Gas turbine engine stationary vane with contoured platform

Abstract

A gas turbine engine includes a rotor rotatable about a central axis. The gas turbine engine includes a turbine stage including a stationary portion and a rotating portion, the rotating portion being comprised of a number of rotating blades, and a plurality of stationary vanes arranged to define the stationary portion. Each stationary vane includes an inner rail having an inlet face, a suction side face, a pressure side face, and a platform. A vane portion extends from the platform along a radial line and defines one of a first stagger angle and a second stagger angle relative to the central axis. The platform has an elliptical cross-section in a plane including the central axis.

Description

BACKGROUND

[0001] Gas turbine engines are used in many applications, including power generation. Gas turbine engines used for power generation are typically designed to have optimal performance at a specific load. Operation away from this design point can result in additional unwanted emissions and lower operating efficiency. SUMMARY

[0002] A gas turbine engine includes a rotor rotatable about a central axis. The gas turbine engine includes a turbine stage including a stationary portion and a rotating portion, the rotating portion being comprised of a number of rotating blades, and a plurality of stationary vanes arranged to define the stationary portion. Each stationary vane includes an inner rail having an inlet face, a suction side face, a pressure side face, and a platform. A vane portion extends from the platform along a radial line and defines one of a first stagger angle and a second stagger angle relative to the central axis. The platform has an elliptical cross-section in a plane including the central axis.

[0003] In another construction, a gas turbine engine includes a first stationary vane including an inner rail having an inlet face, a suction side face, a pressure side face, and a platform. A vane portion extends from the platform along a radial line and defines one of a first stagger angle and a second stagger angle relative to a central axis. A second stationary vane identical to the first stationary vane includes a suction side face positioned in contact with a pressure side face of the first stationary vane to define a first throat area when the first and second stationary vanes are oriented at the first stagger angle and a second throat area when the first and second stationary vanes are oriented at the second stagger angle. The inlet face of the first stationary vane cooperates with the inlet face of the second stationary vane to define a continuous annular surface when the first and second stationary vanes are oriented at the first stagger angle and the platform of the first stationary vane cooperates with the platform of the second stationary vane to define a continuous curved surface, and the platform of the first stationary vane cooperates with the platform of the second stationary vane to define a stepped surface when the first and second stationary vanes are oriented at the second stagger angle.

[0004] In yet another configuration, a method for setting a throat area for a row of stationary airfoils for a gas turbine engine includes forming each stationary airfoil in the row to include an inner rail, an airfoil portion, and an outer rail, the inner rail having an inlet face, a suction side face, a pressure side face, and a platform, the airfoil portion extending from the platform along a radial line and defining a first stagger angle, the outer rail including a bolt face. The method also includes adjusting the plane of the bolt face of each of the stationary airfoils to define a second stagger angle and positioning the suction side face of each stationary airfoil in contact with the pressure side face of an adjacent stationary airfoil. When the stationary airfoils are unadjusted, the inlet face of each of the stationary airfoils cooperates to define a continuous annular surface, the platform of each of the stationary airfoils cooperates to define a continuously curved surface, and the airfoil portion of each of the stationary airfoils cooperates to define a first throat area, and when the stationary airfoils are adjusted, the platform of each of the stationary airfoils cooperates to define a stepped surface, and the airfoil portion of each of the stationary airfoils cooperates to define a second throat area. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] To easily identify the discussion of any particular element or act, the most significant digit(s) in a reference number refers to the drawing number in which the element is first introduced.

[0006] Figure 1 is a cross-sectional longitudinal view of a gas turbine engine.

[0007] Figure 2 A bladed stage of a gas turbine engine is shown.

[0008] Figure 3 A partial row of stationary airfoils of a gas turbine engine is shown.

[0009] Figure 4 is a radial view of a partial row of stationary airfoils of a gas turbine engine.

[0010] Figure 5 Two on-design airfoils of a gas turbine engine are shown.

[0011] Figure 6 A pair of off-design airfoils of a gas turbine engine is shown. DETAILED DESCRIPTION

[0012] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The application is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and not of limitation.

[0013] Various techniques relating to systems and methods will now be described with reference to the drawings, where like reference numerals refer to like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged device. It should be understood that functions described as being performed by certain system elements can be performed by multiple elements. Similarly, for example, one element can be structured to perform functions described as being performed by multiple elements. Many innovative teachings presented herein will be described with reference to exemplary, non-limiting embodiments.

[0014] Moreover, it should be understood that the words or phrases used herein, and variations thereof, unless otherwise indicated, are broad terms commonly used in the technical field of the present disclosure. For example, the terms “include,” “have,” and “comprise” and variations thereof, as used herein, are intended to be inclusive, unless otherwise indicated. The singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of the term “and / or,” as used herein, signifies all possible combinations of the entities or items so conjoined, including correlation and / or causation. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. The phrases “associated with,” “associated therewith,” and the like as used herein, can mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, have, have a property of, or the like. Additionally, the term “comprising” is used herein to mean the open-ended nomenclature that the compositions, methods, steps, components, and / or elements so conjoined can include, but are not limited to, any available, known, or hereafter developed compositions, methods, steps, components, and / or elements.

[0015] In addition, although the terms "first", "second", "third" etc. can be used to refer to various elements, information, functions or actions in this article, these elements, information, functions or actions should not be limited by these terms. On the contrary, these numerical adjectives are used to distinguish different elements, information, functions or actions from each other. For example, without departing from the scope of this disclosure, the first element, information, function or action can be referred to as the second element, information, function or action, and similarly, the second element, information, function or action can be referred to as the first element, information, function or action.

[0016] Additionally, the term "adjacent" can mean that one element is relatively close to, but not in contact with, another element, or that the element is in contact with another part, unless the context clearly indicates otherwise. Furthermore, unless otherwise explicitly stated, the phrase "based on" is intended to mean "based at least in part on." The terms "approximately" or "substantially" or similar terms are intended to encompass variations in values ​​that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of 20% will fall within the meaning of these terms unless otherwise specified.

[0017] Figure 1 An example of a gas turbine engine 100 is shown, which includes a compressor section 106, a combustion section 108, and a turbine section 110 arranged along a central axis 104. The compressor section 106 includes a plurality of compressor stages 102, each stage including a set of rotating blades 112 and a set of stationary vanes 114 or adjustable guide vanes. The compressor section 106 is in fluid communication with an inlet section 116 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 106. During operation of the gas turbine engine 100, the compressor section 106 draws in atmospheric air and compresses the air for delivery to the combustion section 108.

[0018] In the illustrated configuration, the combustion section 108 includes a plurality of individual combustors 118 that each operate to mix a flow of fuel with compressed air from the compressor section 106 and combust the air-fuel mixture to produce a flow of high temperature, high pressure combustion gases or exhaust gases 120. Of course, many other arrangements of the combustion section 108 are possible.

[0019] The turbine section 110 includes a plurality of turbine stages 122, each stage including a number of rotating blades and a number of stationary blades or airfoils. The turbine stages 122 are arranged to receive exhaust gas 120 from the combustion section 108 at a turbine inlet 124 and expand the gas to convert heat and pressure energy into rotational or mechanical work. The turbine section 110 is connected to the compressor section 106 to drive the compressor section 106. For gas turbine engines used for power generation or as prime movers, the turbine section 110 is also connected to a generator, pump, or other device to be driven.

[0020] A control system 126 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters of the gas turbine engine 100 and control various operations of the gas turbine engine 100. In a preferred configuration, the control system 126 is typically microprocessor-based and includes memory devices and data storage devices for collecting, analyzing, and storing data. Furthermore, the control system 126 provides output data to various devices, including monitors, printers, indicators, and the like, which allow a user to interact with the control system 126 to provide input or adjustments. In the example of a power generation system, a user may input a power output setpoint, and the control system 126 adjusts various control inputs to achieve that power output in an efficient manner.

[0021] The control system 126 can control various operating parameters, including but not limited to variable inlet guide vane position, fuel flow rate and pressure, engine speed, valve position, and generator load. Of course, other applications may have fewer or more controllable devices. The control system 126 also monitors various parameters to ensure that the gas turbine engine 100 is operating normally. Some monitored parameters may include inlet air temperature, compressor outlet temperature and pressure, combustor outlet temperature, fuel flow rate, generator power output, etc. Many of these measurements are displayed to the user and recorded for later review if necessary. It is also desirable to determine the turbine inlet temperature. However, as will be discussed in more detail, this temperature is difficult to measure directly.

[0022] Figure 2 A single stage 200 comprising a row of stationary vanes 202 and a row of rotating blades 204 is better shown. Figure 2 is a longitudinal cross-section taken in a plane passing through and containing the central axis 104. The row of stationary vanes 202 includes a plurality of stationary vanes 206 stacked in a circumferential direction and in contact with each other. Each stationary vane 206 includes an inner rail 208 that defines a platform 218 and is positioned adjacent to the rotor 216 to form a seal therebetween. The outer rail 210 engages the casing 214 to maintain the row of stationary vanes 202 in a desired operating position. More specifically, the outer rail 210 of each stationary vane 206 includes a bolt face 222 that is received within a receiving groove 220. The receiving groove 220 is machined to a plane perpendicular to the central axis 104 of the gas turbine engine 100. Each bolt face is machined to a desired plane that determines the stagger angle 402 ( Figure 4 ). Any adjustment to the plane into which the bolt faces 222 are machined results in a corresponding change in the stagger angle 402 of the row of stationary vanes 202.

[0023] The row of stationary vanes 202 is centered about central axis 104 (sometimes referred to as the longitudinal axis or axis of rotation), with each stationary vane 206 extending along a radial line 212 extending radially from central axis 104 .

[0024] Figure 3 A partial row of stationary vanes 300 is shown, including a first stationary vane 302 and a second stationary vane 304 positioned in or near an operational position. The second stationary vane 304 is identical to the first stationary vane 302. As used herein, the term "identical" means that the blades or vanes are manufactured to the same design, including certain dimensional and angular tolerances. Thus, identical blades may have slight dimensional or angular differences. Because the first and second stationary vanes 302, 304 are identical, only the first stationary vane 302 will be described in detail.

[0025] The first stationary airfoil 302 includes an inner rail 208 disposed adjacent to or in contact with the rotor 216. Airfoil portions 312 extend from the inner rail 208 to an opposite end that may include the outer rail 210. Each airfoil portion 312 extends along a different radial line, such that the first stationary airfoil 302 follows a first radial line 316 and the second stationary airfoil 304 follows a second radial line 318. The outer rail 210 is attached to a stationary element, such as a casing 214, a housing, a shroud, a blade ring, etc.

[0026] Inner rail 208 includes an inlet face 306, a suction side 308, a pressure side 310, and a platform 218 from which an airfoil portion 312 extends. Each of suction side 308 and pressure side 310 is a flat surface that is arranged to abut one another during stacking of the row of stationary airfoils 202.

[0027] Each stationary airfoil 206 (e.g., the first stationary airfoil 302) is stacked in contact with another stationary airfoil 206 (e.g., the second stationary airfoil 304). More specifically, the pressure side 310 of the first stationary airfoil 302 is in direct contact with the suction side 308 of the second stationary airfoil 304 to define a flow path 320 between the associated airfoil portions 312.

[0028] The inlet face 306 of the first stationary vane 302 cooperates with the inlet face 306 of the second stationary vane 304 to partially define a continuous annular surface extending around the central axis 104. As used herein, the term "continuous" means that there are no undesirable steps in the continuous annular surface. As will be appreciated by those of ordinary skill in the art, there will be a small discontinuity or gap at the interface between each suction side face 308 and pressure side face 310. However, this discontinuity will not be a step where the inlet face 306 of the first stationary vane 302 or the second stationary vane 304 extends out of the plane of the other inlet face 306. In other words, "continuous" means that the inlet face 306 of each of the first stationary vane 302 and the second stationary vane 304 are in the same plane (within design tolerances), only the interface between them is offset from that plane.

[0029] The platform 218 of the first stationary vane 302 cooperates with the platform 218 of the second stationary vane 304 to partially define a continuous curvilinear surface that defines an inner boundary of the flow path 320. This continuous curvilinear surface is circular in cross-section taken perpendicular to the central axis 104. However, as Figure 2 shown, the continuous curvilinear surface formed by the platforms 218 defines an elliptical cross-section.

[0030] Figure 4 is a radial view of a portion row 400 of stationary vanes better illustrating the stagger angle 402. The vane portion 312 inherently defines a chord 404 extending between a tangent point at the leading edge and a tangent point at the trailing edge. The chord 404 cooperates with the interface between the suction side face 308 and the pressure side face 310 to define the stagger angle 402. Of course, lines other than the chord 404 can be used to define the orientation of the vane portion 312.

[0031] To adjust the stagger angle 402 of a particular row of stationary vanes 202, one adjusts the plane in which the bolt face 222 is machined. Additionally, one can need to change the angle of the suction side face 308 and the pressure side face 310.

[0032] Changing the stagger angle 402 changes the size of the throat area 406. The throat area 406 is selected to ensure that the flow area can accommodate the maximum expected flow rate for the design of the gas turbine engine 100. Thus, for lower flow engines, one can rotate the vane portion 312 to a more closed position resulting in a smaller throat area 406.

[0033] When designing a gas turbine engine 100, one performance parameter is the throat area 406, which is the primary influencer of the pressure ratio created by the compressor section 106 (when the throat area 406 is in the compressor section 106) and influences the efficiency of the turbine section 110 (when the throat area 406 is in the turbine section 110). This throat area 406 is fixed by the geometry of the stationary airfoils 206, which are typically formed as castings, and altering castings is expensive. When developing different variations of the gas turbine engine 100 with higher or lower mass flows, it may be necessary to change this throat area 406 to optimize the performance of the new gas turbine engine 100.

[0034] Figure 5 The first stationary airfoil 302 is shown positioned in contact with the second stationary airfoil 304, with the bolt face 222 machined to the design plane to achieve the designed stagger angle 402. A first interface edge 502 is defined by the intersection of the platform 218 and the suction side 308 of the first stationary airfoil 302, and a second interface edge 504 is defined by the intersection of the platform 218 and the pressure side 310 of the second stationary airfoil 304. When the first stationary airfoil 302 and the second stationary airfoil 304 are arranged with the designed stagger angle 402, the first interface edge 502 and the second interface edge 504 are adjacent to each other to define a common edge 506.

[0035] Figure 6 The first and second stationary fins 302 and 304 are shown arranged at an off-design stagger angle 402 , where the bolt face 222 of each fin is machined at an angle slightly different than the design angle.

[0036] Forming each bolt face 222 at an angle that deviates from the design may result in a step pattern at the inlet face 306 and at the platform 218. Steps in the flow path 320 may trip the flow, reduce the performance of the gas turbine engine 100, and be susceptible to damage from hot gas impingement. Each inlet face 306 may be machined or ground to eliminate the step pattern. However, the platform 218 generally cannot be modified because the modification would likely change the flow area. The illustrated arrangement of the platform 218 significantly reduces the size of the step at the platform 218 so that the step is within an acceptable tolerance (i.e., less than 0.25 mm). As shown Figure 6 As shown, the deviation from the designed stagger angle shifts the positions of the first interface edge 502 and the second interface edge 504 relative to each other such that there is no common edge 506. However, the size of the step is small and remains within the design tolerances.

[0037] While exemplary embodiments of the disclosure have been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements can be made to the embodiments disclosed herein without departing from the spirit and scope of the disclosure in its broadest form.

[0038] The description in this document should not be interpreted to imply that any particular element, step, act, or function is necessary or essential to the claims' scope: the scope resides in the claims alone, and their equivalents. In addition, none of these claims are intended to invoke the industrial-objectureation of the claims, unless the exact words "for use in" are followed by a participle.

Claims

1. A gas turbine engine comprising a rotor rotatable about a central axis, the gas turbine engine comprising: a turbine stage, the turbine stage comprising a stationary portion, a rotating portion and a housing, the rotating portion being composed of a plurality of rotating blades; as well as a plurality of stationary fins arranged to define the stationary portion, each stationary fin comprising: an outer rail, wherein the outer rail is configured to engage the casing to retain the stationary vane in an operational position, wherein the outer rail includes a bolt face configured to be received within a receiving recess in the casing, wherein the receiving recess is machined to a plane perpendicular to a central axis of the gas turbine engine; an inner rail having an inlet face, a suction side, a pressure side, and a platform, wherein the platform has an elliptical cross-section in a plane including the central axis; and an airfoil portion extending from the platform along a radial line, wherein the airfoil portion is configured to define a designed stagger angle relative to the central axis, wherein the bolt face is machined to a plane defining the designed stagger angle, and wherein, when a first and a second stationary airfoil of the plurality of stationary airfoils are arranged with the designed stagger angle, a first interface edge and a second interface edge are adjacent to each other to define a common edge, wherein the first interface edge is defined by the intersection of the platform and the suction side of the first stationary airfoil, and the second interface edge is defined by the intersection of the platform and the pressure side of the second stationary airfoil; or wherein the airfoil portion is configured to define an off-design stagger angle relative to the central axis, wherein the bolt face is machined to a plane defining the off-design stagger angle, and wherein, when a first and a second stationary airfoil of the plurality of stationary airfoils are arranged with the off-design stagger angle, positions of a first interface edge and a second interface edge are displaced relative to each other such that a step exists at the inlet face and at the platform, wherein the first interface edge is defined by the intersection of the platform and the suction side of the first stationary airfoil, and the second interface edge is defined by the intersection of the platform and the pressure side of the second stationary airfoil.

2. The gas turbine engine according to claim 1, wherein: The difference between the designed stagger angle and the deviated stagger angle is less than five degrees.

3. The gas turbine engine according to claim 1, wherein: The inlet face defines a continuous annular surface when the stationary airfoils are arranged at the designed stagger angle, and defines a stepped annular surface when the stationary airfoils are arranged at the off-design stagger angle.

4. The gas turbine engine according to claim 1, wherein: The platforms of adjacent stationary vanes cooperate to define a stepped interface, the stepped interface including a step between each pair of adjacent stationary vanes, and wherein each step is less than 0.25 mm.

5. The gas turbine engine according to claim 1, wherein: The plurality of stationary vanes define a first throat area when the stationary vanes are arranged at the designed stagger angle, and define a second throat area when the stationary vanes are arranged at the off-design stagger angle, the second throat area being smaller than the first throat area.

6. The gas turbine engine according to claim 5, wherein: The second throat area is less than ten percent smaller than the first throat area.

7. A method of setting a throat area of ​​a row of stationary airfoils for a gas turbine engine, the gas turbine engine including a casing, the method comprising: Each stationary fin in the row of stationary fins is formed to include an outer rail, wherein the outer rail is configured to engage the casing to retain the stationary vane in an operational position, wherein the outer rail includes a bolt face configured to be received within a receiving recess in the casing, wherein the receiving recess is machined to a plane perpendicular to a central axis of the gas turbine engine; an inner rail having an inlet face, a suction side, a pressure side, and a platform, wherein the platform has an elliptical cross-section in a plane including the central axis; and an airfoil portion extending from the platform along a radial line, wherein the tab portion is formed to define a designed stagger angle, and the bolt face is machined to a plane defining the designed stagger angle; adjusting the plane of the bolt face of each of the stationary fins to define an off-design stagger angle; and The suction side of each stationary airfoil is positioned in contact with the pressure side of an adjacent stationary airfoil, wherein, when the stationary airfoils are not adjusted, the inlet face of each of the stationary airfoils cooperates to define a continuous annular surface, the platforms of each of the stationary airfoils cooperate to define a continuously curved surface, and the airfoil portions of each of the stationary airfoils cooperate to define a first throat area, and wherein, when the stationary airfoils are adjusted, the platforms of each of the stationary airfoils cooperate to define a stepped surface, and the airfoil portions of each of the stationary airfoils cooperate to define a second throat area.

8. The method of claim 7, wherein: Each bolt face defines an original plane, and wherein adjusting the plane of the bolt face of each of the stationary tabs includes removing material from each bolt face such that a new bolt face is non-parallel to the original plane.

9. The method of claim 7, wherein: The difference between the designed stagger angle and the deviated stagger angle is less than five degrees.

10. The method of claim 7, wherein: The stepped surface includes a step between each pair of adjacent stationary vanes, and wherein each step is less than 0.25 mm.

11. The method according to claim 7, wherein: The second throat area is smaller than the first throat area.

12. The method of claim 7, wherein: The second throat area differs from the first throat area by less than ten percent.

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