Patent Application
20140023517
The present disclosure relates in general to turbine systems, such as gas turbine systems, and more particularly to nozzles in turbine systems.
Turbine systems are widely utilized in fields such as power generation. For example, a conventional gas turbine system includes a compressor, a combustor, and a turbine. During operation of the gas turbine system, various components in the system are subjected to high temperature flows, which can cause the components to fail. Since higher temperature flows generally result in increased performance, efficiency, and power output of the gas turbine system, the components that are subjected to high temperature flows should be cooled to allow the gas turbine system to operate at increased temperatures, increased efficiency, and/or reduced emissions.
As discussed, during operation of a turbine system, the various components thereof are subjected to high temperatures and otherwise subjected to high stress environments. In many cases, this can lead to cracking of various components. One component that is of particular concern is the nozzle. A typically turbine section nozzle includes an airfoil portion extending between inner and outer sidewall. The peripheral edges, and in particular the pressure side and suction side slash faces, of the sidewalls have linear profiles. For example, some edges have singular linear profiles that extend throughout the entire edge. Other profiles are “dogleg” profiles, which include two linear portions that meet to define an angle therebetween. In dogleg profiles in particular, the intersection between the linear portions creates a high stress concentration region. Relief radii have been introduced at the intersections, but only slightly reduce the stress concentration level. Singular linear profiles eliminated the high stress concentrations at the intersection. However, the construction of a slash face with a singular linear profile requires that the slash face be in close proximity to the leading edge and/or trailing edge of the airfoil, thus creating additional high stress concentration regions.
Accordingly, an improved nozzle for use in a turbine system is desired in the art. In particular, a nozzle design that reduces or eliminates stress concentrations in the sidewalls thereof would be advantageous.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one embodiment, a nozzle for a turbine system is disclosed. The nozzle includes an airfoil, an inner sidewall, and an outer sidewall. The airfoil includes exterior surface defining a pressure side and a suction side extending between a leading edge and a trailing edge. The airfoil further defines a tip and a root. The inner sidewall is connected to the airfoil at the tip. The inner sidewall includes a peripheral edge defining a pressure side slash face, a suction side slash face, a leading edge face, and a trailing edge face. The outer sidewall is connected to the airfoil at the root. The outer sidewall includes a peripheral edge defining a pressure side slash face, a suction side slash face, a leading edge face, and a trailing edge face. At least one of the inner sidewall pressure side slash face, the inner sidewall suction side slash face, the outer sidewall pressure side slash face, or the outer sidewall suction side slash face has a generally curvilinear profile.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
As is generally known in the art, air or another suitable working fluid is flowed through and compressed in the compressor section 12. The compressed working fluid is then supplied to the combustor section 14, wherein it is combined with fuel and combusted, creating hot gases of combustion. After the hot gases of combustion are flowed through the combustor section 14, they may be flowed into and through the turbine section 18.
For example, as shown, the turbine section 18 may include a plurality of buckets 26 and a plurality of nozzles 24. Each of the plurality of buckets 26 and nozzles 24 may be at least partially disposed in the hot gas path 20. Further, the plurality of buckets 26 and the plurality of nozzles 24 may be disposed in one or more annular arrays, each of which may define a portion of the hot gas path 20.
The turbine section 16 may include a plurality of turbine stages. Each stage may include a plurality of buckets 26 disposed in an annular array and a plurality of nozzles 24 disposed in an annular array. For example, in one embodiment, the turbine section 16 may have three stages, as shown in
It should be understood that the turbine section 16 is not limited to three stages, but rather that any number of stages are within the scope and spirit of the present disclosure.
It should be understood that hot gas path components according to the present disclosure are not limited to components in turbine sections 16. Rather, hot gas path components may be components at least partially disposed in flow paths for compressor sections 12 or any other suitable sections of a system 10.
As shown, a nozzle 24 according to the present disclosure includes one or more airfoils 40, an inner sidewall 42, and an outer sidewall 44. The airfoil 40 extends between the inner and outer sidewalls 42, 44 and is connected thereto. The airfoil 40 includes exterior surfaces defining a pressure side 52, a suction side 54, a leading edge 56, and a trailing edge 58. As is generally know, the pressure side 52 and the suction side 54 each generally extend between the leading edge 56 and the trailing edge 58. The airfoil 40 further defines and extends between a tip 62 and a root 64. The inner sidewall 42 is connected to the airfoil 40 at the tip 62, while the outer sidewall 44 is connected at the root 64.
As discussed, the sidewalls 42, 44 are connected to the airfoil 40. In some embodiments, the nozzle 24 is formed as a single, unitary component, such as through casting, and the sidewalls 42, 44 and airfoil 40 are thus connected. In other embodiments, the airfoil 40 and sidewalls 42, 44 are formed separately. In these embodiments, the airfoil 40 and sidewalls 42, 44 may be welded, mechanically fastened, or otherwise connected together.
As discussed, each nozzle 24 includes one or more airfoils 40. Each airfoil 40 extends between and is connected to the sidewalls 42, 44. One, two (as shown), three, four or more airfoils 40 may thus be included in a nozzle 24. Further, as discussed, the nozzle 24 may be included in an annular array of nozzles 24 as a nozzle assembly.
The inner sidewall 42 includes a peripheral edge 70. The peripheral edge 70 defines the periphery of the inner sidewall 42. In exemplary embodiments, a peripheral edge 70 may thus include and define various faces which correspond to the various surfaces of the airfoil(s) 40. For example, as shown, a peripheral edge 70 may define a pressure side slash face 72, a suction side slash face 74, a leading edge face 76, and a trailing edge face 78.
Similarly, the outer sidewall 44 includes a peripheral edge 80. The peripheral edge 80 defines the periphery of the outer sidewall 44. In exemplary embodiments, a peripheral edge 80 may thus include and define various faces which correspond to the various surfaces of the airfoil(s) 40. For example, as shown, a peripheral edge 80 may define a pressure side slash face 82, a suction side slash face 84, a leading edge face 86, and a trailing edge face 88.
As discussed above, nozzle 24 peripheral edges with reduced or eliminated stress concentration regions are desired. As such, in exemplary embodiments, one or more of the inner sidewall 42 pressure side slash face 72, the inner sidewall 42 suction side slash face 74, the outer sidewall 44 pressure side slash face 82, or the outer sidewall 44 suction side slash face 84 has a generally curvilinear profile. Having a curvilinear profile means that, in a profile view such as that shown in
The use of a curvilinear profile for a slashface 72, 74, 82, 84 is particularly advantageous. For example, intersections between linear portions are eliminated, thus eliminating high stress concentration regions that are caused by such intersections. Further, by curving the profile, the subject slashface 72, 74, 82, 84 is spaced from the leading edge 56 and/or trailing edge 58 of the nozzle airfoil 40 by an increased distance (discussed below) relative to a singular linear profile. This thus reduces the associated high stress concentration regions at these locations. Additionally, curving of the profiles as described herein provides a variety of other advantages. For example, such curving provides a relatively more optimum aerodynamic shape to the inner sidewall 42 and/or outer sidewall 44. Thus, the nozzles 24 in general have improved aerodynamics. Further, the relative positioning of the various adjacent slashfaces of adjacent nozzles is relatively more optimum, as discussed below.
As discussed, any one or more slash faces 72, 74, 82, 84 of a nozzle 24 may have curvilinear profiles. In exemplary embodiments, all of the slash faces 72, 74, 82, 84 have curvilinear profiles. Further, in exemplary embodiments, each nozzle 24 in a nozzle assembly has mating slash face 72, 74, 82, 84 profiles, which may be curvilinear. Thus, for example, the inner sidewall 42 pressure side slash face 72 may mate with the inner sidewall 42 suction side slash face 74 of an adjacent nozzle 24, the inner sidewall 42 suction side slash face 74 may mate with the inner sidewall 42 pressure side slash face 72 of an adjacent nozzle 24, the outer sidewall 44 pressure side slash face 82 may mate with the outer sidewall 44 suction side slash face 84 of an adjacent nozzle 24, and the outer sidewall 44 suction side slash face 84 may mate with the outer sidewall 44 pressure side slash face 82 of an adjacent nozzle 24. Such mating, and the use of seals (not shown) therebetween, may facilitate sealing of the nozzle assembly, thus preventing hot gas or cooling flow leakage therethrough.
In some embodiments, the curve 100 and curvilinear profile of one or more slash faces 72, 74, 82, 84 may be further defined by a minimum distance 112 between the slash face 72, 74, 76, 78 and the leading edge 56 of the airfoil 40 and/or a minimum distance 114 between the slash face 72, 74, 76, 78 and the trailing edge 58 of the airfoil 40. By maintaining a suitable minimum distance 112 and/or 114, stress concentrations at these locations may be reduced and or eliminated. Required minimum distances 112, 114 to reduce stress concentrations below a required level may be determined for a particular nozzle 24 based on the individual characteristics of that nozzle 24, and the curves 100 and curvilinear profiles, and thus the sidewalls 42, 44, may be designed such the distances 112 and/or 114 are equal to or greater than the required minimum distances. The required minimum distances may be predetermined for a nozzle 24 or determined during design of the nozzle 24, such as through design iterations when designing the curves 100 for the slash face 72, 74, 82, 84 curvilinear profiles. The curves 100 and curvilinear profiles may thus be designed such that the minimum distances 112, 114 are equal to or greater than the required minimum distances.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
