform at the root end 212. The fillet 214 may include a welded or brazed fillet that may be formed via conventional MIG welding, TIG welding, brazing, etc. The fillet 214 may include a feature that is integral to the investment casting process or definition.

[0044] 4 illustrates a top view of the tip shroud 220 according to an embodiment of the present disclosure. With collective reference to FIGS. 3 and 4, the tip shroud 220 includes a body 227 configured to couple to the airfoil 202 at the radially outer end 222. For example, the body 227 may couple along the pressure side 204, the suction side 206, the leading edge 208, and the trailing edge 210 of the airfoil 202. The body 227 has a leading edge 229 and a trailing edge 231 opposite the leading edge 229.

[0045] In various embodiments, the blade 200 includes a fillet 228 proximate the radially outer end 222 of the airfoil 202, the fillet 228 connecting the airfoil 202 and the tip shroud 220. The fillet 228 may include a welded or brazed fillet that may be formed via conventional MIG welding, TIG welding, brazing, or the like. The fillet 228 may include a configuration that is integral to the investment casting process or definition. In certain embodiments, the fillets 214 and / or 228 may have a shape, contour, or the like to enhance aerodynamic efficiency.

[0046] The tip shroud 220, and more particularly the body 227, may include a pair of axially opposite extending wings 230 configured to couple to the airfoil 202 at the radially outer end 222 of the airfoil 202 (e.g., via a fillet 228). More particularly, the tip shroud 220 may include an upstream wing 232 and a downstream wing 234. The upstream wing 232 extends generally circumferentially away from a tip rail 250 beyond the pressure side 204 of the airfoil 202, and the downstream wing 234 extends generally circumferentially away from the tip rail 250 beyond the suction side 206 of the airfoil 202. Upstream wing 232 includes a radially outer surface 236 facing generally radially outward from axis A of rotor shaft 110 (FIG. 1) and a radially inner surface 238 (not shown, dashed lines) facing generally radially inward toward axis A of rotor shaft 110 (FIG. 1). Similarly, downstream wing 234 includes a radially outer surface 240 facing generally radially outward from axis A of rotor shaft 110 (FIG. 1) and a radially inner surface 242 (not shown, dashed lines) facing generally radially inward toward axis A of rotor shaft 110 (FIG. 1).

[0047] The tip shroud 220 includes a tip rail 250 extending radially from the body 227. The tip rail 250 has an upstream side 252 and a downstream side 254 opposite the upstream side 252. The upstream side 252 of the tip rail 250 faces generally circumferentially toward the pressure side 204 of the airfoil 202 and melds smoothly with radial outer surface 236 of the upstream side wing 232. Similarly, the downstream side 254 of the tip rail 250 faces generally circumferentially toward the suction side 206 of the airfoil 202 and melds smoothly with radial outer surface 240 of the downstream wing 234.

[0048] The tip shroud 220 also includes a first cutter tooth 260 extending from the tip rail 250 from one of the upstream side 252 (as shown) and downstream side 254 of the tip rail and disposed adjacent the leading edge 229 of the body 227. The tip shroud 220 also includes a second cutter tooth 262 extending from the tip rail 250 from the other of the upstream side 252 and downstream side 254 of the tip rail 250 (as shown) at a location axially spaced from the first cutter tooth 260. That is, the second cutter tooth 262 is spaced apart from the first cutter tooth 260 in the axial direction (Y direction) along the tip rail 250. Thus, the cutter teeth 260, 262 are axially offset along the tip rail 250. The axial distance from the first cutter tooth 260 may be any desired distance, for example, to balance the tip shroud 220 and / or to increase the creep life of the tip shroud 220. Each cutter tooth 260, 262 may include any form of protrusion of material from the tip rail 250 that increases the width of the tip rail 250 along a desired length. Each cutter tooth 260, 262 thus increases mass and increases resistance to wear.

[0049] In one exemplary embodiment, the location of the second cutter tooth 262 axially away from the first cutter tooth 260 may be within a range of 30% to 50% of the tip rail axial length LTR. The distance between the cutter teeth 260, 262 may be measured, for example, from the axial rear end 266 of the cutter tooth 260 to the axial forward end 268 of the cutter tooth 262. In FIG. 4, the first cutter tooth 260 extends from the upstream side 252 of the tip rail 250 and the second cutter tooth 262 extends from the downstream side 254 of the tip rail 250. FIG. 5 illustrates an alternative embodiment in which the first cutter tooth 260 extends from the downstream side 254 of the tip rail 250 and the second cutter tooth 262 extends from the upstream side 252 of the tip rail 250.

[0050] The tip shroud 220 of Figures 4 and 5 can be manufactured as shown and described herein. In other embodiments, the tip shroud 220 can be modified from an existing tip shroud having a different arrangement of cutter teeth. A method for retrofitting a turbine blade tip shroud is described with reference to Figures 4, 6, and 7. Figure 6 is a plan view of an exemplary prior art tip shroud 20 to which the method can be applied. Although a particular prior art tip shroud 20 is described herein, it is emphasized that the teachings of the present disclosure are not limited to this particular tip shroud, but may be applied to a wide variety of tip shrouds now known or later developed.

[0051] The tip shroud 20 includes a body 27 that may include a pair of axially oppositely extending wings 30 configured to couple to an airfoil (in this page) at its radially outer end. More specifically, the tip shroud 20 may include an upstream wing 32 and a downstream wing 34. The upstream wing 32 extends generally circumferentially away from the tip rail 50 across the pressure side of the airfoil, and the downstream wing 34 extends generally circumferentially away from the tip rail 50 across the suction side 206 of the airfoil (not shown).

[0052] 6, the tip shroud 20 includes a tip rail 50 having opposing one another cutter teeth 60, 62 adjacent the leading edge 29 of the body 27 of the tip shroud 20. A first cutter tooth 60 extends from the tip rail 50 from its upstream side 52 and a second cutter tooth 62 extends from the tip rail 50 from its downstream side 54. Thus, the cutter teeth 60, 62 are opposite one another with respect to the tip rail 50.

[0053] The use of tip shrouds 20 on turbine blades 200 of turbine 108 (FIG. 1) can cause the tip shrouds to become unbalanced, which can shorten creep life and / or adversely affect the aerodynamic performance of the tip shroud and the turbine. Rather than replacing turbine blades 200 or replacing tip shrouds 20, it has been discovered that the turbine shroud can be rebalanced and its creep life extended by modifying the tip shroud, and more particularly the position of the cutter teeth thereon.

[0054] FIG. 7 is a plan view showing a portion of a method for modifying the tip shroud 20. The tip shroud 20 may be modified in a number of ways. According to an embodiment of the present disclosure, one of the cutter teeth 60, 62 may be removed from a selected side of the tip rail 50. That is, the tip shroud 20 may be altered by removing selected cutter teeth 60 or 62 extending from selected sides of the upstream side 52 and downstream side 54 of the tip rail 50 of the tip shroud 20. For purposes of explanation only, the selected side will be referred to as the downstream side 54 and the cutter teeth 62 as the cutter teeth selected for removal. Here, the cutter teeth 62 on the downstream side 54 (FIG. 6) are removed, leaving the cutter teeth 60 on the upstream side 52. As will be appreciated, the other cutter teeth 60 may alternatively be removed. The cutter teeth 62 may be removed using any now known or later developed technique, such as, for example, machining, cutting, etc.

[0055] As can be seen by comparing Figures 6 and 7, in addition to removing the cutter teeth 62, the method may optionally include removing a portion of at least one of a pair of axially oppositely extending wings 32, 34. In one non-limiting example, removing a portion of the wings 32, 34 may include rounding an edge surface 70 (e.g., of the wing 32) from a more linear end profile 70 (shown in Figure 6) to a rounded leading edge surface 270 of Figure 7. In another non-limiting example, removing a portion of the wings 32, 34 may include forming a linear edge surface 272 (e.g., at the wing 34) instead of a pointed trailing edge surface 72 of the wing 34 (as shown in Figure 6).

[0056] Although a particular example of removing a portion of one or more wings 32, 34 is illustrated, it will be appreciated that one or more wings 32, 34 may be modified in numerous alternative ways. Removal of a portion may be done for any reason, such as removing a damaged portion, balancing weight after use, extending creep life, improving aerodynamics, among many other reasons.

[0057] FIG. 4 illustrates the tip shroud 220 after additional modification according to an embodiment of the present disclosure. More specifically, FIG. 4 illustrates the tip shroud 220 after forming new cutter teeth 262 on the tip shroud 20 of FIG. 7. The cutter teeth 262 are formed on selected sides of the upstream side 252 and downstream side 254 (as shown) of the tip rail 250, opposite the remaining (first) cutter teeth 60 and axially spaced from the remaining cutter teeth 260, which have now been renumbered. For ease of illustration, in the embodiment of FIG. 4, the selected side is the downstream side 254. As a result, the cutter teeth 260 (labeled 60 in FIG. 6) extend from the upstream side 252 (52 in FIG. 6) of the tip rail 220, and the new cutter teeth 262 extend from the downstream side 254 (54 in FIG. 6) of the tip rail 250.

[0058] 5 and 6, it will be appreciated that in an alternative embodiment, cutter teeth 60 may be removed from upstream side 52 and new cutter teeth 260 may be added to upstream side 252 axially spaced from the location of cutter teeth 60. In this case, the selected side is upstream side 52.

[0059] 8 and 9 show plan views of the tip shroud 220 with a set of data points superimposed thereon that define a particular surface profile. The data points shown in the drawings are schematic representations and may not match the data points in the tables described below. As shown in FIGS. 4-5, 8, and 9, the tip rail 250 also includes a forward-most and radially outermost origin 280 at its axially forward end and an aft-most and radially outermost origin 282 at its axially aft end. The forward-most and radially outermost origins 280, 282 may serve as an origin for a particular surface profile described herein. As shown in FIGS. 4, 5, 8, and 9, the "tip rail axial length LTR" is the distance between the forward-most and radially outermost origin 280 and the aft-most and radially outermost origin 282.

[0060] 8 and 9, various surface profiles of the tip shroud 220 according to embodiments of the present disclosure will now be described. The surface profiles are identified in the form of X, Y, and possibly Z coordinates, respectively, listed in Tables I and II. Although the X, Y, and Z coordinate values ​​in Tables I-II are expressed in normalized or non-dimensionalized form with values ​​between 0% and 100%, it will be apparent that any or all of the values ​​may be expressed in distance units instead, so long as the percentages and proportions are maintained. To convert any of the X, Y, Z values ​​in Tables I-II to actual respective X, Y or Z coordinate values ​​from an associated origin (e.g., origin 280 on tip rail 250) in distance units, such as inches or meters, the non-dimensional values ​​given in Tables I-II can be multiplied by a normalization parameter value. As previously mentioned, the normalization parameter used herein is the tip rail axial length LTR. In any case, each surface profile can be identified by connecting the actual X, Y, Z values ​​with smooth continuing arcs or lines depending on the surface profile, resulting in various nominal tip shroud surface profiles.

[0061] The values ​​in Tables I-II are non-dimensionalized values, shown to three decimal points, generated to determine various nominal surface profiles of the tip shroud 220 at ambient, non-operating, or non-hot conditions, and do not account for any coatings, although embodiments may account for other conditions and / or coatings. ± values ​​may be added to the values ​​listed in Tables I-II to account for typical manufacturing tolerances and / or coating thicknesses. In one embodiment, a tolerance of approximately 10-20% may be applied. For example, a tolerance of approximately 10-20 percent applied to the X coordinate of the tip rail surface profile may define a surface profile range at low or room temperature. The tip shroud surface profile as embodied herein is robust to this range of variations without compromising mechanical and aerodynamic functionality.

[0062] The surface profile can be scaled larger or smaller, such as geometrically, without impairing operation. Such scaling can be facilitated by multiplying the normalized / non-dimensionalized values ​​by a common scaling factor (i.e., the actual desired distance of the normalized parameters), which may be, for example, a number larger or smaller than the distance units that may have originally been used for the tip shroud of a given tip rail axial length. For example, the non-dimensionalized values ​​of Table I may be uniformly multiplied by 2, 0.5, or any other desired scaling factor of the associated normalized parameter. In various embodiments, the X, Y, and Z distances can be scaled as a function of the same constant or number (e.g., tip rail axial length LTR) to provide a scaled up or scaled down tip shroud. Alternatively, the values ​​may be multiplied by a larger or smaller desired constant.

[0063] Although the Cartesian values ​​in Tables I-II provide coordinate values ​​at a given location, only a portion of the Cartesian coordinate values ​​defined in each table may be employed. In one non-limiting example, referring to FIG. 8, the tip rail side surface profile may use a portion of the X and Y coordinate values ​​defined in Table I, e.g., points 5 through 16. Any portion of the X, Y, and Z Cartesian coordinate values ​​defined in Tables I-II may be employed.

[0064] FIG. 8 illustrates a number of X and Y coordinate points that define the profile of the tip rail sides, including at least a portion of the upstream side 252 and downstream side 254. In this embodiment, the sides 252, 254 of the tip rail 250 have a shape with a nominal profile that substantially follows at least a portion of the X and Y Cartesian coordinate values ​​set forth in Table I (below), beginning at a forward-most and radially outermost point 280. The Cartesian coordinate values ​​are non-dimensional values ​​between 0% and 100% that can be converted to distance by multiplying X and Y by the tip rail axial length LTR expressed in distance units. Again, the normalization parameter for the X and Y coordinates is the tip rail axial length LTR of the tip rail 250. When scaling up or down, the X and Y coordinate values ​​in Table I can be multiplied by the desired tip rail axial length LTR of the tip rail 250 to identify the corresponding actual X and Y coordinate values ​​of the tip shroud side surface shape. Collectively, the actual X and Y coordinate values ​​created specify a tip rail side profile for any desired size of tip shroud according to an embodiment of the present disclosure. As shown in FIG. 8, the X and Y values ​​may be connected with a line to define the tip rail side profile.

[0065] Tip rail side profile [non-dimensional value] [Table I]

[0066] In another embodiment, the tip shroud 220 may also include leading and trailing edge surface profiles, as described herein in connection with Table II. Figure 9 is a plan view of the tip shroud 220 showing data points for the leading and trailing edge surfaces 290, 292. As understood in the art, the leading and trailing edge surfaces 290, 292 of adjacent tip shrouds 220 on adjacent blades 200 (Figure 3) collectively mate to define a radially inner surface for the hot gas path in the turbine 108 (Figure 1), for example, via the wings 230, 234.

[0067] The leading edge surface 290 and the trailing edge surface 292 may have a nominal profile that substantially follows at least a portion of the Cartesian coordinate values ​​of the X, Y, Z values ​​set forth in Table II (below) and may have a shape originating from the forward-most and radially outermost point 280. The Cartesian coordinate values ​​are dimensionless values ​​between 0% and 100% and are converted to distances by multiplying by the tip rail axial length LTR. That is, the normalization parameter for the X, Y, Z coordinates is the same as the tip rail axial length LTR. When scaling up or down, the X, Y, Z coordinate values ​​in Table II may be multiplied by the actual desired tip rail axial length LTR to determine the corresponding actual X, Y, Z coordinate values ​​for the leading and trailing edge surface shapes. The actual X, Y coordinate values ​​may be smoothly combined with each other to form the leading and trailing edge surface shapes.

[0068] Leading and trailing surface profiles [non-dimensionalized values] [Table II]

[0069] Other embodiments of the present disclosure may include any combination of the surface profiles described herein, i.e., a surface profile in Table I may be used with a surface profile in Table II, and vice versa.

[0070] The [X, Y, Z] data points of each table may be smoothly joined (with lines and / or arcs) to each other to form a surface profile for each tip rail upstream, tip rail downstream, tip shroud leading edge, and / or tip shroud trailing edge using any curve fitting technique now known or later developed that generates an appropriate curved surface for the tip shroud. Curve fitting techniques include, but are not limited to, extrapolation, interpolation, smoothing, polynomial regression, and / or other mathematical curve fitting functions. Curve fitting techniques may be performed manually and / or computationally, for example, through statistical and / or numerical-analysis software.

[0071] The disclosed surface profiles provide unique geometries for improving turbine life and reliability, for example, by rebalancing to address creep or other wear, and / or achieving normalized aerodynamic and mechanical blade or tip shroud loadings. The disclosed point locations defined in Tables I-II provide for efficient, safe, and smooth operation of the GT system 100 or other suitable turbine system. Also, any scale of tip shroud 220, as previously described, can be employed, so long as the interactions between other stages of the turbine 108 (FIG. 1), aerodynamic efficiency, and normalized aerodynamic and mechanical blade or airfoil loadings are maintained in the scaled turbine.

[0072] The one or more surface profiles of the tip shroud 220 and the axially offset cutter teeth 260, 262 described herein improve the reliability and efficiency of the overall GT system 100. The one or more surface profiles of the tip shroud 220 also meet all aeromechanical and stress requirements.

[0073] The apparatus and devices of the present disclosure are not limited to any particular turbomachine, engine, turbine, jet engine, power generation system, or other system, and may be used with turbomachines, such as aircraft systems, power generation systems (e.g., simple cycle, combined cycle), and / or other systems (e.g., nuclear reactors). Additionally, the apparatus of the present disclosure may be used with other systems not described herein that may benefit from the increased efficiency of the apparatus and devices described herein.

[0074] Approximate expressions used throughout the specification and claims may be applied to modify any quantitative expression that may be permissibly changed without resulting in a change in the basic function to which it relates. Thus, values ​​modified by terms such as "about", "approximately", "substantially" and the like are not limited to the exact values ​​specified. In at least some instances, approximation expressions may correspond to the precision of the instrument for measuring the value. Throughout the specification and claims, range limitations may be combined and / or interchanged. Such ranges are specified and include all subranges contained therein, unless the context or language indicates otherwise. "About" applied to a particular value in a range applies to both endpoints and may indicate ±10% of the stated value, unless dependent on the precision of the instrument for measuring the value.

[0075] Corresponding structures, materials, acts, and equivalents of all means-plus-function or step-plus-function components in the following claims are intended to include any structure, material, or act for performing a function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting of the disclosure in the disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The embodiments were chosen and described in order to best explain the principles and practical application of the disclosure and to enable those skilled in the art to understand the disclosure in various embodiments with various modifications as suited to the particular use contemplated. [Explanation of symbols]

[0076] 20:Tip shroud 27:Body 30:Wing 32:Upstream wing 34:Downstream wing 50:Tip rail 52:Upstream 54:Downstream 60:Cutter tooth 70:Edge face 72:Sharp trailing edge surface 90:Turbomachinery 100:Gas turbine (GT) system 102:Compressor 104:Combustor 105:Combustion zone 106:Fuel nozzle assembly 108:Turbine 110:Rotor shaft 112:Nozzle 114:Rotating blades 115:Stationary nozzle section 116:Rotor wheel 120:Radially outer endwall 122:Radially inner endwall 124:Casing 130:Airfoil 200:Turbine blade 202:Airfoil 204:Pressure side 206:Suction side 208:Leading edge 210:Trailing edge 212: root end 213: endwall 214: fillet 220: tip shroud 222: radially outer end 224: dovetail 226: radially inner end 227: body 228: fillet 229: leading edge 230: wing 231: trailing edge 232: upstream wing 234: downstream wing 236: radially outer surface 238: radially inner side 240: radially outer side 242: radially inner surface 250: tip rail 252: upstream side 254: downstream side 260: first cutter tooth 262: second cutter tooth 266: axially aft end 268: axially forward end 270: rounded leading surface 272: straight edge surface 280, 282: origin 290: leading surface 292: Trailing edge surface

Claims

1. A turbine blade (200) tip shroud (220), comprising: a body (227) configured to couple to the airfoil (202) at a radially outer end (222) of the airfoil (202), the body (227) having a leading edge (229) and a trailing edge (231) opposite the leading edge (229); a tip rail (250) extending radially from the body (227), the tip rail (250) having an upstream side (252) and a downstream side (254) opposite the upstream side (252); a first cutter tooth (260) extending from the tip rail (250) from one of the upstream (252) and downstream (254) sides of the tip rail (250) and directly adjacent a leading edge (229) of the body (227); a second cutter tooth (262) extending from the tip rail (250) at a position axially spaced from the first cutter tooth (260) from the other of the upstream side (252) and the downstream side (254) of the tip rail (250); A turbine blade (200) tip shroud (220).

2. 2. The turbine blade (200) tip shroud (220) of claim 1, wherein a first cutter tooth (260) extends from an upstream side (252) of the tip rail (250) and a second cutter tooth (262) extends from a downstream side (254) of the tip rail (250).

3. The turbine blade (200) tip shroud (220) of any of the preceding claims, wherein a location axially away from the first cutter tooth (260) is within a range of 30% to 50% of an axial length of the tip rail (250).

4. A method of modifying a turbine blade (200) tip shroud (220), comprising: removing a first cutter tooth (260) extending from a selected side of an upstream side (252) and a downstream side (254) of a tip rail (250) of a turbine blade (200) tip shroud (220), the first cutter tooth (260) being opposite a second cutter tooth (262) extending from the tip rail (250) from the other side of the upstream side (252) and the downstream side (254) of the tip rail (250); forming a third cutter tooth on a selected one of the upstream (252) and downstream (254) sides of the tip rail (250) axially spaced from the second cutter tooth (262); The method includes:

5. The method of claim 4, wherein the first cutter tooth (260) and the second cutter tooth (262) are directly adjacent a leading edge (229) of the body (227) of the turbine blade (200) tip shroud (220).

6. The method of claim 4, wherein the second cutter tooth (262) extends from an upstream side (252) of the tip rail (250) and the third cutter tooth extends from a downstream side (254) of the tip rail (250).

7. The method of claim 4, wherein the axial distance from the second cutter tooth (262) is in the range of 30% to 50% of the axial length of the tip rail (250).

8. 5. The method of claim 4, wherein the body (227) of the turbine blade (200) tip shroud (220) includes a pair of axially oppositely extending wings (230), and further comprising removing a portion of at least one of the pair of axially oppositely extending wings (230).

9. 9. The method of claim 8, wherein removing at least a portion of one of the pair of axially opposed wings (230) comprises rounding the end face (270) from a more straight end face (272) shape.

10. The method of claim 8, wherein removing a portion of at least one of the pair of axially opposed wings (230) comprises forming a straight end surface (272).

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