Cover band configurations for turbine rotor blades

Abstract

A turbine blade contains a tip shroud attached to the outer tip of the blade. The tip shroud may include a planar component extending axially and circumferentially, in which an inner surface faces an outer surface, and a shroud edge that connects the inner and outer surfaces and defines an outer profile of the tip shroud. The tip shroud may include a sealing lip projecting from the outer surface of the tip shroud and a cutting tooth arranged on the sealing lip. The cutting tooth may be designed as a circumferential section of the sealing lip that is thickened in the axial direction. The sealing lip may further include a leakage gap formed through it, designed to increase the leakage rate during operation.

Description

BACKGROUND TO THE INVENTION

[0001] This application relates to tip trim configurations for turbine blades in gas turbines. In particular, but by no means limited to, the present application relates to the design and configuration of sealing rails on turbine blade tip trims.

[0002] In general, internal combustion or gas turbine engines (hereafter referred to as "gas turbines") contain compressor and turbine sections in which rows of blades are axially stacked in stages. Each stage usually contains a set of circumferentially spaced, stationary guide vanes and a set of rotor blades that rotate around a central turbine axis or shaft. During operation, the compressor rotor blades generally rotate on the shaft and, acting in conjunction with the guide vanes, compress a flow of air. This compressed air supply is then used within a combustion chamber to burn a fuel supply. The resulting flow of hot, expanding combustion gases, often called a working fluid, is then expanded through the turbine section of the drive.Inside the turbine, the working fluid is deflected by the guide vanes onto the rotor blades to drive their rotation. The rotor blades are connected to a central shaft in such a way that the rotation of the rotor blades sets the shaft in motion. In this way, the energy contained in the fuel is converted into the mechanical energy of the rotating shaft, which can be used, for example, to turn the compressor blades to generate the compressed air required for combustion, or to turn the coils of a generator to produce electrical power. Due to the temperatures of the hot gas path, the velocity of the working fluid, and the rotational speed of the drive during operation, the rotor blades within the turbine are subjected to particularly extreme mechanical and thermal loads.

[0003] Many industrial applications, such as those encompassing power generation and aviation, continue to rely heavily on gas turbines, and as a result, the development of more efficient drives remains a constant and important goal. It is recognized that even incremental improvements in machine performance, efficiency, or cost-effectiveness are significant in the highly competitive markets that have developed around this technology. While there are several well-known strategies for improving gas turbine efficiency, such as increasing the size of the drive, firing temperatures, or rotational speeds, each of these generally places additional stress on these already highly stressed hot gas path components.Consequently, there remains a need for improved devices, processes, or systems that mitigate such operational stresses or, alternatively, increase the longevity of such components so that they can better withstand them.

[0004] As is evident, this need is particularly apparent with regard to turbine rotor blades, where market competition is extremely high and the numerous design requirements are highly complex and often conflicting. In themselves, novel rotor blade designs, such as those presented herein, which successfully balance these requirements in ways that optimize or improve one or more desired performance criteria—while still adequately supporting structural robustness, component longevity, cost-effective drive operation, and / or efficient coolant utilization—represent technological advantages of considerable value. BRIEF DESCRIPTION OF THE INVENTION

[0005] The present application thus describes a turbine rotor blade comprising a tip shroud attached to the outer tip of the blade. The tip shroud may include a planar component extending axially and circumferentially, in which an inner surface faces an outer surface, and a shroud edge connecting the inner and outer surfaces and defining an outer profile of the tip shroud. The tip shroud may include a sealing strip projecting from the outer surface of the tip shroud and a cutting tooth arranged on the sealing strip. The cutting tooth may be designed as a circumferential section of the sealing strip that is thickened in the axial direction. The sealing strip may further include a leakage gap formed through it, designed to increase the leakage rate during operation in order to achieve an aerothermal gain.

[0006] In one aspect, a turbine blade for a gas turbine comprises a wing panel defined between a concave pressure side and a laterally opposite convex suction side, wherein the pressure side and the suction side extend axially between a leading and an opposite trailing edge and radially between an outer tip and an inner end attached to a root configured to couple the wing panel to a rotor disk. The wing panel further comprises a tip shroud attached to the outer tip of the wing panel, wherein the tip shroud includes a planar component extending axially and circumferentially, in which an inner surface faces an outer surface, and a shroud edge connecting the inner surface to the outer surface and defining an outer profile of the tip shroud.The guide vane further includes a sealing rail projecting from the outer surface of the tip cover strip, the sealing rail having a leakage gap formed through it, the leakage gap being designed to increase a leakage rate during operation.

[0007] Assuming correct installation, the aforementioned rotor blade can be described according to the turbine's orientation characteristics, which may include: radial, axial, and circumferential directions defined with respect to a central axis of the turbine; forward and reverse directions defined with respect to a front end of the turbine where a working fluid enters the turbine and a rear end of the turbine where the working fluid exits the turbine; and a direction of rotation defined with respect to an expected direction of rotation of the rotor blade around the central axis of the turbine during operation.According to the orientation properties, the sealing rail can project from the outer surface along an axis approximately aligned with the radial direction to define a height, wherein the sealing rail can extend along an axis approximately aligned with the circumferential direction to define a length, wherein the sealing rail can have a narrow thickness relative to its length, extending along an axis approximately aligned with the axial direction, and wherein the sealing rail can have opposing and substantially flat rail sides, wherein a front rail side and a rear rail side can correspond to the forward and reverse directions of the turbine, respectively.

[0008] The aforementioned running blade can further have a cutting tooth arranged on the sealing rail, wherein the cutting tooth has a circumferential section of the sealing rail that is thickened in the axial direction, wherein the narrow thickness of the sealing rail can be defined along a circumference of the sealing rail by rail edges extending between the front and rear rail sides, wherein the rail edges can include: an outer and an opposing inner rail edge, wherein the inner rail edge can be defined at the connection that the sealing rail makes with the outer surface of the tip cover strip, and the outer rail edge can be offset from the inner rail edge by the height of the sealing rail;and a rail edge that is forward in the direction of rotation and an opposite rail edge that is rearward in the direction of rotation, each of which can be positioned near the edge of the cover strip such that the rail edge that is forward in the direction of rotation leads the rail edge that is rearward in the direction of rotation during operation for the given direction of rotation of the guide vane.

[0009] Additionally, the sealing rail can have height sections between which the height of the sealing rail varies, wherein the height sections are defined in the circumferential direction and divide an entirety of the length of the sealing rail into two non-overlapping sections, a first height section and a second height section, wherein the leakage gap can have the sealing rail of the first height section being significantly reduced compared to the height of the sealing rail within the second height section, wherein the sealing rail can include a circumferentially defined cutting tooth section that coincides with the cutting tooth, and wherein an entirety of the cutting tooth section can be arranged within the second height section.

[0010] Alternatively, in some embodiments, the sealing rail can have circumferential sections defined relative to the cutting tooth, which can include a front section (in the direction of rotation), a cutting tooth section, and a rear section (in the direction of rotation), wherein the cutting tooth section can coincide with a circumferential length of the cutting tooth, wherein the front section (in the direction of rotation) can extend from the cutting tooth section to the front edge of the rail (in the direction of rotation), and wherein the rear section (in the direction of rotation) can extend from the cutting tooth section to the rear edge of the rail (in the direction of rotation). The sealing rail can also have vertical sections between which the height of the sealing rail varies, wherein the vertical sections are defined circumferentially and divide an entirety of the length of the sealing rail into two non-overlapping sections, a first vertical section and a second vertical section.where the leakage gap may exhibit that the height of the sealing rail within the first height section is significantly reduced compared to the height of the sealing rail within the second height section.

[0011] In the embodiments mentioned last, the first height section can have the section that is forward in the direction of rotation, wherein the second height section can have both the cutting tooth section and the section that is rear in the direction of rotation, wherein the significantly reduced height of the first height section can be less than 90% of the height of the second height section.

[0012] Alternatively, the first height section can have the rear section in the direction of rotation, while the second height section can have both the cutting tooth section and the front section in the direction of rotation, with the significantly reduced height of the first height section being less than 90% of the height of the second height section.

[0013] Alternatively, the first height section can have one of the front and rear sections in the direction of rotation, the second height section can have both the other of the front and rear sections in the direction of rotation and the cutting tooth section, the height of the second height section being essentially constant.

[0014] In the last-mentioned alternative, the height of the sealing rail within the first height section can vary in such a way that the outer edge of the first height section forms a shaped profile, whereby the shaped profile can have a corrugated profile.

[0015] In another configuration of the latter alternative, the height of the sealing rail within the first height section can vary such that the outer edge of the first height section forms a shaped profile, wherein the shaped profile can have an inwardly sloping profile in which the height of the sealing rail decreases as the first height section extends away from the cutting tooth section.

[0016] In a further configuration of the last-mentioned alternative, the height of the sealing rail within the first height section can vary in such a way that the outer edge of the first height section forms a shaped profile, whereby the shaped profile can have a concave cover strip edge.

[0017] In some embodiments of any of the aforementioned rotor blades having a cutting tooth, the sealing rail may have circumferential sections defined relative to the cutting tooth, including a cutting tooth section coinciding with a circumferential length of the cutting tooth, a forward section extending from the cutting tooth section to the forward rail edge in the direction of rotation, and a rearward section extending from the cutting tooth section to the rearward rail edge in the direction of rotation, wherein the leakage gap may includethat both the height of the sealing rail within the forward section in the direction of rotation is significantly reduced compared to the height of the sealing rail within the cutting tooth section, and the height of the sealing rail within the rear section in the direction of rotation is significantly reduced compared to the height of the sealing rail within the cutting tooth section.

[0018] Additionally, the height of the sealing rail within the front section (in the direction of rotation) and the rear section (in the direction of rotation) can each be between 50% and 80% of the height of the sealing rail within the cutting tooth section, wherein the height of the sealing rail within the front section (in the direction of rotation) and the height of the sealing rail within the rear section (in the direction of rotation) can be approximately equal, and wherein the cutting tooth can be positioned circumferentially at the approximate center point of the sealing rail such that the circumferential length of the front section (in the direction of rotation) and the rear section (in the direction of rotation) are approximately equal.

[0019] Furthermore, or as an alternative, the height of the sealing rail within the front section in the direction of rotation and the rear section in the direction of rotation can each be between 40% and 90% of the height of the sealing rail within the cutting tooth section, wherein the height of the sealing rail within the front section in the direction of rotation and the height of the sealing rail within the rear section in the direction of rotation can be different, wherein the cutting tooth can be positioned at the approximate center point of the sealing rail in the circumferential direction, such that the circumferential length of the front section in the direction of rotation and the rear section in the direction of rotation are approximately the same.

[0020] In other embodiments of any of the aforementioned rotor blades having a cutting tooth, the sealing rail may have circumferential sections defined relative to the cutting tooth, which may include a cutting tooth section coinciding with a circumferential length of the cutting tooth, a rotationally forward section extending from the cutting tooth section to the rotationally forward rail edge, and a rotationally aft section extending from the cutting tooth section to the rotationally aft rail edge, wherein the heights of the sealing rail within the cutting tooth section, the rotationally forward section, and the rotationally aft section may be substantially constant, and wherein the leakage gap may have one or more openings defined through the sealing rail.

[0021] In particular, the one or more openings may have such that at least one of the one or more openings is defined by each of the front section and the rear section of the sealing rail in the direction of rotation, wherein the one or more openings may each have an enclosed passage extending axially through the thickness of the sealing rail between an inlet formed by the front side of the rail and an outlet formed by the rear side of the rail.

[0022] Additionally or as an alternative, the one or more openings can each have an enclosed passage extending axially through the thickness of the sealing rail between an inlet formed by the front side of the rail and an outlet formed by the rear side of the rail, wherein the enclosed passage can be inclined at least one of the one or more openings with respect to the sealing rail.

[0023] In another aspect, a turbine blade for a gas turbine comprises a wing panel defined between a concave pressure side and a laterally opposite convex suction side, wherein the pressure side and the suction side extend axially between a leading and an opposite trailing edge and radially between an outer tip and an inner end attached to a root configured to couple the wing panel to a rotor disk. The wing panel further comprises a tip cover attached to the outer tip of the wing panel, wherein the tip cover has a planar component extending axially and circumferentially, in which an inner surface faces an outer surface, and a cover edge connecting the inner surface to the outer surface and defining an outer profile of the tip cover.The rotor blade further comprises sealing rails projecting from the outer surface of the tip cover strip, the sealing rails including a front sealing rail positioned in front of a rear sealing rail and oriented substantially parallel to it. At least one of the sealing rails has a leakage gap formed through it, the leakage gap being designed to increase a leakage rate during operation.

[0024] Assuming proper installation, the aforementioned rotor blade can be described according to the second aspect in terms of the turbine's orientation properties, which include: radial, axial, and circumferential directions defined relative to a central axis of the turbine; forward and reverse directions defined relative to a front end of the turbine where a working fluid enters the turbine and a rear end of the turbine where the working fluid exits the turbine; and a direction of rotation defined relative to an expected direction of rotation of the rotor blade around the central axis of the turbine during operation.According to the orientation properties, each of the sealing rails can project from the outer surface along an axis approximately aligned with the radial direction to define a height, each of the sealing rails can extend along an axis approximately aligned with the circumferential direction to define a length, each of the sealing rails can have a narrow thickness extending along an axis approximately aligned with the axial direction, and each of the sealing rails can have opposing and substantially flat rail sides, with a front rail side and a rear rail side corresponding to the forward and reverse directions of the turbine, respectively.

[0025] In addition, in some embodiments, the rotor blade may further have a cutting tooth arranged on each of the sealing rails, wherein the cutting tooth has a circumferential section of the sealing rail that is thickened in the axial direction, wherein each of the sealing rails may have defined circumferential sections relative to the cutting tooth arranged on them, wherein the circumferential sections include a cutting tooth section that coincides with a circumferential length of the cutting tooth, a forward section in the direction of rotation extending from the cutting tooth section to the forward rail edge in the direction of rotation, and a rearward section in the direction of rotation extending from the cutting tooth section to the rearward rail edge in the direction of rotation, wherein the forward sealing rail may have a substantially constant height above the cutting tooth section, the forward section in the direction of rotation, and the rearward section in the direction of rotation.wherein the rear sealing rail may have the leakage gap, wherein the leakage gap has at least one of the following: that the height of the rear sealing rail within the forward section in the direction of rotation is significantly reduced compared to a constant height that the rear sealing rail has both above the rear section in the direction of rotation and above the cutting tooth section; and that the height of the rear sealing rail within the rear section in the direction of rotation is significantly reduced compared to a substantially constant height that the rear sealing rail has both above the forward section in the direction of rotation and above the cutting tooth section.

[0026] In other embodiments, each of the sealing rails can have circumferential sections defined relative to the cutting tooth arranged thereon, wherein the circumferential sections include a cutting tooth section coinciding with a circumferential length of the cutting tooth, a forward section extending from the cutting tooth section to the forward rail edge in the direction of rotation, and a rear section extending from the cutting tooth section to the rear rail edge in the direction of rotation, wherein the rear sealing rail can have a substantially constant height above the cutting tooth section, the forward section, and the rear section in the direction of rotation, wherein the forward sealing rail can have the leakage gap, the leakage gap comprising at least one of the following:that the height of the front sealing rail within the section at the front in the direction of rotation is significantly reduced compared to a constant height that the front sealing rail has over both the section at the rear in the direction of rotation and the cutting tooth section, and that the height of the front sealing rail within the section at the rear in the direction of rotation is significantly reduced compared to an essentially constant height that the front sealing rail has over both the section at the front in the direction of rotation and the cutting tooth section.

[0027] In further embodiments, each of the sealing rails can have circumferential sections defined relative to the cutting tooth arranged thereon, wherein the circumferential sections include a cutting tooth section coinciding with a circumferential length of the cutting tooth, a forward section in the direction of rotation extending from the cutting tooth section to the forward edge of the rail in the direction of rotation, and a rear section in the direction of rotation extending from the cutting tooth section to the rear edge of the rail in the direction of rotation, wherein each of the front sealing rail and the rear sealing rail can have the leakage gap, wherein the leakage gap of the front sealing rail can have at least one such that the height of the front sealing rail within the forward section in the direction of rotation is greater than or equal to a constant height.the front sealing rail has a significantly reduced height over both the rear section in the direction of rotation and the cutting tooth section, and the height of the front sealing rail within the rear section in the direction of rotation is significantly reduced compared to a substantially constant height that the front sealing rail has over both the front section in the direction of rotation and the cutting tooth section, wherein the leakage gap of the rear sealing rail may have at least one of the following: the height of the rear sealing rail within the front section in the direction of rotation is significantly reduced compared to a constant height that the rear sealing rail has over both the rear section in the direction of rotation and the cutting tooth section, and the height of the rear sealing rail within the rear section in the direction of rotation is significantly reduced compared to a substantially constant height,which significantly reduces the rear sealing rail over both the forward section in the direction of rotation and the cutting tooth section.

[0028] In further embodiments, each of the sealing rails can have circumferential sections defined relative to the cutting tooth arranged thereon, wherein the circumferential sections include a cutting tooth section coinciding with a circumferential length of the cutting tooth, a forward section in the direction of rotation extending from the cutting tooth section to the forward edge of the rail in the direction of rotation, and a rear section in the direction of rotation extending from the cutting tooth section to the rear edge of the rail in the direction of rotation, wherein the forward sealing rail can have a substantially constant height above the cutting tooth section, the forward section in the direction of rotation, and the rear section in the direction of rotation, and wherein the rear sealing rail can have a substantially constant height above the cutting tooth section, the forward section in the direction of rotation, and the rear section in the direction of rotation.wherein the leakage gap may have one or more openings defined by at least one of the front sealing rail and the rear sealing rail, wherein the one or more openings may each have an enclosed passage extending axially through the thickness of the sealing rail between an inlet formed by the front rail side and an outlet formed by the rear rail side.

[0029] These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments in conjunction with the drawings and the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and other features of this invention will be more fully understood and appreciated when the following more detailed description of exemplary embodiments of the invention is studied more carefully in conjunction with the accompanying drawings, which show: Fig. 1 a schematic representation of an exemplary gas turbine which may include turbine blades according to aspects and embodiments of the present application; Fig. 2 a sectional view of the compressor section of the gas turbine according to Fig. 1; Fig. 3 a sectional view of the turbine section of the gas turbine according to Fig. 1; Fig. 4 a perspective view of an exemplary turbine rotor blade having a conventional tip cover band; Fig. 5 a perspective view of a tip cover band of a conventional turbine rotor blade having a single sealing rail; Fig. 6 a perspective view of a tip cover band of a conventional turbine rotor blade having two sealing rails; Fig. 7 a side view of an exemplary connection point formed between the sealing rails of a turbine rotor blade fitted with a cover strip and the stationary structure opposite it; Fig. 8 an external perspective of an exemplary installed arrangement of turbine rotor blades fitted with tip cover bands; Fig. 9 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 10 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 11 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 12 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 13 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 14 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 15 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 16 a perspective view of a running blade with tip cover strip having two sealing rails, according to an exemplary embodiment of the present invention; Fig. 17 a perspective view of a running blade with a tip cover strip having a single sealing rail, according to an exemplary embodiment of the present invention; Fig. 18 a perspective view of a guide vane with a tip cover strip having a single sealing rail, according to an exemplary embodiment of the present invention; Fig. 19 a perspective view of a guide vane with a tip cover strip having a single sealing rail, according to an exemplary embodiment of the present invention; Fig. 20 a perspective view of a running blade with tip cover strip having a single sealing rail, according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0031] Aspects and advantages of the present application are explained below in the following description, or may be apparent from the description, or may be experienced through practical application of the invention. Reference is now made in detail to existing embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical designations to refer to features in the drawings. Identical or similar designations in the drawings and the description may be used to refer to identical or similar parts of embodiments of the invention. As is evident, each example is provided to illustrate the invention, not to limit it.Indeed, it will be obvious to those skilled in the art that modifications and alterations can be made to the present invention without deviating from its scope or extent. For example, features illustrated or described as part of one embodiment can be applied to another embodiment to give yet another embodiment. It is intended that the present invention encompasses such modifications and alterations as fall within the scope of the appended claims and their equivalents. It should be understood that the scopes and limits mentioned herein include all sub-areas contained within the prescribed limits, including the limits themselves, unless otherwise specified. Furthermore, certain terms have been chosen to describe the present invention and its components, subsystems, and parts.To the extent possible, these terms have been chosen based on the terminology commonly used in the technological field. It will be recognized that such expressions are often subject to different interpretations. For example, what may be described here as a single component may elsewhere be described as consisting of multiple components, or vice versa.Therefore, to understand the scope of protection of the present invention, attention should be paid not only to the specific terminology used, but also to the accompanying description and context, as well as the structure, configuration, function, and / or use of the component referred to and described, including the manner in which the expression refers to the various figures, and, of course, the precise use of the terminology in the appended claims. Furthermore, although the following examples are presented with respect to certain types of gas turbines or turbine drives, the technology of the preceding application may also be applicable, without limitation, to other categories of turbines, as would be understood by a person skilled in the art in the relevant technological field.Accordingly, it should be understood that, unless otherwise stated, the use of the term ‘gas turbine’ herein is intended in a broad sense and without limitation with regard to the applicability of the preceding invention to the various types of turbines.

[0032] Given the way gas turbines operate, several terms prove particularly useful in describing certain aspects of their function. As is understood, these terms can be used both to describe and to apply stress to the gas turbine or any of its subsystems—for example, the compressor, combustion chamber, or turbine—as well as to describe or apply stress to components or subcomponents used within them. In the latter case, the terminology should be understood as describing these components as they would be if properly installed and / or functioning within the gas turbine or primary subsystem. These terms and their definitions are, unless specifically stated otherwise, as follows.

[0033] The terms "forward" or "front" and "backward" or "rear" refer to directions in relation to the orientation of the gas turbine and, in particular, the relative positioning of the compressor and turbine sections of the drive. Thus, the expression "forward" or "front" in the sense used herein refers to the compressor end, while "backward" or "rear" refers to the turbine end. It is recognized that each of these expressions can be used to indicate a direction of movement or relative position along the central axis of the drive. As mentioned above, these expressions can be used to describe features of the gas turbine or one of its primary subsystems, as well as components or subcomponents positioned within it.For example, if a component, such as a turbine blade, is described or claimed to have a "front side," it can be understood that this refers to a side facing the forward direction as defined by the orientation of the gas turbine (that is, the compressor is referred to as the front end, while the turbine is referred to as the rear end). To take an important subsystem like the turbine as another example (and assuming a typical gas turbine arrangement, such as the one in...) Fig. (as illustrated in Figure 1), the forward and reverse directions can be defined relative to a front end of the turbine where a working fluid enters the turbine and a rear end of the turbine where the working fluid exits the turbine.

[0034] The terms “downstream” and “upstream” are used herein to indicate a position within a specified conduit or flow path relative to the direction of a flow (hereafter referred to as the “flow direction”) moving through it. Thus, the term “downstream” refers to the direction in which a fluid flows through the specified conduit, while “upstream” refers to the opposite direction. These terms can be understood as referring to the flow direction through the conduit under the assumption of normal or expected operation. As is recognized, the working fluid within the compressor and turbine sections of the gas turbine is directed downstream and through an annular working fluid flow path, which is usually defined around the central or common axis of the gas turbine.The term "flow direction," as used herein, refers within the compressor and turbine sections of the gas turbine to a reference direction that represents an idealized flow direction of the working fluid through the working fluid flow path of the gas turbine during an expected or normal operating condition. Thus, within the compressor and turbine sections, the terminology "flow direction" refers to a flow that runs parallel to the central axis of the gas turbine and is oriented downstream or back.

[0035] Thus, for example, the flow of a working fluid through the working fluid flow path of the gas turbine can be described as beginning as air, which is pressurized by the compressor according to the flow direction, becoming combustion gases in the combustion chamber after being burned with a fuel, and finally expanding according to the flow direction as it passes through the turbine. Likewise, the working fluid flow can be described as beginning at a front or upstream point towards a front or upstream end of the gas turbine, moving essentially in a downstream or reverse direction, and finally terminating at a rear or downstream point towards a rear or downstream end of the gas turbine.

[0036] Since many components of gas turbines rotate during operation, such as compressor and turbine blades, the terms "front" and "rear" can be used to distinguish the relative positioning of subcomponents or subregions according to the expected rotational motion within the gas turbine. As can be seen, these terms can thus differentiate a position according to the direction of rotation—hereafter referred to as the "direction of rotation"—within the compressor or turbine. In the sense used here, such a direction of rotation can be understood as the expected direction of rotation for a component under the assumption of normal or expected operation of the gas turbine.

[0037] Additionally, given the configuration of gas turbines, particularly the arrangement of the compressor and turbine sections around a common shaft or rotor, and the cylindrical configuration common to many combustion chamber types, terms describing a position relative to an axis are regularly used. In this context, it is recognized that the term "radial" refers to a movement or position perpendicular to an axis. Therefore, it may be necessary to describe a relative distance from a central axis. For example, if a first component is located closer to the central axis than a second component, the first component is described as being either "radially inside" or "inside" the second component.Conversely, if the first component is located farther from the central axis, the first component is described as being either "radially outside" or "external" to the second component. As used herein, the term "axial" refers to a movement or position parallel to an axis, whereas the terms "circumferential" or "peripheral" refer to a movement or position around an axis. Unless otherwise specified or fully evident from the context, these terms should be understood as referring to the central axis of the compressor and / or turbine sections of the gas turbine as defined by the rotor extending through each, even if the terms describe or claim features of non-integral components—such as rotor or guide vanes—operating therein.Unless otherwise specified, the terms may be used in relation to the longitudinal axis of certain components or subsystems within the gas turbine, such as the longitudinal axis around which conventional cylindrical or tubular combustion chambers are usually arranged.

[0038] Finally, the term "rotating blade," without further specificity, refers to the rotating blades of either the compressor or the turbine, and can therefore include both compressor rotating blades and turbine rotating blades. The term "guide vane," without further specificity, refers to the stationary blades of either the compressor or the turbine, and can therefore include both compressor guide vanes and turbine guide vanes. The term "blades" can be used to refer generally to any type of blade. Thus, without further specificity, the term "blades" includes all types of gas turbine blades, including compressor rotating blades, compressor guide vanes, turbine rotating blades, turbine guide vanes, and the like.

[0039] By referring to the characters as a background with a special feature, they illustrate Fig. 1, Fig. 2 to Fig. 3. An exemplary gas turbine according to the present invention, or within which the present invention can be used. It will be clear to those skilled in the field that the present invention is not limited to this type of use. As mentioned, the present invention can be used in gas turbines, such as those used in power generation and aviation, in steam turbines, and in other types of rotary machines, as would be recognized by a person skilled in the field. The examples provided are therefore not intended to be limiting, unless otherwise stated. Fig. Figure 1 shows a schematic representation of a gas turbine 10. In general, gas turbines operate by extracting energy from a pressurized flow of hot gas, which is produced by the combustion of a fuel in a stream of compressed air. As in Fig. As illustrated in Figure 1, the gas turbine 10 can be configured with an axial compressor 11, which is mechanically coupled to a downstream turbine section or turbine 12 via a common shaft or rotor, and a combustion chamber 13, which is positioned between the compressor 11 and the turbine 12. As shown in Fig. As illustrated in Figure 1, the gas turbine can be designed around a common central axis 19.

[0040] Fig. Figure 2 illustrates a view of an exemplary multi-stage axial compressor 11, which is installed in the gas turbine after Fig. 1 can be used. As illustrated, the compressor 11 can have several stages, each of which can contain a series of compressor impeller blades 14 and a series of compressor guide vanes 15. Thus, a first stage can contain a series of compressor impeller blades 14 rotating on a central shaft, followed by a series of compressor guide vanes 15 that remain stationary during operation. Fig. Figure 3 illustrates a partial view of an exemplary turbine section or turbine 12, which is located in the gas turbine according to Fig. 1. The turbine 12 can contain multiple stages. Three exemplary stages are illustrated, although there may be more or fewer. Each stage can contain multiple turbine guide vanes or guide blades 17, which remain stationary during operation, followed by multiple rotor blades or runner blades 16, which rotate around the shaft during operation. The turbine guide vanes 17 are generally spaced circumferentially apart and fixed about the axis of rotation to an outer casing. The turbine runner blades 16 can be mounted on a turbine impeller or rotor disk (not illustrated) for rotation about a central axis. It is recognized that the turbine guide vanes 17 and the turbine runner blades 16 lie in the hot gas path or working fluid flow path through the turbine 12.The direction of flow of the combustion gases or working fluid within the working fluid flow path is indicated by the arrow.

[0041] In an example of the operation of a gas turbine 10, the rotation of the compressor blades 14 within the axial compressor 11 can compress an airflow. Energy can be released in the combustion chamber 13 when the compressed air is mixed with a fuel and ignited. The resulting flow of hot gases or a working fluid from the combustion chamber 13 is then directed over the turbine blades 16, causing them to rotate on the shaft. In this way, the energy of the working fluid flow is converted into the mechanical energy of the rotating blades and, given the connection between the blades and the shaft, into the mechanical energy of the rotating shaft. The mechanical energy of the shaft can then be used to drive the rotation of the compressor blades 14, thus generating the required compressed air supply, and also, for example, to drive a generator to produce electricity.

[0042] For background purposes, show Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8 Views of conventional turbine rotor blades with a shroud band. 16. As is recognized, these figures are provided to illustrate common configurations of such rotor blades and to delineate spatial relationships between components and regions within such blades for later reference, while also describing geometric boundary conditions and other criteria that influence their internal and external design. While the blade in this example is a rotor blade, it is recognized that, unless otherwise stated, the present invention can also be applied to other types of blades within the gas turbine. As mentioned above, the description of such components may include terminology that derives a meaning based on the orientation and function of the gas turbine and, in particular, the working fluid flow path, and it should therefore be understood in this context.For example, where applicable, it can be assumed that a description relating to the impeller blade or any other component assumes that it is properly installed and operating within the drive under expected or normal conditions.

[0043] By now focusing special attention on Fig. As directed 4, the rotor blade 16 can include a root 21 configured for attachment to a rotor disk. The root 21 can, for example, include a dovetail 22 configured for mounting in an associated dovetail groove around the circumference of a rotor disk. The root 21 can further include a shaft 23 extending between the dovetail 22 and a platform 24. The platform 24 generally forms, as illustrated, the connection between the root 21 and a blade 25, the blade being the active component of the rotor blade 16 that captures the flow of the working fluid through the turbine 12 and generates the desired rotation. The platform 24 can define the inner end of the blade 25. The platform 24 can also define a section of the inner boundary of the working fluid flow path through the turbine 12.

[0044] The rotor blade 25 typically comprises a concave pressure side 26 and a convex suction side 27 opposite in the circumferential or lateral direction. The pressure side 26 and the suction side 27 can extend axially between a leading and an opposite trailing edge 28 and 29, respectively, and radially between an inner end, which may be defined at the junction with the platform 24, and an outer tip, which may include a tip cover 41. The rotor blade 25 may have a curved or contoured shape designed to enhance desired aerodynamic performance. The rotor blade 16 may further include an internal configuration with one or more cooling channels through which a coolant is circulated during operation.Such cooling channels can extend radially outwards from a connection to a supply source formed through the root 21 of the rotor blade 16. The cooling channels can be straight, curved, or a combination thereof, and can include one or more outlet or surface openings through which a coolant is discharged from the rotor blade 16 and into the working fluid flow path.

[0045] In the sense used here, the rotor blade 16 and its components can be described according to orientation properties of the turbine 12. It should be understood that in such cases, the rotor blade 16 is assumed to be properly installed within the turbine 12. Such orientation properties can include radial, axial, and circumferential directions defined with respect to the central axis 19 of the turbine 12. A forward and reverse direction can be defined relative to a front end of the turbine 12, where the working fluid enters the turbine 12 from the combustion chamber 13, and a rear end of the turbine 12, where the working fluid exits the turbine 12. A direction of rotation can be defined relative to an expected direction of rotation of the rotor blade 16 about the central axis 19 of the turbine 12 during operation.As can be seen, the sealing rail 42 can be described according to these orientation properties such that it projects from the outer surface 44 of the top cover strip 41 along an axis that is approximately aligned with the radial direction to define a height. The sealing rail 42 can extend along an axis that is approximately aligned with the circumferential direction to define a length. As illustrated, the sealing rail 42 can have a narrow thickness relative to its length, extending along an axis that is approximately aligned with the axial direction.

[0046] By now focusing on the Fig. 5 and Fig. As referenced in Section 6, the tip trim band 41 may be positioned near or at the outer end of the blade 25. The tip trim band 41 may generally include a planar component extending axially and circumferentially, which is held at its center by the blade 25. For descriptive purposes, and as used herein, the tip trim band 41 includes an inner surface 45 and an outer surface 44, as well as a trim band edge or rim 46. The inner surface 45 lies substantially opposite the outer surface 44 over the narrow radial thickness of the tip trim band 41. The rim 46 of the tip trim band 41 connects the inner surface 45 to the outer surface 44. In the sense used herein, the rim 46 of the tip trim band 41 defines a circumferential profile or circumferential shape of the tip trim band 41.

[0047] The top cover strip 41 can further include one or more sealing rails projecting from the outer surface 44. As intended, it shows Fig. 5 a top cover strip 41 having a single sealing rail 42, while the top cover strip 41 according to Fig. Figure 6 shows one with two sealing rails 42. As explained below, the configurations shown for any of the sealing rails 42 can be used with any of these configurations. In general, the sealing rail 42 is a rib-like projection extending radially outward from the outer surface 44 of the tip cover 41. As illustrated, the sealing rail 42 can extend circumferentially between opposite ends of the tip cover 41 and thus be described as being aligned relative to the direction of rotation, or “direction of rotation,” of the rotor blade 16. The sealing rail 42 can extend over substantially the entire circumferential length of the outer surface 44 of the tip cover 41. As used herein, the circumferential length of the tip cover 41 is the length of the tip cover 41 in the direction of rotation 50.As described in more detail below, each of the one or more sealing rails 42 can contain a cutting tooth 43.

[0048] For descriptive purposes, and as used herein, the sealing rails 42 comprise opposing rail sides, with a front rail side 56 corresponding to the forward direction of the gas turbine and a rear rail side 57 corresponding to the reverse direction. In cases where two sealing rails are provided on the tip cover 41, a front sealing rail 76 can be similarly distinguished from a rear sealing rail 77. As can be seen, the front rail side 56 faces toward and in the direction of flow of the working fluid through the turbine 13, while the rear rail side 57 faces away from it. As illustrated, the sealing rail 42 can have an approximately rectangular profile. Thus, the front rail side 56 and the rear rail side 57 can both have a rectangular shape.Furthermore, the front rail side 56 and the rear rail side 57 of the sealing rail 42 can be connected to each other along circumferentially narrow rail edges, which, as used herein, are referred to as: opposing and approximately parallel outer and inner rail edges; and opposing and approximately parallel rail edges leading in the direction of rotation and rail edges trailing in the direction of rotation. In particular, the inner rail edge 58 can be defined at the junction between the sealing rail 42 and the outer surface 44 of the tip cover 41. The outer rail edge 59 is radially offset from the outer surface 44 of the tip cover 41. This radial offset, as is recognized, generally represents the height of the sealing rail 42. As is recognized, the rail edge 62 leading in the direction of rotation projects radially from the edge 46 of the tip cover 41 that projects beyond the suction side 27 of the blade 25.Configured in this way, the leading rail edge 62 in the direction of rotation is so named because it "leads" the sealing rail 42 when the rotor blade 16 rotates during operation. At the opposite end of the sealing rail 42, the trailing rail edge 63 projects radially from the edge 46 of the tip shroud 41, which projects beyond the pressure side 26 of the blade 25. The trailing rail edge 63 is thus so named because it "lags" behind the sealing rail 42 when the rotor blade 16 rotates during operation.

[0049] As used herein, the sealing rail 42 is described such that it has non-overlapping circumferential sections which can be defined with respect to the cutting tooth section 70, which coincides with the circumferential length and position of the cutting tooth 43. Thus, as in the Fig. 5 and Fig. As shown in Figure 6, as used herein, a leading section 72 and a trailing section 73 of the sealing rail 42 are defined on each side of the cutting tooth 43. In particular, the leading section 72, as illustrated, extends from the cutting tooth section 70 to the leading edge of the rail 62, while the trailing section 73 extends from the cutting tooth section 70 to the trailing edge of the rail 63. As can be seen, these designated circumferential sections are defined with respect to the Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18, Fig. 19 to Fig. 20 is used to describe exemplary embodiments of the present invention.

[0050] The tip cover 41 can include fillet areas designed to create smooth surface transitions between the differing surfaces between the tip cover 41 and the blade 25, and between the tip cover 41 and the sealing rail 42. Configurations of the tip cover 41 can include an outer fillet area formed between the outer surface 44 of the tip cover 41 and each of the leading rail side 56 and the trailing rail side 57 of the sealing rail 42. The tip cover 41 can further include an inner fillet area formed between the inner surface 45 of the tip cover 41 and the pressure and suction sides 26, 27 of the blade 25. The fillet areas can be designed to create smooth curved transitions between the different planar surfaces that would otherwise have abrupt or steeply angled transitions.It has been recognized that such rounded areas can improve aerodynamic performance and distribute stress concentrations that would otherwise occur in these areas.

[0051] As can be seen, the sealing rail 42 is usually used to prevent leakage across the turbine stages, since this leakage has a negative impact on the drive efficiency. By now, on Fig. Figure 7, which is specifically referenced, shows a side view of an exemplary interface formed between the sealing rails 42 of a tip-covered turbine rotor blade and the stationary structure 65 surrounding the blade step. As illustrated, the sealing rails 42 extend radially to narrow a radial gap 66 that exists between the tip-cover 41 and the surrounding stationary structure 65, which defines the outer boundary of the working fluid flow path. In some conventional designs, the stationary structure 65 may include a wearable jacket 67 or honeycomb jacket 67, which lies directly opposite the tip-cover 41 above the radial gap 66. In operation, the sealing rail 42 may project radially into the honeycomb jacket 67 to cut a path through it.In such cases, the cutting tooth 43 is designed to cut a groove in the honeycomb shell 67 that is slightly wider than the width of the sealing rail 42. As can be seen, the honeycomb shell 67 may be designed to improve sealing stability, and the use of the cutting tooth 43 can reduce overlapping and rubbing between stationary and rotating parts by clearing this wider path. In general terms, the cutting tooth 43 is a region of increased width along the circumferential length of the sealing rail 42. Specifically, the cutting tooth 43 may include a narrow circumferential section of the sealing rail 42 that is axially thickened. As illustrated, this axially thickened region may extend radially between the outer surface 44 of the top cover strip 41 and the outer edge of the sealing rail 42.The cutting tooth 43 can be positioned near the central or middle area of ​​the sealing rail 42, so that it is supported by the profile of the blade 25. Other positions of the cutting tooth 43 are also possible.

[0052] By now on Fig. As specifically referred to in Section 8, the tip cover bands 41 can be configured to include a contact connection point where contact surfaces and edges engage with similar surfaces or edges formed on the tip cover bands 41 adjacent to them. This can be done, for example, to reduce leakage or harmful vibration. Fig. Figure 8 shows an external view of the tip cover strips 41 of rotor blades as they might appear in an assembled state. For descriptive purposes, and as used herein, the edge 46 of the tip cover strip 41 includes a forward contact edge and a rearward contact edge relative to the direction of rotation 50 of the rotor blade. Thus, as shown, in a leading position, the tip cover strip 41 has a rearward contact edge that is in contact with, or comes close to contact with, the forward contact edge of the tip cover strip 41 in the lagging position relative to the direction of rotation. This contact area between the adjacent tip cover strips 41 may generally be referred to as a contact connection point or contact interface.With the given profile of the exemplary configuration, the contact interface can also be referred to as a "Z-notch" interface, although other configurations are also possible. More generally, the edge 46 of a tip cover strip 41 can be provided with a notched section at the formation of this contact interface, which is designed to engage or be in contact with a corresponding notched section in an adjacent tip cover strip 41 in a desired manner. As further described in . Fig. As illustrated in Figure 8, the profile of the lace cover tape 41 can have a shell-like shape from an external perspective, although other configurations are also possible. As can be seen, the exemplary shell shape is one that works well in terms of reducing leakage while also minimizing the weight of the lace cover tape.

[0053] By now focusing on the Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18, Fig. 19 to Fig. Reference is made to Section 20, in which the present invention is explained with regard to various exemplary embodiments. As will be evident, these embodiments propose various new configurations for the tip cover bands of rotor blades, which can be used, for example, to advantageously influence the leakage occurring above the tip. In particular, it has been found that by increasing the leakage above the tip in the specific manner provided herein, certain aspects of the operating behavior can be improved. These advantages include a reduction in the temperatures and other stresses that this region of the rotor blade experiences during operation. While in some cases these stress reductions may be incremental in nature, they can nevertheless lead to significant performance advantages because of the region of the blade they affect.As is recognized, this outer radial portion of the rotor blade—which includes the outer radial tip of the blade and the tip cover band held there—is one that is important in determining the component's service life. Because of this service life-limiting aspect of this area, a small or incremental reduction of certain load factors can lead to disproportionate gains in extending the component's service life.

[0054] More precisely, and as can be seen, the various sealing rail configurations proposed herein are shaped to allow an increased level of tip leakage. This leakage is then directed and channeled along specific leakage flow paths created by the configurations presented. While such leakage usually has a negative impact on machine efficiency, it has been found that the resulting benefits to the service life of the rotor blades can more than compensate for this negative impact, provided the increased leakage flows are metered and / or controlled. For example, one factor enabling this compensatory benefit is the fact that, as mentioned above, the service life of rotor blades is often limited by the fatigue strength of this outer radial region.This means that the way in which this region withstands the extreme operational loads that occur here is usually a significant factor in determining the service life of the rotor blade. As is recognized, the high stress levels in this region of the rotor blade are caused by several factors, including the narrowness of the blade in this area, the higher rotational speeds, the weight of the tip trim, the stress concentration geometries, and the way in which the tip trim is cantilevered outwards from the supporting blade. Consequently, this region is more susceptible to suffering life-limiting damage, for example, if localized hotspots develop.It has been found that by allowing the additional leakage above the tip, as proposed herein, the occurrence of such localized hot spots can be significantly reduced or even prevented. Further advantages of the present configurations include a reduction in mechanical stresses, including the mitigation of certain detrimental vibration responses. Another advantage relates to the way in which the present invention can be used to reduce the weight of the tip cover strip by removing sections of the sealing rail.

[0055] By referring specifically to the various figures shown, several examples are provided that demonstrate how the sealing rails of the present invention can be used in conjunction with different types of top cover strips. As shown in the Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15 to Fig. Figure 16 illustrates the sealing rails shown in relation to a top cover strip that has a double sealing rail configuration. As shown in the Fig. 17, Fig. 18, Fig. 19 to Fig. Figure 20 illustrates alternative sealing rail configurations in relation to top cover tapes that have a single sealing rail. Unless otherwise stated, it should be understood that each of the different sealing rail configurations shown in relation to the Fig. Figures 9-20 are provided and can be used as part of a single or double sealing rail assembly. Thus, any sealing rail configuration shown in relation to any of the sealing rails in a double sealing rail configuration can also be used independently as part of a single sealing rail configuration. Furthermore, it should be understood that, unless otherwise specified, any sealing rail configuration illustrated in the figures as applied to a top cover strip with a single sealing rail can also be used for a sealing rail in a double sealing rail assembly.

[0056] Accordingly, the present invention comprises a tip cover strip 41 having one or more sealing rails 42, in which at least one of these sealing rails 42 forms a leakage gap 78, which, as provided herein, is configured to allow increased levels of leakage above the tip. As can be seen, according to some embodiments, the leakage gap 78 is formed by reducing the height of the sealing rail 42 over a circumferentially defined section, for which examples are given in the exemplary embodiments of the Fig. Figures 9 to 14 and 17 to 20 illustrate this. According to other embodiments, as described in the Fig. 15 and Fig. As illustrated in Figure 16, the leakage gap 78 is formed via an opening that extends through the thickness of the sealing rail 42.

[0057] By now focusing on the Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. As referenced in Section 14, various exemplary top cover strips 41 are illustrated, which have sealing rail configurations in which a leakage gap 78 is formed by reducing the height of at least one of these sealing rails 42 within a section defined along the circumference. As can be seen, one way in which this type of sealing rail configuration is defined and described in particular is by referring herein to designated “height sections” of the sealing rail 42. As used herein, such “height sections” represent reference sections of the sealing rail defined along the circumference, and they are described as they occur within circumferentially defined limits along the circumferential length of the sealing rail 42.It should be understood that these “height sections” divide the entire length of the sealing strip (for reference only) into two non-overlapping sections in the circumferential direction: a first height section 81, which refers to the height section in which the leakage gap 78 is formed; and a second height section 82, which refers to the height section that does not contain the leakage gap. For illustrative purposes, a dotted outline of the full (unreduced) height of the sealing strip 42 is provided in those height sections where the height of the sealing strip 42 is to be reduced to form a leakage gap 78. In this way, the location and extent of the height reduction within that particular height section of the sealing strip 42 can be clearly illustrated.As explained below, the specific sealing rail configurations according to the present invention can further differentiate between the sealing rails within a double sealing rail arrangement according to a relative front and rear positioning by referring to front and rear sealing rails. For a specific description within a single sealing rail, reference can also be made to the front and rear edge sections in the direction of rotation, which, as already described, are defined relative to the direction of rotation of the rotor blade during operation and the position of the cutting tooth section positioned between them.

[0058] Thus, as in the example of the Fig. 9, Fig. 10 to Fig. Figure 11 illustrates that, according to certain preferred embodiments of the present invention, the leakage gap 78 can be formed on either the front sealing rail 76 or the rear sealing rail 77 and may be absent on the other. Thus, in the Fig. 9 and Fig. Figure 10 illustrates the leakage gap 78 at the rear sealing rail 77, while it is missing at the front sealing rail 76, whereas in Fig. Figure 11 illustrates the leakage gap 78 at the front sealing rail 76, while it is absent at the rear sealing rail 76. As mentioned above regarding the nature and positioning of the leakage gap 78, the sealing rail configurations shown in the Fig. 9, Fig. 10 to Fig. Figure 11 illustrates how they are used on the sealing rails of top cover tapes with only a single sealing rail.

[0059] In Fig. 9. The leakage gap 78 can be more specifically described as being formed at the leading edge section 72 of the rear sealing rail 76 in the direction of rotation. In the provided example, the leakage gap 78 is formed by the fact that the leading edge section 72 of the rear sealing rail 76 has a significantly reduced height compared to the other sections or the remainder of the rear sealing rail 76. This configuration can alternatively be described in terms of the first and second height sections 81, 82, which have been explained above. As can be seen, the first height section 81 in this example can be defined as the approximate entirety of the leading edge section 72 in the direction of rotation, and the second height section 82 is defined as the approximate entirety of both the cutting tooth section 70 and the trailing edge section 73 in the direction of rotation.In an alternative arrangement (not illustrated), the leakage gap 78 can instead be formed at the rear edge section 73 in the direction of rotation. Accordingly, in the general description of possible embodiments of the present invention with respect to the first and second height sections 81, 82, the first height section 81 can contain any one of the front section 72 or rear section 73 in the direction of rotation, wherein the second height section 82 then contains both: the remaining single part of the front section 81 and the rear section 82 in the direction of rotation; and the cutting tooth section. As illustrated, the reduced height of the sealing rail 42 within the first height section 81 can be essentially constant. However, other possible configurations, as shown in the figures, include... Fig. Listed in sections 17-20, the sealing rail height varies within the first height section 81. The height of the sealing rail 42 within the second height section 82 can be essentially constant.

[0060] When defining the type of leakage gap 78, the significantly reduced height of the first height section 81 can be defined in relation to the height of the second height section 82. According to preferred embodiments, the significantly reduced height of the first height section 81 is less than 90% of the height of the second height section. According to other embodiments, the significantly reduced height can be defined in relation to the height of the cutting tooth 43 or the cutting tooth section 70. For example, the significantly reduced height can be between 40% and 90% of the height of the sealing rail 42 within the cutting tooth section 43. According to still further embodiments, as described below, the significantly reduced height is between 50% and 80% of the height of the sealing rail 42 within the cutting tooth section 43.

[0061] According to other embodiments, the leakage gap 78 can be configured as a reduced height section on each of the front and rear sections 72, 73 in the direction of rotation. Examples of this type of embodiment are given in the Fig. 10 and Fig. 11 shown. As can be seen, the rear sealing rail 77 is in Fig. 10 set up in this way, while in Fig. 11 this is the front sealing rail 76. In each exemplary configuration, both are true: the height of the sealing rail 42 within the forward section 72 (in the direction of rotation) is significantly reduced compared to the height of the sealing rail 42 within the cutting tooth section 70; and the height of the sealing rail 42 within the rear section 73 (in the direction of rotation) is significantly reduced compared to the height of the sealing rail 42 within the cutting tooth section 70. According to preferred embodiments, the forward section 72 and the rear section 73 (in the direction of rotation) can each have a sealing rail height between 40% and 90% of the height of the sealing rail 42 within the cutting tooth section 70.According to other embodiments, the front section 72 and the rear section 73, respectively, can each have a sealing rail height between 50% and 80% of the height of the sealing rail 42 within the cutting tooth section 70. As in . Fig. As illustrated in Figure 10, the reduction in the height of the sealing rail 42 within the front section 72 and the rear section 73 (in the direction of rotation) can be arranged such that both are approximately the same. Alternatively, as shown in Fig. Figure 11 illustrates that the relative heights of the sealing rail within these sections may be offset or different. For example, as shown in Fig. Figure 11 illustrates that the height of the sealing rail 42 within the front section 72 in the direction of rotation is greater than that of the rear section 73 in the direction of rotation.

[0062] As in the Fig. 12, Fig. 13 to Fig. As illustrated in Figure 14, alternative embodiments of the present invention include cases in which the leakage gap 78 is formed as circumferential sections with reduced height on each side of the front and rear sealing rails 76, 77. These configurations can be produced according to the principles already described. According to an exemplary embodiment, as shown in Figure 14, the leakage gap 78 is formed as circumferential sections with reduced height on each side of the front and rear sealing rails 76, 77. Fig. As illustrated in Figure 12, the rear sections 73 of both the front sealing rail 76 and the rear sealing rail 77, in the direction of rotation, are configured to contain the leakage gap 78 in the form of a reduced height section. As shown in Fig. As illustrated in Figure 13, the rear section 73 of the front sealing rail 76 (in the direction of rotation) and the front section 72 of the rear sealing rail 77 (in the direction of rotation) can be configured to contain the leakage gap 78 in the form of a reduced height section. As shown in Fig. As illustrated in Figure 14, according to a further embodiment, the front and rear sections 72, 73 of both the front sealing rail 76 and the rear sealing rail 77, in the direction of rotation, are configured to contain the leakage gap 78 in the form of a reduced height section. Other possible configurations are also feasible.

[0063] As in the Fig. 15 and Fig. As illustrated in Figure 16, alternative embodiments of the present invention include cases in which the leakage gap 78 is configured as one or more openings defined by the sealing rail 42, instead of the reduced height sections described above. Such openings can generally be defined as an enclosed passage extending axially through the thickness of the sealing rail 42 between an inlet formed by the front rail side 56 and an outlet formed by the rear rail side 57. In such cases, as illustrated, the height of the sealing rail 42 within the cutting tooth section 70, the front section 72 (in the direction of rotation), and the rear section 73 (in the direction of rotation) can be substantially constant and not reduced.According to exemplary embodiments, the leakage gap 78 includes at least one of the openings formed by at least one of the front and rear sections 72, 73 (in the direction of rotation) and at least one of the front and rear sealing rails 76, 77. According to the exemplary embodiments of the... Fig. 15 The leakage gap 78 contains a single opening formed through each of the front and rear sections 72, 73 of both the front and rear sealing rails 76, 77. According to alternative embodiments, the leakage gap 78 can contain multiple instances of the opening formed through each of the different sections of each sealing rail. An example of this is shown in Fig. Figure 16 shows an arrangement in which the leakage gap 78 has several openings formed through the front and rear sections 72, 73 of the rear sealing rail 77, respectively, in the direction of rotation. As illustrated, the front sealing rail 76 can be left untouched, so that it does not contain the leakage gap 78.

[0064] In the preceding examples, the reduced height sections forming the exemplary leakage gaps 78 were illustrated to have a constant height. According to further embodiments, as described in the Fig. 17, Fig. 18, Fig. 19 to Fig. As illustrated in Figure 20, the leakage gap 78 can also be configured as a reduced-height sealing rail section by varying the sealing rail height according to the circumferential position in accordance with a preferred contour or shape, which is referred to herein as a “molded profile”. Although each of the Fig. 17, Fig. 18, Fig. 19 to Fig. Figure 20 illustrates how the shaped profile is included in both the front and rear sections 72, 73 (in the direction of rotation). It should be understood that this is merely exemplary. It should be understood that the shaped profile may be included in only one of the front and rear sections 72, 73 of the sealing rail 42 (in the direction of rotation), while the remaining sealing rail section has a constant height, which may, for example, be equal to the height of the cutting tooth section 70. Furthermore, it should be understood that, although the exemplary shaped profiles are illustrated with respect to the tip cover strips 41 with a single sealing rail 42, possible embodiments of the present invention include the use of such shaped profiles on tip cover strips 41 with double sealing rail configurations.It should further be understood that any of the preceding leakage gap configurations explained in relation to top deck tapes with double sealing rail arrangements may be used on top deck tapes having only a single sealing rail.

[0065] As in Fig. As illustrated in Figure 17, the leakage gap 78, according to a preferred embodiment, is formed by a shaped profile of the sealing rail 42 that is concave along the cover edge 46. In this example, the outer rail edge 59 is configured as a concave surface that slopes down and then returns to its full height as it extends between the cutting tooth 43 and the rail edge 62, 63, which is forward in the direction of rotation. Fig. As illustrated in Figure 18, an alternative configuration of the shaped profile includes an inwardly sloping profile in which the height of the sealing rail 42 gently narrows or tapers as the sealing rail extends away from the cutting tooth 43. As shown in the Fig. 19 and Fig. As illustrated in Figure 20, the shaped profile according to further preferred embodiments is omitted, as is a corrugated or ribbed profile along the edge of the cover strip 46. This corrugated profile can be smoothly curved, as in the exemplary embodiment according to Figure 20. Fig. 19, or it may be of a more rectangular type, as in the exemplary embodiment according to Fig. 20. Other embodiments are also possible.

[0066] As a person skilled in the art will recognize, the many varying features and configurations described above in relation to the various exemplary embodiments can also be selectively applied to create the other possible embodiments of the present invention. For the sake of brevity and considering the capabilities of a person skilled in the art, not all of the possible iterations are listed or explained in detail, although all combinations and possible embodiments encompassed by the various claims below and elsewhere are intended to be part of the present application. Furthermore, those skilled in the art will perceive improvements, changes, and modifications from the preceding description of various exemplary embodiments of the invention.Such improvements, changes, and modifications within the technical knowledge are to be encompassed by the attached claims. Furthermore, it should be obvious that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications can be made to it without departing from the scope and extent of the application as defined by the following claims and their equivalents.

[0067] A turbine blade contains a tip shroud attached to the outer tip of the blade. The tip shroud may include a planar component extending axially and circumferentially, in which an inner surface faces an outer surface, and a shroud edge that connects the inner and outer surfaces and defines an outer profile of the tip shroud. The tip shroud may include a sealing lip projecting from the outer surface of the tip shroud and a cutting tooth arranged on the sealing lip. The cutting tooth may be designed as a circumferential section of the sealing lip that is thickened in the axial direction. The sealing lip may further include a leakage gap formed through it, designed to increase the leakage rate during operation.

Claims

[1] Turbine blade for a gas turbine, which contains: a blade defined between a concave pressure side and a laterally opposite convex suction side, wherein the pressure side and the suction side extend axially between a leading and an opposite trailing edge and radially between an outer tip and an inner end attached to a root configured to couple the blade to a rotor disk; a tip cover band attached to the outer tip of the blade, the tip cover band comprising: an axially and circumferentially extending planar component in which an inner surface faces an outer surface; and a cover band edge connecting the inner surface to the outer surface and defining an outer profile of the tip cover band; a sealing rail that protrudes from the outer surface of the top cover strip; wherein the sealing rail has a leakage gap formed through it, wherein the leakage gap is designed to increase a leakage rate during operation. [2] Rotor blade according to claim 1, wherein, assuming proper installation therein, the rotor blade can be described according to orientation characteristics of the turbine, which include: a radial, axial and circumferential direction, defined relative to a central axis of the turbine; a front and rear direction defined relative to a front end of the turbine where a working fluid enters the turbine and a rear end of the turbine where the working fluid exits the turbine; a direction of rotation defined relative to an expected direction of rotation of the rotor blade around the central axis of the turbine during operation; wherein, according to the orientation properties: the sealing rail projects from the outer surface along an axis that is approximately aligned with the radial direction to define a height; the sealing rail extends along an axis that is approximately aligned with the circumferential direction to define a length; the sealing rail has a narrow thickness relative to its length, extending along an axis that is approximately aligned with the axial direction; The sealing rail has opposing and essentially flat rail sides, with a front rail side and a rear rail side corresponding to the forward and reverse directions of the turbine, respectively. [3] Guide vane according to claim 2, which further comprises a cutting tooth arranged on the sealing rail, wherein the cutting tooth has a circumferential section of the sealing rail which is thickened in the axial direction; wherein the narrow thickness of the sealing rail is defined along a circumference of the sealing rail by rail edges extending between the front and rear rail sides; including the rail edges: an outer and an opposing inner rail edge, wherein the inner rail edge is defined at the connection that makes the sealing rail with the outer surface of the top cover strip and the outer rail edge is offset from the inner rail edge by the height of the sealing rail; a front rail edge in the direction of rotation and an opposite rear rail edge in the direction of rotation, each positioned near the edge of the deck strip such that the front rail edge in the direction of rotation leads the rear rail edge in the direction of rotation during operation with the given direction of rotation of the guide vane. [4] Guide vane according to claim 3, wherein the sealing rail has height sections between which the height of the sealing rail varies, wherein the height sections are defined in the circumferential direction and divide an entirety of the length of the sealing rail into two non-overlapping sections: a first height section and a second height section; where the leakage gap shows that the sealing rail of the first height section is significantly reduced compared to the height of the sealing rail within the second height section; wherein the sealing rail contains a circumferentially defined cutting tooth section which coincides with the cutting tooth, and wherein an entirety of the cutting tooth section is arranged within the second height section. [5] Guide vane according to claim 3, wherein the sealing rail has defined circumferential sections relative to the cutting tooth, comprising: a forward section in the direction of rotation; a cutting tooth section; and a rear section in the direction of rotation; where: the incisor section coincides with a circumference of the incisor; the section extending forward in the direction of rotation from the cutting tooth section to the rail edge extending forward in the direction of rotation; the rear section in the direction of rotation extends from the cutting tooth section to the rear rail edge in the direction of rotation; wherein the sealing rail has height sections between which the height of the sealing rail varies, wherein the height sections are defined in the circumferential direction and divide an entirety of the length of the sealing rail into two non-overlapping sections: a first height section and a second height section; where the leakage gap shows that the height of the sealing rail within the first height section is significantly reduced compared to the height of the sealing rail within the second height section. [6] Guide vane according to claim 5, wherein the first height section has a section that is forward in the direction of rotation and a section that is rear in the direction of rotation; wherein the second height section includes both the cutting tooth section and the section leading in the direction of rotation; where the significantly reduced height of the first elevation section is less than 90% of the height of the second elevation section. [7] Guide vane according to claim 5, wherein the first height section has one of the front section in the direction of rotation and one of the rear section in the direction of rotation; the second elevation section exhibits both: the other from the section that is forward in the direction of rotation and the section that is rear in the direction of rotation; and the incisor section; where the height of the second elevation section is essentially constant. [8] Guide vane according to claim 7, wherein the height of the sealing rail within the first height section varies such that the outer edge of the first height section forms a shaped profile; wherein the shaped profile has at least one of: a wavy profile; an inwardly sloping profile in which the height of the sealing rail decreases as the first height section extends away from the cutting tooth section; and a concave cover strip edge. [9] Guide vane according to claim 3, wherein the sealing rail has defined circumferential sections relative to the cutting tooth, comprising: a cutting tooth section coinciding with a circumferential length of the cutting tooth; a forward section in the direction of rotation extending from the cutting tooth section to the rail's forward edge in the direction of rotation; and a rearward section in the direction of rotation extending from the cutting tooth section to the rail's rearward edge in the direction of rotation; wherein the leakage gap comprises both: that the height of the sealing rail within the forward section in the direction of rotation is significantly reduced compared to the height of the sealing rail within the cutting tooth section; and that the height of the sealing rail within the rear section in the direction of rotation is significantly reduced compared to the height of the sealing rail within the cutting tooth section. [10] Guide vane according to claim 9, wherein the height of the sealing rail within the forward section in the direction of rotation and the rear section in the direction of rotation is between 50% and 80% of the height of the sealing rail within the cutting tooth section; wherein the height of the sealing rail within the front section in the direction of rotation and the height of the sealing rail within the rear section in the direction of rotation are approximately the same; wherein the cutting tooth is positioned at the approximate center of the sealing rail in the circumferential direction such that the circumferential length of the front section in the direction of rotation and that of the rear section in the direction of rotation are approximately equal. [11] Guide vane according to claim 9, wherein the height of the sealing rail within the forward section in the direction of rotation and the rear section in the direction of rotation is between 40% and 90% of the height of the sealing rail within the cutting tooth section; wherein the height of the sealing rail within the front section in the direction of rotation and the height of the sealing rail within the rear section in the direction of rotation are different; wherein the cutting tooth is positioned at the approximate center of the sealing rail in the circumferential direction such that the circumferential length of the front section in the direction of rotation and that of the rear section in the direction of rotation are approximately equal. [12] Guide vane according to claim 3, the sealing rail having circumferential sections defined relative to the cutting tooth, comprising: a cutting tooth section that coincides with a circumferential length of the cutting tooth; a forward section in the direction of rotation extending from the cutting tooth section to the rail edge that is forward in the direction of rotation; and a rearward section in the direction of rotation extending from the cutting tooth section to the rail edge that is rearward in the direction of rotation; wherein the height of the sealing rail within the cutting tooth section, the forward section in the direction of rotation and the rear section in the direction of rotation is essentially constant; wherein the leakage gap has one or more openings defined through the sealing rail. [13] Guide vane according to claim 12, wherein the one or more openings have or have openings such that at least one of the one or more openings is defined through each of the front section in the direction of rotation and the rear section in the direction of rotation of the sealing rail; wherein the one or more openings each have or have an enclosed passage extending axially through the thickness of the sealing rail between an inlet formed by the front side of the rail and an outlet formed by the rear side of the rail. [14] Guide vane according to claim 12, wherein the one or more openings each have an enclosed passage which extends axially through the thickness of the sealing rail between an inlet formed by the front side of the rail and an outlet formed by the rear side of the rail; wherein the enclosed passage is inclined at least one of the one or more openings with respect to the sealing rail. [15] Rotor blade for a turbine of a gas turbine, which contains; a blade defined between a concave pressure side and a laterally opposite convex suction side, wherein the pressure side and the suction side extend axially between a leading and an opposite trailing edge and radially between an outer tip and an inner end attached to a root configured to couple the blade to a rotor disk; a tip cover band attached to the outer tip of the blade, the tip cover band comprising: an axially and circumferentially extending planar component in which an inner surface faces an outer surface; and a cover band edge connecting the inner surface to the outer surface and defining an outer profile of the tip cover band; Sealing rails projecting from the outer surface of the top cover strip, the sealing rails comprising a front sealing rail positioned in front of a rear sealing rail and oriented substantially parallel to it; wherein at least one of the sealing rails has a leakage gap formed by it, wherein the leakage gap is designed to increase a leakage rate during operation.

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