Patent Publication Number: US-2023139869-A1

Title: Turbine blade

Description:
BACKGROUND 
     Turbines, including steam turbines and gas turbines operate in a high-temperature environment. High temperature fluid flows between adjacent blades and is expanded to produce mechanical work that is used to drive a device such as an electrical generator. During operation of the turbine, some of the fluid leaks across a tip of the blades which results in a loss in efficiency. While many tip seal arrangements exist, the high temperature operating environment, particularly in gas turbines causes differential thermal growth between the various components that make up the seal arrangement making efficient sealing difficult. 
     BRIEF SUMMARY 
     A turbine blade includes a root arranged to attach the turbine blade to a rotor and a vane extending in a radial direction 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 trench wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a pressure-side pocket and a second trench wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a suction-side pocket. 
     In another arrangement, 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 in a radial direction 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 trench 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 trench including a first trench wall, a second trench wall, and a trench bottom. A pressure-side pocket is defined by the first trench wall and a portion of the perimeter wall and a suction-side pocket is defined by the second trench wall and a portion of the perimeter wall. 
     In yet another arrangement, 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 in a radial direction from the platform 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 curved trench 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 trench including a trench bottom that is radially nearer the platform than the tip surface. A pressure-side pocket is defined by a pressure-side wall, a leading-edge wall, a first suction-side wall, a first trench wall, and a second suction-side wall that each extend radially away from the tip surface and a suction-side pocket is defined by a third suction-side wall and a second trench wall that each extend radially away from the tip surface. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. 
         FIG.  1    is a longitudinal cross-sectional view of a gas turbine engine  100  taken along a plane that contains a longitudinal axis or central axis. 
         FIG.  2    illustrates a turbine blade suitable for use with the gas turbine engine of  FIG.  1   . 
         FIG.  3    illustrates a tip portion of the turbine blade of  FIG.  2   . 
         FIG.  4    is an outlet view of a trench of the tip portion of  FIG.  3   . 
         FIG.  5    illustrates another tip portion suitable for use with the turbine blade of  FIG.  2   . 
         FIG.  6    illustrates a split cooling hole suitable for use in the blade tip of  FIG.  3    or  FIG.  5   . 
         FIG.  7    is a section view taken along line VII-VII of  FIG.  6    illustrating the interior arrangement of the split cooling hole. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments. 
     Also, it should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and/or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary. 
     Also, although the terms “first”, “second”, “third” and so forth 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. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure. 
     In addition, the term “adjacent to” may mean: that an element is relatively near to but not in contact with a further element; or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated. 
       FIG.  1    illustrates an example of a gas turbine engine  100  including 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  with each compressor stage  116  including a set of rotating blades  118  and a set of stationary 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 constructions, a single one-piece rotor  122  extends the length of the gas turbine engine  100  and is supported for rotation by a bearing at either end. In other constructions, the rotor  122  is assembled from several separate spools that are attached to one another or may include multiple disk sections that are attached via a bolt or plurality of bolts. 
     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 that air for delivery to the combustion section  106 . The illustrated compressor section  102  is an example of one compressor section  102  with other arrangements and designs being possible. 
     In the illustrated construction, the combustion section  106  includes a plurality of separate combustors  126  that each operate to mix a flow of fuel with the compressed air from the compressor section  102  and to combust that air-fuel mixture to produce a flow of high temperature, high pressure combustion gases or exhaust gas  128 . Of course, many other arrangements of the combustion section  106  are possible. 
     The turbine section  110  includes a plurality of turbine stages  130  with each turbine stage  130  including a number of rotating turbine blades  104  and a number of stationary turbine vanes  108 . The turbine stages  130  are arranged to receive the exhaust gas  128  from the combustion section  106  at a turbine inlet  132  and expand that gas to convert thermal and pressure energy into rotating or mechanical work. The turbine section  110  is connected to the compressor section  102  to drive the compressor section  102 . For gas turbine engines  100  used for power generation or as prime movers, the turbine section  110  is also connected to a generator, pump, or other device to be driven. As with the compressor section  102 , other designs and arrangements of the turbine section  110  are possible. 
     An exhaust portion  112  is positioned downstream of the turbine section  110  and is arranged to receive the expanded flow of exhaust gas  128  from the final turbine stage  130  in the turbine section  110 . The exhaust portion  112  is arranged to efficiently direct the exhaust gas  128  away from the turbine section  110  to assure efficient operation of the turbine section  110 . Many variations and design differences are possible in the exhaust portion  112 . As such, the illustrated exhaust portion  112  is but one example of those variations. 
     A control system  134  is coupled to the gas turbine engine  100  and operates to monitor various operating parameters and to control various operations of the gas turbine engine  100 . In preferred constructions the control system  134  is typically micro-processor based and includes memory devices and data storage devices for collecting, analyzing, and storing data. In addition, the control system  134  provides output data to various devices including monitors, printers, indicators, and the like that allow users to interface with the control system  134  to provide inputs or adjustments. In the example of a power generation system, a user may input a power output set point and the control system  134  may adjust the various control inputs to achieve that power output in an efficient manner. The control system  134  can control various operating parameters including, but not limited to variable inlet guide vane positions, fuel flow rates and pressures, engine speed, valve positions, 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 assure that the gas turbine engine  100  is operating properly. Some parameters that are monitored may include inlet air temperature, compressor outlet temperature and pressure, combustor outlet temperature, fuel flow rate, generator power output, bearing temperature, and the like. Many of these measurements are displayed for the user and are logged for later review should such a review be necessary. 
       FIG.  2    illustrates a turbine blade  200  of the type used as a rotating blade  118  in 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 a vane portion). In most constructions, the root  202 , the platform  204 , and the airfoil  206  are formed as a single unitary component that is cast, forged, machined, additively manufactured, or made using any combination thereof or other suitable manufacturing techniques. 
     The root  202  is arranged to attach the turbine blade  200  to a rotor  122 , a disk, or another component that supports the turbine blade  200  for rotation about the central axis  114 . The root  202  can include lobes or hooks that engage corresponding lobes or hooks to attach the turbine blade  200  to the rotor  122 . Of course, other arrangements of the root  202 , beyond that illustrated in  FIG.  2    are possible. Other arrangements could include a curved root  202  or could include fastening mechanisms in addition to the geometry of the root  202 . Any arrangement and geometry of the root  202  could be employed as desired. As previously discussed, several turbine blades  200  are positioned adjacent one another to define a row of rotating blades  118 . 
     The platform  204  is formed between the root  202  and the airfoil  206 . The platform  204  includes a surface that cooperates with the same surface in other turbine blades  200  to define an inner annular flow path surface. 
     The airfoil  206  extends in a radial direction (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  that cooperate to define a vane perimeter  216 . 
       FIG.  3    better illustrates the tip portion  300  of the turbine blade  200  of  FIG.  2   . The tip portion  300  includes a tip surface  302  that is 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 construction, the perimeter wall  304  is broken into two separate wall portions with other constructions including 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 the gas turbine art, the perimeter wall  304  is sometimes referred to as a squealer tip and is employed to at least partially define a tip seal between the airfoil  206  and a stationary surface adjacent 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 . 
     A first trench wall  306  extends from an upstream or leading edge  208  side of the suction-side surface  214  to a downstream or trailing edge  210  side of the suction-side surface  214 . The first trench wall  306  extends radially from the tip surface  302  to a height that is preferably equal to the height of the perimeter wall  304  (e.g., between 2 mm and 15 mm). A second trench 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 trench wall  308  extends radially from the tip surface  302  to a height that is preferably equal to the height of the perimeter wall  304  (e.g., between 2 mm and 15 mm). In the illustrated construction, the first trench wall  306  includes a perimeter portion  322  that defines a portion of the perimeter wall  304 . 
     In the illustrated construction, the first trench wall  306  and the second trench wall  308  are parallel to one another, spaced apart from one another, and curved to define a trench  310  therebetween. The trench  310  includes a first open end that is near the leading edge  208  of the airfoil  206  and a second open end that is near the trailing edge  210  of the airfoil  206 . In this context, the term “near” refers to the relative proximity of the described opening to the leading edge  208  or the trailing edge  210 . Thus, “near the leading edge  208 ” would simply mean nearer to the leading edge  208  then to the trailing edge  210 . In most constructions, the first trench wall  306  and the second trench wall  308  are between 5 mm and 20 mm from one another with other widths being possible. As will be discussed with regard to  FIG.  5   , the first trench wall  306  and the second trench wall  308  can have different shapes and different arrangements. For example, non-parallel trench walls could be employed. The trench  310  defines a trench bottom  312  that is substantially parallel to the tip surface  302  but that, as illustrated in  FIG.  4    is depressed or located closer to the root  202  than the tip surface  302 . 
     The perimeter wall  304  and the first trench wall  306  cooperate to define a pressure-side pocket  316  and a first wall gap  318 . Similarly, the perimeter wall  304  and the second trench wall  308  cooperate to define a suction-side pocket  314  and a second wall gap  320 . In addition, the perimeter wall  304 , the first trench wall  306 , and the second trench wall  308  define radially extending side surfaces. It should be noted that the radially extending surfaces could deviate slightly from a true radial direction, however, the surface extends predominantly in a radial direction. 
     A plurality of cooling holes  324  are formed in the various radially extending surfaces and provide an outlet for cooling air. Some cooling air is discharged by a portion of the plurality of cooling holes  324  into the suction-side pocket  314  and the pressure-side pocket  316 . The first wall gap  318  and the second wall gap  320  provide an outlet for that cooling air. Thus, the perimeter wall  304  and the first trench wall  306  substantially surround the pressure-side pocket  316  and the perimeter wall  304  and the second trench wall  308  substantially surround the suction-side pocket  314 . In this context, “substantially” means that the walls surround at least fifty percent of the respective suction-side pocket  314  and the pressure-side pocket  316 . While some constructions could completely surround the suction-side pocket  314  and the pressure-side pocket  316 , most constructions provide for the first wall gap  318  and the second wall gap  320 . While “substantially surround” could mean as little as fifty percent, most constructions include walls that surround at least 70 percent and up to a 90 percent of the first wall gap  318  and the second wall gap  320 . 
       FIG.  4    better illustrates the increased depth  402  of the trench bottom  312  with respect to the tip surface  302 . As illustrated, the increased depth  402  is between 2 mm and 15 mm with other ranges and differences being possible. 
     In addition, and with continued reference to  FIG.  4    the tip portion  300  operates to produce a first space vortex  404 , a trench vortex  406 , a second space vortex  408 , and a suction side tip-leakage vortex  410  each formed between the tip portion  300  and the stationary component adjacent the tip portion  300 . The first space vortex  404  and the second space vortex  408  are formed in the pressure-side pocket  316  and the suction-side pocket  314  respectively and each produce pressure drops and flow efficiencies that reduce the total flow across the tip portion  300 . The trench vortex  406  is formed in the trench  310  and also functions to produce a pressure drop that reduces the flow toward the suction side of the blade. Any flow that does pass over the tip portion  300  forms the suction side tip-leakage vortex  410 , which has reduced size and intensity compared to conventional blade tip configurations. The width and the depth of the trench  310 , the suction-side pocket  314 , and the pressure-side pocket  316  can all be varied to control or adjust the size, depth and strength of the various vortices to achieve the desired leakage across the tip portion  300 . 
       FIG.  5    illustrates another construction of a tip portion  500  suitable for use with the turbine blade  200 . Like the first construction of the tip portion  300 , the tip portion  500  of  FIG.  5    includes a perimeter wall  502  that extends around a portion of the vane perimeter  216 . The perimeter wall  502  of  FIG.  5    includes three separate portions rather than the two portions of  FIG.  3   . The perimeter wall  502  extends radially away from the tip surface  302  and defines substantially radially extending walls. 
     A first trench wall  504  extends from a leading edge  208  side of the suction-side surface  214  to a trailing edge  210  side of the suction-side surface  214 . A second trench 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 trench wall  504  to define a trench  508  having a trench bottom  510 . 
     The perimeter wall  502  cooperates with the first trench wall  504  to at least partially surround and define a pressure-side pocket  512  and a first wall gap  516 . Similarly, the perimeter wall  502  and the second trench wall  506  cooperate to define a suction-side pocket  514  and a second wall gap  518 . 
     The tip portion  500  of  FIG.  5    is substantially the same as the tip portion  300  of  FIG.  3    with the exception of the first trench wall  504  and the second trench wall  506 . Rather than curved, parallel trench walls, the first trench wall  504  and the second trench wall  506  are straight and parallel to one another. Like the trench  310  of  FIG.  3   , the trench  508  preferably has a width between 5 mm and 20 mm with other widths also being possible. As with the trench  310 , the second trench  508  could employ non-parallel trench walls or walls of differing heights as desired. 
       FIG.  6    illustrates one of the cooling holes  324  as including a split cooling hole  600  and looking in the viewing direction  326  shown in  FIG.  3   . As illustrated in  FIG.  3   , split cooling holes  600  are formed in at least a portion of the interior or radially extending walls of the perimeter wall  304 , the first trench wall  306 , and the second trench wall  308 . Thus, a portion of the cooling holes  324 , in the construction illustrated in  FIG.  3    include some split cooling holes  600 . 
     As illustrated in  FIG.  6    each split 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 an inner surface of the tip surface  302  to a cooling hole branch point  608  located in the first trench wall  306 , the perimeter wall  304 , or the second trench wall  308 . At the cooling hole branch point  608 , the cooling hole inlet leg  602  branches into two cooling hole branches  606  with each of the cooling hole branches  606  including a separate and distinct cooling hole outlet  604 . While the illustrated construction illustrates a split cooling hole  600  with two cooling hole branch  606 , other constructions may include three or more cooling hole branches  606 . 
     The split cooling holes  600  can be formed using a drilling or boring operation or could be formed using an additive manufacturing process during the formation of the turbine blade  200  or the tip portion  300 ,  500  of the turbine blade  200 . 
       FIG.  7    is a section view taken along line VII-VII of  FIG.  6    that better illustrates other features of the split cooling hole  600 . As can be seen, the cooling hole inlet leg  602  is angled obliquely with respect to the tip surface  302  and the first trench wall  306 . In preferred constructions, the cooling hole inlet leg  602 , the cooling hole branch point  608 , and the cooling hole branches  606  include smooth aerodynamic transitions (curves rather than sharp corners) to assure smooth and efficient cooling air flow therethrough. 
     While the illustrated construction of the split cooling hole  600  includes substantially symmetric (about the section line VII-VII) cooling hole branches  606 , other constructions may include asymmetric cooling hole branches  606  such that the cooling hole outlet  604  of each cooling hole branch  606  can be directed to different angles and serve to cool different areas in the first trench wall  306 , second trench wall  308 , or perimeter wall  304  from which they exit while still consuming the same cooling mass flow as one straight through hole. 
     Additionally, the positioning of the cooling hole outlets  604  in the perimeter wall  304 , first trench wall  306 , and second trench wall  308  makes it possible to directly cool these features (often referred to as a squealer tip). In particular, the illustrated arrangement allows for direct cooling of the inner surfaces (surfaces inside the perimeter of the airfoil  206 ) which increases the cooling effectiveness at the perimeter wall  304 , first trench wall  306 , and second trench wall  308  which are directly cooled by heat conduction through the split cooling holes  600 . 
     During operation of the gas turbine engine  100 , high-pressure, high-temperature exhaust gas  128  flows between adjacent turbine blades  200  where it is expanded 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 tip surface  302  of the turbine blade  200  and the stationary component adjacent the turbine blade  200 . The addition of the tip portion  300  or the tip portion  500  enhances the seal during operation. Specifically, exhaust gas  128  tends to leak across the tip surface  302  from the pressure-side surface  212  to the suction-side surface  214 . The addition of the perimeter wall  304  or the perimeter wall  502  enhances the seal. However, the further addition of the trench  310  or the trench  508  creates the pressure-side pocket  316  or the pressure-side pocket  512  and the suction-side pocket  314  or the suction-side pocket  514  which create flow conditions at the tip portion  300  or the tip portion  500  of the turbine blade  200  that makes flow from the pressure-side surface  212  to the suction-side surface  214  more difficult, thereby enhancing the sealing efficiency. 
     The arrangement of the perimeter wall  304 , the first trench wall  306 , and the second trench wall  308  of the tip portion  300  as well as the perimeter wall  502 , the first trench wall  504 , and second trench wall  506  of the tip portion  500  are provided with direct cooling air to reduce their operating temperatures and reduce the likelihood of damage, such as oxidation during operation. Cooling air extracted from the compressor section  102  passes through the turbine blades  200 , the split cooling holes  600 , and the plurality of cooling holes  324  to directly cool the various walls as required. 
     In addition, during certain operating conditions it is possible that cooling air can become trapped in the suction-side pocket  314 ,  514  or the pressure-side pocket  316 ,  512 . The first wall gap  318  and the second wall gap  320  as well as the first wall gap  516  and the second wall gap  518  provide an outlet for that trapped cooling air to allow for its efficient escape. 
     Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form. 
     None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words “means for” are followed by a participle.