Turbine blade

Abstract

A turbine blade (200) includes a root (202) arranged to attach the turbine blade (200) to a rotor (122) and vanes extending in a radial direction from the root (202) to a tip surface (302). The vanes include a leading edge (208), a trailing edge (210), a pressure side surface (212), and a suction side surface (214) that cooperate to define a vane perimeter (216). A perimeter wall (304) extends radially from the tip surface (302) and surrounds a portion of the vane perimeter (216). A first groove wall (306) extends across the tip surface (302) and cooperates with the perimeter wall (304) to substantially enclose a pressure side cavity (316), and a second groove wall (308) extends across the tip surface (302) and cooperates with the perimeter wall (304) to substantially enclose a suction side cavity (314).

Description

Background Art

[0001] Turbines, including steam turbines and gas turbines, operate in high-temperature environments. High-temperature fluid flows between adjacent blades and expands to generate mechanical work for driving equipment such as generators. During the operation of the turbine, some fluid leaks across the tips of the blades, which results in efficiency losses. Although there are many tip seal devices, especially in gas turbines, the high-temperature operating environment causes differential thermal growth between the various components that make up the seal device, making efficient sealing difficult. Summary of the Invention

[0002] A turbine blade includes a root arranged to attach the turbine blade to a rotor and a vane extending radially from the root to a tip surface. The vane includes a leading edge, a trailing edge, a pressure side surface, and a suction side surface that cooperate to define a vane perimeter. A perimeter wall extends radially from the tip surface and surrounds a portion of the vane perimeter. A first groove wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a pressure side cavity, and a second groove wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a suction side cavity.

[0003] In another device, a turbine blade includes a root arranged to attach the turbine blade to a rotor, a platform coupled to the root, and a vane extending radially from the platform to a tip surface. The vane includes a leading edge, a trailing edge, a pressure side surface, and a suction side surface that cooperate to define a vane perimeter. A perimeter wall extends radially from the tip surface and surrounds a portion of the vane perimeter. A groove extends from a first portion of the suction side surface near the leading edge to a second portion of the suction side surface near the trailing edge, the groove including a first groove wall, a second groove wall, and a groove bottom. A pressure side cavity is defined by the first groove wall and a portion of the perimeter wall, and a suction side cavity is defined by the second groove wall and a portion of the perimeter wall.

[0004] In yet another device, a turbine blade includes a root arranged to attach the turbine blade to a rotor, a platform coupled to the root, and vanes extending radially from the platform to a tip surface. The vanes include a leading edge, a trailing edge, a pressure side surface, and a suction side surface that cooperate to define a vane perimeter. A curved groove extends from a first portion of the suction side surface near the leading edge to a second portion of the suction side surface near the trailing edge. The groove includes a groove bottom that is radially closer to the platform than the tip surface. A pressure side cavity is defined by pressure side walls, a leading edge wall, a first suction side wall, a first groove wall, and a second suction side wall that each extend radially away from the tip surface, and a suction side cavity is defined by a third suction side wall and a second groove wall that each extend radially away from the tip surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] To facilitate identification of the discussion of any particular element or act, one or more of the most significant digits in the reference numerals refer to the figure number in which the element is first introduced.

[0006] Figure 1 is a longitudinal cross-sectional view of a gas turbine engine 100 taken along a plane including a longitudinal axis or center axis.

[0007] Figure 2 Illustrates a turbine blade adapted to be used with Figure 1 a gas turbine engine.

[0008] Figure 3 Illustrates Figure 2 the tip portion of a turbine blade.

[0009] Figure 4 is Figure 3 an exit view of a groove in the tip portion.

[0010] Figure 5 Illustrates another tip portion adapted to be used with Figure 2 a turbine blade.

[0011] Figure 6 Illustrates Figure 3 or Figure 5 a split cooling hole adapted to be used with a blade tip.

[0012] Figure 7 is a cross-sectional view taken along Figure 6 line VII-VII of which illustrates the internal arrangement of the split cooling hole.

[0013] Before explaining any embodiments of the present invention in detail, it should be understood that the present invention is not limited in its application to the details of the construction and the arrangement of components set forth in this specification or illustrated in the following drawings. The present invention is capable of other embodiments and of being practiced or carried out in various ways. Moreover, it should be understood that the terminology and phrases used herein are for the purpose of description and should not be regarded as limiting.

[0014] Various techniques related to systems and methods will now be described with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout the specification. The drawings described below and the various embodiments used herein to describe the principles of the present disclosure are by way of example only and should not be construed in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged device. It should be understood that functions described as being performed by certain system elements may be implemented by multiple elements. Similarly, for example, an element may be configured to implement functions described as being performed by multiple elements. Numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0015] Moreover, it should be understood that, unless explicitly limited in some instances, the words or phrases used herein should be construed broadly. For example, the terms "comprising," "having," and "including" and their derivatives mean including but not limited to. As used herein, the singular forms "a," "an," and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. Additionally, as used herein, the term "and / or" means and includes any and all possible combinations of one or more of the associated listed items. The term "or" is inclusive and means and / or unless the context clearly indicates otherwise. The phrases "associated with" and "associated therewith" and their derivatives may mean including, included within, interconnected with, containing, contained within, connected to or coupled with, capable of communicating with, cooperating with, interlacing, juxtaposing, adjacent to, bound to or bound together with, having, having the property of, and so forth. Furthermore, although multiple embodiments or configurations may be described herein, any features, methods, steps, components, etc. described with respect to one embodiment are equally applicable to other embodiments in the absence of a contrary specific statement.

[0016] Moreover, although the terms "first", "second", "third", etc. may be used herein to refer to various elements, information, functions or acts, these elements, information, functions or acts should not be limited by these terms. Instead, these numerical adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function or act may be referred to as a second element, information, function or act, and, similarly, a second element, information, function or act may be referred to as a first element, information, function or act, without departing from the scope of the present disclosure.

[0017] Additionally, the term "adjacent to" may mean that one element is relatively close to, but does not contact, another element; or that the element contacts another part, unless the context clearly indicates otherwise. Further, the phrase "based on" is intended to mean "at least partially based on", unless otherwise clearly stated. The term "about" or "substantially" or similar terms are intended to cover variations within the normal industrial manufacturing tolerances of the stated dimensions. If no industrial standard is available, then a 20% variation will fall within the meaning of these terms, unless otherwise stated.

[0018] Figure 1 An example of a gas turbine engine 100 is illustrated, which includes a compressor section 102, a combustion section 106, and a turbine section 110 arranged along a central axis 114. The compressor section 102 includes a plurality of compressor stages 116, where each compressor stage 116 includes a set of rotating blades 118 and a set of stationary guide vanes 120 or adjustable guide vanes. A rotor 122 supports the rotating blades 118 for rotation about the central axis 114 during operation. In some configurations, a single one-piece rotor 122 extends the length of the gas turbine engine 100 and is supported for rotation by bearings at either end. In other configurations, the rotor 122 is assembled from several individual spools, which are attached to each other or may include a plurality of disk sections attached via one or more bolts.

[0019] The compressor section 102 is in fluid communication with an inlet section 124 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 102. During operation of the gas turbine engine 100, the compressor section 102 draws in atmospheric air and compresses the air for delivery to the combustion section 106. The illustrated compressor section 102 is an example of a compressor section 102, where other arrangements and designs are possible.

[0020] In the illustrated configuration, the combustion section 106 includes a plurality of individual burners 126, each burner operating to mix a fuel stream with compressed air from the compressor section 102 and combust the air-fuel mixture to produce a stream of high-temperature, high-pressure combustion gases or exhaust gases 128. Of course, many other arrangements of the combustion section 106 are possible.

[0021] The turbine section 110 includes a plurality of turbine stages 130, where each turbine stage 130 includes a plurality of rotating turbine blades 104 and a plurality of stationary turbine guide vanes 108. The turbine stages 130 are arranged to receive the exhaust gas 128 from the combustion section 106 at the turbine inlet 132 and expand the gas to convert thermal energy and pressure energy into rotational or mechanical work. The turbine section 110 is connected to the compressor section 102 to drive the compressor section 102. For a gas turbine engine 100 used for power generation or acting as a prime mover, the turbine section 110 is also connected to a generator, a pump, or other equipment to be driven. Like the compressor section 102, other designs and arrangements of the turbine section 110 are possible.

[0022] The exhaust section 112 is located downstream of the turbine section 110 and is arranged to receive the expanded flow of the exhaust gas 128 from the final turbine stage 130 in the turbine section 110. The exhaust section 112 is arranged to efficiently direct the exhaust gas 128 away from the turbine section 110 to ensure the efficient operation of the turbine section 110. In the exhaust section 112, many variations and design differences are possible. Accordingly, the illustrated exhaust section 112 is just one example of those variations.

[0023] The control system 134 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters and control various operations of the gas turbine engine 100. In a preferred configuration, the control system 134 is generally microprocessor-based and includes memory devices and data storage devices for collecting, analyzing, and storing data. Additionally, the control system 134 provides output data to various devices (including monitors, printers, indicators, etc.), which allow a user to interface with the control system 134 to provide input or make adjustments. In an example of a power generation system, a user can input a power output set point, and the control system 134 can adjust various control inputs to achieve the power output in an efficient manner.

[0024] The control system 134 can control various operating parameters, including but not limited to variable inlet guide vane position, fuel flow rate and pressure, engine speed, valve position, generator load, and generator excitation. Of course, other applications may have fewer or more controllable devices. The control system 134 also monitors various parameters to ensure the proper operation of the gas turbine engine 100. Some of the parameters monitored can include inlet air temperature, compressor outlet temperature and pressure, burner outlet temperature, fuel flow rate, generator power output, bearing temperature, etc. Many of these measurements are displayed to the user and recorded for later review when needed.

[0025] Figure 2Illustrated is a turbine blade 200 of the type of rotating blade 118 that serves as one of the turbine stages 130. The turbine blade 200 includes a root 202, a platform 204, and an airfoil 206 (sometimes referred to as a vane or vane section). In most configurations, the root 202, the platform 204, and the airfoil 206 are formed as a single integral component, which is cast, forged, machined, additively manufactured, or made using any combination thereof or other suitable manufacturing techniques.

[0026] The root 202 is arranged to attach the turbine blade 200 to the rotor 122, a disk, or another component that supports the turbine blade 200 to rotate it about a central axis 114. The root 202 may include projections or hooks that engage corresponding projections or hooks to attach the turbine blade 200 to the rotor 122. Of course, other arrangements of the root 202 Figure 2 other than the arrangement illustrated are possible. Other arrangements may include a bent root 202, or may include fastening mechanisms other than the geometry of the root 202. Any arrangement and geometry of the root 202 may be employed as needed. As previously discussed, several turbine blades 200 are positioned adjacent to each other to define a row of rotating blades 118.

[0027] The platform 204 is formed between the root 202 and the airfoil 206. The platform 204 includes surfaces that cooperate with the same surfaces in other turbine blades 200 to define an internal annular flow path surface.

[0028] The airfoil 206 extends radially (i.e., radially with respect to the central axis 114) from the platform 204 to a tip portion 300. The airfoil 206 includes a leading edge 208, a trailing edge 210, a pressure side surface 212, and a suction side surface 214, which cooperate to define a vane perimeter 216.

[0029] Figure 3 Better illustrated Figure 2 is the tip portion 300 of the turbine blade 200. The tip portion 300 includes a tip surface 302 surrounded by the vane perimeter 216. A perimeter wall 304 extends along a portion of the vane perimeter 216 and extends above the tip surface 302. In the illustrated configuration, the perimeter wall 304 is divided into two separate wall portions, where other configurations include a single perimeter wall 304 that extends around a portion of the perimeter wall 304 or three or more wall portions that cooperate to define the perimeter wall 304. In gas turbine technology, the perimeter wall 304 is sometimes referred to as a squealer tip and is used to at least partially define a tip seal between the airfoil 206 and a stationary surface adjacent to the tip portion 300. The tip seal inhibits leakage across the airfoil 206 from the pressure side surface 212 to the suction side surface 214.

[0030] The first groove wall 306 extends from the upstream or leading edge 208 side of the suction side surface 214 to the downstream or trailing edge 210 side of the suction side surface 214. The first groove wall 306 extends radially from the end surface 302 to a height preferably equal to the height of the perimeter wall 304 (e.g., between 2 mm and 15 mm). The second groove wall 308 extends from the upstream or leading edge 208 side of the suction side surface 214 to the downstream or trailing edge 210 side of the suction side surface 214. The second groove wall 308 extends radially from the end surface 302 to a height preferably equal to the height of the perimeter wall 304 (e.g., between 2 mm and 15 mm). In the illustrated configuration, the first groove wall 306 includes a perimeter portion 322 that defines a part of the perimeter wall 304.

[0031] In the illustrated configuration, the first groove wall 306 and the second groove wall 308 are parallel to each other, spaced apart from each other, and curved to define a groove 310 therebetween. The groove 310 includes a first open end proximate to the leading edge 208 of the airfoil 206 and a second open end proximate to the trailing edge 210 of the airfoil 206. In this context, the term "proximate" refers to the relative proximity of the described opening to the leading edge 208 or the trailing edge 210. Thus, "proximate to the leading edge 208" will only mean closer to the leading edge 208 than to the trailing edge 210. In most configurations, the distance between the first groove wall 306 and the second groove wall 308 is between 5 mm and 20 mm, where other widths are possible. As will be discussed with respect to Figure 5 what follows, the first groove wall 306 and the second groove wall 308 can have different shapes and different arrangements. For example, non-parallel groove walls can be employed. The groove 310 defines a groove bottom 312 that is generally parallel to the end surface 302 but is recessed or positioned closer to the root 202 than the end surface 302 as Figure 4 illustrated therein.

[0032] The perimeter wall 304 and the first groove wall 306 cooperate to define a pressure side cavity 316 and a first wall gap 318. Similarly, the perimeter wall 304 and the second groove wall 308 cooperate to define a suction side cavity 314 and a second wall gap 320. Additionally, the perimeter wall 304, the first groove wall 306, and the second groove wall 308 define a radially extending side surface. It should be noted that the radially extending surface may deviate slightly from the true radial direction; however, the surface mainly extends in the radial direction.

[0033] Multiple cooling holes 324 are formed in each radially extending surface and provide an outlet for cooling air. Some of the cooling air is discharged through a portion of the multiple cooling holes 324 into the suction side cavity 314 and the pressure side cavity 316. The first wall gap 318 and the second wall gap 320 provide an outlet for the cooling air. Thus, the perimeter wall 304 and the first groove wall 306 substantially surround the pressure side cavity 316, and the perimeter wall 304 and the second groove wall 308 substantially surround the suction side cavity 314. In this context, "substantially" means that the walls surround at least fifty percent of the respective suction side cavity 314 and pressure side cavity 316. While some configurations may completely surround the suction side cavity 314 and the pressure side cavity 316, most configurations provide the first wall gap 318 and the second wall gap 320. While "substantially surround" may mean as low as fifty percent, most configurations include walls that surround at least 70% and up to 90% of the first wall gap 318 and the second wall gap 320.

[0034] Figure 4 Better illustrates the increased depth 402 of the groove bottom 312 relative to the end surface 302. As illustrated, the increased depth 402 is between 2 mm and 15 mm, where other ranges and variations are possible.

[0035] Additionally, and continuing to refer Figure 4 , the end portion 300 operates to generate a first spatial vortex 404, a groove vortex 406, a second spatial vortex 408, and a suction side tip leakage vortex 410 that are each formed between the end portion 300 and a stationary component adjacent to the end portion 300. The first spatial vortex 404 and the second spatial vortex 408 are formed in the pressure side cavity 316 and the suction side cavity 314, respectively, and each generate a pressure drop and flow efficiency that reduce the total flow across the end portion 300. The groove vortex 406 is formed in the groove 310 and is also used to generate a pressure drop that reduces the flow toward the suction side of the blade. Any flow that does pass through the end portion 300 forms a suction side tip leakage vortex 410 that has a reduced size and strength compared to a conventional blade tip configuration. The widths and depths of the groove 310, the suction side cavity 314, and the pressure side cavity 316 can all be varied to control or regulate the size, depth, and strength of the various vortices to achieve the desired leakage across the end portion 300.

[0036] Figure 5 Illustrates another configuration of an end portion 500 adapted to be used with a turbine blade 200. Like the first configuration of the end portion 300, Figure 5 the end portion 500 of Figure 5 includes a perimeter wall 502 that extends around a portion of the guide vane perimeter 216. Figure 3The two parts. The perimeter wall 502 extends radially away from the end surface 302 and defines a substantially radially extending wall.

[0037] The first groove wall 504 extends from the leading edge 208 side of the suction side surface 214 to the trailing edge 210 side of the suction side surface 214. The second groove wall 506 extends from the leading edge 208 side of the suction side surface 214 to the trailing edge 210 side of the suction side surface 214 and cooperates with the first groove wall 504 to define a groove 508 having a groove bottom 510.

[0038] The perimeter wall 502 cooperates with the first groove wall 504 to at least partially surround and define the pressure side cavity 512 and the first wall gap 516. Similarly, the perimeter wall 502 and the second groove wall 506 cooperate to define the suction side cavity 514 and the second wall gap 518.

[0039] Figure 5 The end portion 500 of Figure 3 is substantially the same as the end portion 300 of Figure 3 except for the first groove wall 504 and the second groove wall 506. Instead of being curved, parallel groove walls, the first groove wall 504 and the second groove wall 506 are straight and parallel to each other. Like

[0040] Figure 6 One of the cooling holes 324 is illustrated as including a bifurcated cooling hole 600 and viewed in the Figure 3 viewing direction 326 shown in Figure 3 As illustrated in Figure 3 the bifurcated cooling hole 600 is formed in at least a portion of the perimeter wall 304, the first groove wall 306, and the second groove wall 308 or the radially extending walls. Thus, in the

[0041] As Figure 6As illustrated, each bifurcated cooling hole 600 includes a cooling hole inlet leg 602 and two cooling hole branches 606. The cooling hole inlet leg 602 extends from a cooling hole inlet 610 disposed on the inner surface of the end surface 302 to a cooling hole branch point 608 located in the first groove wall 306, the perimeter wall 304, or the second groove wall 308. At the cooling hole branch point 608, the cooling hole inlet leg 602 branches into two cooling hole branches 606, where each of the cooling hole branches 606 includes a separate and distinct cooling hole outlet 604. Although the illustrated configuration depicts a bifurcated cooling hole 600 having two cooling hole branches 606, other configurations may include three or more cooling hole branches 606.

[0042] The bifurcated cooling hole 600 may be formed using drilling or reaming operations or using an additive manufacturing process during the formation of the turbine blade 200 or the end portions 300, 500 of the turbine blade 200.

[0043] Figure 7 is a cross-sectional view taken along line VII-VII of Figure 6 which better illustrates other features of the bifurcated cooling hole 600. As can be seen, the cooling hole inlet leg 602 is angled obliquely with respect to the end surface 302 and the first groove wall 306. In a preferred configuration, the cooling hole inlet leg 602, the cooling hole branch point 608, and the cooling hole branches 606 include smooth aerodynamic transitions (curved, rather than sharp corners) to ensure a smooth and efficient cooling of the air flow passing therethrough.

[0044] Although the illustrated configuration of the bifurcated cooling hole 600 includes generally symmetric (about the section line VII-VII) cooling hole branches 606, other configurations may include asymmetric cooling hole branches 606 such that the cooling hole outlets 604 of each cooling hole branch 606 may be directed at different angles and used to cool different regions of the first groove wall 306, the second groove wall 308, or the perimeter wall 304 from which they exit, while still consuming the same cooling mass flow as a single straight through hole.

[0045] Additionally, the positioning of the cooling hole outlets 604 in the perimeter wall 304, the first groove wall 306, and the second groove wall 308 allows for the direct cooling of these features (commonly referred to as the scalloped end). In particular, the illustrated arrangement allows for the direct cooling of the inner surface (the surface on the perimeter inside of the airfoil 206), which increases the cooling effectiveness at the perimeter wall 304, the first groove wall 306, and the second groove wall 308, which are directly cooled by heat conduction through the bifurcated cooling hole 600.

[0046] During operation of a gas turbine engine 100, high pressure and high temperature exhaust gas 128 flows between adjacent turbine blades 200 where it expands to extract energy in the form of rotational work. Due to the high temperature of the exhaust gas 128, it is difficult to form a seal between the end surface 302 of the turbine blade 200 and stationary components adjacent to the turbine blade 200. The addition of the end portion 300 or the end portion 500 enhances the seal during operation. Specifically, the exhaust gas 128 tends to leak from the pressure side surface 212 to the suction side surface 214 across the end surface 302. The addition of the perimeter wall 304 or the perimeter wall 502 enhances the seal. However, the further addition of the grooves 310 or the grooves 508 forms the pressure side cavities 316 or the pressure side cavities 512 and the suction side cavities 314 or the suction side cavities 514, which create flow conditions at the end portions 300 or 500 of the turbine blade 200 that make flow from the pressure side surface 212 to the suction side surface 214 more difficult, thereby enhancing the seal efficiency.

[0047] The arrangement of the perimeter wall 304, the first groove wall 306, and the second groove wall 308 of the end portion 300 and the perimeter wall 502, the first groove wall 504, and the second groove wall 506 of the end portion 500 are provided with direct cooling air to reduce their operating temperature and the likelihood of damage such as oxidation during operation. Cooling air extracted from the compressor section 102 passes through the turbine blade 200, the bifurcated cooling holes 600, and the plurality of cooling holes 324 to directly cool the various walls as needed.

[0048] Additionally, under certain operating conditions, it is possible that cooling air may become trapped in the suction side cavities 314, 514 or the pressure side cavities 316, 512. The first wall gap 318 and the second wall gap 320 and the first wall gap 516 and the second wall gap 518 provide an outlet for the trapped cooling air to allow for its efficient escape.

[0049] While the exemplary embodiments of the present disclosure have been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein can be made without departing from the spirit and scope of the present disclosure in its broadest form.

[0050] No description in this application should be construed as implying that any particular element, step, act, or function is an essential element that must be included within the scope of the claims: the scope of patentable subject matter is defined only by the allowed (granted) claims. Moreover, none of these claims is intended to invoke means plus function claim construction, unless the exact phrase "means for" is followed by a participle.

Claims

1. A turbine blade, comprising: A root, which is arranged to attach the turbine blade to a rotor; A vane, which extends radially from the root to a tip surface, the vane including a leading edge, a trailing edge, a pressure side surface, and a suction side surface that cooperate to define a vane perimeter; A perimeter wall, which extends radially from the tip surface and surrounds a portion of the vane perimeter; A first groove wall, which extends across the tip surface and cooperates with the perimeter wall to substantially enclose a pressure side cavity; And A second groove wall, which extends across the tip surface and cooperates with the perimeter wall to substantially enclose a suction side cavity, Wherein the perimeter wall includes a first wall gap and a second wall gap, Wherein the first wall gap provides an opening between the pressure side cavity and the pressure side surface, and the second wall gap provides an opening between the suction side cavity and the suction side surface; And Wherein the first groove wall and the second groove wall cooperate to define a groove having a groove bottom, the groove extending from a first portion of the suction side surface near the leading edge to a second portion of the suction side surface near the trailing edge.

2. The turbine blade according to claim 1, wherein the bottom of the groove is closer to the root in the radial direction than the end surface.

3. The turbine blade according to claim 1, wherein the first groove wall and the second groove wall are parallel to each other and spaced apart by at least 5 mm.

4. The turbine blade according to claim 1, wherein, The turbine blade further includes a plurality of cooling holes, each of the plurality of cooling holes forming a radially extending surface through one of the first groove wall, the second groove wall, and the perimeter wall.

5. The turbine blade according to claim 1, wherein the first groove wall is a curved wall having a perimeter portion that defines a part of the perimeter wall.

6. The turbine blade according to claim 1, wherein one of the perimeter wall, the first groove wall, and the second groove wall at least partially defines at least one bifurcated cooling hole.

7. The turbine blade according to claim 6, wherein the at least one bifurcated cooling hole includes a single cooling hole inlet branch and two cooling hole branches, each cooling hole branch extending from the cooling hole inlet branch to a separate and distinct cooling hole outlet.

8. The turbine blade according to claim 1, further comprising a platform coupled to the root, wherein the guide vane extends in the radial direction from the platform to the end surface.

Images