Structural design (of a turbine blade) and cooling (of the same)

Abstract

Turbine blade comprising a profile (25) defined by a concave outer wall (26) on the pressure side and a convex outer wall (27) on the suction side, connected along a leading and trailing edge (28, 29) and forming a radially extending chamber between them for receiving the flow of a coolant, wherein the turbine blade further comprises: a rib arrangement that divides the chamber into radially extending flow channels (40); wherein the rib arrangement includes a cambered rib (62) with a wave profile cross-section; wherein the wave profile cross-section comprises at least one reciprocating “S” shape and wherein the turbine blade comprises a turbine rotor blade or a turbine guide vane; wherein the rib arrangement comprises two camber line ribs (62), wherein a camber line rib (63) on the pressure side includes one located near the outer wall (26) on the pressure side, and a camber line rib (64) on the suction side includes one located near the outer wall (27) on the suction side, wherein both the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side comprise a corrugated profile cross-section, and wherein the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side define a central flow channel between them; wherein the outer wall (26) on the pressure side and the camber line rib (63) on the pressure side define a pressure-side flow channel between them and wherein the outer wall (27) on the suction side and the camber line rib (64) on the suction side define a suction-side flow channel between them; the rib arrangement includes: - four transverse ribs (67) on the pressure side, which connect the outer wall (26) on the pressure side with the curvature line rib (63) on the pressure side and thereby divide the pressure-side flow channel; - four transverse ribs (68) on the suction side, which connect the outer wall (27) on the suction side with the camber line rib (64) on the suction side and thereby divide the suction-side flow channel; and - two central transverse ribs (69) that connect the camber line rib (63) on the pressure side with the camber line rib (64) on the suction side and thereby divide the central flow channel; wherein two of the four transverse ribs (67) on the pressure side are designed such that they form a connection angle with the outer wall (26) on the pressure side of less than approximately 60 degrees; wherein two of the four transverse ribs (68) on the suction side are designed such that they form a connection angle with the outer wall (27) on the suction side of less than approximately 60 degrees; and wherein one of the two central transverse ribs (69) forms a connection angle of less than approximately 60 degrees at the camber line rib (64) on the suction side as well as at the camber line rib (63) on the pressure side.

Description

GENERAL STATE OF THE ART

[0001] This invention relates to turbine profiles and in particular hollow turbine profiles, such as rotor blades or guide vanes, with internal channels for passing fluids such as air to cool the profiles.

[0002] Combustion or gas turbines (hereinafter referred to as "gas turbines") consist of a compressor, a combustion chamber, and a turbine. As is widely known in the field, compressed air is mixed with fuel in the combustion chamber to generate energy, ignited, and then expanded through the turbine. The turbine components, particularly the circumferentially arranged rotor and guide vanes, are exposed to a harsh environment characterized by the extremely high temperatures and pressures of the combustion products that expand through them. To withstand the repeated thermal cycling, as well as the extreme temperatures and mechanical stresses of this environment, the turbine profiles must be robustly constructed and actively cooled.

[0003] As can be seen, turbine rotor and guide vanes often contain internal connecting channels or circuits that form a cooling system through which a coolant, usually air taken from the compressor, is circulated. Such cooling circuits are typically formed by internal ribs that provide the necessary structural reinforcement of the airfoil and have multiple flow paths designed to maintain the airfoil within an acceptable temperature range. The air flowing through these cooling channels is often discharged through film cooling vents located at the leading edge, trailing edge, suction side, and pressure side of the airfoil.

[0004] It is evident that the efficiency of gas turbines increases with rising combustion temperatures. Therefore, there is a continuous need for technological advancements that enable turbine blades to withstand ever higher temperatures. These advancements sometimes involve new materials capable of withstanding the higher temperatures, but just as often they involve improvements to the internal airfoil design to optimize blade structure and cooling. However, since the use of coolant reduces the efficiency of the turbine, new designs that rely too heavily on increased coolant usage simply replace one power loss with another. Consequently, there remains a need for new airfoil designs that incorporate internal airfoil construction and coolant flow optimization to improve coolant efficiency.

[0005] One consideration that further complicates the design of internally cooled profiles is the temperature gradient that develops between the inner and outer structures of the profiles during operation. Since they are exposed to the influence of the hot gas path, the outer walls of the profile are typically at much higher temperatures during operation than many of the inner fins, where, for example, coolant may flow through channels defined on each side. A common profile design actually features a four-wall arrangement, in which very long inner fins run parallel to the outer walls on the pressure and suction sides. It is known that a high cooling effect can be achieved with the flow channels located near the walls, which are incorporated into the four-wall arrangement; however, the outer walls experience significantly greater thermal expansion than the inner walls.This unbalanced expansion causes stress to build up at the junctions between the inner ribs and outer walls, which can lead to fatigue at low load cycles and thus shorten the blade's service life. The development of profile structures that utilize coolant more efficiently while simultaneously reducing stresses caused by unbalanced thermal expansion between the inner and outer surfaces therefore remains a key concern for the technology industry.

[0006] US 2011 / 0236221A1 discloses a turbine blade with a profile design, comprising an arrangement with four walls, including outer walls on the pressure and suction sides, a cambered rib on the suction side with a corrugated cross-section comprising several reciprocating "S" shapes, and an arcuate cambered rib on the pressure side, with at least four transverse ribs on both the pressure and suction sides, dividing the pressure-side flow channel and the suction-side flow channel, and with at least one central transverse rib dividing the central flow channel, the transverse ribs being substantially perpendicular to the outer walls and cambered ribs.

[0007] GB 602 530 A discloses a gas turbine rotor blade with an internal rib arrangement comprising a camber line rib on the pressure side and a camber line rib on the suction side, each having a corrugated cross-section with several reciprocating “S” shapes and defining a continuous pressure-side flow channel and a continuous suction-side flow channel with the associated outer walls.

[0008] US 8 070 442 B1 discloses a turbine blade with an internal rib configuration comprising camber line ribs on the pressure side and suction side with a zigzag profile, as well as transverse ribs that run between and connect the camber line ribs on the pressure side and suction side.

[0009] Based on this, one object of the invention is to create turbine blades with profile structures that allow for more efficient use of coolant while simultaneously reducing stresses caused by unbalanced thermal expansion between inner and outer surfaces. BRIEF DESCRIPTION OF THE INVENTION

[0010] To solve the above problem, the invention provides a turbine blade with the features of independent claim 1 and a turbine rotor blade with the features of independent claim 10. Particularly preferred embodiments of the invention are specified in the dependent claims.

[0011] These and other features of the present application will become apparent from the following detailed description of the preferred embodiments in conjunction with the drawings and the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other features of this invention can be more fully understood and followed by reference to the following more detailed description of exemplary embodiments of the invention in conjunction with the associated drawings, in which: Fig. 1 is a simplified representation of an exemplary turbine in which certain embodiments of the present application may be used; Fig. 2 a sectional view of the compressor section of the combustion turbine of Fig. 1 is; Fig. 3 a sectional view of the turbine section of the combustion turbine of Fig. 1 is; Fig. 4 a perspective view of a turbine rotor blade of the type in which embodiments of the present invention can be used; Fig. 5 a cross-sectional view of a turbine rotor blade with an inner wall design or rib arrangement according to the conventional design; Fig. 6 is a cross-sectional view of a turbine rotor blade with an inner wall design according to an embodiment of the present invention; Fig. 7 a cross-sectional view of a turbine rotor blade with an inner wall design or rib arrangement according to an alternative embodiment of the present invention; Fig. 8 is a cross-sectional view of a turbine rotor blade with an inner wall design or rib arrangement according to an alternative embodiment of the present invention; and Fig. 9 is a cross-sectional view of a turbine rotor blade with an inner wall design or rib arrangement according to an alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] To clearly describe the present invention, it is necessary to select certain terms when referring to and describing corresponding machine components in a gas turbine. Where possible, common industry terms are used and applied according to their recognized meaning. Unless otherwise specified, such terms should be interpreted broadly in accordance with the context of this application and the scope of the appended claims. The person skilled in the art will recognize that a particular component can often be designated using several different or overlapping terms. A part described here as a single component may, in another context, comprise several components and be described as consisting of several components.Alternatively, a part described here as possibly comprising several components may elsewhere be referred to as a single component. Accordingly, when understanding the scope of the present invention, attention should be paid not only to the terminology and description provided here, but also to the structure, design, function, and / or use of the component.

[0014] In addition, several descriptive terms may be used regularly here, and it should prove helpful to define these terms at the beginning of this section. Unless otherwise stated, these terms and their definitions are as follows. The terms "in the direction of flow" and "against the direction of flow" are terms that indicate a direction with respect to the flow of a fluid, such as the working fluid through the turbine, or, for example, the airflow through the combustion chamber, or of coolant through one of the turbine's component systems. The term "in the direction of flow" corresponds to the flow direction of the fluid, and the term "against the direction of flow" refers to the direction opposite to the flow.The terms "front" and "rear" without further specification refer to directions, with "front" referring to the front end or compressor end of the power unit and "rear" to the rear end or turbine end. It is often necessary to describe parts located at different radial positions relative to a central axis. The term "radial" refers to a movement or position perpendicular to an axis. In such cases, if a first component is closer to the axis than a second component, it is indicated here that the first component is "radially inward" to the second component or "further inward" than the second component. Conversely, if the first component is farther from the axis than the second component, it may be indicated here that the first component is "radially outward" to the second component or "further outward" than the second component.The term "axial" refers to a movement or position parallel to an axis. The term "circumferential" refers to a movement or position around an axis. It is clear that these terms can be applied to the turbine's central axis.

[0015] The background is illustrated in the figures. Fig. 1, Fig. 2, Fig. 3 to Fig. 4. An exemplary combustion turbine in which embodiments of the present application can be used. Those skilled in the art understand that the present invention is not limited to this particular type of use. The present invention can be used in combustion turbines such as those used in power generation, in aircraft, and in other types of power machines. The examples mentioned are not intended to be limiting unless otherwise stated.

[0016] Fig. Figure 1 is a simplified representation of a combustion turbine. In general, combustion turbines work by extracting energy from a pressurized stream of hot gas, which is produced by burning a fuel in a stream of compressed air. As in Fig. As shown in Figure 1, the combustion turbine 10 can be designed with an axial compressor 11, which is mechanically coupled via a common shaft or rotor to a turbine section located at the rear in the direction of flow or to the turbine 13 and a combustion chamber 12, which is placed between the axial compressor 11 and the turbine 13.

[0017] Fig. Figure 2 illustrates a representation of an exemplary multi-stage axial compressor 11, which is used in the combustion turbine of Fig. 1 can be used. As shown, the axial compressor 11 can have a plurality of stages. Each stage can have a series of compressor impeller blades 14, followed by a series of compressor guide vanes 15. Thus, a first stage can have a series of compressor impeller blades 14 rotating around a central shaft, followed by a series of compressor guide vanes 15 that remain stationary during operation.

[0018] Fig. Figure 3 illustrates a partial representation of an exemplary turbine section or an exemplary turbine 13, which is or is located in the combustion turbine of Fig. 1. The turbine 13 can have a plurality of stages. Three exemplary stages are shown, but the turbine 13 may have more or fewer stages. A first stage has a plurality of turbine blades or turbine rotor blades 16 that rotate around the shaft during operation, and a plurality of guide vanes or turbine guide vanes 17 that remain stationary during operation. The turbine guide vanes 17 are generally spaced apart circumferentially and are fixed around the axis of rotation. The turbine rotor blades 16 can be mounted on a turbine wheel (not shown) so that they rotate around the shaft (not shown). A second stage of the turbine 13 is also shown.The second stage also features a plurality of circumferentially spaced turbine guide vanes 17, followed by a plurality of circumferentially spaced turbine rotor blades 16, which are also mounted on a turbine wheel to enable rotation. A third stage is also shown and likewise features a plurality of turbine guide vanes 17 and rotor blades 16. It can be seen that the turbine guide vanes 17 and the turbine rotor blades 16 are located in the hot gas path of the turbine 13. The direction of hot gas flow through the hot gas path is indicated by the arrow. As an average expert can see, the turbine 13 may have more, or in some cases fewer, stages than the one shown in Figure 1. Fig. 3 shown. Each additional stage can have a series of turbine guide vanes 17, followed by a series of turbine rotor blades 16.

[0019] In one operational example, the rotation of the compressor blades 14 in the axial compressor 11 compresses an airflow. Energy can be released in the combustion chamber 12 when the compressed air is mixed with a fuel and ignited. The resulting hot gas flow from the combustion chamber 12, which can be referred to as the working fluid, is then directed over the turbine blades 16, causing them to rotate around the shaft. The energy of the working fluid flow is thereby converted into the mechanical energy of the rotating blades and, due to 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 necessary supply of compressed air, and, for example, to drive a generator to produce electricity.

[0020] Fig. Figure 4 is a perspective view of a turbine blade 16 of the type in which embodiments of the present invention can be used. The turbine blade 16 has a base 21 by which the turbine blade 16 is attached to an impeller disk. The base 21 can have a dovetail designed to be mounted in a corresponding dovetail slot on the circumference of the impeller disk. The base 21 can further have a shaft extending between the dovetail and a platform 24 located at the junction of the profile 25 and the base 21, which defines a section of the inner boundary of the flow path through the turbine 13. It can be seen that the profile 25 is the effective component of the turbine blade 16, which receives the working fluid flow and causes the impeller disk to rotate.Although the blade in this example is a turbine rotor blade 16, it can be seen that the present invention can also be applied to other types of blades in the combustion turbine 10, including turbine guide vanes 17. It can be seen that the profile 25 of the turbine rotor blade 16 has a concave outer wall 26 on the pressure side and a circumferentially or laterally opposing convex outer wall 27 on the suction side, each extending axially between the opposing leading and trailing edges 28, 29. The side walls 26 and 27 also extend radially from the platform 24 to a more outwardly located tip 31. (It can be seen that the application of the present invention may not be limited to turbine rotor blades, but may also be applicable to guide vanes.)The use of guide vanes in the various embodiments described here is exemplary unless otherwise stated.

[0021] Fig. Figure 5 shows an internal wall structure as it may be found in a conventionally designed rotor blade profile 25. As indicated, the outer surface of the profile 25 can be defined by a relatively thin outer wall 26 on the pressure side and outer wall 27 on the suction side, which may be connected by a plurality of radially extending and intersecting ribs 60. The ribs 60 are designed to structurally reinforce the profile 25 while simultaneously defining a plurality of radially extending and substantially separate flow channels 40. The ribs 60 are usually radially extended so that they subdivide the flow channels 40 over a large proportion of the radial height of the profile 25; however, as explained in more detail below, the flow channel can be connected along the circumference of the profile, thus defining a cooling channel.The flow channels 40 can therefore be fluidically connected at the outer or inner edge of the profile 25, as well as via several smaller cross-connection channels or impact cooling openings (not shown) that may be positioned between them. In this way, certain flow channels 40 can together form a winding or meandering cooling channel. Additionally, film cooling openings (not shown) may be included, which represent outlet openings through which coolant from the flow channels 40 exits onto the outer surface of the profile 25.

[0022] The ribs 60 can comprise two different designs, which can then be further subdivided as shown here. A first design, a camber line rib 62, is usually a very long rib that runs parallel or approximately parallel to the camber line of the profile, which is a reference line extending from the leading edge 28 to the trailing edge 29 and connecting the midpoints between the outer wall 26 on the compression side and the outer wall 27 on the suction side. As is often the case, the conventional design of Fig. 5. Two bulging line ribs 62, a bulging line rib 63 on the pressure side, which, considering how it is offset from and located near the outer wall 26 on the pressure side, can also be referred to as the inner wall on the pressure side, and a bulging line rib 64 on the suction side, which, considering how it is offset from and located near the outer wall 27 on the suction side, can also be referred to as the inner wall on the suction side. As mentioned, this type of configuration is often described as having a four-wall arrangement due to the widespread presence of four main walls, which include the two side walls 26, 27 and the two bulging line ribs 63, 64. It can be seen that the outer walls 26, 27 and the bulging line ribs 62 are cast as single-piece components.

[0023] The second rib configuration is referred to here as transverse rib 66. The transverse ribs 66 are the shorter ribs shown, which connect the walls and inner ribs of the arrangement with four walls. As indicated, the four walls can be connected by several transverse ribs 66, which can be further subdivided according to which walls they connect. The transverse ribs 66 that connect the outer wall 26 on the compression side with the camber line rib 63 on the compression side are referred to here as transverse ribs 67 on the compression side. The transverse ribs 66 that connect the outer wall 27 on the suction side with the camber line rib 64 on the suction side are referred to as transverse ribs 68 on the suction side. Finally, the transverse ribs 66 that connect the camber line rib 63 on the compression side with the camber line rib 64 on the suction side are referred to as central transverse ribs 69.

[0024] In general, the internal design with four walls in a profile 25 aims to provide effective cooling near the walls, with the cooling air flowing in channels adjacent to the outer walls 26, 27 of the profile 25. It can be seen that cooling near the walls is advantageous because the cooling air is located very close to the hot outer surfaces of the profile, and the resulting heat transfer coefficients are high due to the high flow velocity achieved by restricting the flow through narrow channels. However, such designs tend to exhibit fatigue at low load cycles due to differing rates of thermal expansion within the profile 25, which can ultimately shorten the service life of the rotor blade. For example, the outer walls 27 on the suction side expand more under the influence of heat during operation than the cambered fin 64 on the suction side.Due to this differential expansion, the length of the camber line of profile 25 tends to lengthen, thereby generating stresses between each of these structures and the structures connecting them. Furthermore, the outer wall 26 on the compression side expands more under the influence of heat than the cooler camber line rib 63 on the compression side. In this case, the length of the camber line of profile 25 tends to shorten due to the difference, thereby generating stresses between each of these structures and the structures connecting them. The opposing forces within the profile, which in one case tend to shorten the profile camber line and in the other case tend to lengthen it, can lead to further stress concentrations.How differently these forces manifest themselves, taking into account the special structural design of a profile, and the way in which the forces are then balanced and compensated, significantly determine the partial service life of the turbine running blade 16.

[0025] In a typical scenario, the outer wall 27 on the suction side tends to bend outwards at the apex of its curvature due to thermal expansion caused by the high temperatures of the hot gas path. It can be seen that the thermal expansion of the cambered rib 64 on the suction side, being an inner wall, is not as pronounced, and therefore it does not tend to bend outwards to the same extent. The cambered rib 64 thus resists the thermal expansion of the outer wall 27. Since, in conventional designs, cambered ribs 62 have a rigid geometry offering little or no compliance, this rigidity and the resulting stress concentrations can be considerable.The problem is exacerbated by the fact that the transverse ribs 66 used to connect the cambered rib 62 to the outer wall 27 have linear profiles and are generally oriented at right angles to the walls they connect. The transverse ribs 66 therefore function in such a way that they essentially maintain the "cold" spatial relationship between the outer wall 27 and the cambered rib 64 when the heated structures expand at significantly different rates. Conventional arrangements with little or no "flexibility" integrated into the design are consequently hardly suitable for reducing stresses that concentrate in certain areas of the structure. The differing rates of thermal expansion lead to fatigue problems at low load cycles, thus shortening the component's service life.

[0026] In the past, many different internal cooling systems and structural designs for profiles have been evaluated, and attempts have been made to resolve this problem. One such approach proposes subcooling the outer walls 26, 27 to reduce the temperature gradient and thus the thermal expansion gradient. However, it is apparent that this is usually achieved by increasing the amount of coolant circulated through the profile. Since the coolant is typically air drawn from the compressor, its increased use negatively impacts the efficiency of the compressor, and this is therefore a solution that is preferably avoided. Other solutions have proposed the use of improved manufacturing processes and / or more complex internal cooling arrangements that utilize the same amount of coolant but more efficiently.While these solutions have proven effective to some extent, they each increase either the cost of operating the power machine or the cost of manufacturing the part and do not directly address the underlying problem, namely the geometric shortcomings of the conventional design given the way profiles expand during operation under the influence of heat.

[0027] The teaching of the present invention relates generally to certain curved, bubble-shaped, sinusoidal, or corrugated internal ribs (hereinafter referred to as "corrugated ribs") that mitigate unbalanced thermal stresses commonly found in the profile of turbine blades. Within the scope of this general concept, the present application describes several ways in which this can be achieved, including cambered ribs 62 and / or transverse ribs 66, as well as certain types of angled connections between them. It can be seen that these novel arrangements—which, as described in the appended claims, can be used separately or in combination—reduce the stiffness of the internal structure of the profile 25, thereby providing targeted flexibility with which stress concentrations are distributed and loads are transferred to other structural areas that are better able to withstand them.This can include, for example, transferring the stress to an area that distributes it over a larger surface, or perhaps a structure that delivers compressive stress, which is usually more preferred, rather than tensile stress. In this way, stress concentrations and strains that shorten the service life can be avoided.

[0028] Fig. 6, Fig. 7 to Fig. Figure 8 shows cross-sectional views of a turbine rotor blade 16 with an inner wall design according to embodiments of the present invention. The present invention particularly includes the design of ribs 60, which are typically used both for structural reinforcement and as subdivisions, dividing the hollow profiles 25 into substantially separate radially extending flow channels 40, which can, as desired, be connections for generating cooling channels. These flow channels 40 and the circuits they form are used to direct a flow of coolant through the profile 25 in a specific manner, enabling its targeted and more efficient use. Although the examples shown here are depicted as they could be used in turbine rotor blades 16, it is evident that the same concepts can also be applied to turbine guide vanes 17.In one embodiment, the rib arrangement of the present invention has a cambered rib 62 with a corrugated cross-section. (The term "cross-section" here refers to the shape that the ribs have in the cross-sectional representations of . Fig. 6, Fig. 7 to Fig. 8 exhibit.) A camber line rib 62, as previously described, is one of the longer ribs that typically extend from a position near the leading edge 28 of the profile 25 towards the trailing edge 29. These ribs are referred to as “camber line ribs” because the path they take is approximately parallel to the camber line of the profile 25, which is a reference line extending between the leading edge 28 and the trailing edge 29 of the profile 25 through a cluster of points equidistant between the concave outer wall 26 on the compression side and the convex outer wall 27 on the suction side. According to the present application, a “corrugated profile cross-section” comprises one that, as specified, has a noticeably curved and sinusoidal shape. In other words, the “corrugated profile cross-section” is one that has a reciprocating “S” profile cross-section.Examples of this particular type of corrugated profile cross-section are described previously in . Fig. 6 and Fig. 7 explained.

[0029] The segment or portion of the camber line rib 62, which is designed with the corrugated profile cross-section, can vary depending on the design criteria. In the examples presented, the camber line corrugated rib 62 typically extends from a position near the leading edge 28 of the profile 25 to a position beyond the midpoint of the camber line of the profile 25. It can be seen that the corrugated section of the camber line rib 62 can be shorter while still providing the same types of performance advantages discussed here. The number of curves and the length of the corrugated segment of the camber line rib 62 can be varied to achieve the best results. In certain embodiments, the camber line rib 62 of the present invention is defined by the number of complete reciprocating "S" shapes it contains.In a preferred embodiment of this type, the curvature line rib 62 has at least one continuous reciprocating "S" shape. In a further embodiment, the curvature line rib 62 has at least two successive and continuous reciprocating "S" shapes. It can be seen that the in . Fig. 6 and Fig. In the seven examples presented, each path involves more than two complete "S" shapes. Regarding its overall length, the wave segment of the camber line rib 62 can extend over a substantial portion of the length of the camber line of the profile 25. As shown in Fig. 6 and Fig. As shown in Figure 7, in a preferred embodiment, the wave section of the camber line rib 62 is, for example, over 50% of the length of the camber line of the profile 25. In other words, the wave section of the camber line rib 62 begins near the leading edge 28 of the profile 25 and extends rearward and well beyond the apex of the curvature of the profile 25. It can be seen that shorter lengths can also be used with performance advantages, for example, wave sections of at least 15% of the camber line rib 62.

[0030] It can be seen that a camber line rib 62, due to its coiled profile, follows a path whose direction changes. The camber line rib 62 of the present invention can nevertheless be described as having a general arc path along which it coils, and that this path typically extends from a starting point near the leading edge 28 and an end point near the trailing edge 29 of the profile 25. It can be seen that, in a camber line rib 62, this general arc path runs approximately parallel to the camber line of the profile 25.

[0031] Many well-known designs of profile 25, for example the previously discussed four-wall example of Fig. 5, have two convex line ribs 62. This design can be described as having a convex line rib 63 on the pressure side, which is located closer to the outer wall 26 on the pressure side, and a convex line rib 64 on the suction side, which is located closer to the outer wall 27 on the suction side. The present invention, as described in Fig. 6 and Fig. As shown in Figure 7, the design can include configurations in which both the camber line rib 64 on the suction side and the camber line rib 63 on the pressure side are designed as wave ribs. In alternative embodiments, only one of these camber line ribs 62 may have a wave profile cross-section. It can be seen that the present invention can also be used in configurations with only a single camber line rib 62.

[0032] In profiles 25, which contain two cambered ribs 62, it can be seen that the cambered rib 63 on the pressure side and the cambered rib 64 on the suction side define a central flow channel 40. The corrugated cross-section for the cambered rib 63 on the pressure side, as well as the cambered rib 64 on the suction side, can be defined with respect to the shape that successive segments of the cambered rib 62 assume relative to the central flow channel 40. That is, the corrugated cross-section of the cambered rib 62 with respect to the central flow channel 40 can, for example, be described as having two successive segments in which a first concave segment transitions into a second convex segment.In an alternative embodiment, the wave profile cross-section can have four or more successive segments, wherein: a first concave segment transitions into a second convex segment; the second convex segment transitions into a third concave segment; and the third concave segment transitions into a fourth convex segment.

[0033] As in Fig. As shown in Figure 8, an alternative embodiment features a repetition of convex segments. In this type of wave rib design, it can be seen that the wave profile cross-section for the camber line ribs 62 (relative to the central flow channel) has convex segments arranged one after the other. In a preferred embodiment of this type, the camber line ribs 62 each have at least four of these convex segments arranged one after the other, as shown in the illustration. (It can be seen that in this type of embodiment, a short concave segment can be used to connect the much longer convex segments in order to avoid stress concentrations.)

[0034] The teaching of the present invention includes specific designs of the transverse ribs 66, which can be used to adjust the compliance of the profile 25. Transverse ribs 66 are the shorter ribs that run transversely across the profile 25. They are used to connect the camber line ribs 62 either to other camber line ribs or to one of the outer walls 26, 27 of the profile 25. It can be seen that in such a design, the transverse ribs 66 also serve as subdivisions of the flow channels 40 formed between the outer walls 26, 27 and the camber line ribs 62. As shown, the outer wall 26 on the compression side and the camber line rib 63 on the compression side are designed to define a compression-side flow channel between them.Similarly, the outer wall 27 on the suction side and the cambered rib 64 on the suction side are designed to define a suction-side flow channel 40 between them. The central flow channel 40 is defined between the cambered rib 64 on the suction side and the cambered rib 63 on the pressure side. As indicated, these flow channels 40 can then be further subdivided by the transverse ribs 66. In certain embodiments of the present invention, several transverse ribs 67 on the pressure side connect the outer wall 26 on the pressure side to the cambered rib 63 on the pressure side. The transverse ribs 67 on the pressure side thus subdivide the pressure-side flow channel into several separate, axially adjacent flow channels 40.Likewise, several transverse ribs 68 on the suction side connect the outer wall 27 on the suction side with the camber line rib 64 on the suction side and divide the suction-side flow channel 40 into several separate, axially adjacent flow channels 40. Central transverse ribs 69 connect the camber line rib 63 on the pressure side with the camber line rib 64 on the suction side and likewise divide the central flow channel.

[0035] The camber line ribs 62 and transverse ribs 66 can be designed as radially extending walls. These ribs can therefore be the ones shown in the cross-sectional views of Fig. 6, Fig. 7 to Fig. The eight profiles shown are formed and simultaneously extend radially between the two ends of the profile 25. In this way, the pressure-side flow channels, suction-side flow channels, and central flow channels 40 can extend radially between a more inward end, located near the contact surface between the profile 25 and the base 21, and a more outward end, located near the more outward tip 31 of the profile 25. During operation, a quantity of coolant can be supplied to one or more of the more inward ends of the flow channels 40 via a supply channel that extends through a base 21. It can be seen that the flow channels 40 can be selectively connected at their more inward or more outward ends to create a winding coolant path through the profile 25.

[0036] The rib arrangement of the present invention can have several transverse ribs 66 on both the pressure and suction sides of the profile 25. In preferred embodiments, at least five transverse ribs 67 can be included on the pressure side and five transverse ribs 68 on the suction side. Several central transverse ribs 69 can also be provided. As shown, the present invention can, in preferred embodiments, have at least two central transverse ribs 69. The present invention further describes a connection arrangement by which the transverse ribs 66 are connected to the outer walls 26, 27 and / or the camber line ribs 62. It can be seen that the angle at which the transverse ribs 66 intersect these walls 26, 27 or camber line ribs 62 can be described as the "connection angle".(It can be seen that the aforementioned “connection angle” is the smaller of the two angles formed on either side of each end of a transverse rib between the transverse rib and the wall it intersects.) In conventional profile designs, as mentioned previously, the connection angle is a steep angle, generally close to 90°. It can be seen that such steep angles provide a rigid structure. The teaching of the present invention includes angles of less than 90° as a way in which the structure of a profile 25 or specific areas of the structure can be made more compliant. According to one embodiment, as shown in . Fig. 6 and Fig. As shown in Figure 7, at least two of the transverse ribs 67 on the pressure side are designed such that they form a connection angle with the outer wall 26 on the pressure side of less than approximately 60 degrees. According to a further embodiment, as indicated, at least two of the transverse ribs 68 on the suction side can be designed such that they form a connection angle with the outer wall 27 on the suction side of less than approximately 60 degrees. The central transverse ribs 69 can be similarly shaped, and in embodiments of the present invention, at least one connection angle of less than approximately 60 degrees is provided at the cambered rib 64 on the suction side as well as at the cambered rib 63 on the pressure side.If improved compliance is required, in embodiments three of the transverse ribs 67 on the pressure side and three of the transverse ribs 68 on the suction side may be provided such that they have a connection angle with the outer walls 26, 27 of less than approximately 60 degrees, and at least two of the central transverse ribs 69 may be designed such that they form a connection angle of less than approximately 60 degrees at the camber line rib 64 on the suction side as well as at the camber line rib 63 on the pressure side.

[0037] The present invention further describes another way in which transverse ribs 66 can improve structural compliance. The transverse ribs 66 are usually designed with a linear profile cross-section, which noticeably leads to a stiff and inflexible design. According to certain embodiments of the present invention, the transverse ribs 66 are designed to have a curved profile cross-section. In particular, the central transverse ribs 69, as in each of the examples in Fig. 6, Fig. 7 to Fig. Figure 8 shows a curved, arcuate, or bent profile cross-section. With this profile cross-section, the transverse ribs 66 become much more compliant and are able to compensate for relative movement between the component walls they connect. The direction in which the curved profile cross-section of the transverse rib is oriented can be influenced to accommodate the different expected stresses. According to a preferred embodiment, as shown in Figure 8, the profile cross-section of the transverse rib is shaped as follows: Fig. As shown in Figure 6, the arc of the central transverse rib 69 can be guided such that the concave surface of the central transverse ribs 69 is directed towards the leading edge 28 of the profile 25. This alignment can be performed on all of the central transverse ribs 69 contained in a given structure, or on a fraction thereof. In an alternative embodiment, as shown in Fig. As shown in Figure 7, the arc of the central transverse ribs 69 can be guided such that the convex surface of the transverse rib is directed away from the leading edge 28 of the profile 25. This type of profile cross-section can be used for all central transverse ribs 69 or only a fraction of them.

[0038] As in Fig. As shown in Figure 9, an alternative embodiment features a cambered rib 62 that has a repetition of concave segments. In this type of corrugated rib design, it can be seen that the corrugated profile cross-section for the cambered ribs 62 (relative to the central flow channel 40) has convex segments arranged one after the other. In a preferred embodiment of this type, the cambered ribs 62 each have at least four of these concave segments arranged one after the other, as shown in the illustration. (It can be seen that in this type of embodiment, a short convex segment can be used to connect the much longer convex segments in order to avoid stress concentrations.)

[0039] Fig. Figure 9 also features alternative embodiments of the transverse ribs 66. As already mentioned, according to the present invention, the central transverse ribs 69 can have a curved or bent profile cross-section. In addition, according to alternative embodiments, the transverse ribs 67, 68 on the pressure and suction sides can also have curved profiles. Exemplary types of curved profiles are shown along the suction side of the profile 25 in Figure 9. Fig. Figure 9 shows that, as indicated, the transverse ribs 67, 68 on the suction and pressure sides can, in particular, form an arc between the walls they connect. The arc can be oriented such that a convex surface faces the leading edge 28 of the profile 25. Alternatively, the arc can be oriented such that a concave surface faces the leading edge 28 of the profile 25. As also shown in Fig. As shown in Figure 9, the transverse ribs 66, similar to the camber line ribs 62, can be designed to have an "S" shape. As indicated, in a preferred embodiment, the central transverse ribs 69 can have this design. In alternative embodiments, an "S" shape can be used either for the transverse ribs 67 on the pressure side or for the transverse ribs 68 on the suction side, or for both. Furthermore, in a preferred embodiment, as shown in the direction of the leading edge 28 of the profile 25 in Fig.As shown in Figure 9, the transverse rib 67 on the compression side, the transverse rib 68 on the suction side, and the central transverse rib 69 form a corrugated cross-section or an "S" shape by alternating the orientation of the arcs formed by each rib. Thus, the transverse rib 67 on the compression side has a convex surface in the direction of the leading edge 28, the central transverse rib 69 has a concave surface in the direction of the leading edge 28, and the transverse rib 68 on the suction side has a convex surface in the direction of the leading edge 28 of the profile 25.

[0040] According to the present invention, the internal structure of a profile can have wave-like ribs along the camber line direction of the profile. By manufacturing the camber line rib 62 in this way as a spring, the internal framework of the profile can be made more flexible, thus achieving performance advantages. The transverse ribs of the profile structure can additionally be curved to further increase the flexibility of the load path and to create more compliant connections to the camber line ribs 62 and the outer walls 26, 27 that they connect.While conventional linear rib designs are subject to high stress and exhibit fatigue at low load cycles due to the differences in behavior under heat influence between the cavity walls for internal cooling and the much hotter outer walls, the present invention provides a spring-like construction that is better able to distribute stress concentrations, which can be used to improve the service life of the component, as explained herein.

[0041] As a person skilled in the art will recognize, the many different features and designs previously described in relation to the various embodiments can be further applied to develop 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 possible repetitions are detailed or discussed, although all combinations and possible embodiments that include the various claims below or are otherwise contained are intended to be part of this application. The invention is defined by the claims.

[0042] A turbine blade has a profile defined by a concave outer wall on the pressure side and a convex outer wall on the suction side, connected along leading and trailing edges, forming a radially extending chamber between them for receiving the flow of a coolant. The turbine blade may further feature a rib arrangement that divides the chamber into radially extending flow channels. The rib arrangement may include a cambered rib with a corrugated cross-section. The corrugated cross-section may have at least one reciprocating "S" shape. REFERENCE MARK LIST: 10 Combustion turbine 11 axial compressors 12 Combustion chamber 13 Turbine 14 Compressor impeller blades 15 Compressor guide vanes 16 turbine rotor blades 17 Turbine guide vanes 21 feet 24 platform 25 Profile 26 Outer wall on the print side 27 Outer wall on the suction side 28 Leading edge 29 trailing edge 31 top 40 Flow channel 60 rib 62 Curvature line rib 63 Curvature line rib on the pressure side 64 Curvature line rib on the suction side 66 transverse rib 67 transverse ribs on the pressure side 68 transverse ribs on the suction side 69 central transverse rib

Claims

[1] Turbine blade comprising a profile (25) defined by a concave outer wall (26) on the pressure side and a convex outer wall (27) on the suction side, connected along a leading and trailing edge (28, 29) and forming a radially extending chamber between them for receiving the flow of a coolant, wherein the turbine blade further comprises: a rib arrangement that divides the chamber into radially extending flow channels (40); wherein the rib arrangement includes a cambered rib (62) with a wave profile cross-section; wherein the wave profile cross-section comprises at least one reciprocating “S” shape and wherein the turbine blade comprises a turbine rotor blade or a turbine guide vane; wherein the rib arrangement comprises two camber line ribs (62), wherein a camber line rib (63) on the pressure side includes one located near the outer wall (26) on the pressure side, and a camber line rib (64) on the suction side includes one located near the outer wall (27) on the suction side, wherein both the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side comprise a corrugated profile cross-section, and wherein the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side define a central flow channel between them; wherein the outer wall (26) on the pressure side and the camber line rib (63) on the pressure side define a pressure-side flow channel between them and wherein the outer wall (27) on the suction side and the camber line rib (64) on the suction side define a suction-side flow channel between them; the rib arrangement includes: - four transverse ribs (67) on the pressure side, which connect the outer wall (26) on the pressure side with the curvature line rib (63) on the pressure side and thereby divide the pressure-side flow channel; - four transverse ribs (68) on the suction side, which connect the outer wall (27) on the suction side with the camber line rib (64) on the suction side and thereby divide the suction-side flow channel; and - two central transverse ribs (69) that connect the camber line rib (63) on the pressure side with the camber line rib (64) on the suction side and thereby divide the central flow channel; wherein two of the four transverse ribs (67) on the pressure side are designed such that they form a connection angle with the outer wall (26) on the pressure side of less than approximately 60 degrees; wherein two of the four transverse ribs (68) on the suction side are designed such that they form a connection angle with the outer wall (27) on the suction side of less than approximately 60 degrees; and wherein one of the two central transverse ribs (69) forms a connection angle of less than approximately 60 degrees at the camber line rib (64) on the suction side as well as at the camber line rib (63) on the pressure side. [2] Turbine blade according to claim 1, wherein the shaft profile cross-section comprises at least two successive reciprocating ‘S’ shapes and wherein the turbine blade comprises a turbine rotor blade. [3] Turbine blade according to claim 1, wherein the camber line ribs (63, 64) on the pressure side and on the suction side begin near the leading edge (28) of the profile (25) and wind back and forth over an arc path extending towards the trailing edge (29) of the profile (25), the arc path being approximately parallel to a camber reference line of the profile (25); and wherein the arc path of the camber line ribs (63, 64) on the pressure side and on the suction side has a length that is at least 15% of a length of the camber reference line of the profile (25) or at least 50% of a length of the camber reference line of the profile (25). [4] Turbine blade according to claim 2, wherein the shaft profile cross-section for the camber line rib (63) on the pressure side and / or the camber line rib (64) on the suction side comprises a section which, with respect to the central flow channel, has at least two successive segments in which a first concave segment transitions into a second convex segment. [5] Turbine blade according to claim 1, wherein the shaft profile cross-section for the camber line rib (63) on the pressure side as well as the camber line rib (64) on the suction side comprises a section which, with respect to the central flow channel, has at least four successive segments, wherein a first concave segment transitions into a second convex segment and the second convex segment transitions into a third concave segment and the third concave segment transitions into a fourth convex segment; and / or wherein the wave profile cross-section for the camber line rib (63) on the pressure side as well as the camber line rib (64) on the suction side comprises one which has at least three convex segments placed one behind the other with respect to the central flow channel; and / or wherein the wave profile cross-section for the camber line rib on the pressure side as well as the camber line rib on the suction side comprises one which has at least three concave segments placed one behind the other with respect to the central flow channel. [6] Turbine blade according to claim 1, wherein the rib arrangement is arranged such that the pressure-side flow channel, the suction-side flow channel and the central flow channel extend radially between a first end located near a more inward boundary of the profile (25) and a second end located near a more outward boundary of the profile (25); and wherein the pressure-side flow channel, the suction-side flow channel and / or the central flow channel are connected to a supply channel designed to receive a flow of cooling medium through a foot (21) of the turbine blade during operation. [7] Turbine blade according to claim 1, wherein three of the four transverse ribs (67) on the pressure side are designed to form a connection angle with the outer wall (26) on the pressure side of less than approximately 60 degrees; wherein three of the four transverse ribs (68) on the suction side are designed such that they form a connection angle with the outer wall (27) on the suction side of less than approximately 60 degrees; and the two central transverse ribs (69) form a connection angle of less than approximately 60 degrees at the camber line rib (64) on the suction side as well as at the camber line rib (63) on the pressure side. [8] Turbine blade according to claim 1, wherein one of the central transverse ribs (69) comprises an arc between the camber line rib (64) on the suction side and the camber line rib (63) on the pressure side; and / or wherein both central transverse ribs (69) comprise an arc between the camber line rib (64) on the suction side and the camber line rib (63) on the compression side and wherein the arc of each of the two central transverse ribs (69) comprises a concave surface directed towards the leading edge; and / or wherein both central transverse ribs (69) comprise an arc between the camber line rib (64) on the suction side and the camber line rib (63) on the compression side and wherein the arc of each of the two central transverse ribs (69) comprises a convex surface directed towards the leading edge (28). [9] Turbine blade according to claim 1 or 8, wherein one of the central transverse ribs (69) comprises a profile cross-section with an “S” shape and wherein the “S” shape, with respect to the leading edge (28) of the profile (25), has two successive curved surfaces, wherein a first concave surface transitions into a second convex surface. [10] Turbine blade (16) comprising a profile (25) defined by a concave outer wall (26) on the pressure side and a convex outer wall (27) on the suction side, connected along a leading and trailing edge (28, 29) and forming a radially extending chamber between them for receiving the flow of a coolant, wherein the turbine blade (16) further includes: a rib arrangement that divides the chamber into radially extending flow channels (40); wherein the rib arrangement comprises a cambered rib (62) with a corrugated cross-section, the corrugated cross-section comprising at least two successive reciprocating “S” shapes; and wherein the camber line rib (62) begins with the wave profile cross-section near the leading edge (28) of the profile (25) and The wave profile cross-section follows an arc path that runs towards the trailing edge (29) of the profile (25). winds, with the arc path running approximately parallel to a curvature reference line of the profile (25); wherein the rib arrangement comprises two camber line ribs (62), wherein a camber line rib (63) on the pressure side includes one located near the outer wall (26) on the pressure side, and a camber line rib (64) on the suction side includes one located near the outer wall (27) on the suction side, wherein both the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side comprise a corrugated profile cross-section, and wherein the camber line rib (63) on the pressure side and the camber line rib (64) on the suction side define a central flow channel between them; wherein the outer wall (26) on the pressure side and the camber line rib (63) on the pressure side define a pressure-side flow channel between them and wherein the outer wall (27) on the suction side and the camber line rib (64) on the suction side define a suction-side flow channel between them; the rib arrangement includes: - four transverse ribs (67) on the pressure side, which connect the outer wall (26) on the pressure side with the curvature line rib (63) on the pressure side and thereby divide the pressure-side flow channel; - four transverse ribs (68) on the suction side, which connect the outer wall (27) on the suction side with the camber line rib (64) on the suction side and thereby divide the suction-side flow channel; and - two central transverse ribs (69) that connect the camber line rib (63) on the pressure side with the camber line rib (64) on the suction side and thereby divide the central flow channel; wherein two of the four transverse ribs (67) on the pressure side are designed such that they form a connection angle with the outer wall (26) on the pressure side of less than approximately 60 degrees; wherein two of the four transverse ribs (68) on the suction side are designed such that they form a connection angle with the outer wall (27) on the suction side of less than approximately 60 degrees; and wherein one of the two central transverse ribs (69) forms a connection angle of less than approximately 60 degrees at the camber line rib (64) on the suction side as well as at the camber line rib (63) on the pressure side.

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