Patent Description:
Gas turbine engines for power generation typically comprise a first stage (e.g., in the compressor and/or turbine) that intakes air through a nozzle comprising nozzle guide vanes. In the turbine section, the walls of these vanes have a region, near the trailing edge (i.e., the aft of the vane, downstream from the throat), that is difficult to keep cool. Temperatures in this region can exceed material and coating limits. If the temperature is excessive, the vane wall can bulge outward into the flow path of the air, oxidize, and/or deform under the mechanical stress. While techniques exist to cool the vane wall on the pressure side (e.g., through-wall film cooling), the usage of such techniques to cool the vane wall on the suction side generally result in large penalties in turbine performance.

<CIT> illustrates an existing vane comprising an insert to aid in cooling of the vane wall. However, the insert poses manufacturing problems. In addition, the insert is not capable of extending into the trailing-edge region of the vane. Thus, such an insert is incapable of improving the cooling of the vane wall in the trailing-edge region.

Further, <CIT> discloses a turbine distributor vane including an inner hollow portion and a corrugated sleeve.

<CIT> relates to an airfoil portion of a rotor blade or a guide vane of a turbo-machine.

<CIT> discloses a crimped insert for internal cooling of a turbine vane.

<CIT> relates to a turbine assembly including a self-locking, resilient and preloadable impingement device for cooling turbine blades or vanes.

The present disclosure is directed toward overcoming one or more of the problems of the prior art and as discovered by the inventors.

In accordance with the present invention, a nozzle guide vane, a turbine and a gas turbine engine as set forth in claims <NUM>, <NUM> and <NUM>, respectively, is provided. Further embodiments of the invention are inter alia disclosed in the dependent claims.

The details of embodiments of the present disclosure, both as to their structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:.

The detailed description set forth below, in connection with the accompanying drawings, is intended as a description of various embodiments, and is not intended to represent the only embodiments in which the disclosure may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that embodiments of the invention can be practiced without these specific details. In some instances, well-known structures and components are shown in simplified form for brevity of description.

For clarity and ease of explanation, some surfaces and details may be omitted in the present description and figures. In addition, references herein to "upstream" and "downstream" are relative to the flow direction of the primary gas (e.g., air) used in the combustion process, unless specified otherwise. It should be understood that "upstream" refers to a position that is closer to the source of the primary gas or a direction towards the source of the primary gas, and "downstream" refers to a position that is farther from the source of the primary gas or a direction that is away from the source of the primary gas. Thus, a trailing edge or end of a component (e.g., a vane) is downstream from a leading edge or end of the same component. Also, it should be understood that, as used herein, the terms "side," "top," "bottom," "front," and "rear" are used for convenience of understanding to convey the relative positions of various components with respect to each other, and do not imply any specific orientation of those components in absolute terms (e.g., with respect to the external environment or the ground).

<FIG> illustrates a schematic diagram of a gas turbine engine <NUM>, according to an embodiment. Gas turbine engine <NUM> comprises a shaft <NUM> with a central longitudinal axis L. A number of other components of gas turbine engine <NUM> are concentric with longitudinal axis L, and all references herein to radial, axial, and circumferential directions are relative to longitudinal axis L. A radial axis may refer to any axis or direction that radiates outward from longitudinal axis L at a substantially orthogonal angle to longitudinal axis L, such as radial axis R in <FIG>. As used herein, the term "axial" will refer to any axis or direction that is substantially parallel to longitudinal axis L.

In an embodiment, gas turbine engine <NUM> comprises, from an upstream end to a downstream end, an inlet <NUM>, a compressor <NUM>, a combustor <NUM>, a turbine <NUM>, and an exhaust outlet <NUM>. In addition, the downstream end of gas turbine engine <NUM> may comprise a power output coupling <NUM>. One or more, including potentially all, of these components of gas turbine engine <NUM> may be made from stainless steel and/or durable, high-temperature materials known as "superalloys. " A superalloy is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Examples of superalloys include, without limitation, Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX single crystal alloys.

Inlet <NUM> may funnel a working fluid F (e.g., a gas, such as air) into an annular flow path <NUM> around longitudinal axis L. Working fluid F flows through inlet <NUM> into compressor <NUM>. While working fluid F is illustrated as flowing into inlet <NUM> from a particular direction and at an angle that is substantially orthogonal to longitudinal axis L, it should be understood that inlet <NUM> may be configured to receive working fluid F from any direction and at any angle that is appropriate for the particular application of gas turbine engine <NUM>. While working fluid F will primarily be described herein as air, it should be understood that working fluid F could comprise other fluids, including other gases.

Compressor <NUM> may comprise a series of compressor rotor assemblies <NUM> and stator assemblies <NUM>. Each compressor rotor assembly <NUM> may comprise a rotor disk that is circumferentially populated with a plurality of rotor blades. The rotor blades in a rotor disk are separated, along the axial axis, from the rotor blades in an adjacent disk by a stator assembly <NUM>. Compressor <NUM> compresses working fluid F through a series of stages corresponding to each compressor rotor assembly <NUM>. The compressed working fluid F then flows from compressor <NUM> into combustor <NUM>.

Combustor <NUM> may comprise a combustor case <NUM> housing one or more, and generally a plurality of, fuel injectors <NUM>. In an embodiment with a plurality of fuel injectors <NUM>, fuel injectors <NUM> may be arranged circumferentially around longitudinal axis L within combustor case <NUM> at equidistant intervals. Combustor case <NUM> diffuses working fluid F, and fuel injector(s) <NUM> inject fuel into working fluid F. This injected fuel is ignited to produce a combustion reaction in one or more combustion chambers <NUM>. The combusting fuel-gas mixture drives turbine <NUM>.

Turbine <NUM> may comprise one or more turbine rotor assemblies <NUM> and stator assemblies <NUM>. Each adjacent pairing of a stator assembly <NUM> with a turbine rotor assembly <NUM> may correspond to one of a plurality or series of stages. Turbine <NUM> extracts energy from the combusting fuel-gas mixture as it passes through each stage. The energy extracted by turbine <NUM> may be transferred (e.g., to an external system) via power output coupling <NUM>.

The exhaust E from turbine <NUM> may flow into exhaust outlet <NUM>. Exhaust outlet <NUM> may comprise an exhaust diffuser <NUM>, which diffuses exhaust E, and an exhaust collector <NUM> which collects, redirects, and outputs exhaust E. It should be understood that exhaust E, output by exhaust collector <NUM>, may be further processed, for example, to reduce harmful emissions, recover heat, and/or the like. In addition, while exhaust E is illustrated as flowing out of exhaust outlet <NUM> in a specific direction and at an angle that is substantially orthogonal to longitudinal axis L, it should be understood that exhaust outlet <NUM> may be configured to output exhaust E towards any direction and at any angle that is appropriate for the particular application of gas turbine engine <NUM>.

<FIG> illustrates a side view of a vane <NUM>, according to an embodiment. One or more stator assemblies <NUM> may comprise one or a plurality of vanes <NUM>. In an embodiment in which vane <NUM> is a nozzle guide vane, the stator assembly <NUM> in the first stage of turbine <NUM> may comprise vanes <NUM>, whereas subsequent stages of turbine <NUM> may comprise different vanes. However, it should be understood that one or more subsequent stages (e.g., second stage) of turbine <NUM> could also comprise vanes <NUM>. Vane <NUM> comprises a casing, with a longitudinal axis A that passes through the leading and trailing ends of vane <NUM>. In <FIG>, only a suction-side wall <NUM> of the casing of vane <NUM> is visible. It should be understood that the pressure-side wall of the casing of vane <NUM> is on the opposite side of vane <NUM> as suction-side wall <NUM>.

<FIG> illustrates a top or bottom cross-sectional view of a trailing-edge region of a vane <NUM>, according to an example. As illustrated, vane <NUM> comprises a suction-side wall <NUM> and a pressure-side wall <NUM>. Suction-side wall <NUM> is on the side of vane <NUM> along which the airflow produces suction, and pressure-side wall <NUM> is on the side of vane <NUM> along which the airflow produces pressure. For convenience of understanding, internal components of vane <NUM> may be described as having a "suction side" and a "pressure side," even though those components do not themselves experience suction or pressure. It should be understood that, in these cases, the "suction side" refers to a side that is closest to suction-side wall <NUM>, and the "pressure side" refers to a side that is closest to pressure-side wall <NUM>.

Suction-side wall <NUM> and pressure-side wall <NUM> define an internal cavity <NUM> within vane <NUM>. It should be understood that vane <NUM> may comprise additional side walls in a plane that intersects both of the planes of suction-side wall <NUM> and pressure-side wall <NUM>, such that internal cavity <NUM> is fully enclosed, with the exception of various passages or openings.

In an embodiment, a plurality of pins <NUM> extend from suction-side wall <NUM> and pressure-side wall <NUM> into internal cavity <NUM>, along or parallel to a transverse axis T that intersects longitudinal axis A (e.g., an orthogonal, acute, or obtuse angle). Some pins 234A, referred to herein as "partial pins," extend only partially into internal cavity <NUM> from suction-side wall <NUM> and/or pressure-side wall <NUM>. Other pins 234B, referred to herein as "full pins," extend entirely through internal cavity <NUM> from suction-side wall <NUM> to pressure-side wall <NUM>. In an embodiment, each pin <NUM> is cylindrical. However, it should be understood that pins <NUM> may have a different shape or cross-section.

Internal cavity <NUM> may be in fluid communication with an external environment of vane <NUM> via one or more passages. For example, pressure-side wall <NUM> of vane <NUM> may comprise one or a plurality of rows of film holes <NUM>. Each film hole <NUM> may fluidly connect internal cavity <NUM> to the external environment. As illustrated, each film hole <NUM> may extend at an angle through pressure-side wall <NUM>, such that the air flows from internal cavity <NUM>, through film hole <NUM>, to the external environment in a generally downstream direction. It should be understood that the air flowing through passages <NUM> will mix with air flowing over pressure-side wall <NUM>. The cooling air flowing through film holes <NUM> may act to cool pressure-side wall <NUM>.

In addition, vane <NUM> may comprise one or a plurality of passages <NUM> through the trailing edge of vane <NUM>. Passages <NUM> may be arranged in a row through the trailing edge of vane <NUM>. Each passage <NUM> may fluidly connect internal cavity <NUM> to the external environment. As illustrated, each passage <NUM> may extend along or parallel to longitudinal axis A (i.e., through the leading and trailing edges) of vane <NUM>, such that the air flows from internal cavity <NUM>, through passage <NUM>, to the external environment in a substantially downstream direction. It should be understood that the air flowing through passages <NUM> will mix with air flowing across the trailing edge of vane <NUM>. In the illustrated embodiment, passages <NUM> are arranged between suction-side wall <NUM> and pressure-side wall <NUM>, and suction-side wall <NUM> extends farther downstream than pressure-side wall <NUM>, such that the air exits vane <NUM> on the pressure side of vane <NUM>.

In an embodiment, vane <NUM> comprises a volumetric insert <NUM> within internal cavity <NUM>. As illustrated, insert <NUM> may have a generally wedge-shaped cross-section, and may be positioned between partial pins 234A extending from suction-side wall <NUM> and partial pins 234A extending from pressure-side wall <NUM>. In other words, insert <NUM> is tightly positioned and held between partial pins 234A. Notably, a suction-side wall <NUM> of insert <NUM> is substantially parallel to suction-side wall <NUM> of vane <NUM> to form a narrow suction-side passage <NUM>, and a pressure-side wall <NUM> of insert <NUM> is substantially parallel to pressure-side wall <NUM> of vane <NUM> to create a narrow pressure-side passage <NUM>.

Suction-side wall <NUM> and pressure-side wall <NUM> of insert <NUM> may define an internal cavity <NUM> and an outlet <NUM> that provides fluid communication between internal cavity <NUM> of insert <NUM> and internal cavity <NUM> of vane <NUM>. In other words, air may flow from internal cavity <NUM> to internal cavity <NUM> via outlet <NUM>. Outlet <NUM> may be positioned at a downstream end of insert <NUM>, and may comprise a row of impingement holes.

During operation, cooling air flows through passages <NUM> and <NUM> between insert <NUM> and the internal surfaces of suction-side wall <NUM> and pressure-side wall <NUM>, respectively. This cooling air may be introduced into vane <NUM> at an upstream position. Once introduced, the cooling air flows along the internal surfaces of the walls of vane <NUM>, via passages <NUM> and <NUM>, to cool the vane walls. In other words, insert <NUM> constrains the flow of cooling air to narrow passages <NUM> and <NUM>, abutting the vane walls, to cool the vane walls.

However, insert <NUM> is limited by manufacturing constraints, such as minimum bend radius and core thickness. Thus, insert <NUM> is unable to be extended far enough downstream to maintain a constant internal flow area in the trailing-edge region of vane <NUM>. Consequently, as cooling air exits passages <NUM> and <NUM> at the downstream end of insert <NUM>, a sudden expansion in the internal cooling air flow decreases the velocity of the cooling air, thereby reducing the cooling effectiveness of the air flow on the vane walls. This can result in excessive temperatures in the trailing-edge region of vane <NUM>, and particularly in trailing-edge area <NUM> of suction-side wall <NUM>.

<FIG> illustrates a top or bottom cross-sectional view of a trailing-edge region of vane <NUM>, with a fin <NUM> to improve cooling of a trailing-edge area <NUM> of suction-side wall <NUM>, according to an embodiment. In this embodiment, fin <NUM> comprises a thin rectangular section that extends more downstream into the trailing-edge region of vane <NUM> than insert <NUM>. The trailing edge of insert <NUM> may be modified to accommodate fin <NUM>. For example, as illustrated, a recess, notch, groove, or other deformity may be formed in the downstream edge of suction-side wall <NUM> of insert <NUM>, such that the downstream end of insert <NUM> overlaps with an upstream end <NUM> of fin <NUM>. In addition, outlet <NUM> may be removed from insert <NUM>, since it is no longer necessary for cooling of suction-side wall <NUM> of vane <NUM>, because of the addition of fin <NUM>.

Specifically, fin <NUM> is positioned downstream (i.e., aftward) of insert <NUM> to act as an extension of insert <NUM> in the downstream direction. Fin <NUM> effectively extends passage <NUM> (e.g., illustrated in <FIG>, <FIG>, and <FIG>) and passage <NUM> (e.g., illustrated in <FIG> and <FIG>) to maintain the speed of the cooling air flowing at a speed, which, in turn, maintains the cooling coefficient of the cooling air for a greater distance (i.e., beyond insert <NUM>) toward the trailing end of vane <NUM>. Thus, cooling air with a higher cooling coefficient flows over trailing-edge area <NUM> of suction-side wall <NUM>, thereby preventing excessive temperatures or otherwise reducing temperatures in trailing-edge area <NUM>.

<FIG> illustrates a rear cross-sectional view of a trailing-edge region of a vane <NUM>, cut along a lateral axis that is orthogonal to longitudinal axis A of vane <NUM>, according to an embodiment. As illustrated, fin <NUM> is positioned within internal cavity <NUM>, closer to suction-side wall <NUM> than pressure-side wall <NUM>. Alternatively, fin <NUM> could be positioned equidistantly between suction-side wall <NUM> and pressure-side wall <NUM> or closer to pressure-side wall <NUM> than suction-side wall <NUM>. However, since suction-side wall <NUM> is more susceptible to excessive temperatures within trailing-edge area <NUM> (e.g., due to the lack of existing cooling techniques), it is generally preferable to position fin <NUM> so as to extend passage <NUM>. Notably, as illustrated, when suction-side wall <NUM> of vane <NUM> is curved, fin <NUM> may follow this curve, so as to be substantially concentric or parallel with the curve of suction-side wall <NUM>. In other words, passage <NUM> is of uniform width at every point between fin <NUM> and the internal surface of suction-side wall <NUM>. This uniformity ensures a consistent, constant flow area through passage <NUM>, downstream from insert <NUM>, to prevent sudden expansion of cooling air. As a result, the cooling air may maintain a higher velocity along suction-side wall <NUM>. This can increase the internal heat transfer coefficient by approximately <NUM>% and reduce the temperature in trailing-edge area <NUM> of suction-side wall <NUM> by approximately <NUM>-<NUM> (<NUM>-<NUM> degrees Fahrenheit).

<FIG> illustrates a side view of a trailing-edge region of a vane <NUM>, according to an embodiment. In this view, a portion of pressure-side wall <NUM> has been removed to illustrate the positions of insert <NUM> and fin <NUM>. In an embodiment, internal cavity <NUM> may be divided into a plurality of sections by one or more ribs <NUM>. In the illustrated embodiment, internal cavity <NUM> is divided into three sections by two ribs 600A and 600B. However, it should be understood that internal cavity <NUM> could be divided into any number of sections (e.g., two, four, five, etc.) by any number of ribs <NUM> (e.g., one, three, four, etc.), or may consist of only a single section with no ribs.

In the illustrated embodiment of <FIG>, fin <NUM> is a substantially two-dimensional structure that cooperates with insert <NUM> at the downstream end of insert <NUM>. In alternative unclaimed examples, fin <NUM> may be a three-dimensional structure, for example, formed with a triangular or other cross-sectional shape. In either embodiment or example, fin <NUM> may comprise sheet metal (e.g., approximately <NUM>,<NUM> (<NUM> inches) thick) and may comprise one or a plurality of pieces of material. In an unclaimed example in which fin <NUM> is a three-dimensional structure, fin <NUM> may be formed by bending the sheet metal into the three-dimensional structure. However, it should be understood that other materials and methods of manufacture may be used to create fin <NUM>. In any case, the trailing, downstream end of insert <NUM> may be configured to accommodate or otherwise correspond to the leading, upstream end of fin <NUM>. For example, when vane <NUM> is assembled, fin <NUM> may tightly abut or mate with insert <NUM>, so as to be contiguous with insert <NUM> and provide a substantially or nearly continuous, planar surface on the side of passage <NUM> opposite suction-side wall <NUM>. In other words, fin <NUM> lies in the same plane as suction-side wall <NUM> of insert <NUM> to form a substantially uniform passage <NUM>.

As illustrated, the leading, upstream edge of fin <NUM> may tightly abut the trailing, downstream edge of insert <NUM>, with little or no space between fin <NUM> and insert <NUM>. In an embodiment, fin <NUM> is not joined or otherwise coupled to insert <NUM>. This may facilitate assembly and disassembly of vane <NUM>. However, in an alternative embodiment, fin <NUM> could be joined or otherwise coupled to insert <NUM>.

<FIG> illustrates a cross-sectional view of a trailing-edge region of a vane <NUM>, with a volumetric fin <NUM> to improve cooling of the trailing-edge region of suction-side wall <NUM>, according to an unclaimed example useful for understanding the invention. Whereas fin <NUM> of the embodiment illustrated in <FIG>, had a linear cross-section, fin <NUM> as illustrated in <FIG>, has a substantially triangular cross-section. The dimensions of this triangular cross-section may be selected such that the upstream end of fin <NUM> is substantially identical or similar in dimension as the downstream end of insert <NUM>. Thus, when vane <NUM> is assembled, fin <NUM> may tightly abut or mate with insert <NUM>, so as to provide a substantially or nearly continuous, planar surface on the side of passage <NUM> opposite pressure-side wall <NUM>, as well as on the side of passage <NUM> opposite suction-side wall <NUM>. In other words, the suction-side wall of fin <NUM> may lie in the same plane as suction-side wall <NUM> of insert <NUM> to form a substantially uniform passage <NUM> along suction-side wall <NUM> of vane <NUM>, and the pressure-side wall of fin <NUM> may lie in the same plane as pressure-side wall <NUM> of insert <NUM> to form a substantially uniform passage <NUM> along pressure-side wall <NUM> of vane <NUM>.

Essentially, fin <NUM> of <FIG> is a wedge that extends both passages <NUM> and <NUM> beyond the downstream end of insert <NUM>. As illustrated, the downstream end of insert <NUM> may be configured to accommodate at least a portion of fin <NUM>. For example, as illustrated, a recess may be formed in suction-side wall <NUM> of insert <NUM>, at the downstream end of insert <NUM>. The recess may be configured in size and shape to receive an upstream end <NUM> of fin <NUM>. In an alternative embodiment, a recess could be formed in pressure-side wall <NUM> of insert <NUM>, and fin <NUM> could be reversed such that upstream end <NUM> fits into the recess in pressure-side wall <NUM> of insert <NUM>. This example of fin <NUM> may be formed by bending a flat piece of sheet metal back over itself to an acute angle (e.g., that matches the angle of pressure-side wall <NUM> relative to suction-side wall <NUM> of insert <NUM>), and then bending an end of the folded-over piece back towards upstream end <NUM>, and optionally downstream of the upstream edge of upstream end <NUM> so that upstream end <NUM> may overlap with the downstream end of insert <NUM>.

<FIG> illustrates a top or bottom cross-sectional view of a trailing-edge region of a vane <NUM>, with a volumetric fin <NUM> to improve cooling of the trailing-edge region of suction-side wall <NUM>, according to another unclaimed example useful for understanding the invention. As with the example illustrated in <FIG>, the example illustrated in <FIG>, also has a substantially triangular cross-section. However, in this example, the downstream ends of suction-side wall <NUM> and pressure-side wall <NUM> of insert <NUM> converge to a substantially symmetrical flat or pointed end <NUM>. Essentially, the downstream end of insert <NUM> comprises a first recess on the suction side and a second recess on the pressure side. A suction-side end <NUM> of fin <NUM> may be configured to overlap with end <NUM> on the suction side of insert <NUM>, and a pressure-side end <NUM> of fin <NUM> may be configured to overlap with end <NUM> on the pressure side of insert <NUM>. In other words, end <NUM> of insert <NUM> can slide into the interior of fin <NUM> between suction-side end <NUM> and pressure-side end <NUM> of fin <NUM>. Thus, as in <FIG>, when vane <NUM> is assembled, fin <NUM> may tightly abut or mate with insert <NUM>, so as to provide a substantially or nearly continuous, planar surface on both the side of passage <NUM> opposite suction-side wall <NUM> and the side of passage <NUM> opposite pressure-side wall <NUM>. In other words, the suction-side wall of fin <NUM> may lie in the same plane as suction-side wall <NUM> of insert <NUM> to form a substantially uniform passage <NUM> along suction-side wall <NUM> of vane <NUM>, and the pressure-side wall of fin <NUM> may lie in the same plane as pressure-side wall <NUM> of insert <NUM> to form a substantially uniform passage <NUM> along pressure-side wall <NUM> of vane <NUM>. Similarly to the example of <FIG>, in the example of <FIG>, fin <NUM> acts as a wedge that extends both passages <NUM> and <NUM> beyond the downstream end of insert <NUM>. This example of fin <NUM> may be formed by bending a flat piece of sheet metal in half and back over itself to an acute angle (e.g., that matches the angle of pressure-side wall <NUM> relative to suction-side wall <NUM> of insert <NUM>), to form the triangular cross-section illustrated in <FIG>.

A gas turbine engine <NUM> for power generation may comprise a plurality of nozzle guide vanes <NUM> in the initial one or two stages of the intake of turbine <NUM>. Each nozzle guide vane <NUM> may be hollow with an internal cavity <NUM>. An insert <NUM> is inserted into internal cavity <NUM> to provide a cooling system within each nozzle guide vane <NUM>. Specifically, the suction-side and pressure-side walls of insert <NUM> are substantially parallel to the corresponding surfaces of internal cavity <NUM> to form narrow passages <NUM> and <NUM> within internal cavity <NUM>, respectively. Passages <NUM> and <NUM> provide a flow path, in contact with internal surfaces of suction-side wall <NUM> and pressure-side wall <NUM>, for cooling air. Thus, cooling air may flow over these internal surfaces to cool suction-side wall <NUM> and pressure-side wall <NUM>.

In an embodiment, a fin <NUM> is inserted downstream and abutting insert <NUM> to extend the effective inner surfaces of narrow cooling passages <NUM> and <NUM> beyond the downstream end of insert <NUM>. This maintains the speed of the cooling air downstream from insert <NUM> and closer to the trailing-edge region of each vane <NUM>, by eliminating the sudden expansion and reduced speed of the cooling air at the downstream end of insert <NUM>. In turn, this improves the cooling coefficient closer to the trailing-edge region of each vane <NUM>, including in trailing-edge area <NUM> of suction-side wall <NUM>. For example, experiments have found that the presence of fin <NUM> can increase the internal heat transfer coefficient by approximately <NUM>% and reduce the temperature of trailing-edge area <NUM> of suction-side wall <NUM> by approximately <NUM>-<NUM> (<NUM>-<NUM> degrees Fahrenheit).

As discussed above, fin <NUM> may comprise one or more pieces of sheet metal or other material that is formed into a two-dimensional structure (e.g., with a linear cross-section) or a three-dimensional structure (e.g., with a triangular cross-section) by bending or other method of manufacture. Regardless of the particular shape of fin <NUM>, downstream end of insert <NUM> may be configured to accommodate or otherwise correspond to (e.g., overlap) an upstream end <NUM> of fin <NUM>, such that the surfaces defining passages <NUM> and <NUM> remain substantially uniform and contiguous across the position at which the downstream end of insert <NUM> abuts the upstream end of fin <NUM>.

Vane <NUM> may comprise a plurality of internal pins <NUM>, including partial pins 234A and full pins 234B, arranged in a grid. The area of vane <NUM> comprising full pins 234B may be limited to the downstream end of internal cavity <NUM> corresponding to the trailing edge of vane <NUM>. All pins <NUM> in the area extending from the upstream end of vane <NUM> to the downstream end of fin <NUM> may be partial pins 234A. Partial pins 234A may be cast in pairs, with each pair comprising a first partial pin 234A extending from suction-side wall <NUM> and a second partial pin 234A extending from pressure-side wall <NUM> and aligned with the first partial pin 234A along a transverse axis T. A gap may exist between each pair of partial pins 234A, and collectively, the gaps between all pairs of partial pins 234A may form a slot that is sized and shaped to receive fin <NUM> and insert <NUM>. Thus, during assembly of vane <NUM>, fin <NUM> may be inserted into the slot (e.g., via an opening in the outer shroud of vane <NUM>) before insert <NUM> is inserted, and positioned as close to the trailing edge of vane <NUM> as it can fit, for example, such that the downstream end of fin <NUM> abuts the most upstream row of full pins 234B near the trailing edge of vane <NUM>. Next, insert <NUM> may be inserted into the slot (e.g., via an opening in the outer shroud of vane <NUM>), and positioned such that the downstream end of insert <NUM> abuts and/or overlaps the upstream end of fin <NUM>. It should be understood that partial pins 234A may tightly surround fin <NUM> and insert <NUM>, so as to prevent movement (e.g., in a transverse direction) of fin <NUM> and insert <NUM>. In addition, fin <NUM> is prevented from movement in the upstream direction by insert <NUM> and in the downstream direction by one or more rows of full pins 234B.

<FIG> illustrates a partially disassembled view of a vane <NUM>, according to an embodiment. As illustrated, insert <NUM> has been removed from vane <NUM>, exposing an opening <NUM> and fin <NUM>. In the illustrated embodiment, insert <NUM> and fin <NUM> are assembled, through an opening <NUM> in vane <NUM>, into the slot formed by partial pins 234A. Due to design constraints on vane <NUM>, opening <NUM> is limited in size. As illustrated, fin <NUM> may be assembled first into the downstream portion of the slot formed by partial pins 234A. Fin <NUM> may be formed as a single piece with one or more slots that are sized and spaced to tightly receive one or more corresponding rib extensions <NUM> (e.g., 610A and 610B) which extend, along transverse axis T, from ribs <NUM>. Thus, fin <NUM> may be inserted through opening <NUM> laterally, and then slid downstream so that the slots in fin <NUM> slide around rib extensions <NUM>. In an alternative embodiment, rib extensions <NUM> may be slotted to accept an unslotted, continuous fin <NUM>. Next, insert <NUM> may be assembled through opening <NUM> to abut the upstream end of fin <NUM> at the downstream end of insert <NUM>.

Aspects described in connection with one embodiment are intended to be able to be used with the other embodiments. Any explanation in connection with one embodiment applies to similar features of the other embodiments, and elements of multiple embodiments can be combined to form other embodiments.

Claim 1:
A nozzle guide vane (<NUM>) comprising:
a casing having an upstream end and a downstream end, wherein the casing comprises a first suction-side wall (<NUM>) from the leading end to the trailing end, a first pressure-side wall (<NUM>) from the leading end to the trailing end, a first internal cavity (<NUM>) between the first suction-side wall (<NUM>) and the first pressure-side wall (<NUM>), and a plurality of partial pins (234A) that extend from the first suction-side wall (<NUM>) and the first pressure-side wall (<NUM>) partially into the first internal cavity (<NUM>);
an insert (<NUM>) having an upstream end and a downstream end, wherein the insert (<NUM>) comprises a second suction-side wall (<NUM>), a second pressure-side wall (<NUM>), and a second internal cavity (<NUM>) between the second suction-side wall (<NUM>) and the second pressure-side wall (<NUM>), wherein the insert (<NUM>) is configured to fit within a slot in the first internal cavity (<NUM>) between the partial pins (234A) extending from the first suction-side wall (<NUM>) and the partial pins (234A) extending from the first pressure-side wall (<NUM>); and
a fin (<NUM>) configured to fit within the slot between the downstream end of the insert (<NUM>) and the downstream end of the casing;
characterized in that
the fin (<NUM>) has a linear cross-section, wherein the fin (<NUM>), when seated between the downstream end of the insert (<NUM>) and the downstream end of the casing, is in a same plane as the second suction-side wall (<NUM>) of the insert (<NUM>), to form a uniform passage (<NUM>) extending between the first suction-side wall (<NUM>) and the second suction-side wall (<NUM>) and between the first suction-side wall (<NUM>) and the fin (<NUM>).