Patent Description:
Gas turbine systems are widely used to generate power. Gas turbine hot gas path rotating blades, and in particular the blade tips, require cooling during operation. In addition, gas turbine hot gas path nozzles may require cooling during operation. Significant amounts of air may be used for cooling the blades and nozzles. However, overall efficiency of the gas turbine system can be increased if the extent of air used for cooling is reduced. Turbine blades and nozzles are commonly manufactured as monolithic structures using an investment casting process. The investment casting process presents a number of challenges for achieving advanced heat transfer designs in certain areas, e.g., the blade tip, or the leading and/or trailing edge of the nozzle and/or blade. One approach to address these challenges is to manufacture a part of the airfoil, e.g., tip or edge coupon, separately and attach it to the rest of the airfoil, e.g., the airfoil body of a blade or nozzle. In this manner, advanced cooling arrangements can be implemented in, for example, the blade tip or nozzle airfoil leading or trailing edge, and put into practice in both new and used components. One challenge with using separate tips or coupons that are later attached is adequately coupling the part to the rest of the airfoil of the blade or nozzle. Current practices include welding, brazing and bonding. <CIT> discloses in an airfoil for a blade or nozzle formed from two vane halves joined together at the mean chamber line, the two vane halves together forming an airfoil body including openings in the leading edge and trailing edge of the body. In order to provide a complete aerodynamic airfoil, leading edge and trailing edge inserts are used to close the openings.

<CIT> discloses attaching a replacement or connecting part to a turbine component with keyed engagement. <CIT> discloses an airfoil having a wall covered by rows of ceramic tablets. <CIT> discloses a segmented trailing edge insert for an airfoil. <CIT> discloses an airfoil with an internally cooled supplemental element joined to its outer wall to replace a removed portion. <CIT> discloses a coupon for replacing a cutout of a gas turbine component.

The claims provide an airfoil for a blade or nozzle of a turbomachine as defined in claim <NUM> and a method for making such an airfoil as defined in claim <NUM>.

The illustrative aspects of the present invention are designed to solve the problems herein described and/or other problems not discussed.

It is noted that the drawings of the disclosure are not to scale.

As an initial matter, in order to clearly describe the current disclosure it will become necessary to select certain terminology when referring to and describing relevant machine components within a blade for a turbomachine. When doing this, if possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part.

In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, "downstream" and "upstream" are terms that indicate a direction relative to the flow of a fluid, such as the working fluid through the turbine engine or, for example, the flow of air through the combustor or coolant through one of the turbine's component systems. The term "downstream" corresponds to the direction of flow of the fluid, and the term "upstream" refers to the direction opposite to the flow. The terms "forward" and "aft," without any further specificity, refer to directions, with "forward" referring to the front or compressor end of the gas turbine system, and "aft" referring to the rearward or turbine end of the gas turbine system. It is often required to describe parts that are at differing radial positions with regard to a center axis. The term "radial" refers to movement or position perpendicular to an axis. In cases such as this, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is "radially inward" or "inboard" of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is "radially outward" or "outboard" of the second component. The term "axial" refers to movement or position parallel to an axis. Finally, the term "circumferential" refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the rotor of the gas turbine system.

Where an element or layer is referred to as being "on," "engaged to," "disengaged from," "connected to" or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be 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.

The disclosure falling outside the scope of the claims provides an attachment for part of an airfoil, such as a tip for a blade, or an edge coupon for a nozzle or blade. The airfoil may be used in, for example, a turbomachine The disclosure provides a blade for a turbomachine, a tip for a blade of a turbomachine and a related method for attaching the tip. The blade may include a tip body having a shape at least partially configured for coupling to an airfoil body of the blade. At least one coolant passage is positioned in the tip body and configured for fluid communication with at least one coolant passage in the airfoil body. A retention member extends from the tip body for coupling to a tip retention member seat in the airfoil body.

In an embodiment according to the invention, the retention member and retention member seat attachment are applied to an edge coupon for an airfoil for a nozzle or blade of a turbomachine. This embodiment provides an airfoil for a nozzle or blade of a turbomachine, an edge coupon for an airfoil and a related method. In this embodiment, the airfoil includes an airfoil body including at least one first coolant passage, and an edge opening in a leading edge or a trailing edge of the airfoil body. Similar to the first embodiment, the edge opening has an edge coupon retention member seat in or on an inner surface of the airfoil body. The airfoil also includes an edge coupon having a shape at least partially configured for coupling to the edge opening in the airfoil body. The edge coupon includes an edge coupon body, at least one second coolant passage in the edge coupon body configured for fluid communication with the at least one first coolant passage in the airfoil body, and a retention member extending from the edge coupon body for coupling to the edge coupon retention member seat in the airfoil body.

<FIG> shows a schematic illustration of an illustrative gas turbine system <NUM>. Gas turbine system <NUM> includes a compressor <NUM> and a combustor <NUM>. Combustor <NUM> includes a combustion region <NUM> and a fuel nozzle assembly <NUM>. Engine <NUM> also includes a turbine <NUM> and a common compressor/turbine rotor <NUM>. In one embodiment, engine <NUM> is a MS7001FB engine, sometimes referred to as a 9FB engine, commercially available from General Electric Company, Greenville, S. The present disclosure is not limited to any one particular engine and may be implanted in connection with other engines including, for example, the MS7001FA (7FA) and MS9001FA (9FA) engine models of General Electric Company.

In operation, air flows through compressor <NUM> and compressed air is supplied to combustor <NUM>. Specifically, the compressed air is supplied to fuel nozzle assembly <NUM> that is integral to combustor <NUM>. Fuel nozzle assembly <NUM> is in flow communication with combustion region <NUM>. Fuel nozzle assembly <NUM> is also in flow communication with a fuel source (not shown in <FIG>) and channels fuel and air to combustion region <NUM>. Combustor <NUM> ignites and combusts fuel. Combustor <NUM> is in flow communication with turbine <NUM> in which gas stream thermal energy is converted to mechanical rotational energy. Turbine <NUM> is rotatably coupled to and drives rotor <NUM>. Compressor <NUM> also is rotatably coupled to rotor <NUM>. In the illustrative embodiment, there is a plurality of combustors <NUM> and fuel nozzle assemblies <NUM>. In the following discussion, unless otherwise indicated, only one of each component will be discussed.

<FIG> is cross-section illustration of an illustrative turbine <NUM> showing a rotating blade <NUM> coupled to rotor <NUM>, and a nozzle <NUM> that may be used with gas turbine system <NUM> in <FIG>. Rotating blade <NUM> includes an airfoil body <NUM>, a root end <NUM> for coupling to rotor <NUM>, and a blade tip or shroud <NUM> at an outer end thereof. Nozzle <NUM> includes an airfoil body <NUM> held in turbine <NUM> by a radially outer platform <NUM>. Nozzle <NUM> also includes a radially inner platform <NUM>.

The disclosure generally includes two alternative embodiments that employ a retention member and retention member seat attachment for coupling a part to an airfoil of a blade or nozzle. The first example relates to a tip attachment for a blade and does not form part of the claimed subject-matter, while the invention relates to an edge coupon attachment applicable to a leading and/or trailing edge of blades and/or nozzles. Thus, the first example is described relative to a blade alone, while the invention is described relative to a blade and nozzle, interchangeably.

<FIG> shows a perspective view of a blade <NUM> for a turbomachine of the type in which the various embodiments of the disclosure may be employed. Blade <NUM> includes an airfoil body <NUM> including at least one first coolant passage <NUM> (in phantom) therein. Blade <NUM> may also include a root <NUM> by which blade <NUM> attaches to rotor <NUM> (<FIG>). Root <NUM> may include a dovetail configured for mounting in a corresponding dovetail slot in the perimeter of the rotor disc. Root <NUM> may further include a shank that extends between the dovetail and a platform <NUM>, which is disposed at the junction of airfoil body <NUM> and root <NUM> and defines a portion of the inboard boundary of the flow path through turbine <NUM> (<FIG>). It will be appreciated that airfoil body <NUM> is the active component of blade <NUM> that intercepts the flow of working fluid and induces the rotor disc to rotate. It will be seen that airfoil body <NUM> of blade <NUM> includes a concave pressure side (PS) outer wall <NUM> and a circumferentially or laterally opposite convex suction side (SS) outer wall <NUM> extending axially between opposite leading and trailing edges <NUM>, <NUM>, respectively. Walls <NUM> and <NUM> also extend in the radial direction from platform <NUM> to a tip <NUM>. As understood in the field, coolant passage(s) <NUM> can have a variety of shapes such as but not limited to: linear, sinusoidal (<FIG>), etc. Coolant passage(s) <NUM> can deliver a coolant, e.g., air from compressor <NUM> (<FIG>), through airfoil body <NUM> and/or to tip <NUM>.

Referring to the exploded perspective view of <FIG>, tip <NUM> has a shape that is at least partially configured for coupling to airfoil body <NUM>, i.e., at least part of tip <NUM> has a commensurate shape to airfoil body <NUM> so, collectively, they can form a unitary blade <NUM>, when coupled. Tip <NUM> may include a tip body <NUM>. Tip body <NUM> can be solid, or as shown, include at least one coolant passage <NUM> therein configured for fluid communication with coolant passage(s) <NUM> in airfoil body <NUM>. Tip body <NUM> can include a complete tip, a portion of a complete tip, or multiple portions of a tip. Coolant passage(s) <NUM> may have a large variety of shapes and paths to cool tip body <NUM> including a base <NUM> and/or a rail <NUM> (<FIG>) thereof. Further, coolant passage(s) <NUM> can pass through any part of tip <NUM>, e.g., a body, a tip plate, a tip rail, etc. Coolant passage(s) <NUM> and <NUM> do not need to have a one-to-one correspondence.

With continuing reference to <FIG>, in accordance with a comparative example not according to the invention, and in contrast to conventional tip-blade attachment arrangements, airfoil body <NUM> includes a tip retention member seat <NUM> in or on airfoil body <NUM>. In the example shown in <FIG>, tip retention member seat <NUM> is on an inner surface <NUM> of airfoil body <NUM>, i.e., either extending from or in inner surface <NUM>. Here, tip retention member seat <NUM> may include a protrusion or ridge <NUM> extending inwardly from inner surface <NUM> of a wall of airfoil body <NUM>. In <FIG>, tip retention member seat <NUM> includes ridge <NUM> that extends entirely about inner surface <NUM>. Although shown as a continuous ridge <NUM>, it is understood that seat <NUM> may be segmented. For example, in <FIG>, inner surface <NUM> is shown as defining a single coolant passage <NUM>, but it is understood that coolant passage <NUM> may include a number of coolant passages <NUM>. In this latter case, tip retention member seat <NUM> may be segmented, i.e., includes a number of seats <NUM> within respective coolant passages <NUM>. For example, as shown in <FIG>, airfoil body <NUM> may include a number of coolant passages <NUM>, each with one or more tip retention member seats <NUM> on inner surfaces <NUM> thereof, i.e., extending into or facing respective coolant passages <NUM>. Ridge <NUM> may be discontinuous along an inner surface <NUM> of any particular coolant passage, e.g., as in coolant passage 145A in <FIG>.

<FIG> also shows tip <NUM> including a retention member(s) <NUM> extending from tip body <NUM> for coupling to tip retention member seat(s) <NUM>. In one example, retention member <NUM> may include a flexible element <NUM> having a retention seat engaging element <NUM> at a distal end thereof for engaging with tip retention member seat <NUM> on inner surface <NUM> of airfoil body <NUM>. As shown in <FIG>, each retention member <NUM> may be configured to extend into a coolant passage <NUM> in airfoil body <NUM> to engage a tip retention member seat <NUM>. Any number of retention member seats <NUM> spaced about airfoil body <NUM> may be employed. Similarly, any number of corresponding retention members <NUM> spaced about tip <NUM> may be used to engage retention member seats <NUM>.

Flexible element <NUM> may be sufficiently flexible to allow retention seat engaging element <NUM> to flex and pass into engagement with tip retention member seat <NUM>, but rigid enough to hold the two together. A length of each retention member <NUM> may be configured to ensure tip <NUM> is tightly held to airfoil body <NUM>. A brazing material <NUM> may also be provided for coupling tip <NUM> to airfoil body <NUM> along at least mating surfaces of tip body <NUM> and airfoil body <NUM>. Brazing material <NUM> may include any known or later developed brazing or welding material used to fixedly couple tip to an airfoil body such as but not limited to: AMS4777, AMS4782, DF4B, D15, BNi-<NUM>, or AMS4783. Differential heating and different coefficient of thermal expansion (CTE) between materials may be used to enable a robust retention arrangement. Differential heating may be used during assembly of tip <NUM> to airfoil body <NUM>. For example, airfoil body <NUM> could be heated to allow easy insertion of tip <NUM>. Upon cooling, gaps will close and provide intimate contact between the parts. Similarly, in another example, the material of tip <NUM> can be designed to have a slightly lower CTE than airfoil body <NUM> to enable assembly.

Referring to <FIG>, a method of forming blade <NUM> for a turbomachine not falling within the scope of the claims will now be described. Airfoil body <NUM> may be provided including at least one first coolant passage <NUM> therein. Further, airfoil body <NUM> may include a retention member seat <NUM>, such as ridge <NUM>, extending inwardly from inner surface <NUM> of a previously manufactured airfoil body <NUM>. Ridge <NUM> may be discontinuous on inner surface <NUM> of airfoil body <NUM>. As shown in <FIG>, in one embodiment, airfoil body <NUM> may also be manufactured with retention member seat <NUM> as an integral ridge <NUM> extending inwardly from inner surface <NUM> of airfoil body <NUM>.

Tip 154A may also have a shape at least partially configured for coupling to airfoil body <NUM>. Tip 154A may include tip body <NUM>, coolant passage(s) <NUM> therein, and retention member(s) <NUM> extending from tip body <NUM> for coupling to retention member seat(s) <NUM> in airfoil body <NUM>. Each retention member <NUM> may include flexible element <NUM> having retention seat engaging element <NUM> at a distal end thereof for engaging with one of retention member seat(s) <NUM> of airfoil body <NUM>.

<FIG> shows coupling tip 154A to airfoil body <NUM> such that coolant passage(s) <NUM> is/are in fluid communication with coolant passage(s) <NUM> in airfoil body <NUM>. As explained herein, and as shown best in <FIG>, at least one retention member <NUM> couples to at least one retention member seat <NUM> in airfoil body <NUM> to couple tip 154A to airfoil body <NUM>. Each retention member <NUM> may flex as its retention seat engaging element <NUM> passes over inner surface <NUM> of airfoil body <NUM>, and/or ridge <NUM>. A mating or engaging surfaces may be slanted to assist in the necessary application of bending force and alignment of parts. The coupling can also include metallurgically coupling tip 154A to airfoil body <NUM>, e.g., with brazing material <NUM>, along at least portions of mating surfaces of tip body 160A and airfoil body <NUM>, once element <NUM> and seat <NUM> are mated. In one example, the metallurgical coupling may include heating tip 154A and airfoil body <NUM>, pressing tip body 160A to airfoil body <NUM>, e.g., with a force F assisted by retention member <NUM> interaction with seat <NUM>, and brazing tip body 160A to airfoil body <NUM>. Alternatively, the same process can be performed at room temperature, depending on the materials and the tip/airfoil body arrangement. Brazing material <NUM> can optionally be pre-placed at the joint interface prior to assembly. For example, brazing material <NUM> could be deposited using various deposition methods on to mating surface(s), and then prepped prior to assembly. As noted, brazing material <NUM> may include any now known or later developed brazing or welding material used to fixedly couple tip to an airfoil body, see list herein. The force may be applied either at or close to bonding temperature to enable locking of tip 154A to airfoil body <NUM>.

Referring to <FIG>, in another example, two or more retention member seats <NUM>, or sets thereof, may be provided in an airfoil body <NUM> at different lengthwise positions, e.g., at different radial positions in airfoil body <NUM> from root <NUM> (<FIG>). For example, a first retention member seat 170A may be positioned at a first lengthwise position R1 on airfoil body <NUM>, and a second retention member seat 170B may be positioned at a second, different lengthwise position R2 on airfoil body <NUM>. In this fashion, a first tip 154A may be coupled to airfoil body <NUM>, and can be removed after use, e.g., by cutting away a distal end <NUM> of airfoil body <NUM> to which tip 154A is coupled. The cutting can be made using any now known or later developed metal cutting process, e.g., laser cutting, water jet, electro-discharge machining. Distal end <NUM> includes first retention member seat 170A such that cutting it away removes tip 154A and its related seat, but leaves second retention member seat 170B. Thereafter, another tip 154B (<FIG>) may be coupled to airfoil body <NUM> by coupling at least one retention member <NUM> thereof to second retention member seat 170B in airfoil body <NUM>. Coupling of tip 154B may be completed as described for tip 154A. It is understood that a distance between a new distal end <NUM> of airfoil body <NUM> and second retention member seat 170B is precisely controlled to ensure proper engagement of retention member <NUM> of tip 154B, e.g., by cutting accuracy, machining, etc. Since tip 154A can be replaced, tip 154B may allow for changes in coolant passages <NUM> in the tip of a blade. For example, coolant passage(s) <NUM> in tip 154B can be more advanced, e.g., more precise in path, more numerous, smaller or larger, etc., to provide better cooling than tip 154A.

<FIG> and <FIG> show various drawings of an embodiment of the invention in which an edge coupon <NUM> is attached using a retention member and retention member seat attachment on a blade <NUM> and/or a nozzle <NUM>. For purposes of description, edge coupon <NUM> attachment will illustrated mostly relative to a nozzle <NUM>, but as noted above, the second embodiment is described relative to nozzle <NUM> and blade <NUM> collectively, e.g., with reference to leading and trailing edges thereof collectively, or with reference to airfoil bodies thereof collectively. That is, edge coupon <NUM> attachment is equally applicable leading or trailing edges of nozzle <NUM> or blade <NUM>. It is noted that <FIG> shows blade <NUM> including an edge coupon <NUM> in a leading edge <NUM> thereof, and an edge coupon <NUM> in trailing edge <NUM> thereof. It is emphasized that only one edge coupon can also be employed in blade <NUM>.

With further regard to nozzle <NUM>, <FIG> shows a perspective view of an illustrative stationary vane or nozzle <NUM> of the type in which the present embodiment may be employed. As noted previously, nozzle <NUM> includes airfoil body <NUM> held in turbine <NUM> (<FIG>) by radially outer platform <NUM>. Outer platform <NUM> may include any now known or later developed mounting configuration for mounting in a corresponding mount in the casing. Nozzle <NUM> may further include inner platform <NUM> for positioning between adjacent turbine rotor blades <NUM> (<FIG>). Platforms <NUM>, <NUM> define respective portions of the outboard and inboard boundary of the flow path through turbine <NUM>. It will be appreciated that airfoil body <NUM> is the active component of nozzle <NUM> that intercepts the flow of working fluid and directs it towards turbine rotor blades <NUM> (<FIG>). It will be seen that airfoil body <NUM> of nozzle <NUM> includes a concave pressure side (PS) outer wall <NUM> and a circumferentially or laterally opposite convex suction side (SS) outer wall <NUM> extending axially between opposite leading and trailing edges <NUM>, <NUM>, respectively. Sidewalls <NUM> and <NUM> also extend in the radial direction from platform <NUM> to platform <NUM>. Nozzle <NUM> and/or airfoil body <NUM> include at least one first coolant passage <NUM> (in phantom) therein. As understood in the field, coolant passage(s) <NUM> can have a variety of shapes such as but not limited to: linear, sinusoidal (<FIG>), etc. Coolant passage(s) <NUM> can deliver a coolant, e.g., air from compressor <NUM> (<FIG>), through airfoil body <NUM>, coupon(s) <NUM>, and/or platforms <NUM>, <NUM>.

<FIG> shows a schematic view of an airfoil for blade <NUM> or nozzle <NUM> of turbomachine <NUM> according to the present embodiment. <FIG> shows a schematic view of any edge <NUM>, <NUM>; <NUM>, <NUM>, i.e., leading or trailing edge, of the airfoil of blade <NUM> or nozzle <NUM>. As illustrated, the airfoil includes an airfoil body <NUM>, <NUM> including at least one first coolant passage <NUM>, <NUM>, and an edge opening <NUM> in leading edge <NUM>, <NUM> or a trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>. Edge opening <NUM> has an edge coupon retention member seat <NUM> in or on an inner surface <NUM> of airfoil body <NUM>, <NUM>.

Edge coupon retention member seat <NUM>, e.g., 270A, 270B, may either extend from, or be located, in inner surface <NUM>. Here, coupon retention member seat(s) <NUM> may include a protrusion or ridge <NUM> extending inwardly from inner surface <NUM> of a wall of airfoil body <NUM>, <NUM>. In the left side of <FIG>, coupon retention member seat(s) <NUM> includes ridge <NUM> that extends substantially an entire length of cooling passage <NUM>, <NUM> exposed by edge opening <NUM>. Although shown as a continuous ridge <NUM>, it is understood that seat(s) <NUM> may be segmented. That is, each coupon retention member seat <NUM> (270A, 270B) may be segmented to include a number of spaced seats <NUM> within respective coolant passages <NUM>, <NUM>. Ridge <NUM> may be discontinuous along an inner surface <NUM> of any particular coolant passage <NUM>, <NUM>, e.g., the ridges <NUM> in phantom in the right side of <FIG> is segmented. In this manner, the retention member seat(s) <NUM> may include a plurality of retention member seats spaced about edge opening <NUM> in airfoil body <NUM>, <NUM>. In addition, and as will be described in greater detail herein, a number of retention member seat(s) <NUM> may be axially spaced relative to a leading edge <NUM>, <NUM> or trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>, respectively.

<FIG> also shows a schematic view of an edge coupon <NUM> having a shape at least partially configured for coupling to edge opening <NUM> in airfoil body <NUM>, <NUM>. Edge coupon <NUM> can include any now known or later developed form of edge structure for an airfoil that is added into a previously manufactured part with edge opening <NUM>, or replaces part of a previously manufactured airfoil having edge opening <NUM> formed therein, e.g., after use. Edge coupon <NUM> includes an edge coupon bodv <NUM>. and at least one second coolant passage <NUM> in edge coupon body <NUM>. Second cooling passage(s) <NUM> is configured for fluid communication with first coolant passage(s) <NUM> in airfoil body <NUM>, <NUM>. Second cooling passage(s) <NUM> may communicate with first coolant passage(s) <NUM> in an aligned linearlv fashion, or may join together to collectively form a coolant passage. Edge coupon <NUM> also includes a retention member <NUM> extending from edge coupon body <NUM> for coupling to edge coupon retention member seat <NUM> in airfoil body <NUM>, <NUM>.

Retention member <NUM> may be similar to retention member <NUM> (<FIG>). In one embodiment, retention member <NUM> may include a flexible element <NUM> having a retention seat engaging element <NUM> at a distal end thereof for engaging with edge coupon retention member seat <NUM> on inner surface <NUM> of airfoil body <NUM>, <NUM>. As shown in <FIG>, each retention member <NUM> is configured to extend into coolant passage <NUM> in airfoil body <NUM>, <NUM> to engage an edge coupon retention member seat <NUM>. Any number of retention member seats <NUM> spaced about airfoil body <NUM>, <NUM> may be employed. Similarly, any number of corresponding retention member(s) <NUM> spaced about edge coupon <NUM> may be used to engage retention member seat(s) <NUM>.

Flexible element <NUM> may be sufficiently flexible to allow retention seat engaging element <NUM> to flex and pass into engagement with edge coupon retention member seat <NUM>, but rigid enough to hold the two together. A length of each retention member <NUM> may be configured to ensure edge coupon <NUM> is tightly held to airfoil body <NUM>, <NUM>. A brazing material <NUM> may also be provided for coupling edge coupon <NUM> to airfoil body <NUM>, <NUM> along at least mating surfaces of edge coupon <NUM> and airfoil body <NUM>, <NUM>. Brazing material <NUM> may include any known or later developed brazing or welding material used to fixedly couple tip to an airfoil body such as but not limited to: AMS4777, AMS4782, DF4B, D15, BNi-<NUM>, or AMS4783. Differential heating and different coefficient of thermal expansion (CTE) between materials may be used to enable a robust retention arrangement. Differential heating may be used during assembly of edge coupon <NUM> to airfoil body <NUM>, <NUM>. For example, airfoil body <NUM>, <NUM> could be heated to allow easy insertion of edge coupon <NUM>. Upon cooling, gaps will close and provide intimate contact between the parts. Similarly, in another example, the material of edge coupon <NUM> can be designed to have a slightly lower CTE than airfoil body <NUM>, <NUM> to enable assembly.

Similar to the multiple radially spaced tip retention seats 170A. 170B for multiple tips 154A, 154B described relative to <FIG>, airfoil body <NUM>, <NUM> also includes a number of retention member seats 270A, 270B that are axially spaced relative to the leading edge <NUM>, <NUM> or trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM> to allow for different edge coupons 198A, 198B to be employed. As shown in <FIG>, retention member seat <NUM> includes a first retention member seat 270A at a first axial depth position D1 relative to leading edge <NUM>, <NUM> or trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>, and a second retention member seat 270B at a second, different axial depth D2 position relative to the leading edge <NUM>, <NUM> or trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>. As shown in <FIG> and <FIG>, a first edge coupon 198A are coupled to airfoil body <NUM>, <NUM> in edge opening 220A. Subsequently, first edge coupon 198A can be removed from airfoil body <NUM>, <NUM> after use, e.g., by cutting out first edge coupon 198A. The cutting can be made using any now known or later developed metal cutting process, e.g., laser cutting, water jet, electro-discharge machining. As first edge coupon 198A is removed, as shown in <FIG>, a new edge opening 220B is formed which extends axially deeper into airfoil body <NUM>, <NUM>, removing first retention member seat 270A, but leaving second retention member seat 270B. Thereafter, as shown in <FIG> and <FIG>, another edge coupon 198B may be coupled to airfoil body <NUM>, <NUM> by coupling at least one retention member <NUM> thereof to second retention member seat 270B in airfoil body <NUM>, <NUM>. Coupling of second edge coupon 198B may be completed as described for edge coupon 220A. It is understood that a depth of edge opening 220B is precisely controlled to ensure proper engagement of retention member <NUM> of second edge coupon 198B, e.g., by cutting accuracy, machining, etc. Since first edge coupon 198A can be replaced, second edge coupon 198B may allow for changes in coolant passages <NUM>, <NUM> in leading edge <NUM>, <NUM> and/or trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>. For example, coolant passage(s) <NUM> in second edge coupon 198B can be more advanced, e.g., more precise in path, more numerous, smaller or larger, etc., to provide better cooling than first edge coupon 198A.

<FIG> shows an edge coupon <NUM> in both leading and trailing edges <NUM>, <NUM> of nozzle <NUM>; <FIG> shows edge coupon <NUM> in leading edge <NUM> of nozzle <NUM>, and <FIG> shows edge coupon <NUM> in trailing edge <NUM> of nozzle <NUM>. <FIG> shows edge coupons <NUM> applied to both leading and trailing edges <NUM>, <NUM> of blade <NUM>. While shown in both leading edge <NUM> and trailing edge <NUM>, it is understood that it can be in just one of the edges of blade <NUM>, similar to that shown for nozzle <NUM>.

Referring to <FIG>, a method of forming an airfoil for blade <NUM> or nozzle <NUM> of a turbomachine will now be described. Airfoil body <NUM>, <NUM> is provided including at least one first coolant passage <NUM>, <NUM> therein and an edge opening <NUM> in leading edge <NUM>, <NUM> or a trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM>, respectively. That is, airfoil body <NUM>, <NUM> may include manufacturing the airfoil body with edge opening <NUM> and the at least one retention member seat <NUM> as an integral ridge extending inwardly from inner surface <NUM> of airfoil body <NUM>, <NUM>.

Edge opening <NUM> has edge coupon retention member seat(s) <NUM> in or on inner surface <NUM> of airfoil body <NUM>, <NUM>. Further, airfoil body <NUM>, <NUM> may include an added retention member seat <NUM> as ridge <NUM> extending inwardly from inner surface <NUM> of a previously manufactured airfoil body <NUM>, <NUM>. Ridge <NUM> may be discontinuous on inner surface <NUM> of airfoil body <NUM>, <NUM>.

Edge coupon <NUM> may also be provided having a shape at least partially configured for coupling to airfoil body <NUM>, <NUM>. Edge coupon <NUM> includes: an edge coupon body <NUM>, second coolant passage(s) <NUM> in edge coupon body <NUM>, and retention member(s) <NUM> extending from edge coupon body <NUM> for coupling to retention member seat(s) <NUM> in airfoil body <NUM>, <NUM>. Each retention member <NUM> may include flexible element <NUM> having retention seat engaging element <NUM> at a distal end thereof for engaging with one of retention member seat(s) <NUM> of airfoil body <NUM>, <NUM>.

<FIG>, <FIG> and <FIG> show coupling edge coupon 198A to airfoil body <NUM>, <NUM> such that coolant passage(s) <NUM> is/are in fluid communication with coolant passage(s) <NUM> in airfoil body <NUM>, <NUM>. As explained herein, and as shown best in <FIG> and <FIG>, at least one retention member <NUM> couples to at least one retention member seat <NUM> in airfoil body <NUM>, <NUM> to couple edge coupon 198A to airfoil body <NUM>, <NUM>. Each retention member <NUM> may flex as its retention seat engaging element <NUM> passes over inner surface <NUM> of airfoil body <NUM>, <NUM>, and/or ridge <NUM>. A mating or engaging surfaces may be slanted to assist in the necessary application of bending force and alignment of parts. The coupling can also include metallurgically coupling edge coupon 198A to airfoil body <NUM>, <NUM>, e.g., with brazing material <NUM>, along at least mating surfaces of edge coupon 198A and airfoil body <NUM>, <NUM>, once element <NUM> and seat <NUM> are mated. In one embodiment, the metallurgical coupling may include heating edge coupon 198A and airfoil body <NUM>, <NUM>, pressing edge coupon body <NUM> to airfoil body <NUM>, <NUM>, e.g., with a force F assisted by retention member <NUM> interaction with seat <NUM>, and brazing edge coupon 198A to airfoil body <NUM>, <NUM>. Alternatively, the same process can be performed at room temperature, depending on the materials and edge coupon/airfoil body arrangement. Brazing material <NUM> can optionally be pre-placed at the joint interface prior to assembly. For example, brazing material <NUM> could be deposited using various deposition methods on to the surface, and then prepped prior to assembly. As noted, brazing material <NUM> may include any now known or later developed brazing or welding material used to fixedly couple edge coupon to an airfoil body, see list herein. The force may be applied either at or close to bonding temperature to enable locking of edge coupon <NUM> to airfoil body <NUM>, <NUM>.

As shown in <FIG>, providing airfoil body <NUM>, <NUM> includes providing a first retention member seat 270A at a first depth position D1 in airfoil body <NUM>, <NUM>, and a second retention member seat 270B at a second, different depth position D2 in airfoil body <NUM>, <NUM>. Each depth is relative to a respective leading edge <NUM>, <NUM> or trailing edge <NUM>, <NUM>. The method includes removing an edge coupon, e.g., edge coupon 198A, from airfoil body <NUM>, <NUM>, the edge coupon coupled 198A coupled to first retention member seat 270A. The removing includes, as shown in <FIG>, enlarging edge opening 220B, i.e., enlarging the old edge opening 220A to new edge opening 220B, to remove first retention member seat 270A, leaving second retention member seat 270B. Thereafter, as shown in <FIG>, another edge coupon 198B is coupled to airfoil body <NUM>, <NUM>, including coupling retention member(s) <NUM> to second retention member seat(s) 270B in airfoil body <NUM>, <NUM>.

Embodiments of the disclosure may also include edge coupon <NUM>. As shown best in <FIG>, edge coupon <NUM> includes edge coupon body <NUM> having a shape at least partially configured for coupling to edge opening <NUM> in leading edge <NUM>, <NUM> or a trailing edge <NUM>, <NUM> of airfoil body <NUM>, <NUM> of blade <NUM>, or nozzle <NUM>. Edge coupon <NUM> includes coolant passage(s) <NUM> in edge coupon body <NUM> configured for fluid communication with coolant passage(s) <NUM> in airfoil body <NUM>, <NUM>. Edge coupon <NUM> also includes retention member(s) <NUM> extending from edge coupon body <NUM> for coupling to edge coupon retention member seat(s) <NUM> in edge opening <NUM> in airfoil body <NUM>, <NUM>. Retention member <NUM> may include flexible element <NUM> having retention seat engaging element <NUM> at a distal end thereof for engaging with edge coupon retention member seat <NUM> on inner surface <NUM> of airfoil body <NUM>, <NUM>. As shown in <FIG>, each retention member <NUM> is configured to extend into a coolant passage <NUM> in airfoil body <NUM>, <NUM> to engage an edge coupon retention member seat <NUM>.

Airfoil bodies <NUM>, <NUM>, tip <NUM> (154A or 154B) and/or edge coupon <NUM> may include any now known or later developed metal or metal alloy capable of withstanding the operational environment within turbomachine <NUM>, e.g., a superalloy or other material that is highly oxidation resistant and creep resistant. As used herein, "superalloy" refers to an alloy having numerous excellent physical characteristics compared to conventional alloys, such as but not limited to: high mechanical strength, high thermal creep deformation resistance, like R195, Amdry <NUM>, Rene <NUM>, CM247, Haynes alloys, Incalloy, MP98T, TMS alloys, CMSX single crystal alloys. In one embodiment, superalloys for which teachings of the disclosure may be especially advantageous are those superalloys having a high gamma prime (γ') value. "Gamma prime" (γ') is the primary strengthening phase in nickel-based alloys. Example high gamma prime superalloys include but are not limited to: Rene <NUM>, N5, GTD <NUM>, MarM <NUM> and IN <NUM>. Tip <NUM> and/or edge coupon <NUM> may include alloys listed above (i.e., R195, Amdry <NUM>, Rene <NUM>, CM247, Haynes alloys, Incalloy, MP98T, TMS alloys, CMSX single crystal alloys) plus other alloys such as but not limited to: H214, MMC, ODS. Airfoil body <NUM>, <NUM> may include, for example: Rene N5, Rene N4, Rene <NUM>, GTD111, GTD444, IN738, or CMSX alloys, etc. Airfoil body <NUM>, <NUM>, tip body <NUM> and/or edge coupon <NUM> may also include a metal matrix composite (MMC). Airfoil body <NUM>, <NUM>, tip <NUM> and/or edge coupon <NUM> may be manufactured using one of investment casting, injection molding or additive manufacturing (e.g., direct metal laser melting (DMI,M), electron beam manufacturing (EBM), binder-jetting, etc.).

Referring to <FIG>, while a particular form of retention member <NUM>, <NUM> and retention member seat <NUM>, <NUM> have been illustrated, there are a wide variety of alternative embodiments. For example, <FIG> shows, for example, a tip <NUM> or edge coupon <NUM> with a multiple fingered, tip retention member <NUM>, <NUM> including a flexible element <NUM>, <NUM> and retention seat engaging elements <NUM>, <NUM> in mating retention seat(s) <NUM>, <NUM> in airfoil body <NUM>, <NUM>. <FIG> shows a different form of retention seat <NUM>, <NUM> on airfoil body <NUM>, <NUM>. In any of the embodiments described herein, it is recognized that the male and female part position may be reversed, where possible.

The disclosure provides advanced heat transfer airfoil coupon and/or tip arrangements that are not possible/easy to manufacture via investment casting. As described, the tip and/or coupon may be manufactured as a separate piece and then joined to the airfoil body. The advanced heat transfer arrangement may reduce cooling air flow, increasing gas turbine efficiency - lower fuel cost/higher power generation, and/or the life of the component. The retention feature also reduces the risk of part failure and separation during operation, and allows for replacement or upgrading of used parts. The new or replacement parts can include more advanced cooling passages than the previous part, allowing for improvement in the cooling of the tip, and/or leading and/or trailing edge.

Accordingly, a value modified by a term or terms, such as "about," "approximately" and "substantially," are not to be limited to the precise value specified. "Approximately" as applied to a particular value of a range applies to both values, and unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/-<NUM>% of the stated value(s).

Claim 1:
An airfoil for a blade (<NUM>) or nozzle (<NUM>, <NUM>) of a turbomachine (<NUM>), the airfoil comprising:
an airfoil body (<NUM>) including at least one first coolant passage (<NUM>, 145A, <NUM>), and an edge opening (<NUM>, 220A) in a leading edge (<NUM>, <NUM>) or a trailing edge (<NUM>, <NUM>) of the airfoil body (<NUM>), the edge opening (<NUM>, 220A) having an edge coupon retention member seat (<NUM>) in or on an inner surface (<NUM>, <NUM>) of the at least one first coolant passage (<NUM>, 145A, <NUM>) of the airfoil body (<NUM>); and
an edge coupon (<NUM>, 198A) having a shape at least partially configured for coupling to the edge opening (<NUM>, 220A) in the airfoil body (<NUM>), the edge (<NUM>, <NUM>) coupon including:
an edge coupon body (<NUM>),
at least one second coolant passage (<NUM>) in the edge coupon body (<NUM>) configured for fluid communication with the at least one first coolant passage (<NUM>, 145A, <NUM>) in the airfoil body (<NUM>), and
a retention member (<NUM>) extending from the edge coupon body (<NUM>) into an interior of the at least one first coolant passage (<NUM>, 145A, <NUM>) of the airfoil body for coupling to the edge coupon retention member seat (<NUM>) in the airfoil body (<NUM>),
wherein the retention member seat (<NUM>) includes a first retention member seat (<NUM>, 270A) at a first axial depth position relative to the leading edge (<NUM>, <NUM>) or the trailing edge (<NUM>, <NUM>) of the airfoil body (<NUM>), and a second retention member seat (<NUM>, 170B, 270B) at a second, different axial depth position relative to the leading edge (<NUM>, <NUM>) or the trailing edge (<NUM>, <NUM>) of the airfoil body (<NUM>),
wherein the edge coupon may be removed by cutting out the edge coupon (198A), thereby enlarging the edge opening (220A) to form a new edge opening (220B), thereby removing first retention member seat (270A) and leaving the second retention member seat (270B), such that a further edge coupon may subsequently be coupled to airfoil body (<NUM>, <NUM>), by coupling a retention member (<NUM>) of the further edge coupon (198B) to the second retention member seat (270B).