Strut cover for a turbine

Abstract

A turbine operable to produce an exhaust flow along a central axis includes a strut and a strut shroud. The strut has a flow portion located within the exhaust flow. The strut shroud has a length and is positioned to surround the flow portion of the strut. The strut shroud includes a leading edge portion, a mid-chord portion, and a trailing edge portion. The mid-chord portion has a consistent profile, and the trailing edge portion has a trailing edge center positioned such that the mid-chord portion and the trailing edge portion define a main chord plane. The leading edge portion defines a leading edge nose, and the leading edge portion is twisted relative to the main chord plane, and the leading edge nose defines a curve along the length that does not coincide with the main chord plane.

Description

BACKGROUND OF THE INVENTION

[0001] A turbine engine that includes a gas turbine and a steam turbine includes an exhaust section through which a working fluid exits the turbine. In the case of a gas turbine, the working fluid is a combustion gas stream, while the steam turbine discharges a stream of steam and / or water vapor. Typically, struts are placed in this exhaust stream to support components located within the stream, such as bearings. These struts can disrupt the flow and create an increased back pressure that reduces the efficiency of the turbine. SUMMARY OF THE INVENTION

[0002] In one configuration, a turbine operable to produce an exhaust stream along a central axis includes a strut and a strut shroud. The strut has a flow portion located within the exhaust stream, and the strut shroud has a length and is positioned to surround the flow portion of the strut. The strut shroud includes a leading edge portion, a mid-chord portion, and a trailing edge portion. The mid-chord portion has a uniform cross-section, and the trailing edge portion has a trailing edge center positioned such that the mid-chord portion and the trailing edge portion define a main chord plane. The leading edge portion defines a leading edge nose, and the leading edge portion is twisted relative to the main chord plane, and the leading edge nose defines a curve along the length that does not coincide with the main chord plane.

[0003] In another configuration, a turbine includes an exhaust portion having an inner flow liner and an outer flow liner that cooperate to define an annular flow space arranged to receive a flow along a flow direction. A strut shroud is positioned within the annular flow space and has a length normal to the flow direction between the inner flow liner and the outer flow liner. The strut shroud includes: a uniform mid-chord portion that defines a main chord plane; a trailing edge portion having a trailing edge center residing in the main chord plane; and a leading edge portion having a leading edge nose that is twisted relative to the main chord plane such that the leading edge nose intersects the main chord plane at no more than one point along the length.

[0004] In yet another configuration, a turbine includes an exhaust portion having an inner flow liner and an outer flow liner that cooperate to define an annular flow space. The strut has a flow portion that is located within the annular flow space and extends along an axis between the inner flow liner and the outer flow liner. A strut shroud is located within the annular flow space and extends between the inner flow liner and the outer flow liner. The strut shroud surrounds the flow portion and includes a leading edge portion, a mid-chord portion, and a trailing edge portion that cooperate to define a plurality of cross-sections normal to the axis. Each cross-section defines an arc, and the arcs in the mid-chord portion and the trailing edge portion overlap each other, and the arcs in the leading edge portion do not overlap each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] To facilitate identification of the discussion of any particular element or action, one or more of the most significant digits in the reference numerals refer to the figure number in which the element was first introduced.

[0006] Figure 1 is a longitudinal cross-sectional view of a gas turbine engine taken along a plane containing a longitudinal axis or a central axis.

[0007] Figure 2 illustrates a strut assembly according to one embodiment.

[0008] Figure 3 illustrates a first arrangement of a plurality of strut assemblies for a gas turbine engine, such as the gas turbine engine shown in Figure 1 the gas turbine engine shown in.

[0009] Figure 4 illustrates a second arrangement of a plurality of strut assemblies for a gas turbine engine, such as the gas turbine engine shown in Figure 1 the gas turbine engine shown in.

[0010] Figure 5 is an axial view of a strut cowl as viewed in the flow direction.

[0011] Figure 6 illustrates a plurality of cross-sectional views of a strut cowl taken along lines 1-1, 2-2, 3-3, 4-4, and 5-5 of Figure 5 the Figure 5 strut cowl.

[0012] Figure 7 is Figure 6 an enlarged view of a portion of the cross-sectional view of. Detailed Description

[0013] Before explaining in detail any embodiments of the present invention, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this specification or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Further, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

[0014] Various techniques related to systems and methods will now be described with reference to the accompanying drawings, where like reference numerals throughout indicate like elements. The drawings described below, as well as the various embodiments used to describe the principles of the present disclosure in this patent document, are for illustration only and should not be construed in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged device. It is to 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 configured to perform functions described as being performed by multiple elements. Many of the innovative teachings of this application will be described with reference to exemplary, non-limiting embodiments.

[0015] In addition, it should also be understood that, unless explicitly restricted in some examples, the terms or phrases used herein should be interpreted broadly. For example, the terms "comprising," "having," and "including" and their derivatives mean including but not limited to. The singular forms "a," "an," and "the" are intended to also include the plural forms unless the context clearly dictates otherwise. In addition, as used herein, the term "and / or" means and encompasses any and all possible combinations of one or more of the associated listed items. The term "or" is inclusive, meaning and / or, unless the context clearly dictates otherwise. The phrases "associated with" and "associated therewith" and their derivatives may mean including, included within, interconnected with, containing, contained within, connected to or coupled with, communicable with, cooperating with, interlaced, juxtaposed, adjacent to, combined with or coupled to, having, having the characteristics of, etc. In addition, although multiple embodiments or configurations may be described herein, any feature, method, step, component, etc. described with respect to one embodiment equally applies to other embodiments not specifically stated to the contrary.

[0016] In addition, although the terms "first," "second," "third," etc. may be used herein to refer to various elements, information, functions, or actions, these elements, information, functions, or actions should not be limited by these terms. Instead, these numerical adjectives are used to distinguish different elements, information, functions, or actions from one another. For example, without departing from the scope of the present disclosure, a first element, information, function, or action can be referred to as a second element, information, function, or action, and similarly, a second element, information, function, or action can be referred to as a first element, information, function, or action.

[0017] In addition, the term "adjacent" may mean: an element is relatively close but not in contact with another element; or the element is in contact with another part, unless the context clearly indicates otherwise. In addition, unless otherwise clearly stated, the phrase "based on" is intended to mean "at least partially based on". The term "about" or "substantially" or similar terms are intended to cover variations in values within the normal manufacturing tolerances of the industry for that dimension. If there is no available industry standard, unless otherwise stated, a twenty percent variation will fall within the meaning of these terms.

[0018] Figure 1 An example of a gas turbine engine 100 is illustrated, which includes a compressor section 102, a combustion section 106, and a turbine section 110 arranged along a central axis 114. The compressor section 102 includes a plurality of compressor stages 116, where each compressor stage 116 includes a set of rotating blades 118 and a set of stationary blades 120 or adjustable guide vanes. A rotor 122 supports the rotating blades 118 for rotation about the central axis 114 during operation. In some configurations, a single one-piece rotor 122 extends the length of the gas turbine engine 100 and is supported for rotation by bearings at either end. In other configurations, the rotor 122 is assembled from a number of separate spools that are attached to each other or may include a plurality of disk sections attached via one or more bolts.

[0019] The compressor section 102 is in fluid communication with an inlet section 124 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 102. During operation of the gas turbine engine 100, the compressor section 102 draws in and compresses the atmospheric air for delivery to the combustion section 106. The illustrated compressor section 102 is an example of a compressor section 102, and other arrangements and designs are possible.

[0020] In the illustrated configuration, the combustion section 106 includes a plurality of individual burners 126, each of which operates to mix a fuel stream with compressed air from the compressor section 102 and combust the air-fuel mixture to produce a high-temperature, high-pressure combustion gas stream or exhaust 128. Of course, many other arrangements of the combustion section 106 are possible.

[0021] The turbine section 110 includes a plurality of turbine stages 130, where each turbine stage 130 includes a number of rotating turbine blades 104 and a number of stationary turbine blades 108. The turbine stages 130 are arranged to receive the exhaust gas 128 from the combustion section 106 at the turbine inlet 132 and expand the gas to convert thermal energy and pressure energy into rotational or mechanical work. The turbine section 110 is connected to the compressor section 102 to drive the compressor section 102. For a gas turbine engine 100 used for power generation or as a prime mover, the turbine section 110 is also connected to a generator, a pump, or other devices to be driven. As with the compressor section 102, other designs and arrangements of the turbine section 110 are possible.

[0022] The exhaust section 112 is located downstream of the turbine section 110 and is arranged to receive the flow of the expanded exhaust gas 128 from the final turbine stage 130 in the turbine section 110. The exhaust section 112 is arranged to efficiently direct the exhaust gas 128 away from the turbine section 110 to ensure the efficient operation of the turbine section 110. The exhaust section 112 also includes one or more strut assemblies 200, which will be discussed in more detail. Many variations and design differences are possible in the exhaust section 112. Thus, the exhaust section 112 shown is only one example of those variations. Figure 2 As such, the exhaust section 112 shown is only one example of those variations.

[0023] The control system 134 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters and control various operations of the gas turbine engine 100. In a preferred configuration, the control system 134 is generally microprocessor-based and includes memory devices and data storage devices for collecting, analyzing, and storing data. Additionally, the control system 134 provides output data to various devices, including monitors, printers, indicators, etc., which allow a user to interface with the control system 134 to provide input or adjustments. In an example of a power generation system, the user can input a power output set point, and the control system 134 can adjust various control inputs to achieve that power output in an efficient manner.

[0024] The control system 134 can control various operating parameters, including but not limited to variable inlet guide vane position, fuel flow rate and pressure, engine speed, valve position, generator load, and generator excitation. Of course, other applications may have fewer or more controllable devices. The control system 134 also monitors various parameters to ensure the proper operation of the gas turbine engine 100. Some of the parameters monitored can include inlet air temperature, compressor outlet temperature and pressure, burner outlet temperature, fuel flow rate, generator power output, bearing temperature, etc. Many of these measurements are displayed for the user and recorded for later review if needed.

[0025] Figure 2 is an enlarged cross-sectional view of the strut assembly 200. It should be understood that most gas turbine engines 100 include a plurality of strut assemblies 200 that are similar or identical to the strut assembly shown Figure 2 in. Typically, the strut assemblies 200 are positioned at a common axial location and are evenly distributed about the central axis 114 of the gas turbine engine 100 (e.g., four strut assemblies 200 will be spaced ninety degrees apart). Of course, other arrangements and spacings are possible, including unequal spacings, axially varying spacings, and even different alignments of the different strut assemblies 200.

[0026] Each strut assembly 200 includes a strut 210 and a strut shroud 500 arranged to cover the strut 210. In the illustrated configuration, the strut 210 includes a first end fixedly attached to the outer casing 202 and a second end fixedly attached to a bearing housing 206 for a bearing (not shown). The flow portion 216 of the strut 210 extends between an inner flow bushing 208 and an outer flow bushing 204, where it may be exposed to the exhaust 128. Of course, as the design of the gas turbine engine 100 may require, each end may be attached to a different component. As described attachment, the strut 210 serves to rigidly attach the outer casing 202 and the bearing housing 206, thereby providing the necessary support for the bearing housing 206 and the rotor 122 supported by the bearing. The strut 210 passes through the outer flow bushing 204 and the inner flow bushing 208 and may or may not be attached to one or both of the outer flow bushing 204 and the inner flow bushing 208. The outer flow bushing 204 and the inner flow bushing 208 cooperate to define an annular flow space 218 through which the exhaust flows in the flow direction 222.

[0027] In many configurations, one or more of the struts 210 are hollow to provide a passage between the interior and exterior of the gas turbine engine 100. This passage is typically used to route instrument lines, air lines, lubricant lines, etc. For example, in the illustrated configuration, one of the struts 210 will include a lubricant line that guides lubricant fluid to and from the bearing. Additionally, vibration sensors within the bearing typically require wires to transmit signals from the sensors to the exterior of the gas turbine engine 100, where they can be routed to the control system 134.

[0028] In some configurations, cross-strut assemblies are provided between some or all adjacent pairs of strut assemblies 200. These cross-strut assemblies provide additional support and stability if desired. Each cross-strut assembly includes a cross-strut (commonly referred to as a gusset), and may include a cross-strut shroud if the cross-strut is in the exhaust flow. The cross-strut provides the desired structural support and can be of any shape, profile, or configuration desired. For example, a box beam, an I-beam, or a solid beam can be used as the cross-strut.

[0029] The cross-strut shroud surrounds or at least partially surrounds the cross-strut and is aerodynamically shaped to reduce any increase in backpressure that might be caused by the cross-strut in the case where the cross-strut is in the exhaust flow leaving the turbine. The cross-strut shroud does not necessarily provide any structural support and, therefore, can be made of thin sheet material. However, some configurations may use a more rigid or thicker material for the cross-strut shroud such that it does provide some structural support. It should be noted that many configurations of the gas turbine engine 100 do not include or do not require cross-strut assemblies.

[0030] In a preferred configuration, each strut 210 is welded to the outer casing 202 and the bearing housing 206. However, certain configurations may use other attachment means, such as fasteners. Similarly, each cross-strut is preferably welded to the strut 210 between which it extends.

[0031] Continuing to refer Figure 2 , the strut shroud 500 extends from the outer flow liner 204 to the inner flow liner 208 and covers the strut 210. As Figure 2 shown, each strut shroud 500 cooperates with the outer flow liner 204 and the inner flow liner 208 to define two wall fillets 220. Of course, other configurations may omit one or both of these wall fillets 220.

[0032] Each strut shroud 500 is aerodynamically shaped and covers one of the struts 210 such that the shape of the strut 210 can be selected for strength and stiffness without regard to aerodynamics. Thus, each strut 210 can be formed of a box beam, an I-beam, a solid beam, a channel beam, or any other shape or combination of desired shapes.

[0033] The aerodynamic shape of the strut shroud 500 includes a curved or elliptical leading edge portion 504 and a narrower curved or elliptical trailing edge portion 620. A tapered surface extends between the leading edge portion 504 and the trailing edge portion 620 to define a mid-chord portion 622 ( Figure 6 shown) to complete the shape.

[0034] In the illustrated configuration, the leading edge portion 504 extends along the length of the strut shroud 500 and maintains a consistent axial position. Accordingly, the leading edge portion 504 is substantially normal to the central axis 114. In the illustrated configuration, the trailing edge portion 620 is disposed normal to the central axis 114. Of course, in some configurations, one or both of the leading edge portion 504 and the trailing edge portion 620 may have a taper or inclination such that the leading edge portion 504 and / or the trailing edge portion 620 define an inclination angle relative to the central axis 114. For example, Figure 6 and Figure 7 the strut shroud 500 shown in

[0035] Figure 3 illustrates a first arrangement 300 of a plurality of strut assemblies, which includes three separate strut assemblies 200 arranged spaced apart from each other by approximately 120 degrees (circumferentially) (i.e., within typical manufacturing tolerances). As Figure 3 shown, each strut assembly 200 extends along an axis that is inclined relative to the radial axis of the gas turbine engine 100. Specifically, each strut assembly 200 extends from the inner flow bushing 208 to the outer flow bushing 204 along a line or axis that is tangent to the bearing housing 206. More specifically, the main chord plane 302 of each strut assembly 200 is arranged to be tangent to the bearing housing 206.

[0036] Although Figure 3 illustrates three equally spaced non-radial strut assemblies 200, other arrangements may vary the spacing between the strut assemblies 200, may include additional strut assemblies 200, or may include one or more radially arranged strut assemblies 200.

[0037] Figure 4 illustrates a second arrangement 400 of a plurality of strut assemblies, which includes six strut assemblies 200 arranged around the perimeter of the bearing housing 206. This arrangement includes a top dead center strut assembly 200 and a bottom dead center strut assembly 200 arranged along a main chord plane 302 that coincides with a radial plane that intersects the central axis 114. Two additional strut assemblies 200 are arranged along a main chord plane 302 that coincides with a radial plane in the upper portion of the gas turbine engine 100. The last two strut assemblies 200 are arranged along a non-radial main chord plane 302 in the lower portion of the gas turbine engine 100.

[0038] As with Figure 3 the arrangement of

[0039] It is important to note that the arrangement, location, or number of strut assemblies 200 employed in the gas turbine engine 100 is not critical to the arrangement of the strut cowl 500, since the Figures 5 to 7 arrangement described is not affected by any of these factors.

[0040] Figure 5 is an axial view of one of the strut cowls 500 as viewed along the flow direction 222 of the exhaust 128. The primary chord plane 302 (sometimes referred to as the skeleton plane or the center plane) is illustrated as passing through the entire length of the strut cowl 500 and substantially bisecting the strut cowl 500. The leading edge nose 502 is defined as the locus of the furthest upstream points (i.e., the leading edge center 604) of the leading edge portions 504 of the respective cross-sections taken parallel to the flow direction of the strut cowl 500. As Figure 5 shown, the leading edge nose 502 defines a curve that does not reside on or coincide with the primary chord plane 302, but rather deviates from the primary chord plane 302 and, in this configuration, crosses the primary chord plane 302 at no more than one location.

[0041] It should be noted that some configurations may include a leading edge nose 502 that defines a curve that never crosses the primary chord plane 302, while the preferred configurations include a single crossing. In some configurations, the leading edge nose 502 may cross multiple times, similar to a parabola, hyperbola, or higher order curve.

[0042] Figure 6 Better illustrates the aerodynamic shape of one possible arrangement of the strut cowl 500. Specifically, Figure 6 five cross-sections are illustrated, each taken at a different distance from the inner flow liner 208 to better illustrate the variation of the shape of the strut cowl 500 along the length of the strut cowl 500.

[0043] Figure 6 Illustrates the primary chord plane 302, which substantially bisects each cross-section (i.e., except for the leading edge portion 504 which may not be bisected). The primary chord plane 302 is parallel to the general flow direction and provides a reference for each cross-section.

[0044] The primary chord plane 302 defines the camber line of each cross-section having a leading edge center 604 and a trailing edge center 614 on the primary chord plane 302. The camber line is defined as the locus of the midpoints between the first curved edge 616 and the second curved edge 618 that define the complete strut cowl 500. For a symmetric strut cowl 500 with an untwisted leading edge center 604, the camber line lies on the primary chord plane 302. The camber lines of the other cross-sections generally coincide with the primary chord plane 302 from the trailing edge center 614 to a point near the leading edge portion 504, where the camber line will diverge slightly to match the twist of the leading edge portion 504 of each cross-section.

[0045] Along Figure 5 Figure 5 Take a first cross-section 602 at a point near the intersection of the strut shroud 500 and the inner flow bushing 208 along line 1-1. This first cross-section 602 defines a trailing edge center 614 that intersects the main chord plane 302 and a leading edge nose 502 that is offset from the main chord plane 302. The distance between the trailing edge center 614 and the leading edge center 604 of the first cross-section 602 defines a first length 624 of the strut shroud 500.

[0046] Along Figure 5 Figure 5 Take a second cross-section 606 of the strut shroud 500 at a point near the intersection of the strut shroud 500 and the outer flow bushing 204 along line 2-2. This second cross-section 606 also defines a trailing edge center 614 that lies on the main chord plane 302 and a leading edge center 604 that is offset from the main chord plane 302. The distance between the trailing edge center 614 and the leading edge center 604 of the second cross-section 606 defines a second length of the strut shroud 500. This second length 626 is shorter than the first length 624 because the strut shroud 500 includes a tapered or inclined trailing edge portion 620.

[0047] Along Figure 5 Figure 5 Take a third cross-section 608 of the strut shroud 500 at a point near the midpoint of the strut shroud 500 along line 3-3. This third cross-section 608 also defines a trailing edge center 614 that lies on the main chord plane 302 and a leading edge center 604 that is offset from the main chord plane 302. The distance between the trailing edge center 614 and the leading edge center 604 of the third cross-section 608 defines a third length of the strut shroud 500. This third length is between the first length 624 and the second length 626.

[0048] Along Figure 5 Figure 5 Take a fourth cross-section 610 of the strut shroud 500 at a point between the first cross-section 602 and the third cross-section 608 of the strut shroud 500 along line 4-4. This fourth cross-section 610 also defines a trailing edge center 614 that lies on the main chord plane 302 and a leading edge center 604 that is offset from the main chord plane 302. The distance between the trailing edge center 614 and the leading edge center 604 of the fourth cross-section 610 defines a fourth length of the strut shroud 500. This fourth length is between the first length 624 and the third length.

[0049] Along Figure 5 Figure 5 Take a fifth cross-section 612 of the strut shroud 500 at a point between the second cross-section 606 and the third cross-section 608 of the strut shroud 500 along line 5-5. This fifth cross-section 612 also defines a trailing edge center 614 that lies on the main chord plane 302 and a leading edge center 604 that is offset from the main chord plane 302. The distance between the trailing edge center 614 and the leading edge center 604 of the fifth cross-section 612 defines a fifth length of the strut shroud 500. This fifth length is between the second length 626 and the third length.

[0050] In Figure 5 , Figure 6 and Figure 7 the configurations shown, the leading edge nose 502 crosses the main chord plane 302 at some point between the first section 602 and the fourth section 610 near the fourth section 610. Of course, other configurations may include different arrangements that cause the leading edge nose 502 to cross the main chord plane 302 at different points. Additionally, different twists are anticipated, including greater twist, lesser twist, and twist in different directions, including configurations where the leading edge nose 502 does not cross the main chord plane 302.

[0051] The leading edge portion 504 of each section is arranged such that regardless of the position of the leading edge center 604, for all sections, the leading edge portion 504 merges into a first curved edge 616 and a second curved edge 618 that are aligned along the length of the strut shroud 500. Thus, when viewed along the length direction, as Figure 6 shown, the first curved edges 616 of all sections overlap each other and appear to coincide. Similarly, the second curved edges 618 of all sections overlap each other and appear to coincide.

[0052] Continuing to refer to Figure 6 , each first curved edge 616 merges into its corresponding trailing edge portion 620 such that when the first curved edges 616 approach their corresponding trailing edge portions 620, they diverge from each other. Similarly, each second curved edge 618 merges into its corresponding trailing edge portion 620 such that when the second curved edges 618 approach the trailing edge portions 620, they diverge from each other.

[0053] In configurations where the trailing edge portions 620 do not have an inclination or slope, the trailing edge portions 620 of each of the individual sections will overlap each other and appear to coincide when viewed along the length direction as shown, for example, in Figure 6 .

[0054] Figure 7 is an enlarged view of the leading edge portion 504 of the strut shroud 500 that better illustrates the deviation of the leading edge portions 504 of the individual sections. As can be seen, the first section 602 defines a first leading edge center 702, which is illustrated as being above the main chord plane 302. This will be the case when viewed in the flow direction (i.e., in Figure 5a corresponding counterclockwise twist to the left of or in the main chord plane 302. The fourth section 610 defines a fourth leading edge center 704, which is illustrated as being slightly below the main chord plane 302. Thus, the leading edge nose 502 crosses the main chord plane 302 at some point between the first section 602 and the fourth section 610. The remaining sections are further offset below the main chord plane 302, with the second section 606 and the fifth section 612 being very close to each other. When viewed from the flow direction, the twist of these sections corresponds to a clockwise twist to the right or in the (i.e., in Figure 5 ). Of course, different twist shapes, directions, magnitudes, and crossing points are possible, such that the present invention should not be limited to the examples provided herein. Thus, Figure 6 and Figure 7 the strut cowl 500 shown in has an aerodynamic shape that includes a twist of the leading edge portion 212 relative to the main chord plane 302, but also includes a mid-chord portion 622 and a trailing edge portion 214 that are symmetric with respect to the main chord plane 302.

[0055] In use, a plurality of struts 210 are attached to the outer housing 202 and the bearing housing 206 or other internal components to support the bearing housing 206 (or any other internal component) at a desired location. The size, shape, and number of the struts 210 are selected to provide the desired support and stiffness for the bearing housing 206 or other internal components. In the illustrated configuration, the bearing housing 206 at least partially supports the rotor 122 and must provide the necessary strength as well as sufficient stiffness for this support to minimize undesirable vibrations.

[0056] The strut cowl 500 extends between the inner flow bushing 208 and the outer flow bushing 204 and covers the struts 210 to protect the internal components from direct contact with the exhaust 128 and to provide an aerodynamic shape that reduces losses that may occur in response to flow disruptions caused by the struts 210. The strut cowl 500 includes a leading edge portion 504 that defines a leading edge nose 502, which is preferably positioned such that the tangent of the leading edge nose 502 is normal to the flow direction.

[0057] However, during operation, the flow leaving the turbine section 110 may have some vortices or rotation. The strut cowl 500 is similarly twisted so that the leading edge nose 502 is aligned normal to the flow at all positions. At some point along the length of the strut cowl 500, the flow leaving the turbine section 110 flows parallel to the central axis 114, and at this point the leading edge nose 502 is aligned with the main chord plane 302 that divides each strut cowl 500. Between this point and the inner flow bushing 208, the leading edge nose 502 may be twisted in a first direction, and between this point and the outer flow bushing 204, the leading edge nose 502 may be twisted in the opposite direction.

[0058] Although the exemplary embodiments of the present disclosure have been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein can be made without departing from the spirit and scope of the present disclosure in its broadest form.

[0059] No description in this application should be construed as implying that any particular element, step, act, or function is a necessary element that must be included within the scope of the claims: the scope of the patent subject matter is defined only by the allowed claims. Additionally, none of these claims is intended to invoke the means-plus-function claim construction unless the exact phrase "means for..." is followed by a participle.

Claims

1. A turbine capable of operating to produce an exhaust flow along a central axis, the turbine comprising: a strut having a flow portion located within the exhaust flow; and a strut shroud having a length and positioned to surround the flow portion of the strut, the strut shroud including a leading edge portion, a mid-chord portion, and a trailing edge portion, the mid-chord portion having a uniform cross-section, and the trailing edge portion having a trailing edge center positioned such that the mid-chord portion and the trailing edge portion are symmetric about a main chord plane, wherein the main chord plane is configured to bisect the central plane of the strut shroud, wherein the leading edge portion defines a leading edge nose, and wherein the leading edge portion is twisted relative to the main chord plane, and wherein the leading edge nose defines a curve along the length that does not coincide with the main chord plane.

2. The turbine according to claim 1 further includes an exhaust section, the exhaust section including an inner flow bushing and an outer flow bushing that cooperate to define an annular flow space, and wherein, The flow portion is disposed within the annular flow space.

3. The turbine according to claim 2, wherein The strut shroud is coupled to the inner flow bushing and the outer flow bushing, and the length extends between the inner flow bushing and the outer flow bushing.

4. The turbine according to claim 3, further comprising a first wall fillet formed between the inner flow bushing and the strut shroud and a second wall fillet formed between the outer flow bushing and the strut shroud.

5. The turbine according to claim 1, wherein, The strut is the first of a plurality of struts, and the strut shroud is the first of a plurality of strut shrouds, and wherein each strut of the plurality of struts and each strut shroud of the plurality of strut shrouds are circumferentially spaced from each other.

6. The turbine according to claim 5, wherein, One of the strut shrouds of the plurality of strut shrouds is arranged at an inclined angle relative to the radial axis of the turbine.

7. The turbine according to claim 1, wherein The leading edge nose is twisted relative to the main chord plane such that the leading edge nose intersects the main chord plane at no more than one point along the length.

8. The turbine according to claim 7, wherein, The leading edge nose crosses the main chord plane at a single point.

9. The turbine according to claim 1, wherein, The main chord plane is a radial plane including the central axis of the turbine.

10. The turbine according to claim 2, wherein, The leading edge portion, the mid-chord portion, and the trailing edge portion cooperate to define a plurality of cross-sections normal to the axis between the inner flow bushing and the outer flow bushing, and wherein each cross-section defines an arc, and wherein the arcs in the mid-chord portion and the trailing edge portion overlap each other, and the arcs in the leading edge portion do not overlap each other.

11. The turbine according to claim 10, wherein, Each of the plurality of cross-sections includes a leading edge center and the trailing edge center, and defines a distance measured from the leading edge center to the trailing edge center, and wherein the distance is not uniform among the plurality of cross-sections.

12. The turbine according to claim 11, wherein, The trailing edge portions of each of the plurality of cross-sections cooperate to define a tapered trailing edge portion.

13. The turbine according to claim 11, wherein, The distance is greater near the inner flow bushing than near the outer flow bushing.

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