Guide vane mechanism for use in a turbine

Abstract

To provide a guide vane mechanism which can be produced by a simple and cost-effective method, and at the same time, brings about enhanced fluid flow characteristics, in particular, with respect to uniformity of a flow.SOLUTION: A guide vane arrangement 110, in particular a guide vane arrangement 110 for use in a turbo pump, comprising a first guide vane 112 and a second guide vane 114, wherein the second guide vane 114 is arranged such that a flow channel 116 is defined between a leading surface 118 of the first guide vane 112 and a trailing surface of the second guide vane 114; A guide vane mechanism 110 comprising a second guide vane 114 disposed proximate to the first guide vane 112, wherein the flow channel 116 is designed such that the fluid flow flows at a desired first flow rate when exiting the flow channel 116.SELECTED DRAWING: Figure 6A

Description

[Technical Field]

[0001] The present disclosure relates to a guide vane mechanism for use in a turbine, a method of operating the guide vane mechanism, and a turbine including the guide vane mechanism. [Background technology]

[0002] Turbines, such as those for use in turbopumps, typically include guide vane mechanisms or guide grids located upstream of the turbine's rotor and operative to accelerate and deflect the fluid flow before it is delivered to the rotor. Specifically, the guide vane mechanisms accelerate and deflect the fluid flow so that it strikes the rotor blades at an angle and flow velocity that allows the rotor to operate at its design conditions.

[0003] Guide vane mechanisms for use in turbopump turbines can be produced in a multi-stage production process. In a first step, the guide vanes and carrier components of the guide vane mechanism, such as the tube body of a turbine manifold pipe or the turbine housing, are cast or machined separately from one another. Then, in a subsequent step, the individual components are welded together. Alternatively, it is known that the guide vanes and carrier components can be integrally formed with one another, for example, by an additive manufacturing process, which can be more cost-effective. Such a guide vane mechanism is known from U.S. Pat. No. 5,629,493. A cost-effective production process involves modifying the surface contours of the guide vanes, resulting in flow channels that do not match those of an ideal, shock-free nozzle, using a characteristic curve method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 3569817(A1) Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure is directed to the objective of identifying a guide vane mechanism that can be produced in a simple and cost-effective manner while at the same time providing enhanced fluid flow characteristics, particularly with respect to flow uniformity. Further, the present disclosure is directed to the objective of providing a method of operating such a guide vane mechanism. Finally, the present disclosure is directed to the objective of identifying a turbine including such a guide vane mechanism. [Means for solving the problem]

[0006] This object is achieved by a guide vane mechanism having the features of claim 1, a method for operating a guide vane mechanism having the features of claim 12, and a turbine having the features of claim 15.

[0007] According to one aspect, there is provided a guide vane mechanism, particularly for use in a turbopump, comprising: a first guide vane; and a second guide vane positioned proximate to the first guide vane such that a flow channel is defined between a leading surface of the first guide vane and a trailing surface of the second guide vane, the flow channel being designed to direct fluid flow at a desired first flow velocity upon exiting the flow channel. The trailing surface of the second guide vane includes a trailing portion disposed adjacent to the trailing edge of the second guide vane and at a first angle relative to an imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, a leading portion disposed adjacent to the leading edge of the second guide vane and at a second angle relative to the imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, and an intermediate portion disposed between the trailing portion and the leading portion and at a third angle relative to the imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, the second angle being greater than both the first and third angles. The portion of the trailing surface between the intermediate portion and the trailing edge includes at least one portion having a convex curvature.

[0008] The first guide vane and the second guide vane may have the same shape, and thus a guide vane referred to herein as a "first guide vane" relative to one adjacent "second guide vane" may also constitute a "second guide vane" relative to another adjacent "first guide vane."

[0009] In some embodiments, the trailing portion of the trailing surface has a linear course. In other embodiments, the trailing portion of the trailing surface does not have a linear course. Thus, the first angle defined by the trailing portion and the imaginary plane may vary along the trailing portion. If the trailing portion has a nonlinear course, the first angle may be the "average" first angle of the trailing portion. Specifically, the first angle may be defined by a line passing through two points, the beginning or upstream end of the trailing portion and the end or downstream end, which is the trailing edge, and the imaginary plane. The beginning of the trailing portion may be the downstream end of the intermediate portion. Alternatively, the beginning of the trailing portion may be the downstream end of a first transition portion between the intermediate portion and the trailing portion. As a further alternative, the beginning of the trailing portion may be the downstream end of a second transition portion between the intermediate portion and the trailing portion. The downstream end of the intermediate portion and / or the first transition portion and / or the second transition portion can be defined by an abrupt change in slope of the trailing surface, for example, if the intermediate portion and / or the first transition portion and / or the second transition portion have a linear course. Alternatively, the downstream end of the intermediate portion and / or the first transition portion and / or the second transition portion can be defined by an inflection point in the course of the trailing surface, for example, if the intermediate portion and / or the first transition portion and / or the second transition portion have a non-linear course.

[0010] If the entire trailing portion has a nonlinear course and the portion of the trailing portion immediately adjacent the trailing edge has a linear or nearly linear course, the first angle can be the angle between the linear portion and an imaginary plane defined by the trailing edges of the first guide vane and the second guide vane.

[0011] The first angle defined by the trailing portion and the imaginary plane can be selected such that fluid flow through the flow channel is controlled to exit the flow channel at a desired flow angle relative to the imaginary plane. The first angle defined by the trailing portion and the imaginary plane can substantially correspond to the desired flow angle that the fluid flow defines with the imaginary plane as it exits the flow channel.

[0012] In some embodiments, the leading portion of the trailing surface has a linear course. In other embodiments, the leading portion of the trailing surface does not have a linear course. Thus, the second angle defined by the leading portion and the imaginary plane may vary along the leading portion. If the course of the leading portion is nonlinear, the second angle may be the "average" second angle of the leading portion. Specifically, the second angle may be defined by a line passing through two points, the start point or upstream end and the end point or downstream end of the leading portion, respectively, and the imaginary plane. The start point of the leading portion may be the leading edge of the second guide vane. The end point of the leading portion may be an inflection point of the curvature, specifically a convex curvature, proximate the upstream end of the intermediate portion or the third transition portion between the leading portion and the intermediate portion.

[0013] The second angle of the leading portion of the trailing surface relative to the imaginary plane is greater than the first angle. Thus, after entering the flow channel, the fluid flow can flow along the leading portion and thereby be deflected to define a flow angle with the imaginary plane that is greater than a desired flow angle for the fluid flow upon exiting the flow channel.

[0014] In some embodiments, the intermediate portion of the trailing surface has a linear course. In other embodiments, the intermediate portion of the trailing surface does not have a linear course. Thus, the third angle defined by the intermediate portion and the imaginary plane may vary along the intermediate portion. If the course of the intermediate portion is nonlinear, the third angle may be the "average" third angle of the intermediate portion. Specifically, the third angle may be defined by a line passing through two points, the beginning or upstream end and the end or downstream end of the intermediate portion, respectively, and the imaginary plane. The third angle is smaller than the second angle. The upstream end may be the leading portion or the downstream end of the third transition portion. The downstream end of the third transition portion may be defined by an inflection point of the curvature, specifically the convex curvature, of the third transition portion adjacent to the intermediate portion.

[0015] Thus, the leading portion has a relatively steep course, particularly a large slope, compared to the intermediate and trailing portions, which eliminates the need for support structures for the leading portion during the additive manufacturing process of the guide vane. In particular, prior art guide vanes with flatter leading portions require the use of support structures during the additive manufacturing process, which can be difficult to remove after the additive manufacturing process due to the somewhat small cross-section of the flow channel formed with the leading faces of the opposing guide vanes. Furthermore, the relatively steep course of the leading portion of the guide vane features of the present disclosure can provide good accessibility to the leading portion, for example, for surface treatment of the leading portion. As a result, the guide vane features can be produced cost-effectively, for example, by additive manufacturing processes.

[0016] For example, the second angle may be greater than 25°, particularly greater than 30°, particularly greater than 35°, particularly in the range of 50° to 70°, preferably in the range of 55° to 65°, particularly about 60°. The first angle may be in the range of 10° to 35° or 15° to 35°, preferably in the range of 20° to 30°, particularly about 25°. The third angle may be in the range of 0° to 25°, for example 1° to 15° or 5 to 20°, preferably in the range of 7° to 20°, particularly about 10°.

[0017] The guide vane mechanism may be made of or include any material that meets certain requirements of the guide vane mechanism (hardness, temperature resistance, etc.). The guide vane mechanism may be composed of a metal, in particular titanium or a titanium alloy or a nickel alloy. The guide vane mechanism may also be made of or include other metallic materials, such as aluminum or steel alloys. The guide vanes of the guide vane mechanism may also be made of or include a ceramic or plastic material.

[0018] In the present disclosure, a surface portion having a convex curvature is a surface portion that protrudes into an adjacent flow channel, and a surface portion having a concave curvature is a surface portion that protrudes away from an adjacent flow channel. Or, in other words, each point on a convex surface portion is located "above" the tangent line when the flow channel is considered to be located "below" the tangent line to a point on the convex surface portion. Or, each point on a convex surface portion is located "above" the tangent line when the flow channel is considered to be located "below" the tangent line to each of the points on the convex surface portion. Similarly, each point on a concave surface portion is located "below" the tangent line when the flow channel is considered to be located "below" the tangent line to a point on the concave surface portion. Or, each point on a concave surface portion is located "above" the tangent line when the flow channel is considered to be located "below" the tangent line to each of the points on the concave surface portion.

[0019] At least one convex portion between the intermediate portion and the trailing edge of the trailing surface protrudes into the flow channel defined by the first and second guide vanes of the trailing surface. The at least one convex portion may be exactly two convex portions. A concave portion may be provided between the two convex portions. The curvature of the at least one convex portion may be adapted to maintain fluid flow parallel to the wall of the trailing surface while attenuating shock waves generated by the wall and / or avoiding the generation of new shock waves and / or avoiding characteristic or shock wave reflections, which may be beneficial for flow uniformity at the exit of the guide vane arrangement.

[0020] In one implementation, the trailing surface of the second guide vane can include a first transition portion between the intermediate portion and the trailing portion, the first transition portion defining a recompression portion of the flow channel where the flow cross-section decreases in the flow direction of the fluid flow through the flow channel, the recompression portion designed to slow the fluid flow to a second flow velocity as it flows through the recompression portion, and optionally, the first transition portion includes a first concave curvature. The first transition portion can also have a linear or substantially linear course. The first transition portion can include any course adapted to reduce the flow cross-section.

[0021] In a further implementation, the trailing surface of the second guide vane can include a second transition portion between the intermediate portion and the trailing portion, the second transition portion having a first convex curvature, optionally defining an additional expansion portion of the flow channel where the flow cross-section increases in the flow direction of the fluid flow through the flow channel, and optionally the additional expansion portion is designed to accelerate the fluid flow to a third flow velocity as it flows through the expansion portion. Thus, in a further implementation comprising a first convex curvature, the first convex curvature of the second transition portion is one portion of at least one portion having a convex curvature between the intermediate portion and the trailing edge. The convex curvature can provide additional expansion to the fluid flow before it exits the flow channel.

[0022] In a further implementation, the first transition section can be disposed between the intermediate section and the second transition section, and optionally, the third flow rate can be approximately equal to the desired first flow rate and / or can be faster than the second flow rate. Thus, in this embodiment, the second transition section can provide additional expansion of the fluid flow after recompression in the recompression section. The additional expansion can be adapted to counteract or weaken shock waves propagating within the flow channel. The second transition section can be designed to accelerate the fluid flow, specifically to a flow rate equivalent to the desired first flow rate.

[0023] In one embodiment, the trailing portion of the trailing surface of the second guide vane can have a second convex curvature. Thus, in embodiments including a second convex curvature, the second convex curvature of the trailing portion is one of at least one portion having a convex curvature between the intermediate portion and the trailing edge. The second convex curvature can be designed to maintain fluid flow parallel to the wall of the trailing surface to avoid or at least attenuate the emergence of a shock wave at the exit of the flow channel.

[0024] In one embodiment comprising a trailing surface having first and second convex curvatures, the trailing portion of the trailing surface of the second guide vane can comprise a second concave curvature between the first and second convex curvatures, and thus the second concave curvature can define a transition from the first convex curvature to the second convex curvature.

[0025] In a further embodiment, the leading section of the second guide vane can have a leading section curvature with an inflection point where the concave curvature changes to a convex curvature, the concave curvature being upstream of the convex curvature. The specific design of the leading section can be adapted to affect the location of the sonic line. The specific design of the leading section, particularly the convex curvature, can be designed to affect the flow characteristics upstream of the recompression section and therefore indirectly affect the effect of the recompression section on the fluid flow.

[0026] In one variation, the trailing surface of the second guide vane can include a third transition portion between the leading portion and the intermediate portion, the third transition portion can include a third convex curvature, and the third transition portion and the outlet portion of the leading surface of the first guide vane can define an expansion portion of the flow channel, where the flow cross-section of the fluid flow through the flow channel increases in the flow direction. The expansion portion can be designed to accelerate the fluid flow to a fourth flow velocity as it flows through the expansion portion, and optionally, the fourth flow velocity can be greater than the desired first flow velocity. Thus, in a variation in which the fourth flow velocity is greater than the desired first flow velocity, the expansion portion overexpands the fluid flow. The third transition portion can define a nozzle throat. Specifically, the convex curvature can define the nozzle throat. In a variation in which the leading portion of the second guide vane can have a curvature with an inflection point where the concave curvature changes to a convex curvature, the concave curvature being upstream of the convex curvature, and the trailing surface of the second guide vane includes a third transition portion having a third convex curvature, the third convex curvature can transition into the convex curvature of the leading portion curvature, or the third convex curvature can be a convex curvature of the leading portion curvature. In a last alternative, the third transition portion can be defined by the convex curvature of the leading portion curvature.

[0027] In a further variation, the third angle of the intermediate portion can be less than the first angle of the trailing portion, thereby deflecting the fluid flow as it flows along the intermediate portion such that the desired flow angle of the fluid flow upon exiting the flow channel is less than the flow angle with an imaginary plane.

[0028] In another variation, the leading surface of the first guide vane can comprise at least one of an inlet portion located proximate the leading edge of the first guide vane and located across the flow channel opposite the leading portion of the trailing surface of the second guide vane, where optionally the inlet portion of the leading surface of the first guide vane and the leading portion of the trailing surface of the second guide vane can define a restriction portion of the flow channel where the flow cross-section is reduced in the flow direction of the fluid flow through the flow channel, and an outlet portion located proximate the trailing edge of the first guide vane, where optionally the projection of the leading portion of the trailing surface of the second guide vane onto an imaginary plane at least partially overlaps with the projection of the outlet portion of the leading surface of the first guide vane onto the imaginary plane.

[0029] In one implementation of another variation, the projection of the intermediate and / or trailing portions of the trailing surface of the second guide vane onto an imaginary plane may not overlap with the projection of the exit portion of the leading surface of the first guide vane onto an imaginary plane.

[0030] A larger angle of the leading portion relative to the imaginary plane necessitates the presence of an intermediate portion that extends at an angle relative to the imaginary plane that is smaller than the angle defined between the trailing portion and the imaginary plane. However, the above design of the second guide vane ensures that the intermediate and / or trailing portions of the trailing surface of the second guide vane are not covered by the outlet portion of the leading surface of the first guide vane when viewed in the direction of the trailing edge of the guide vane, and are therefore easily accessible, for example, for surface treatment or for removing support structures constructed to support the intermediate and / or trailing portions during additive manufacturing of the guide vane feature.

[0031] According to a further aspect, a method includes providing a fluid flow to a flow channel defined between a leading surface of a first guide vane and a trailing surface of a second guide vane; and directing the fluid flow along a trailing portion of the trailing surface of the second guide vane, the trailing portion of the trailing surface being disposed proximate to a trailing edge of the second guide vane, thereby deflecting the fluid flow so that the fluid flow exits the flow channel at a first flow angle with respect to an imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, and at a desired first flow velocity, wherein the fluid flow is directed along a leading portion of the trailing surface of the second guide vane, the trailing portion of the trailing surface being disposed proximate to the leading edge of the second guide vane, thereby deflecting the fluid flow so that the fluid flow exits the flow channel at a second flow angle with respect to an imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, before being directed along the trailing portion of the trailing surface. the fluid flow is directed along an intermediate portion of the ring surface, thereby deflecting the fluid flow to flow at a third flow angle relative to an imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, the second flow angle being greater than each of the third flow angle and the first flow angle; then along a first transition portion of the trailing surface of the second guide vane, the first transition portion being located between the intermediate portion and the trailing portion, defining a recompression portion of the flow channel having a smaller flow cross-section in a flow direction of the fluid flow flowing through the flow channel, the recompression portion being designed such that the fluid flow is decelerated to a second flow velocity as it flows through the recompression portion; and then along a second transition portion of the trailing surface of the second guide vane, the second transition portion being located between the first transition portion and the trailing portion, defining an additional expansion portion of the flow channel having an larger flow cross-section in a flow direction of the fluid flow flowing through the flow channel, the additional expansion portion being designed such that the fluid flow is accelerated to a third flow velocity as it flows through the additional expansion portion;A method is provided for operating the guide vane mechanism such that the third flow rate substantially corresponds to the desired first flow rate, thereby providing a method for the fluid flow to undergo recompression and then additional expansion.

[0032] In one implementation of the method, the fluid flow can be directed along a third transition portion of the trailing surface of the second guide vane, disposed between the leading portion and the intermediate portion, before being directed along the trailing portion of the trailing surface, and the third transition portion and the outlet portion of the leading surface of the first guide vane can define an expansion portion of the flow channel where the flow cross-section increases in the flow direction of the fluid flow flowing through the flow channel, and the expansion portion can be designed such that the fluid flow accelerates to a fourth flow velocity as it flows through the expansion portion, and optionally the fourth flow velocity can be faster than the desired first flow velocity.

[0033] The third transition section, together with the outlet portion of the leading face of the first guide vane, can define a throat of the guide vane feature where the cross-section of the flow channel is smallest. Thus, in this method implementation, the fluid flow can be expanded and then subjected to recompression and additional expansion.

[0034] In further implementations, the method can include at least one of the following features: the first transition portion of the trailing surface of the second guide vane can comprise a first concave curvature, the second transition portion of the trailing surface of the second guide vane can comprise a first convex curvature, the trailing portion of the trailing surface of the second guide vane can comprise a second convex curvature, the third transition portion of the trailing surface of the second guide vane can comprise a third convex curvature, the trailing portion of the trailing surface of the second guide vane can comprise a second concave curvature between the first and second convex curvatures, and the leading portion can comprise a leading portion curvature with a convex curvature downstream of the concave curvature.

[0035] The present disclosure also provides a turbine, in particular a turbine for use in a turbopump, comprising a guide vane arrangement according to one or more of the above-disclosed aspects, implementations, embodiments, etc.

[0036] Further details, advantages, and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings. [Brief explanation of the drawings]

[0037] [Figure 1] 1 shows a schematic diagram of a guide vane mechanism according to the prior art; [Figure 2] The flow structure within a flow channel defined between two adjacent guide vanes of the guide vane arrangement of FIG. 1 is shown schematically by flow density gradient contours within the flow channel. [Figure 3] The enlarged partial view of the relevant throat region and upstream trailing section of FIG. 2 shows a schematic representation of the characteristic fluid flow and resulting shock and expansion waves. [Figure 4] 2 shows a schematic representation of the location of the shock wave in the diagram of the guide vane mechanism of FIG. 1; [Figure 5] 5A and 5B illustrate schematic diagrams of embodiments of optimized guide vane profiles according to the present disclosure compared to the baseline guide vane profiles of FIGS. 1, 2, and 4. [Figure 6A] 1 illustrates a schematic diagram of the operating principle of the optimized guide vane profile of the present disclosure. [Figure 6B] 1 illustrates a schematic diagram of the operating principle of the optimized guide vane profile of the present disclosure. [Figure 6C] 1 illustrates a schematic diagram of the operating principle of the optimized guide vane profile of the present disclosure. [Figure 6D] 1 illustrates a schematic diagram of the operating principle of the optimized guide vane profile of the present disclosure. [Figure 7A] The flow structure in a fluid channel between two adjacent guide vanes with optimized guide vane profiles according to the present disclosure is shown schematically by the flow density gradient contours within the channel. [Figure 7B] 10 shows a schematic representation of the effect of the optimized guide vane profile compared directly to the baseline profile, with the flow angle along the streamlines in the flow channel near the trailing surface. [Figure 8] Two figures comparing the pitchwise static pressure distributions, evaluated exemplarily at an axial position corresponding to the rotor leading edge (LE) plane, are shown using the baseline guide vane profile and the optimized guide vane profile. DETAILED DESCRIPTION OF THE INVENTION

[0038] In the present disclosure, a surface portion having a convex curvature is a surface portion that protrudes into an adjacent flow channel (relative to a surface portion adjacent to the convex curvature), and a surface portion having a concave curvature is a surface portion that protrudes away from an adjacent flow channel (relative to a surface portion adjacent to the concave curvature). Or, in other words, each point on a convex surface portion is located "above" the tangent line when the flow channel is considered to be located "below" the tangent line to a point on the convex surface portion. Or, each point on a convex surface portion is located "above" the tangent line when the flow channel is considered to be located "below" the tangent line to each of the points on the convex surface portion. Thus, each point on a convex surface portion of a guide vane surface adjacent to a flow channel can be considered to be located on the opposite side of the tangent line to a point on the convex surface from the side on which the flow channel is located. Similarly, each point on a concave surface portion is located "below" the tangent line when the flow channel is considered to be located "below" the tangent line to a point on the concave surface portion. Alternatively, each point on the concave surface portion is "above" the tangent to each point on the concave surface portion if the flow channel is considered to be "below" the tangent to each point on the concave surface portion. Thus, each point on the concave surface portion of the guide vane surface adjacent to a flow channel can be considered to be on the same side of the tangent to a point on the concave surface portion as the flow channel is located.

[0039] FIG. 1 shows only a single first guide vane 12 and a single second guide vane 14 of a prior art guide vane arrangement 10. The guide vane arrangement 10 corresponds to the guide vane arrangement of European Patent Application Publication No. 3,569,817, which is incorporated herein by reference. In particular, FIG. 1 shows longitudinal cross-sections of each of the first and second guide vanes 12, 14. However, the guide vane arrangement 10 includes a plurality of first and second guide vanes 12, 14 arranged adjacent to one another to define a plurality of flow channels 16. The first and second guide vanes 12, 14 of the guide vane arrangement 10 are identical in shape and size. Thus, in the arrangement of Figure 1, a guide vane that constitutes a first guide vane 12 relative to a second guide vane 14 located to the right hand side of the first guide vane 12 constitutes a second guide vane relative to another guide vane (not shown in Figure 1) located to the left hand side of the first guide vane 12.

[0040] The first and second guide vanes 12, 14 are integrally formed with each other and with a carrier structure 22, which is shown diagrammatically in FIG. 1 by a dotted line. The carrier structure 22 can be designed, for example, in the form of a rotationally symmetric turbine manifold and / or turbine housing, on which the individual first and second guide vanes 12, 14 of the guide vane arrangement 10 are mounted so as to define a guide grid through which the fluid flow F is supplied to the rotor. The rotor has a plurality of rotor blades and is rotatably mounted in the turbine downstream of the guide vane arrangement 10. The first and second guide vanes 12, 14 are fixedly attached to the turbine manifold and / or turbine housing so as to form a stator upstream of the rotor.

[0041] The leading face 18 of the first guide vane 12 includes an inlet portion 24 positioned adjacent to a leading edge 26 of the first guide vane 12 and an outlet portion 28 positioned adjacent to a trailing edge 30 of the first guide vane 12. The trailing face 20 of the second guide vane 14 defines the flow channel 16 with the leading face 18 of the first guide vane 12 and includes a trailing portion 32 positioned adjacent to a trailing edge 34 of the second guide vane 14, a leading portion 36 positioned adjacent to a leading edge 38 of the second guide vane 14, and an intermediate portion 40 positioned between the trailing portion 32 and the leading portion 36.

[0042] The inlet portion 24 of the leading face 18 of the first guide vane 12 is positioned across the flow channel 16 from the leading portion 36 of the trailing face 20 of the second guide vane 14, and together with the leading portion 36 of the trailing face 20 of the second guide vane 14, define a restriction 42 of the flow channel 16. The restriction 42 of the flow channel 16 reduces the flow cross-section of the fluid flow F in the direction of flow through the flow channel 16. Thus, the fluid flow F is accelerated as it is guided through the restriction 42, i.e., the fluid flow F exits the restriction 42 with a higher flow velocity than when it entered the flow channel 16 in the region of the leading edges 26, 38 of the first and second guide vanes 12, 14.

[0043] As is apparent from FIG. 1, the trailing portion 32 of the trailing surface 20 of the second guide vane 14 is angled at a first angle α with respect to an imaginary plane P defined by the trailing edges 30, 34 of the first and second guide vanes 12, 14. out In particular, imaginary plane P is a plane defined by trailing edges 30, 34 of first and second guide vanes 12, 14. During operation of guide vane mechanism 10, fluid flow F is directed along trailing portion 32, thereby forming a first angle α with respect to imaginary plane P. out a first flow angle α that substantially corresponds toFout The fluid flow F is deflected to exit the flow channel 16 .

[0044] The leading portion 36 of the trailing surface 20 of the second guide vane 14 is angled at a second angle α with respect to an imaginary plane P defined by the trailing edges 30, 34 of the first and second guide vanes 12, 14. in During operation of the guide vane mechanism 10, the fluid flow F is directed along the leading portion 36 before being directed along the trailing portion 32, such that in the region of the leading portion 36 the fluid flow F extends at a substantially second angle α with respect to the imaginary plane P. in The second flow angle α corresponds to Fin The fluid flow F is deflected to flow through the

[0045] The intermediate portion 40 of the trailing surface 20 of the second guide vane 14 is angled at a third angle α with respect to an imaginary plane P defined by the trailing edges 30, 34 of the first and second guide vanes 12, 14. inter During operation of the guide vane mechanism 10, the fluid flow F is guided along the intermediate portion 40, so that in the region of the intermediate portion 40 it extends at a substantially third angle α with respect to the imaginary plane P. inter The third flow angle α corresponds to Finter The fluid flow F is deflected to flow through the

[0046] Second angle α in is the first angle α out and the third angle α inter is the first angle α out Similarly, the second flow angle α Fin is the first flow angle α Fout and the third flow angle α Finter is the first flow angle α Fout In the exemplary embodiment of the guide vane mechanism 10 shown in FIG. out and the first flow angle α Fout is about 25°, the second angle α in and the second flow angle α Fin is about 60°, the third angle αinter and the third flow angle α Finter is about 10°.

[0047] Furthermore, the first and second guide vanes 12, 14 are aligned in such a manner that the leading portion 36 of the trailing surface 20 of the second guide vane 14 is projected onto the imaginary plane P by a projection PR l is a projection PR of the outlet portion 28 of the leading surface 18 of the first guide vane 12 onto the imaginary plane P. o , while the projection PR of the intermediate portion 40 and the trailing portion 32 of the trailing surface 20 of the second guide vane 14 onto the imaginary plane P i , PR t are designed and positioned relative to each other so as not to overlap with the projection onto the imaginary plane P of the exit portion 28 of the leading face 18 of the first guide vane 12. Thus, when viewed from the direction of the trailing edges 30, 34 of the guide vanes 12, 14, only the leading portion 36 of the trailing face 20 of the second guide vane 14 is covered by the exit portion 28 of the leading face 18 of the first guide vane 14, while the intermediate portion 40 and the trailing portion 32 of the trailing face 20 of the second guide vane 14 are freely accessible.

[0048] The trailing surface 20 of the second guide vane 14 includes a first transition portion 48, which is disposed between the intermediate portion 40 and the trailing portion 32 and has a concave curvature. The guide vane arrangement 10 can also be designed with a gentle curve extending along the entire length of the portion of the trailing surface 20 between the first transition portion 48 and the trailing edge 34. In that case, the portions 40 and 32 will bend at some point, forming an angle α inter and α out defines the slope of the wall at the beginning and end of the first transition portion 48.

[0049] The first transition section 48 defines a recompression section 50 where the flow cross section decreases in the direction of flow of the fluid flow F through the fluid channel 16. The recompression section 50 reduces the desired first flow velocity M of the fluid flow exiting the flow channel 16 as the fluid flow F flows through the recompression section 50. out It is designed to be slowed down to

[0050] Finally, the trailing face 20 of the second guide vane 14 includes a second transition portion 44. The second transition portion 44 is disposed between the leading portion 36 and the intermediate portion 40, and is disposed across the flow channel 16 from the outlet portion 28 of the leading face 18 of the first guide vane 12. The second transition portion 44 has a convex curvature. The second transition portion 44 and the outlet portion 28 of the leading face 18 of the first guide vane 12 define an expansion portion 46 of the flow channel 16 where the flow cross-section increases in the direction of the fluid flow F.

[0051] The flow channel 16 generally ensures that the fluid flow F exits the flow channel 16 at a desired first flow velocity M out However, the expansion section 46 is designed to allow the fluid flow F to flow at a desired first flow rate M as it passes through the expansion section 46. out A second flow velocity M faster than exp In other words, the expansion section 46 over-expands the fluid flow F, and the recompression section 50 relieves the over-expansion of the fluid flow F in the expansion section 46.

[0052] During operation of the guide vane mechanism 10, the restriction section 42, the expansion section 46, and the recompression section 50 ensure that the fluid flow F is maintained at a desired first flow rate M out At the same time, the design of the guide vanes 12, 14 allows for the fabrication of the guide vane mechanism 10 by additive manufacturing processes. In particular, the second angle α, which is approximately 60° in the exemplary embodiment of the guide vane mechanism 10 shown in FIG. inallows the leading portion 36 of the trailing face 20 of the second guide vane 14 to be manufactured by an additive manufacturing process without support from a support structure. Thus, the step of removing the support structure that is difficult to access because the leading portion 36 of the trailing face 20 of the second guide vane 14 is covered by the outlet portion 28 of the leading face 18 of the first guide vane 12 can be omitted.

[0053] In contrast, when building guide vane feature 10 layer by layer in an additive manufacturing process, at least low angle intermediate portion 40, and if necessary, trailing portion 32 of trailing face 20 of second guide vane 14, are supported by removable support structure S. However, because the design of guide vane feature 10 allows unobstructed access to intermediate portion 40 and trailing portion 32 of trailing face 20 of second guide vane 14, support structure S is easily removed after layer-by-layer building of guide vane feature 10 is complete. Additive manufacturing allows carrier structure 22 and guide vanes 12, 14 to be manufactured in one piece.

[0054] The prior art guide vane mechanism 10 shown in FIG. 1 is suitable for use in supersonic turbines, and the use of the same basic principles (adjusting the contour along the trailing surface 20 to obtain an average design flow velocity and average design angle at the exit plane P defined by the trailing edges 30 and 34) can also be applied to subsonic turbines.

[0055] It has been found that the profile of the prior art guide vane mechanism 10, illustratively shown in FIG. 1 , with its expansion section 46 and recompression section 50, can result in shock waves and reflected expansion waves in the fluid flow F, and therefore significant flow non-uniformity at the exit of the guide vane mechanism 10. The flow non-uniformity can lead to strong unsteady interactions between the guide vane mechanism and the rotor blades of the rotor downstream of the guide vane mechanism 10, resulting in large fluctuations in power output, aerodynamic forces and moments acting on the rotor blades, and pressure spikes against the rotor blades. All of these characteristics can lead to high cycle fatigue problems and therefore high flow losses that shorten the rotor's useful life and reduce efficiency.

[0056] FIG. 2 of the drawings shows the flow density gradient contour of the fluid flow F in the flow channel 16 between two adjacent first and second guide vanes 12 and 14 of the guide vane mechanism 10, and FIG. 3 shows an enlarged partial view of FIG. 2. The double-expansion fan A occurs in the expansion section 46 of FIG. 1 and includes a right-traveling leg and a left-traveling leg, i.e., a right-traveling expansion wave A-RR and a left-traveling expansion wave A-LR. The right-traveling expansion wave A-RR of the double-expansion fan A is induced by the sharp nozzle throat of the second guide vane 14, i.e., the sharp edge at the transition section 44 between the leading section 36 and the middle section 40 of the trailing face 20 shown in FIG. 1. The left-traveling expansion wave A-LR of the double-expansion fan A is induced by the sharp corner 52 of the trailing edge 30 of the leading face 18 of the first guide vane 12, as shown in FIG. 3.

[0057] Further downstream, the right-traveling expansion wave A-RR of the double-expansion fan A is followed by an oblique shock wave C. Shock wave C is caused by recompression of the flow in the recompression section 50. The oblique shock wave C, or recompression shock wave C, redirects the flow away from the wall defined by the trailing surface 20 of the second guide vane 14 and adjusts the flow direction relative to the wall angle of the trailing portion 32 of the trailing surface 20. The oblique shock wave C is also plotted in the diagram of FIG. 4.

[0058] The left-traveling expansion wave A-LR of the double-expansion fan A is followed by a shock wave B. Shock wave B results from a set of compression waves that merge into a strong oblique shock wave emanating from the trailing edge 30 of the first guide vane 12.

[0059] The left traveling expansion wave A-LR and shock wave B strike the trailing face 20 at the trailing portion 32 of the second guide vane 14 and are reflected as a right traveling expansion wave E and shock wave F (see FIG. 3).

[0060] The reflected right-traveling expansion wave E and shock wave F, along with the right-traveling expansion wave A-RR and recompression shock wave C, travel toward the downstream rotor blade, where the accumulation of these waves causes a sudden rise in pressure on the rotor blade.

[0061] The present disclosure provides optimized guide vane profiles that aim to avoid the generation of shock waves or at least reduce the strength of any shock waves that do occur. Specifically, the optimized guide vane profiles according to the present disclosure have the effect that the shock waves F and C described with respect to the baseline profile of the prior art do not occur or are at least greatly weakened.

[0062] Figure 5 of the drawings shows the optimized guide vane profile in direct comparison with the prior art guide vane profile discussed with respect to Figures 1-4. The prior art guide vane profile is hereinafter referred to as the baseline profile. Figure 5 shows only a single guide vane, which can be any of the multiple guide vanes in guide vane mechanism 110. For example, in this example, the guide vane having the optimized guide vane profile can be second guide vane 114.

[0063] The guide vanes having the optimized guide vane profile according to the present disclosure, and the resulting guide vane arrangement, can have the same features and characteristics as those described above with respect to the first and second guide vanes 12, 14 of the guide vane arrangement 10 according to the prior art embodiment having the baseline profile, except for the differences explicitly described in the following disclosure. Additionally, the same or corresponding features of the guide vane arrangement 110 according to the present disclosure have been numbered with the same reference numerals as the prior art guide vane arrangement 10, plus 100.

[0064] For example, although not shown in the guide vane arrangement 110 of Figures 5-7 according to the present disclosure, an imaginary plane P is defined similarly to the imaginary plane P of the prior art guide vane arrangement 10, i.e., the imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane. As a further example, the first angle α of the guide vane arrangement 110 according to the present disclosure out , the second angle α in , and the third angle α inter is defined in the same manner as the respective angles of the prior art guide vane mechanism 10, i.e., relative to an imaginary plane. If the respective trailing surface segments have a nonlinear course, the respective angles may be the "average" angles of the respective trailing surface segments. Specifically, the angles can be defined by a line passing through two points, the start and end points of the respective trailing surface segments, and the imaginary plane.

[0065] The optimized guide vane profile of guide vane 114 according to one embodiment of the present disclosure features four characteristic profile modifications compared to the baseline profile. Figure 5 shows an expanded view of the associated throat region "1" and supersonic nozzle portion "2" of the trailing surface. The throat region "1" has the primary function of transitioning the flow regime from subsonic to supersonic. The supersonic nozzle portion "2" is the portion of the trailing surface that provides the desired first flow velocity M, as explained above with respect to Figure 1. out and the first flow angle α Fout It features a semi-open expansion that accelerates the flow up to

[0066] As discussed above with respect to FIG. 1 and as can be seen from FIG. 5, the leading portion 36 of the trailing surface 20 of the second guide vane 14 having the baseline profile is angled at a relatively large second angle α with respect to an imaginary plane P defined by the trailing edges 30, 34 of the first and second guide vanes 12, 14. in , and the profile of the leading portion 36 has a generally linear course, i.e., the baseline profile of the leading portion 36 has a generally constant slope between the leading edge 38 and the second transition portion 44.

[0067] In contrast, the profile of leading portion 136 of the optimized guide vane profile exhibits an inflection point 154 between concave portion 156 and convex portion 158, with convex portion 158 located downstream of concave region 156, i.e., closer to the throat defined by second transition portion 44 (which, in the optimized profile, corresponds to third transition portion 144, as described below). The concave and convex shapes of the profile are relative to the interior of each guide vane 114. Concave portion 156 is where the surface profile slopes toward the interior of each guide vane 114, and convex portion is where the surface profile slopes away from the interior of each guide vane 114. Or, in other words, concave portion 156 is where the surface profile protrudes away from fluid channel 116, and convex portion is where the surface profile protrudes into fluid channel 116. A unique guide vane profile upstream of the throat or third transition section 144, having a concave portion 156 and a convex portion 158 and an inflection point 154 therebetween, is labeled with a unique characteristic "α."

[0068] Although not shown, the course of the optimized guide vane profile substantially overlaps the course of the baseline profile at the start and end points of the leading portion, so that the average second angle α of the leading portion defined by a line passing through the two points, the start and end points of the leading portion, is in is the second angle α of the baseline profile in is roughly equivalent to

[0069] The unique feature "α" causes the downstream third transition portion 144 to have a slightly different shape than the corresponding second transition portion 44 of the baseline profile. Nevertheless, the third transition portion 144 has a third convex curvature and, together with the outlet portion 128 of the leading face 118 of the first guide vane 112, defines an expansion portion 146 of the flow channel 116 where the flow cross-section increases in the flow direction of the fluid flow through the flow channel 116 (see also FIG. 6A).

[0070] An additional unique feature, labeled "β," is provided downstream of the throat in throat region "1." This unique feature is provided in second transition region 160 between trailing portion 132 and first transition portion 148 of trailing surface 120. In second transition region 160, the optimized profile of trailing surface 120 according to the present disclosure includes a first convex curvature, labeled "β."

[0071] A third unique feature, labeled "δ," is provided in the trailing portion 132 of the trailing surface 120 at the supersonic nozzle portion "2" downstream of the throat region "1." In the baseline profile, the trailing portion 32 of the trailing surface 20 of the second guide vane 14 has a profile with a monotonic course, specifically a monotonic curvature, or more specifically a slightly monotonic curvature. In contrast, the optimized profile of the trailing portion 132 of the trailing surface 120 according to the present disclosure has a second convex curvature "δ" at the supersonic nozzle portion "2" downstream of the throat region "1," as seen in the enlarged partial view of the supersonic nozzle portion "2" in FIG. 5. As also seen in FIG. 5, the surface profiles of the trailing edges 34, 134 of the baseline profile and the optimized profile overlap one another.

[0072] Finally, a fourth unique feature, labeled "ε," results from the unique features "β" and "δ." In particular, because trailing surface 120 has first and second convex curvatures "β" and "δ" at second transition portion 160 and trailing portion 132, an intermediate portion having concave curvature "ε" is provided between the two convex surface portions "β" and "δ." This concave feature also counteracts the left traveling expansion wave A-LR (originating from the trailing edge of first guide vane 112) impinging on second guide vane 114 (see FIG. 6D).

[0073] The first angle α shown in FIG. out is the average angle defined by a line (not shown) passing through two points, the beginning and end of the trailing portion 132, and the corresponding first angle α of the baseline profile. out It is almost the same as:

[0074] In this embodiment, except for the differences described, the second guide vane 114 may generally correspond to the second guide vane 14 of the prior art, forming a guide vane mechanism 110 with an identical first guide vane 112.

[0075] The beneficial impact of these four unique features on flow uniformity and loss reduction will be explained below with reference to Figures 5 and 6A-6C of the drawings. In particular, Figures 6A-6C schematically illustrate the operating principle of an optimized guide vane profile according to one embodiment of the present disclosure by comparing the flow situation with a guide vane mechanism 10 having a baseline profile.

[0076] Figure 6A shows a guide vane arrangement 110 with an optimized guide vane profile according to one embodiment of the present disclosure, Figure 6B is a close-up of the throat region of Figure 6A having the feature "β," and Figure 6C is a close-up of the supersonic nozzle portion of Figure 6A relating to the feature "δ." The left views of Figures 6B and 6C each show corresponding portions of the trailing surface of the baseline profile.

[0077] The left diagram of Figure 6B shows the trailing surface profile of the intermediate portion 40 immediately downstream of the throat bump first transition portion 44, followed by the trailing surface profile of the downstream first transition portion 48 and trailing portion 32. The first transition portion 48 provides a first bend 64 between the intermediate portion 40 and the trailing portion 32 that protrudes away from the flow channel 16. The first bend 64 may be part of a first concave curvature in the first transition portion 48. Figure 6B also shows the shock wave C in the recompression portion 50 defined by the first transition portion 48.

[0078] The right diagram of Figure 6B showing the optimized guide vane profile also includes a first transition portion 148 having a first bend 164. Additionally, downstream of the first bend 164, a second bend 166 of convex curvature "β" in the second transition portion 160 is additionally shown, which protrudes into the flow channel 116. The intermediate portion 140 is angled at a third angle α with respect to an imaginary plane defined by the trailing edges of the first and second guide vanes 112, 114, the same or approximately the same as the intermediate portion 40 of the baseline profile. interIn one embodiment, the intermediate portion 140 is positioned at a corresponding angle α of the intermediate portion 40 of the baseline profile to mitigate expansion due to the third transition section 144. inter A third angle α that is slightly smaller than inter are arranged in

[0079] From the close-up view of the relevant portion of the supersonic nozzle section in FIG. 6C, it can be seen that compared to the linear or nearly linear course of the trailing surface 20 in the trailing portion 32 of the baseline profile, the optimized profile of the trailing portion 132 provides a third bend 168 of convex curvature "δ" that protrudes into the flow channel 116.

[0080] As seen in and described with respect to Figure 5, the unique feature "α" upstream of the throat in the throat region features a more pronounced throat bump, particularly toward the subsonic portion of the trailing surface 120 profile, which "widens" the throat bump and advances the sonic line further upstream compared to the baseline profile. As a result, a portion of the expansion section 146 is smoothed and the right-traveling expansion wave A-RR is weakened compared to the baseline profile, resulting in smaller flow non-uniformities that can adversely affect downstream rotor blades (see Figure 8).

[0081] It can also be seen from Figure 6B that the expansion fan A of the optimized surface profile is weakened compared to the expansion fan A of the baseline profile.

[0082] Furthermore, weakening the expansion fan A upstream of the recompression shock wave C reduces the flow turning that occurs within the throat (see also FIG. 7B ), and therefore reduces the strength of the recompression shock wave C caused by the compression of the flow in the recompression section 150 at or near the first bend 164. In particular, the reduced flow turning requires a smaller change in flow angle to adjust the flow direction relative to the wall angles of the first transition section 148 and the trailing section 132, ultimately weakening the shock wave C caused by the recompression section 150.

[0083] Furthermore, the reduced recompression caused by the reduced flow deflection downstream of shock C, combined with the reduced overexpansion, results in shock C disappearing or at least being significantly attenuated before reaching the downstream rotor.

[0084] Additionally, unique feature "β" provides a protruding "bump" (second bend 166) into flow channel 116 due to the convex curvature characteristics of feature "β." The "bump" redirects the flow away from shock wave C, thereby inducing additional expansion fan K. Additional expansion fan K further reduces the impact strength of shock wave C until it cancels in the far field. The additional expansion fan K is also shown downstream of shock wave C in the optimized profile flow situation of FIG. 6B. It is also shown schematically that additional expansion fan K cancels shock wave C in the far field. Thus, second transition region 160 defines an additional, second expansion portion of the flow channel.

[0085] Thus, the unique feature "β" reconfigures the expansion-compression design of the prior art baseline profile into an expansion-compression-expansion design. The resulting benefit is that the strength of the shock wave C is reduced until it is cancelled in the far field, which improves flow homogeneity and reduces mixing losses (caused by viscous dissipation at the shock wave).

[0086] The baseline profile did not consider the effect of the trailing edge shock wave B on the supersonic section of the nozzle. The unique feature "δ" directs the supersonic flow in the supersonic nozzle section "2" so that the flow direction remains parallel to the wall defined by the trailing portion 132. This is achieved as explained below. In the guide vane arrangement 10 with the baseline profile, the shock wave B emanating from the trailing edge 30 of the first guide vane 12 redirects the flow toward the wall defined by the trailing portion 32. This redirection compresses the flow and causes a reflected shock wave F to appear, adjusting the flow direction relative to the wall angle (see left diagram in Figure 6C). The convex curvature with its unique feature "δ" "bump" (third bend 168) absorbs such flow deflection by the shock wave B and ensures that the flow remains parallel to the wall contour downstream of the shock wave B defined by the trailing portion 132, thereby avoiding or at least greatly attenuating the appearance of a reflected shock wave F.

[0087] Therefore, the inherent feature "δ" has the benefit of avoiding additional recompression due to the reflected shock wave F, improving the homogeneity of the flow and reducing the mixing losses (caused by viscous dissipation occurring in the reflected shock wave F).

[0088] Finally, in the guide vane mechanism 10 with the baseline profile, the left-traveling expansion wave LR of the expansion fan A, generated by the trailing edge corner 52 of the trailing edge 30 of the opposing leading surface 18 of the first guide vane 12 (the opposing guide vane forming a fluid channel with the second guide vane 14), strikes the trailing surface 20 at the trailing portion 32 of the second guide vane and is reflected as an expansion wave E. These waves travel downstream and affect the flow uniformity at the exit of the guide vane mechanism and the subsequent rotor blade. The inherent feature "ε" characterized by the second concave curvature cancels the incoming left-traveling expansion wave A-LR, thereby ensuring that the flow angle after a wave is parallel to the wall contour downstream of that wave. This is shown schematically in Figure 6D of the drawings. This contributes to a smoother exit flow field.

[0089] The trailing surface 120 of the guide vane mechanism 110 can also be designed to have a gradual, non-linear curvature that extends along the entire length of the trailing surface 120 between the second transition portion 144 and the trailing edge 134. In that case, the intermediate portion 140 bends at a point, forming an angle α inter defines the slope of the wall at the beginning of the first transition portion 148.

[0090] In summary, the combination of the unique features "α," "β," and "δ" reduces the generation of shock waves traveling outward into the far field of the guide vane mechanism 110. The feature "ε" counteracts the reflection of expansion waves traveling into the far field of the guide vane mechanism 110. This improves the homogeneity of the flow field at the exit of the guide vane mechanism before it reaches the rotor. Additionally, the attenuation of the shock waves also reduces viscous and mixing losses, improving nozzle performance.

[0091] 7A shows a Computational Fluid Dynamics (CFD) simulation of the density gradient contour in the flow channel 116 of the optimized guide vane mechanism 110 according to the present disclosure. Compared to the CFD simulation of the baseline profile in FIG. 2, the recompression shock wave C is weaker and nearly disappears in the far field, and the reflected shock wave F also nearly disappears.

[0092] Figure 7B shows simulation data for the flow angle (i.e., the angle from the axial direction, i.e., from an imaginary line perpendicular to "P" in Figure 1) as a function of the streamwise (flow direction) flow through the flow channel. It was found that weakening the expansion fan A upstream of the recompression shock wave C reduces the flow transformation within the throat. Furthermore, it was found that the convex curvature with the "bump" (third bend 168) of characteristic feature "δ" prevents or at least weakens the reflected shock wave F, allowing the flow to remain substantially parallel to the wall contour downstream of the shock wave B, i.e., eliminating or minimizing the flow redirection. Finally, as also seen in Figure 7B, additional flow redirection due to the reflection of the incoming left-traveling expansion wave A-LR is also avoided or at least attenuated by the characteristic feature "ε."

[0093] Figure 8 shows a comparison of the pitchwise normalized static pressure distributions evaluated at the axial position corresponding to the rotor LE plane using the baseline and optimized guide vane profiles. This normalized static pressure distribution is based on simulation data. The pitchwise distribution of the baseline design is affected by the wide and sharp fluctuations caused by the expansion fan and shock waves described above. More specifically, when moving from low to high pitch fractions, the initial downward trend between 0 and 0.2 is attributed to the RR section of the expansion fan A. A rapid pressure increase then appears around pitch fraction 0.2 as a result of the oblique recompression shock wave C. Shock wave C is followed by a downward trend (between 0.2 and 0.5) due to the reflected expansion fan E, followed by a rapid increase due to the propagation of the reflected shock wave F. Finally, at a pitch fraction of approximately 0.8, a particularly rapid pressure increase occurs due to the strong oblique shock wave H, followed by a downward trend. This downward trend can be attributed to the initial part of the RR section of the expansion fan A. Furthermore, this pattern also affects the pitchwise distribution of other quantities such as exit velocity and exit flow angle, which are not shown here.

[0094] Using the guide vane arrangement 110 with the optimized guide vane profile according to the present disclosure, the static pressure distribution is substantially smoother. The pressure spikes caused by the shock waves "F" and "C" and the expansion wave "E" can also be eliminated or at least attenuated.

[0095] The guide vane mechanism 110 according to the present disclosure with an optimized guide vane profile has the effect of weakening and / or avoiding shock waves at the exit of the guide vane mechanism, thereby reducing dynamic loads on the downstream rotor and thereby enhancing rotor life.

[0096] Furthermore, a reduction in flow losses can be realized, thereby increasing the efficiency of a turbine or turbopump equipped with the guide vane mechanism. At the same time, the guide vane mechanism can be produced in a cost-effective manner, for example by additive manufacturing processes, and therefore offers the same advantages in terms of manufacturing processes as the guide vane mechanism known from EP 3 569 817 A. [Explanation of symbols]

[0097] 110 Guide vane mechanism 112 First guide vane 114 Second guide vane 116 Flow Channel 118 Leading Side 120 Trailing side 130 Trailing Edge 132 Trailing part 134 Trailing Edge 136 Reading Section 138 Leading Edge 140 Middle part

Claims

1. A guide vane mechanism (110) for use in a turbine, comprising: a first guide vane (112), a second guide vane (114), the second guide vane (114) being positioned proximate to the first guide vane (112) such that a flow channel (116) is defined between a leading surface (118) of the first guide vane (112) and a trailing surface (120) of the second guide vane (114), the flow channel (116) being designed to cause a fluid flow (F) to flow at a desired first flow velocity upon exiting the flow channel (116); and Equipped with The trailing surface (120) of the second guide vane (114) a trailing portion (132) disposed adjacent to the trailing edge (134) of the second guide vane (114) and disposed at a first angle with respect to an imaginary plane defined by the trailing edge (130) of the first guide vane (112) and the trailing edge (134) of the second guide vane (114); a leading portion (136) disposed adjacent to the leading edge (138) of the second guide vane (114) and disposed at a second angle with respect to the imaginary plane defined by the trailing edge (130) of the first guide vane (112) and the trailing edge (134) of the second guide vane (114); an intermediate portion (140) disposed between the trailing portion (132) and the leading portion (136) and disposed at a third angle with respect to the imaginary plane defined by the trailing edge (130) of the first guide vane (112) and the trailing edge (134) of the second guide vane (114), the second angle being greater than each of the first and third angles; and Equipped with a portion of the trailing surface (120) between the intermediate portion (140) and the trailing edge (134) comprising at least one portion having a convex curvature (β, δ); Guide vane mechanism (110).

2. 2. The guide vane mechanism of claim 1, wherein the trailing surface of the second guide vane comprises a first transition portion between the intermediate portion and the trailing portion, the first transition portion defining a recompression portion of the flow channel at which a flow cross-section decreases in a flow direction of the fluid flow through the flow channel, the recompression portion designed to decelerate the fluid flow to a second flow velocity as it flows through the recompression portion, and optionally the first transition portion comprises a first concave curvature.

3. 2. The guide vane mechanism of claim 1, wherein the trailing surface of the second guide vane comprises a second transition portion between the intermediate portion and the trailing portion, the second transition portion comprising a first convex curvature, optionally the second transition portion defining an additional expansion portion of the flow channel that increases a flow cross-section in the flow direction of the fluid flow through the flow channel, optionally the additional expansion portion being designed such that the fluid flow is accelerated to a third flow velocity as it flows through the additional expansion portion.

4. the trailing surface of the second guide vane comprises a first transition portion between the intermediate portion and the trailing portion, the first transition portion defining the recompression portion of the flow channel at which a flow cross-section of the fluid flow through the flow channel decreases in the flow direction, the recompression portion being designed such that the fluid flow is slowed to a second flow velocity as it flows through the recompression portion, and optionally the first transition portion comprises a first concave curvature; 4. The guide vane mechanism of claim 3, wherein the first transition portion is disposed between the intermediate portion and the second transition portion, and optionally the third flow velocity approximately corresponds to the desired first flow velocity and / or is higher than the second flow velocity.

5. The guide vane arrangement (110) of claim 1, wherein the trailing portion (132) of the trailing surface (120) of the second guide vane (114) comprises a second convex curvature (δ).

6. the trailing surface (120) of the second guide vane (114) comprises a second transition portion (160) between the intermediate portion (140) and the trailing portion (132) comprising a first convex curvature (β), optionally the second transition portion (160) defining an additional expansion portion of the flow channel (116) where a flow cross-section increases in the flow direction of the fluid flow flowing through the flow channel (116), optionally the additional expansion portion being designed such that the fluid flow is accelerated to a third flow velocity as it flows through the additional expansion portion; 6. The guide vane mechanism of claim 5, wherein the trailing portion of the trailing surface of the second guide vane comprises a second concave curvature between the first convex curvature and the second convex curvature.

7. 2. The guide vane mechanism of claim 1, wherein the leading portion of the second guide vane has a leading portion curvature having an inflection point where the concave curvature of a concave portion changes to the convex curvature of a convex portion, the concave portion being upstream of the convex portion.

8. 2. The guide vane mechanism of claim 1, wherein the trailing surface of the second guide vane comprises a third transition portion between the leading portion and the intermediate portion, the third transition portion comprising a third convex curvature, the third transition portion and an outlet portion of the leading surface of the first guide vane defining an expansion portion of the flow channel having an increased flow cross-section in the flow direction of the fluid flow through the flow channel, the expansion portion designed to accelerate the fluid flow to a fourth flow velocity as it flows through the expansion portion, optionally the fourth flow velocity being greater than the desired first flow velocity.

9. The guide vane mechanism (110) of claim 1, wherein the third angle of the intermediate portion (140) is less than the first angle of the trailing portion (132).

10. The leading surface (118) of the first guide vane (112) has: an inlet portion (124) disposed adjacent a leading edge of the first guide vane (112) and disposed on an opposite side of the flow channel (116) from the leading portion (136) of the trailing face (120) of the second guide vane (114), wherein optionally, the inlet portion (124) of the leading face (118) of the first guide vane (112) and the leading portion (136) of the trailing face (120) of the second guide vane (114) define a restriction portion of the flow channel (116) where a flow cross-section is reduced in a flow direction of the fluid flow through the flow channel (116); an outlet portion (128) disposed adjacent to the trailing edge (130) of the first guide vane (112), wherein optionally, a projection of the leading portion (136) of the trailing surface (120) of the second guide vane (114) onto the imaginary plane at least partially overlaps a projection of the outlet portion (128) of the leading surface (118) of the first guide vane (112) onto the imaginary plane; The guide vane mechanism (110) of claim 1, comprising at least one of:

11. 11. The guide vane mechanism of claim 10, wherein a projection of the intermediate portion and / or the first transition portion and / or the second transition portion and / or the trailing portion of the trailing surface of the second guide vane onto the imaginary plane does not overlap with the projection of the outlet portion of the leading surface of the first guide vane onto the imaginary plane.

12. Providing a fluid flow into a flow channel (116) defined between a leading face (118) of the first guide vane (112) and a trailing face (120) of the second guide vane (114); directing the fluid flow along a trailing portion (132) of the trailing surface (120) of the second guide vane (114) disposed proximate to a trailing edge (134) of the second guide vane (114), thereby deflecting the fluid flow such that the fluid flow exits the flow channel (116) at a first flow angle relative to an imaginary plane defined by the trailing edge (130) of the first guide vane (112) and the trailing edge (134) of the second guide vane (114) and at a desired first flow velocity; Including, Before the fluid flow is directed along the trailing portion (132) of the trailing surface (120), being directed along a leading portion of the trailing surface of the second guide vane, the leading portion being disposed adjacent to a leading edge of the second guide vane, thereby deflecting the fluid flow at a second flow angle relative to the imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane; and being guided along an intermediate portion of the trailing surface of the second guide vane, the intermediate portion being disposed between the trailing portion and the leading portion, whereby the fluid flow is deflected to flow at a third flow angle relative to the imaginary plane defined by the trailing edge of the first guide vane and the trailing edge of the second guide vane, the second flow angle being greater than each of the third flow angle and the first flow angle; and a first transition portion (148) of the trailing surface (120) of the second guide vane (114) disposed between the intermediate portion (140) and the trailing portion (132) and defining a recompression portion (150) of the flow channel (116) in which a flow cross-section of the fluid flow through the flow channel (116) decreases in the flow direction, the recompression portion (150) being designed such that the fluid flow slows down to a second flow velocity as it flows through the recompression portion (150), and thereafter a second transition portion (160) of the trailing surface (120) of the second guide vane (114) disposed between the first transition portion (148) and the trailing portion (132) and defining an additional expansion portion of the flow channel (116) that increases a flow cross-section in the flow direction of the fluid flow through the flow channel (116), the additional expansion portion being designed such that the fluid flow is accelerated to a third flow velocity as it flows through the expansion portion, and optionally the third flow velocity substantially corresponds to the desired first flow velocity; A method of operating a guide vane mechanism (110).

13. Before the fluid flow (F) is directed along the trailing portion (132) of the trailing surface (120), 13. The method of claim 12, wherein the fluid flow is guided along a third transition portion of the trailing face of the second guide vane disposed between the leading portion and the intermediate portion, the third transition portion and an outlet portion of the leading face of the first guide vane defining an expansion portion of the flow channel in which a flow cross-section increases in the flow direction of the fluid flow through the flow channel, the expansion portion being designed such that the fluid flow is accelerated to a fourth flow velocity as it flows through the expansion portion, and optionally the fourth flow velocity is higher than the desired first flow velocity.

14. the first transition portion (148) of the trailing surface (120) of the second guide vane (114) comprises a first concave curvature; the second transition portion (160) of the trailing surface (120) of the second guide vane (114) comprises a first convex curvature (β); the trailing portion (132) of the trailing surface (120) of the second guide vane (114) having a second convex curvature (δ); the third transition portion (144) of the trailing surface (120) of the second guide vane (114) comprises a third convex curvature; the trailing portion (132) of the trailing surface (120) of the second guide vane (114) comprises a second concave curvature (ε) between the first convex curvature (β) and the second convex curvature (δ); the leading portion (136) has a leading portion curvature (α) having an inflection point (154) where the concave curvature of the concave portion (156) changes to the convex curvature of the convex portion (158), the concave portion (156) being located upstream of the convex portion (158); The method of claim 12 , comprising at least one of:

15. A turbine comprising the guide vane arrangement (110) of claim 1.

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