JP2015537150A - Curved stator shroud - Google Patents

Abstract

A curvilinear stator shroud vane assembly (30) in a gas turbine engine (10) has an inlet end (12), an outlet end, and a plurality of propulsor components (13). The stator shroud vane assembly (30) further includes a stator shroud (32) having a substantially circular cross section, the shroud extending between the front end (34), the rear end (36), and the front and rear ends. And at least one surface. The shroud has a plurality of pivots (38) disposed circumferentially around the shroud to support the trunnions (44) of the vanes (40), the at least one surface of variable height. Extends circumferentially adjacent to the plurality of pivots. [Selection] Figure 1

Description

  The present disclosure relates generally to gas turbine engines. More particularly, embodiments of the invention relate to a shroud utilized with a pivoting vane in a gas turbine engine.

  In a gas turbine engine, a typical gas turbine engine generally has a front end and a rear end, followed by a plurality of components in series. The air inlet or inlet is located at the front end of the engine. The intake port is followed by a compressor, a combustion chamber, a turbine, and a nozzle at the rear end of the engine in order toward the rear end. One skilled in the art will also appreciate that additional components can be included in the engine, such as, for example, low and high pressure compressors, high and low pressure turbines, and external shafts. However, this is not an exhaustive description. The engine also typically has an internal shaft that is axially disposed through the central longitudinal axis of the engine. The internal shaft is connected to both the turbine and the air compressor so that the turbine provides rotational input to the air compressor to drive the compressor blades.

  In operation, air is pressurized in the compressor and mixed with fuel in the combustor to generate hot combustion gases that flow downstream through the turbine stage. These turbine stages extract energy from the combustion gases. Initially, a high pressure turbine receives hot combustion gases from a combustor, and the high pressure turbine sets a stator nozzle set that directs the combustion gases downstream through a row of high pressure turbine rotor blades extending radially outward from a support rotor disk. Includes solids. In a two stage turbine, the second stage turbine stator nozzle assembly is positioned downstream of the first stage blade, followed by a row of second stage rotor blades extending radially outward from the second support rotor disk. . The turbine converts combustion gas energy into mechanical energy.

  A vane or airfoil is typically designed with a basic or optimal operating position. However, depending on the desired operating conditions of the turbine engine, the vanes may be actuated in different positions. Current stator shroud designs utilize a circular cross section to actuate the vanes. As the vane moves from the open design position to the off-design closed position, it is due to shroud curvature, flow path geometry, and the lower edge shape of the vane, all of which must meet compressor operating requirements. This increases the clearance between the vane and the shroud.

  As this clearance increases, turbulence in the flow can affect the function of the vane shape and the purpose of the structural body. For example, it would be desirable to overcome these and other deficiencies so that the clearance between the vane and the shroud at closed angular positions outside the vane design is reduced.

  According to at least some embodiments, a curvilinear contoured stator shroud vane assembly in a gas turbine engine having an inlet end, an outlet end, and a plurality of propulsion components comprises a stator shroud having a generally circular cross section. The shroud has a front end, a rear end, and at least one surface extending between the front end and the rear end, the shroud being circumferentially disposed about the shroud to support a vane trunnion And at least one surface having a variable height and extending in the circumferential direction adjacent to the plurality of pivot portions.

  According to at least some embodiments, the contoured stator shroud includes at least one front end, a rear end, and at least one surface extending between the front end and the rear end and tapered from the front end to the rear end. A plurality of variable height regions, each having a crest and a trough, and a plurality of pivot apertures spaced about the front end of at least one surface.

  According to yet another embodiment, the contoured stator shroud is circumferentially disposed between the front end, the rear end and at least one surface extending between the front end and the rear end, and the front end and the rear end. And at least one surface has a shell-like chord overhang region extending in the circumferential direction.

  Embodiments of the invention are shown in the following figures.

1 is a side sectional view of a gas turbine engine. The disassembled perspective view of a stator shroud vane assembly. The perspective view of a stator shroud vane assembly. FIG. 3 is a side cross-sectional view of an exemplary stator shroud vane assembly. FIG. 3 is a detailed perspective view of a stator shroud vane assembly. FIG. 6 is a rear view of the stator shroud vane assembly in a first position. FIG. 6 is a rear view of the stator shroud vane assembly in a second position. FIG. 9 is a rear view of the stator shroud vane assembly in a third position. A graph of the vane position associated with the clearance between the shroud and the vane.

  Reference will now be made in detail to the illustrated embodiments, one or more examples of which are illustrated in the drawings. Each example is provided by way of illustration and is not intended to limit the embodiments of the present disclosure. Indeed, those skilled in the art will appreciate that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Accordingly, the present invention is intended to protect such modifications and variations as falling within the scope of the appended claims and their equivalents.

  Reference is made to FIGS. 1-9, which are various embodiments of a curved contour stator shroud that can be used with a pivoting vane. The stator shroud includes a stator shroud overhanging surface on which the vanes pivot during engine operation. The stator shroud overhanging surface has a varying height to eliminate leakage between the vane and the shroud that would normally occur when the vane pivots on the outer surface of the shroud. This reduces any flow turbulence or flow disturbance along the vane or airfoil.

  The term “axial” or “axially” as used herein refers to a dimension along the longitudinal axis of the engine. The term “forward” as used in conjunction with “axial” or “axially” refers to movement in a direction toward the engine inlet, or a component is relatively close to the engine inlet compared to another component. Means that The term “backward” used in conjunction with “axial” or “axially” refers to movement in a direction toward the engine nozzle, or a component is relatively close to the engine nozzle relative to another component. Means that

  As used herein, the term “radial” or “radially” refers to a dimension extending between the central longitudinal axis of the engine and the engine perimeter. The term “proximal” or “proximal direction” used alone or in conjunction with the term “radial” or “radially” is moving in a direction toward the central longitudinal axis, or a configuration It means that the element is relatively close to the central longitudinal axis compared to another component. “Distal” or “distal”, used alone or in conjunction with the terms “radially” or “radially”, is moving in a direction toward the engine perimeter, or some configuration This means that the element is close to the engine periphery compared to another component.

  As used herein, the term “lateral” or “laterally” means a dimension that is perpendicular to both the axial and radial dimensions.

  Referring initially to FIG. 1, a schematic side cross-sectional view of a gas turbine engine 10 having an engine inlet end 12 is shown, generally defined by a compressor 14, a combustor 16, and a multi-stage high pressure turbine 20. Air flows into the propulsor 13. Overall, the propulsor 13 provides thrust or power during operation. The gas turbine 10 can be used in aircraft, power generation, industry, ships, or the like. Depending on the application, the engine inlet end 12 may alternatively include a multi-stage compressor rather than a fan. The gas turbine 10 is axisymmetric about the engine axis 26 or shaft 24 such that various engine components rotate about it. In operation, air enters through the air inlet 12 of the engine 10 and travels through at least one compression stage where the air pressure is increased and sent to the combustor 16. Pressurized air is mixed with fuel and combusted, resulting in hot combustion gases that exit from the combustor 16 toward the high pressure turbine 20. In the high pressure turbine 20, energy is extracted from the hot combustion gases causing rotation of the turbine blades, resulting in rotation of the shaft 24. The shaft 24 passes toward the front of the engine and continues to rotate one or more compressor stages 14, turbofans 18 or inlet fan blades, depending on the turbine design.

  An axisymmetric shaft 24 extends through the turbine engine 10 from the front end 12 to the rear end. The shaft 24 is journaled along its length. The shaft 24 can be hollow to allow rotation of the low pressure turbine shaft 28 therein independently of rotation of the shaft 24. Both shafts 24, 28 can rotate about the central axis 26 of the engine. In operation, the shafts 24, 28 rotate with other structures such as the turbine 20 and compressor 14 rotor assembly connected to the shaft, depending on the application area, for example, power generation, industry or aircraft. Generate output or thrust.

  Still referring to FIG. 1, the inlet 12 includes a turbofan 18 having a plurality of blades. The turbofan 18 is connected to the low pressure turbine 19 by a shaft 28, and generates thrust for the turbofan engine 10. The low pressure air can also be used to assist in cooling the engine components.

  Referring now to FIG. 2, an enlarged perspective view of the stator shroud vane assembly 30 is shown. A plurality of vanes 40 are spaced around the shroud 32, most of which are not shown. Three vanes 40 are shown disassembled from the outer surface of the shroud. However, it should be understood that a plurality of vanes 40 are disposed around the shroud 32 for purposes of clarity. The shroud 32 of the exemplary embodiment is conical with a circular cross-section and having a front end 34 and a rear end 36. The propulsion component 13 of the gas turbine engine 10 can pass within the hollow central portion of the shroud. An exemplary shroud 32 is located in the compressor 14 area of the engine. For example, a multi-stage compressor typically includes a plurality of rows of rotating blades mounted on the rotor and a plurality of rows of stator vanes 40 mounted between the stator casing and the shroud 32. The shroud is axisymmetric with respect to the shaft 24 (FIG. 1) of the engine 10.

  Near the front end 34 are a plurality of pivots 38, represented in the exemplary embodiment as a plurality of circular pockets, into which the vane 40 is fitted for rotation relative to the shroud 32. The The shroud 32 is also tapered from a small diameter near the front end 34 to a large diameter near the rear end 36. As will be further understood by further reading the present disclosure, a clearance is created between the lower edge of the vane 40 and the outer surface of the shroud 32 when the vane 40 is fitted into the pivot 38. The In a typical shroud, the circular cross-section will result in increased clearance between the vane and the shroud when the vane rotates to an off-design position. However, embodiments of the present invention provide a corrugated or variable surface height and reduce clearance at off-design positions of the vane 40.

  The vane 40 includes an outer spindle 44 and an inner spindle 45. The spindles 44, 45 can be formed along a vertical line or at an angle to the vertical. For example, the illustrated spindle is at an angle of 10-15 degrees from the vertical. The inner spindle 45 has a button 42 that fits into the pivot 38 together with the spindle 45. The upper button 56 also controls rotation in the engine casing, through which the outer spindle passes.

  Referring now to FIG. 3, a perspective view of the stator shroud vane assembly 30 is depicted. As described above, the shroud assembly 30 of the present invention is disposed within the compressor 14 of the turbine engine. However, the principles embodied in the curvilinear stator shroud 32 can also be used in alternative locations on the engine where shrouds and vanes or airfoils (eg, turbine stator vanes, etc.) are utilized. The illustrated stator shroud 32 is located on the inner diameter of the vane 40. An engine casing (not shown) can be used to provide an outer pivot position for the vane 40. The stator shroud vane assembly 30 utilizes a shroud 32 having a front end 34 and a rear end 36. The shroud 32 has a substantially circular cross section as partially shown in the drawing. The diameter at the front end 34 can be larger than the diameter at the rear end 36. The front end includes a plurality of pivots 38 on which the vanes 40 can be positioned. The pivot 38 is a concave area in which the vane or airfoil 40 is pivotably positioned using a button or guide 42. In the radially outward position of the vane 40 is a spindle 44 that can be used to mount the second end of the vane 40 to provide guided pivoting or rotation. The spindle 44 can pass through an aperture in the engine casing to stabilize the spindle and allow pivoting movement. A lever arm (not shown) induces rotation with the desired angular displacement providing different positions, improving engine efficiency and performance at multiple operating conditions. The plurality of vanes 40 extend around the periphery of the shroud 32 near the front end 34 of the shroud, but some are not shown for clarity.

  At least one shroud surface 46, such as a stator chord overhanging surface 46, extends rearward from the pivot 38. The stator chord overhanging surface 46 tapers from a small diameter near the pivot 38 to a large diameter near the rear end 36. This axial taper or height change can be curved or linear.

  In addition to this taper, the stator chord overhanging surface 46 is contoured so that the height changes in the circumferential direction. As illustrated by the dashed line 48 extending in the circumferential direction, the curve of the dashed line 48 describes a curvilinear contour of the stator chord overhanging surface 46 that varies between a lower and upper height in the circumferential direction. . Thus, the dashed line does not have a circular surface, but instead depicts a curved contour along the corrugated or sinusoidal surface 46. According to one embodiment of the present disclosure, the stator chord overhanging surface 46 has a corrugated curved contour 48 that reduces the clearance between the vane 40 and the shroud 32 during movement of the vane 40. According to an alternative embodiment, the circumferential height variation can be linear. In any embodiment, the surface 48 includes a plurality of peaks and valleys. The crest and trough axes are either substantially parallel to the engine 26 (FIG. 1) axis or at an angle with respect to the engine axis 26, the engine axis 26 being a shroud taper from the front end to the rear end. Is attached. As further described herein, the curved contour 48 significantly reduces flow field disturbances created by the clearance between the vane 40 and the shroud 32. These clearances will normally adversely affect the original purpose of the vane airfoil shape, function and structure as the vanes move between the open and closed angular positions.

  The exemplary vane or airfoil 40 includes a leading edge 50, a trailing edge 52, and an opposing surface extending therebetween. The opposing surface defines a suction side and a pressure side, which will be understood by those skilled in the art. At the radially outward end of the vane 40 is an outer enlarged portion or button 56. The spindle or trunnion 44 is connected to a lever arm or other feature that can actuate the vane 40 to a desired position. The rotation of the vane 40 can provide more than one optimum for the vane or airfoil and improve efficiency and performance at different operating conditions of the gas turbine engine 10.

  Near the lower end of the vane 40, a fillet 54 connects the vane 40 to the button 42 at the radially inner end. The lower edge 58 or vane overhang of the vane 40 is curved, and during movement of the vane 40, the lower edge 58 is a typical shroud surface represented by line 70 in a completely circular cross-section (FIG. 6). Move away from. This creates a clearance between the vane lower edge 58 and the chord overhanging surface 46 due to the divergent geometry. The increased clearance that occurs in the prior art for the system results in reduced performance, air flow turnover, and increased undesired losses in this area, which hinders improved engine performance. The curved contour represented by the corrugated or curved dashed line 48 reduces the clearance between the shroud 32 and the vane 40, improves the air turning performance, and reduces losses in this region.

  Referring now to FIG. 4, a cross-sectional side view of the assembly 30 of FIG. 3 is depicted. The shroud 32 is shown in a vertical cross section between the front end 34 and the rear end 36 so that a button 42 fitted within the pivot 38 is depicted. The vane 40 further includes a lower spindle or trunnion 45 that extends downwardly into the pivot so that the vane 40 is pivotally secured to the shroud 32, and the upward spindle 44 pivots through the engine casing. Holds movable. Further, as shown in the figure, the stator chord projecting surface 46 is curved in the axial direction between the front end 34 and the rear end 36, more specifically, behind the pivot portion 38. According to an alternative embodiment, the surface 46 is linearly tapered in the axial direction between the front end 34 and the rear end 36.

  Referring now to FIG. 5, a detailed perspective view of shroud 32 and vane 40 is depicted. This detailed view shows both the pivot 38 being empty and filled with vanes 40. The button 42 is fitted in a substantially circular pivot 38 and the vane 40 is connected to the button 42 by a fillet 54. A clearance 60 is shown between the lower edge 58 of the vane and the stator chord overhanging surface 46. The clearance is reduced compared to prior art stators due to the axial curvature between the front end 34 and the rear end 36. Similarly, the clearance is reduced due to the arcuate movement of the vane 40 within the pivot 38 due to the curved contour 48 along the circumferential direction of the overhanging surface 46.

  In FIG. 5, the curved contour 48 is shown more clearly because the dashed line 48 representing the curved contour of the stator shroud 32 is curved. A plurality of axially extending curved contour lines 49 depicting another curvature of the stator 32 are also shown on the stator chord overhanging surface 46. In combination with the lower edge 58 of the vane 40, the clearance between the vane 40 and the stator 32 is reduced, thereby improving engine performance through multiple positions of the pivoting vane 40. In connection with the operation of the engine 10, the vane 40 is closed when the engine speed is zero or nearly zero. In this closed position, the vane 40 is near the highest height of the curved contour surface 48. Alternatively, as the engine speed increases and approaches the maximum value, the vane 40 approaches the lowest height of the curved contour surface 48.

  6-8, the rear view which looked at the front of the shroud 32 is shown, and the vane 40 is shown to move at a plurality of positions. The curved contour of the stator chord overhanging surface 46 is best described with reference to this figure. The corrugated or sinusoidal surface 48 is formed by a plurality of shell-like ridges that vary between a first height and a second height. The term “sinusoidal” is used, but is not limited to mathematically exact sinusoids. The term is used in a general sense to indicate repeated height changes. Dashed line 70 is shown to represent a reference circular shape of a prior art shroud. Line 70 may also represent the base or first height of stator chord overhanging surface 46. Alternatively, the line 70 of the embodiment of the present invention may be above or below the valley or lower height of the stator chord overhanging surface, since the surface 46 also varies in axial height as shown. . The change in the height of the curved contour 48 is indicated by associating the difference between the first height 70 and the second upper height 72 of the curved contour. Accordingly, the overhanging surface 46 changes between the first height and the second height, and such a change in height causes the clearance between the vane 40 over the position shown in FIGS. Reduced. In addition, an axial flow line 70 is shown which indicates the direction of air flow across the stator shroud 32 to and from the vane 40 and is in an axial direction parallel to the engine axis 26 (FIG. 1).

  The vane 40 can rotate, for example, from minus 3 degrees to about 25 degrees. Thus, the exemplary vane 40 can move approximately 14 degrees from the center position in both two directions of rotation. However, this is only an example, and other angular ranges can be designed for vane movement.

  Referring now to FIG. 7, the vane in the center position is shown and the lower edge 58 of the vane is more clearly illustrated. The vane 40 is at 11 degrees according to the exemplary range described above. This is generally the center position. FIG. 7 shows a pair of clearance arrows. The clearance 60 indicates the clearance provided by the curved contour 48 in cooperation with the lower edge 58 of the vane 40. On the other hand, a clearance P is shown which shows a greater clearance between the lower edge 58 and the prior art shroud reference described above as line 70. From this embodiment, it can be clearly understood by those skilled in the art that the curved contour 48 provides a reduction in the difference.

  Referring now to FIG. 8, for example, the second extreme position of the vane 40 at a 25 degree position is illustrated. Again, the clearance 60 is much smaller than the prior art clearance P associated with the circular shroud reference 70.

  It should be understood by those skilled in the art that the vanes can take various shapes and forms depending on the design characteristics of the engine. Accordingly, the shape of the curved contour can be formed to match the shape of the lower edge of the vane with a pre-selected arcuate motion. The shroud surface, spindle angle, vane chord overhang, and travel are all designed / optimized with reduced clearance to account for loss reduction and performance improvements considered when optimizing variable vane systems. The

  Referring now to FIG. 9, a graph depicting the relationship between the vane angle measured in degrees and the clearance between the vane lower edge 58 and the shroud chord overhanging surface 46 is shown. As indicated by line 80 having diamond-shaped data points, the clearance increases substantially constant at an angle of minus 10 degrees to 25 degrees. The stator shroud 32 of this prior art embodiment has a circular shape and the curved contour shape of the embodiment of the present invention does not exist. Conversely, line 82, represented by a square data point, starts from a predefined range of minus 3 degrees and proceeds to a position of 25 degrees. The clearance represented by line 82 is approximately constant from about 0 degrees to about 12 degrees and then increases to the 25 degree position. Thus, by comparing the data points along lines 80, 82, one skilled in the art will appreciate that the clearance in the curvilinear stator shroud is much less than in the prior art.

  The above description of structures and methods has been presented for purposes of illustration. This description is not intended to be exhaustive or to limit the invention to the precise steps and / or forms disclosed, and many modifications and variations are possible in light of the above teaching. Clearly, it can be implemented. The features described herein can be combined in any way. The method steps described herein may be performed in any order physically feasible. While specific forms of curvilinear stator shrouds have been illustrated and described, it is understood that the invention is not limited, but only by the appended claims.

DESCRIPTION OF SYMBOLS 10 Gas turbine engine 12 Engine inlet end 13 Propulsor 14 Compressor 16 Combustor 18 Turbo fan 19 Low pressure turbine 20 Multistage high pressure turbine 24 Shaft 26 Engine axis 28 Low pressure turbine shaft

Claims (20)

  A curvilinear stator shroud vane assembly (30) in a gas turbine engine (10) having an inlet end (12), an outlet end, and a plurality of propulsion components (13) having a generally circular cross-section. A stator shroud (32), the shroud having a front end (34), a rear end (36), and at least one surface extending between the front end and the rear end, the shroud comprising a vane (40); A plurality of pivots (38) circumferentially arranged around the shroud to support the trunnions (44) of said at least one of said at least one surface of variable height A curvilinear contoured shroud vane assembly (30) extending circumferentially adjacent the section.   The contoured stator shroud vane assembly (30) of claim 1, wherein a variable height surface of the at least one surface is disposed adjacent an edge of the vane.   The contoured stator shroud vane assembly (30) of claim 2, wherein the variable height surface is curved to approximate a curvature defined by rotation of an edge of the vane.   4. A contoured stator shroud vane assembly (30) according to claim 3, wherein when the vanes pivot, leakage is suppressed by the vane overhanging surfaces and the variable height surfaces.   The contoured stator shroud vane assembly (30) of claim 1, wherein the plurality of pivots each receive the bottom of a plurality of vanes (40).   The contoured stator shroud vane assembly (30) of claim 1, wherein the axis of curvature of the variable height surface is substantially parallel to the engine axis. A curvilinear stator shroud (32),
A front end (34), a rear end (36), and at least one surface extending between the front end and the rear end and tapered from the front end to the rear end;
A plurality of regions of variable height disposed around the at least one surface, each having a crest and a trough;
A plurality of pivot apertures spaced apart around a front edge of the at least one surface;
A curved contour stator shroud (32).   The curved contour stator shroud (32) of claim 7, wherein the plurality of regions of variable height are curved circumferentially from a first height to a second height.   The curved contour stator shroud (32) of claim 7, wherein the plurality of variable heights are linear in a circumferential direction from a first height to a second height.   8. A contoured stator shroud (32) according to claim 7, wherein the shroud varies in height in the axial direction.   11. A contoured stator shroud (32) according to claim 10, wherein the varying height is curved.   11. A contoured stator shroud (32) according to claim 10, wherein the varying height is linear.   The contoured stator shroud (32) of claim 7, further comprising a vane (40) having a lowermost edge.   14. A contoured stator shroud (32) according to claim 13, wherein the lowermost edge engages a plurality of regions of the variable height during pivotal movement of the vane.   The curved contour stator shroud (32) of claim 7, wherein the plurality of regions of variable height are further curved to approximate a curvature defined by rotation of the lower edge of the vane. A curvilinear stator shroud (32),
A front end (34), a rear end (36), and at least one surface extending between the front end and the rear end;
A plurality of vane mounting portions disposed circumferentially between the front end and the rear end;
A curvilinear contoured shroud (32), wherein the at least one surface has a circumferentially extending shell-like chord overhang region.   17. A contoured stator shroud (32) according to claim 16, wherein the shell-like chord overhang region is curved from a lower height to an upper height of the stator shroud.   The curved contour stator shroud (32) of claim 16, further comprising a plurality of vanes (40) operably connected to the plurality of vane mounts.   The contoured stator shroud (32) of claim 18, wherein the plurality of vanes (40) each have an edge extending between a leading edge and a trailing edge. The contoured stator shroud (32) of claim 1, wherein the edge engages the shell-like chord overhang region during pivotal movement of the vane.