Airfoil shape for turbine nozzles

The subject matter disclosed herein relates to turbine engine airfoils and, more specifically, to airfoils of stator blades or nozzles.

Some aircraft and/or power plant systems, for example certain jet aircraft, gas turbines, and combined cycle power plant systems, employ turbines (also referred to as turbomachines) in their design and operation. Some of these turbines employ airfoils (e.g., turbine stator blades, nozzles, etc.) which during operation are exposed to fluid flows. These airfoils are configured to aerodynamically interact with the fluid flows and generate energy (e.g., creating thrust, turning kinetic energy to mechanical energy, thermal energy to mechanical energy, etc.) from these fluid flows as part of power generation. As a result of this interaction and conversion, the aerodynamic characteristics and losses of these airfoils have an impact on system and turbine operation, performance, thrust, efficiency, and power.

Aspects and advantages are set forth below in the following description, or may be obvious from the description, or may be learned through practice.

According to an exemplary embodiment, the present disclosure includes a turbine nozzle having an airfoil that includes a pressure side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a pressure side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the pressure side are coordinate values that, when connected by smooth continuing arcs, define pressure side sections of the pressure side portion of the nominal airfoil profile at each Z coordinate value. The pressure side sections may be joined smoothly with one another to form the pressure side portion.

According to another exemplary embodiment, the present disclosure includes a turbine nozzle having an airfoil that includes a suction side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a suction side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the suction side are coordinate values that, when connected by smooth continuing arcs, define suction side sections of the suction side portion of the nominal airfoil profile at each Z coordinate value. The suction side sections may be joined smoothly with one another to form the suction side portion.

According to another exemplary embodiment, the present disclosure includes a turbine engine that has an airfoil that includes: a pressure side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a pressure side as set forth in Table I; and a suction side portion of the nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of the suction side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the pressure side are coordinate values that, when connected by smooth continuing arcs, define pressure side sections of the pressure side portion of the nominal airfoil profile at each Z coordinate value. The pressure side sections may be joined smoothly with one another to form the pressure side portion. The X and Y values of the suction side are coordinate values that, when connected by smooth continuing arcs, define suction side sections of the suction side portion of the nominal airfoil profile at each Z coordinate value. The suction side sections may be joined smoothly with one another to form the suction side portion.

Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

A full and enabling disclosure of various embodiments, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a schematic representation of an exemplary turbine having multiple stages with each stage including alternating rows of turbine rotor blades and turbine nozzles according to at least one embodiment of the present disclosure;

FIG. 2 is a perspective view of an exemplary turbine nozzle according to at least one embodiment of the present disclosure; and

FIG. 3 provides a cross-sectional view of an airfoil portion of the turbine nozzle of FIG. 2 .

One or more specific embodiments of the present subject matter will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present subject matter, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Referring now to the drawings, particularly to FIG. 1 , there is illustrated an exemplary turbine 10 of a combustion or gas turbine 12 including a plurality of turbine stages arranged in serial flow order. Each stage of the turbine includes a row of turbine stator blades, vanes, or nozzles disposed axially adjacent to a corresponding row of turbine rotor blades. While four stages are illustrated in FIG. 1 , the exact number of stages of the turbine 10 is a choice of engineering design, and may be more or less than the four stages shown. The four stages are merely exemplary of one turbine design, and are not intended to limit the presently claimed turbine rotor blade in any manner.

As depicted in FIG. 1 , the first stage includes a plurality of turbine nozzles 100 and a plurality of turbine rotor blades 150 . The turbine nozzles 100 are annularly arranged about an axis of a turbine rotor 14 , while the turbine rotor blades 150 are annularly arranged about and coupled to the turbine rotor 14 . A second stage of the turbine 12 includes a plurality of turbine nozzles 200 annularly arranged about the axis of the turbine rotor 14 and a plurality of turbine rotor blades 250 annularly arranged about and coupled to the turbine rotor 14 . A third stage of the turbine 12 includes a plurality of turbine nozzles 300 annularly arranged about the axis of the turbine rotor 14 and a plurality of turbine rotor blades 350 annularly arranged about and coupled to the turbine rotor 14 . In particular embodiments, the turbine 12 may further include a fourth stage, which also includes plurality of turbine nozzles 400 annularly arranged about the axis of the turbine rotor 14 and a plurality of turbine rotor blades 450 annularly arranged about and coupled to the turbine rotor 14 . As will be appreciated, the turbine nozzles 100 , 200 , 300 , 400 may be coupled to the casing of the turbine 12 and remain stationary during operation.

It will be appreciated that the turbine nozzles 100 , 200 , 300 and 400 and turbine rotor blades 150 , 250 , 350 and 450 are disposed or at least partially disposed within a working fluid flowpath or hot gas path 18 of the turbine 12 . The various stages of the turbine 10 at least partially define the hot gas path 18 through which combustion gases, as indicated by arrows 20 , flow during operation of the gas turbine 12 .

FIG. 2 provides a perspective view of an exemplary turbine nozzle 50 as may be incorporated in one of the stages of the turbine 12 . FIG. 3 provides a cross-sectional top view of an airfoil 52 of the turbine nozzle 50 shown in FIG. 2 . In a preferred embodiment of the present disclosure, the turbine nozzle 50 (as described by the points included within Table I below) is a turbine nozzle 200 of the plurality of the turbine nozzles 200 used in the second stage of the turbine 12 , as shown in FIG. 1 . As illustrated in FIGS. 2 and 3 collectively, the turbine nozzle 50 airfoil 52 includes a pressure side 54 and an opposing suction side 56 . The pressure side 54 and the suction side 56 meet or intersect at a leading edge 58 and at a trailing edge 60 of the airfoil 52 . A chord line 62 extends between the leading edge 58 and the trailing edge 60 such that pressure and suction sides 54 , 56 can be said to extend in chord or chordwise between the leading edge 58 and the trailing edge 60 .

As shown in FIG. 2 , the airfoil 52 further includes a first end or root 64 , which intersects with and extends radially outwardly from an inner band 66 of the turbine nozzle 50 . The airfoil 52 terminates radially at a second end or tip 68 of the airfoil 52 . The second end 68 intersects with and extends radially inwardly from an outer band 70 of the turbine nozzle 50 . The pressure and suction sides 54 , 56 can be said to extend in span or a span-wise direction 72 (along the height of the airfoil 52 ) between the root 64 and/or the inner band 66 and the second end 68 or the outer band 70 . In other words, each turbine nozzle 50 includes an airfoil 52 having opposing pressure and suction sides 54 , 56 that extend in chord or chordwise 62 between opposing leading and trailing edges 58 , 60 and that extend in span or span-wise 72 between the root 64 and the second end 68 of the airfoil 52 .

In particular configurations, the airfoil 52 may include a fillet 74 formed between the inner band 66 and the airfoil 52 proximate to the root 64 . The fillet 74 can include a weld or braze fillet, which can be formed via conventional MIG welding, TIG welding, brazing, etc., and the fillet 74 can have a profile that reduces fluid dynamic losses. In particular embodiments, the inner band 66 , airfoil 52 and the fillet 74 can be formed as a single component, such as by casting and/or machining and/or 3D printing and/or any other suitable technique now known or later developed and/or discovered.

The airfoil 52 of the turbine nozzle 50 has a profile at any cross-section taken between the root 64 and the second end 68 . In accordance with the present disclosure, the X, Y, and Z values of the profile are given in Table I as percentage values of the airfoil span or height. As one example, the height of the airfoil 52 of the turbine nozzle 50 may be from about 2 inches to about 50 inches. As another example, the height of the airfoil 52 of the turbine nozzle 50 may be from about 3 inches to about 10 inches. However, it is to be understood that heights below or above this range may also be employed as desired in the specific application.

A hot gas path of a gas turbine requires airfoils that meet system requirements of aerodynamic and mechanical blade loading and efficiency. To define the airfoil shape of each turbine nozzle airfoil, there is a unique set or locus of points in space that meet the stage requirements and that can be manufactured. This unique locus of points meets the requirements for stage efficiency and are arrived at by iteration between aerodynamic and mechanical loadings enabling the turbine to run in an efficient, safe and smooth manner. These points are unique and specific to the system.

The locus of points that defines the airfoil profile of a turbine nozzle includes a set of points with X, Y and Z dimensions relative to a reference origin coordinate system, as provided in Table I and shown in FIG. 2 , respectively. The Cartesian coordinate system of X, Y and Z values given in Table I below defines the profile of the airfoil of a turbine nozzle at various locations along its length or span or, as used herein, height. Table I lists data for a non-coated airfoil, and, as discussed more below, the envelope/tolerance for the coordinates may be about +/−5% in a direction normal to any airfoil surface location and/or about +/−5% of the chord 62 in a direction nominal to any airfoil surface location. As shown in FIG. 2 , the point data origin 76 is defined at or proximate to the leading edge 58 of the airfoil 52 and at or proximate to the root 64 of the airfoil 52 . As will be appreciated, the point data origin 76 corresponds to the non-dimensional Z value of Table I (presented below) at Z equals 0.

The coordinate values for the X, Y and Z coordinates are set forth in non-dimensionalized units in Table I, although units of dimensions may be used when the values are appropriately converted. That is, the X, Y and Z values set forth in Table I are also expressed in non-dimensional form (X, Y, and Z) from 0% to 100% of the radial span or height of the airfoil 52 . As one example, the Cartesian coordinate values of X, Y and Z may be convertible to dimensional distances by multiplying the X, Y and Z values by a height of the airfoil at the leading edge 58 and/or multiplying by a constant number. As another example, the Cartesian coordinate values of X, Y and Z may be convertible to dimensional distances by multiplying the X, Y and Z values by a height of the airfoil at the trailing edge 60 and/or multiplying by a constant number. Thus, to convert the Z value to a Z coordinate value, for example, in inches, the non-dimensional Z value given in Table I is multiplied by the height of the airfoil in inches (where the height of the airfoil is defined along the Z axis).

As described above, the Cartesian coordinate system has orthogonally-related X, Y and Z axes. The X axis lies generally parallel to the turbine rotor centerline, i.e., the rotary axis and a positive X coordinate value is axial toward an exhaust end of the turbine 14 . The positive Y coordinate value extends tangentially in the direction of rotation of the rotor shaft 14 , and the positive Z coordinate value extends radially outwardly toward the second end 68 of the airfoil 52 . All the values in Table I are given at room temperature and are non-filleted.

By defining X and Y coordinate values at selected locations in a Z direction normal to the X, Y plane, the airfoil shape or profile sections (which may be referred to as “pressure side sections” on the pressure side and “suction side sections” on the suction side) of the airfoil 52 of the turbine nozzle 50 along the span or height of the airfoil 52 can be ascertained. Thus, by connecting the X and Y values with smooth continuing arcs, each profile section (which may include a pressure side section and suction side section) at each distance Z is determined. The airfoil profiles of the various surface locations between the distances Z can then be determined by smoothly connecting the adjacent profile sections to one another to form the airfoil profile.

The Table I values are generated and shown to four decimal places for determining the profile of the airfoil. As the turbine nozzle surface heats up during operation of the turbine 14 , mechanical stresses and elevated temperatures will cause a change in the X, Y and Z values. Accordingly, it should be understood that the values for the nominal airfoil profile given in Table I represent ambient, non-operating or non-hot conditions (e.g., room temperature) and are for an uncoated airfoil.

There are typical manufacturing tolerances as well as coatings which may be accounted for in the actual profile of the airfoil 52 . It will therefore be appreciated that +/− typical manufacturing tolerances, i.e., +/− values, including any coating thicknesses, may be additive to the X and Y values given in Table I below. Accordingly, a distance of +/−5% in a direction normal to any airfoil surface location and/or about +/−5% of the chord 62 in a direction nominal to any airfoil surface location may define an airfoil profile envelope for this particular airfoil design, i.e., a range of variation between measured points on the actual airfoil surface at nominal cold or room temperature and the ideal position of those points as given in Table I below at the same temperature. According to another example, a tolerance of about 10-20 percent of a thickness of the airfoil's trailing edge 60 in a direction normal to any airfoil surface location may define a range of variation between measured points on an actual airfoil surface and ideal positions as embodied by the invention in Table I. As should further be understood, the data provided in Table I is scalable and the geometry pertains to all aerodynamic scales and/or RPM ranges. The design of the airfoil 52 for the turbine nozzle 50 is robust to this range of variation without impairment of mechanical and aerodynamic functions.

It will also be appreciated that the airfoil 52 disclosed in the above Table I may be scaled up or down geometrically for use in other similar turbine designs. Consequently, the coordinate values set forth in Table I may be scaled upwardly or downwardly such that the airfoil profile shape remains unchanged. A scaled version of the coordinates in Table I would be represented by X, Y and Z coordinate values of Table I, with the X, Y and Z non-dimensional coordinate values converted to inches, multiplied or divided by a constant number.

An important term in this disclosure is “profile”. The profile is the range of the variation between measured points on an airfoil surface and the ideal position listed in Table I. The actual profile on a manufactured turbine nozzle will be different than those in Table I and the design is robust to this variation meaning that mechanical and aerodynamic function are not impaired. As noted above, a + or −5% profile tolerance is used herein. The X, Y and Z values are all non-dimensionalized relative to the airfoil height.

The disclosed airfoil shape optimizes and is specific to the machine conditions and specifications. It provides a unique profile to achieve 1) interaction between other stages in the turbine 10 ; 2) aerodynamic efficiency; and 3) normalized aerodynamic and mechanical nozzle or airfoil loadings. The disclosed locus of points defined in Table I allow the gas turbine 12 or any other suitable turbine to run in an efficient, safe and smooth manner. As also noted, any scale of the disclosed airfoil 52 may be adopted as long as 1) interaction between other stages in the pressure turbine 10 ; 2) aerodynamic efficiency; and 3) normalized aerodynamic and mechanical nozzle or airfoil loadings are maintained in the scaled turbine. The airfoil 52 described herein thus improves overall gas turbine 12 efficiency. Specifically, the airfoil 52 provides a desired turbine efficiency lapse rate (ISO, hot, cold, part load, etc.). The airfoil 52 also meets all aeromechanics and stress requirements. The turbine nozzle 50 described herein has very specific aerodynamic design requirements such as an upstream bucket radial back pressure (i.e., work splits) and radial velocity triangles for the downstream turbine rotors 150 , 250 , 350 and 450 . Significant cross-functional design effort was required to meet these design goals. The airfoil 52 of the turbine nozzle 50 , thus, is of a specific shape to meet aerodynamic, mechanical, and heat transfer requirements in an efficient and cost-effective manner.

Further, it should be understood that exemplary embodiments of the present disclosure may include the entirety of the nominal airfoil profile set forth in Table I or portions thereof. Such portions may include a portion of the pressure side (or “pressure side portion”), a portion of the suction side (or “suction side portion”), and portions of both the pressure side and suction side.

Thus, exemplary embodiments of the present disclosure include a turbine nozzle having an airfoil that includes a pressure side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a pressure side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the pressure side are coordinate values that, when connected by smooth continuing arcs, define pressure side sections of the pressure side portion of the nominal airfoil profile at each Z coordinate value. The pressure side sections may be joined smoothly with one another to form the pressure side portion.

Exemplary embodiments of the present disclosure also include a turbine nozzle having an airfoil that includes a suction side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a suction side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the suction side are coordinate values that, when connected by smooth continuing arcs, define suction side sections of the suction side portion of the nominal airfoil profile at each Z coordinate value. The suction side sections may be joined smoothly with one another to form the suction side portion.

Exemplary embodiment of the present disclosure also include a turbine engine that has an airfoil, wherein the airfoil includes: a pressure side portion of a nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of a pressure side as set forth in Table I; and a suction side portion of the nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y, and Z of the suction side as set forth in Table I. The Cartesian coordinate values of X, Y, and Z are non-dimensional values from 0% to 100% convertible to dimensional distances by multiplying the Cartesian coordinate values of X, Y and Z by a height of the airfoil defined along the Z axis. The X and Y values of the pressure side are coordinate values that, when connected by smooth continuing arcs, define pressure side sections of the pressure side portion of the nominal airfoil profile at each Z coordinate value. The pressure side sections may be joined smoothly with one another to form the pressure side portion. The X and Y values of the suction side are coordinate values that, when connected by smooth continuing arcs, define suction side sections of the suction side portion of the nominal airfoil profile at each Z coordinate value. The suction side sections may be joined smoothly with one another to form the suction side portion.

A height of each of the suction side portion and pressure side portion may be defined along the Z axis. The height of each of the suction side portion and pressure side portion may be less than or equal to the height of the airfoil. According to exemplary embodiments, the height of the suction side portion and the height of the pressure side portion may be substantially the same. According to exemplary embodiments, the suction side portion and the pressure side portion may each start at a common distance relative to a base of the airfoil and extend toward a tip of the airfoil. According to exemplary embodiments, the height of the suction side portion and/or the height of the pressure side portion may each be equal to or greater than 50% of the height of the airfoil. According to other embodiments, the height of the suction side portion and/or the height of the pressure side portion may each be equal to or greater than 75% of the height of the airfoil. According to other embodiments, the height of the suction side portion and the height of the pressure side portion may each be equal to 100% of the height of the airfoil.

As already described, the turbine engine may include a combustion or gas turbine that has a compressor, combustor, and turbine. The airfoil of the present disclosure may be configured as the airfoil of a turbine nozzle, i.e., a nozzle within the turbine of the gas turbine. More specifically, the airfoil of the present disclosure may be the airfoil of a turbine nozzle that is configured to function as a second stage nozzle in the turbine. In such cases, the turbine includes a second stage that has a row of circumferentially spaced nozzles and a row of circumferentially spaced rotor blades, with the airfoil of the present disclosure being configured as the airfoil of each of the nozzles within the second stage row of nozzles.

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 have 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.