Fluid injection system and fluid injection method for mitigating rotation stall of gas turbine engine

Abstract

To mitigate or prevent a rotation stall condition in a gas turbine engine.SOLUTION: A turbine exhaust section 24 includes an exhaust flow path. The turbine exhaust section 24 also includes an inner wall 86 radially disposed along the exhaust flow path. The turbine exhaust section 24 also includes an outer wall 88 disposed radially outward of the inner wall 86 along the exhaust flow path. A system includes a fluid injection system configured to inject a fluid 73 into a chamber 89, which is radially disposed between the inner wall 86 and the outer wall 88, via a plurality of inner ports 54, 134 disposed in the inner wall 86 and / or a plurality of ports 146 disposed in a front end portion 176 of a strut 92 extending from the inner wall 86 to the outer wall 88.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The subject matter disclosed herein relates to mitigating the formation of rotating stall in the low pressure turbine section of a turbine engine.

Background Art

[0002] Gas turbine engines operate under various conditions (steady state conditions, transient conditions (e.g., start-up or shutdown), full load conditions, or part load conditions, etc.). Unfortunately, when operating under low flow rate operating conditions (e.g., transient conditions or part load conditions), gas turbine engines are prone to enter a rotating stall state. The rotating stall state is such that rotating stall cells are formed in the low pressure turbine section of the gas turbine engine, causing reverse flow. The rotating stall cells rotate at a fraction of the rotational speed of the gas turbine engine (e.g., at a low frequency), thereby causing asynchronous high cycle fatigue in the turbine blades of the low pressure turbine section. Therefore, it is necessary to at least mitigate or prevent the rotating stall state in the gas turbine engine.

Summary of the Invention

[0003] Certain embodiments corresponding to the scope of the invention as originally claimed are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but are only intended to provide a brief overview of possible forms of the invention. Indeed, the invention can encompass various forms similar to or different from the embodiments shown below.

[0004] In one embodiment, the system includes a turbine exhaust section located downstream of the turbine. The turbine exhaust section includes an exhaust flow path. The turbine exhaust section also includes an inner wall disposed radially along the exhaust flow path. The turbine exhaust section further includes an outer wall disposed radially outside the inner wall along the exhaust flow path. The system includes a fluid injection system configured to inject fluid into a chamber disposed radially between the inner wall and the outer wall through a plurality of inner ports disposed on the inner wall. The plurality of inner ports are disposed downstream of the downstream edge of the final stage blade of the turbine.

[0005] In another embodiment, the system includes a turbine exhaust section. The turbine exhaust section includes an exhaust flow path, an inner wall disposed radially along the exhaust flow path, an outer wall disposed radially outside the inner wall along the exhaust flow path, and struts extending radially from the inner wall to the outer wall. The system also includes a fluid injection system configured to inject fluid into a chamber disposed radially between the inner wall and the outer wall through a plurality of ports disposed at the front end portion of the struts. The plurality of ports are disposed downstream of the downstream edge of the final turbine blade of the turbine.

[0006] In another embodiment, the system includes a turbine exhaust section located downstream of the turbine. The turbine exhaust section includes an exhaust flow path, an inner wall disposed radially along the exhaust flow path, and an outer wall disposed radially outside the inner wall along the exhaust flow path. The system also includes a fluid injection system. The fluid injection system includes a fluid supply configured to supply one or more fluids to the turbine exhaust section. The fluid injection system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor, the instructions being for controlling the injection of one or more fluids into a chamber disposed radially between the inner wall and the outer wall through a plurality of inner ports integrally formed in the inner wall. The plurality of inner ports are disposed downstream of the downstream edge of the final stage blade of the turbine.

Brief Description of the Drawings

[0007] These features, aspects, and advantages of the systems and methods of the present invention, as well as other features, aspects, and advantages, can be better understood by reading the following detailed description of the invention with reference to the drawings. In the drawings, like reference characters represent like parts throughout the drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0008] One or more specific embodiments of the present system and method are described below. For the sake of brevity in describing these embodiments, not all features of an actual implementation are described herein. It should be understood that in any actual implementation development, as in various engineering projects or design projects, a number of implementation-specific decisions are made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints that are considered to vary with the implementation. Further, while such development efforts may be complex and time-consuming, it should be understood that they are routine in the business of design, fabrication, and manufacturing for those skilled in the art to obtain the benefits of the present disclosure.

[0009] When introducing elements of various embodiments of the present invention, the articles "a", "an", "the", and "said" are intended to mean that there is one or more of such elements. "Comprising", "including", and "having" are inclusive and are intended to mean that additional elements other than the recited elements may exist.

[0010] The language used herein and throughout the claims to represent approximations can be applied to modify any quantitative expression that can vary within a reasonable amount without causing a change in the relevant basic function. Thus, a value modified by one or more terms such as "about", "approximately", and "substantially" is not limited to the precise value specified. In at least some instances, the language representing approximations may correspond to the precision of the instrument for measuring the value. Throughout this specification and the claims, when ranges are combined and / or are interchangeable with each other, such ranges are identified and, unless the context or language indicates otherwise, are to be taken to include all sub-ranges subsumed therein. "Substantially" as applied to a particular value can indicate ±10% of the recited value, and when used in the context of an angle, can indicate a value that is ±10 degrees greater or less than the recited angle or direction. For example, "substantially perpendicular" includes directions within 10 degrees in either direction (e.g., clockwise or counterclockwise) from perpendicular. For example, an axis or feature that is "substantially perpendicular" includes axes or elements that intersect at an angle between 80 degrees and 100 degrees, and should thus be interpreted more broadly than the unmodified term "perpendicular" which is defined as intersecting at 90 degrees for axes or elements.

[0011] As described in further detail below, the disclosed embodiments include a stall mitigation system configured to mitigate a rotating stall condition in a low pressure turbine section of a turbine (e.g., a gas turbine engine or a steam turbine) by mitigating the formation of rotating stall cells and reverse flow downstream of the final stage blade of the turbine. For example, certain embodiments of the stall mitigation system include a fluid injection system configured to inject fluid into a hub chamber downstream of the final stage blade of the turbine. In certain embodiments, the fluid injection system can include fluid injection ports disposed on the downstream side of the final stage blade at the inner wall (e.g., the inner annular wall) of the turbine. Additionally, or alternatively, the fluid injection system can include fluid injection ports disposed on the downstream side of the final stage blade at the outer wall (e.g., the outer annular wall) of the turbine. In certain embodiments, the fluid injection ports can be angled circumferentially in a direction opposite to the direction of rotation of the rotating stall cell. In certain embodiments, the stall mitigation system includes a fluid extraction system having an ejector configured to extract or discharge the exhaust gas of the chamber from a port in the outer wall, the inner wall, or any suitable location so as to mitigate or prevent a rotating stall condition.

[0012] In certain embodiments, the fluid injection system can include fluid injection ports integrally disposed upstream of a diffuser strut in the exhaust section of a turbine. The fluid injection ports can be disposed in the radially inner portion of the upstream portion of the diffuser strut and, in certain embodiments, can be angled in a direction opposite to the rotational direction of a rotating stall cell. Additionally or alternatively, the fluid injection system can include auxiliary fluid injection ports integrally disposed upstream of an auxiliary diffuser strut in the exhaust section of a gas turbine engine. The auxiliary diffuser strut can be axially aligned with the diffuser strut and can be circumferentially offset from the diffuser strut. The auxiliary fluid injection ports can be disposed radially inward of the upstream portion of the auxiliary diffuser strut and, in certain embodiments, can be angled in a direction opposite to the rotational direction of a rotating stall cell.

[0013] FIG. 1 is a schematic flow diagram of one embodiment of a turbine system 10 having a gas turbine engine 12 with a stall mitigation system 11 configured to reduce a rotating stall condition. As described in further detail below, the stall mitigation system 11 includes a fluid injection system 38 configured to inject a fluid (e.g., compressor bleed air, exhaust gas, carbon dioxide, etc.) into regions where reverse flow is occurring (e.g., flow recirculation, vortex formation, etc.), thereby reducing the reverse flow and / or suppressing a rotating stall condition. In certain embodiments, the turbine system 10 can include an aircraft, a locomotive, a power generation system, or a combination thereof, with a power generation system being illustrated herein. The illustrated gas turbine engine 12 includes an intake 16, a compressor or compressor section 18, a combustor or combustor section 20, a turbine or turbine section 22 (e.g., an expansion turbine), and an exhaust section 24. The turbine 22 is coupled to the compressor 18 through a shaft 26.

[0014] As indicated by the arrow, air enters the gas turbine engine 12 through the intake section 16 and flows into the compressor 18, which compresses the air before it enters the combustor section 20. The illustrated combustor section 20 includes a combustor housing 28 that is concentric or annularly arranged about the shaft 26 between the compressor 18 and the turbine 22. Compressed air from the compressor 18 flows into the combustor 40, where the compressed air is mixed with fuel and burned to drive the turbine 22. The hot combustion gases flow from the combustor section 20 through the turbine 22 and drive the compressor 18 via the shaft 26. For example, the combustion gases can impart power to the turbine rotor blades within the turbine 22 and rotate the shaft 26. After flowing through the turbine 22, the hot combustion gases can flow through the exhaust section 24 and be discharged from the gas turbine engine 12. The exhaust section 24 can include a plurality of struts including main support struts and auxiliary struts downstream of the turbine 22 (such as in the diffuser section of the exhaust section 24). The gas turbine engine 12 can be described from the perspectives of the longitudinal or axis 32 (e.g., the axial direction), the radial or axis 34, and the circumferential or axis 36.

[0015] As will be described in more detail below, the fluid injection system 38 of the stall mitigation system 11 can include fluid injectors or injection ports in the turbine 22 and / or the exhaust section 24 at a plurality of axial positions relative to the longitudinal direction 32, at a plurality of radial positions relative to the radial direction 34, and / or at a plurality of circumferential positions relative to the circumferential direction 36. For example, the plurality of fluid injectors or injection ports of the fluid injection system 38 can be axially arranged at one or more downstream sides or low-pressure turbine stages (e.g., the final turbine stage) of the turbine 22, directly on the plurality of struts, and / or circumferentially arranged between the plurality of struts between the final turbine stage of the turbine 22 and the plurality of struts.

[0016] Furthermore, fluid injection by the fluid injector or injection port can be selectively controlled based on the operating conditions of the turbine system 10. For example, during operating conditions that promote flow reversal and rotating stall conditions (e.g., low flow conditions associated with partial load or transient conditions of the turbine system 10), the fluid injection system 38 is controlled to inject fluid to counteract or suppress reverse flow, and thus the risk of a rotating stall condition can be reduced. However, under normal operating conditions (e.g., full load and / or steady operating conditions), the fluid injection system 38 can be controlled to reduce or stop fluid injection.

[0017] Figure 2 is a side cross-sectional view of an embodiment of the gas turbine engine 12 of FIG. 1 taken along the longitudinal axis 32, showing an embodiment of a fluid injection system 38 coupled to the turbine 22 and the exhaust section 24. As described above with respect to FIG. 1, air flows through the intake section 16 and into the gas turbine engine 12, and is compressed by the compressor 18. Thereafter, the compressed air from the compressor 18 is directed to the combustor section 20, where the compressed air is mixed with fuel in the combustor section 20. The combustor section 20 includes one or more combustors 40. In certain embodiments, the gas turbine engine 12 can include a plurality of combustors 40 arranged in a ring. Alternatively, the combustor section 20 can include an annular combustor (not shown). Further, each combustor section 20 can include a plurality of fuel nozzles 42 attached at or near the head end of each combustor section 20 in an annular or other arrangement.

[0018] In operation, fuel nozzle 42 can inject a fuel-air mixture into combustor 40 at a ratio suitable for optimal combustion, emissions, fuel consumption, and output. Within combustor section 20, the fuel-air mixture burns to produce hot pressurized combustion gases. After combustion, the hot pressurized combustion gases exit combustor section 20 and flow through transition section 44 to turbine 22. The pressurized combustion gases rotate blades 45 that extend radially within turbine 22 and are disposed between stationary vanes 46, causing shaft 26 to rotate, and then flow through exhaust section 24 and are discharged as exhaust gases.

[0019] In the illustrated embodiment, the fluid injection system 38 includes a fluid supply 48, a fluid line 50 (e.g., a conduit, pipe, or tube), a fluid injector or injection port 54, and a controller 56. In a particular embodiment, the controller 56 can include a processor 58, a memory 60, instructions 62 stored in the memory 60 and executable by the processor 58, and a communication circuit 64 configured to communicate with various sensors distributed throughout the fluid supply 48 and the turbine system 10. In the illustrated embodiment, the fluid supply 48 includes a compressor 66, an ejector 68, a manifold 70, and a valve 72. As shown, the fluid supply 48 is configured to take in a fluid 73 (e.g., a gas) from one or more fluid sources 74. The fluid source 74 can include a tank, a container, a device having fluid within the turbine system 10, an air separation unit (ASU), a pipeline, or a connection to another part of the turbine system 10 (e.g., compressor 18). The ASU can separate air into oxygen and nitrogen for use in the turbine system 10. The fluid source 74 can include air 76, an inert gas 78, another gas 80, compressor bleed gas 82 from the compressor 18 of the gas turbine engine 12, or a combination thereof. For example, the inert gas 78 can include nitrogen from an ASU or another source, or another inert gas. The other gas 80 can include exhaust gas extracted from the exhaust section 24, carbon dioxide captured by a carbon capture system, or another gas. The compressor bleed gas 82 can include compressed air or exhaust gas recirculation (EGR) gas, which is recirculated from the exhaust section 24 to the compressor 18 as part of an EGR system.

[0020] The fluid supply unit 48 is configured to receive fluid from one or more fluid sources 74 through a plurality of fluid lines 83 each having a valve 85. The valves 85 are coupled to the controller 56 and are controlled by the controller 56. Accordingly, the controller 56 is configured to selectively control the valves 85 and the fluid supply unit 48 to control the supply of fluid from the fluid source 74 to various injectors or injection ports 54. For example, the controller 56 can selectively open and close the various valves 85 to supply only one fluid or a combination of fluids from among a plurality of fluids (e.g., air, inert gas, other gases, compressor extraction gas, or any combination thereof) of the fluid source 74 to the various injectors or injection ports 54. The compressor 66 of the fluid supply unit 48 can be configured to compress and / or boost the pressure of one or more of the plurality of fluid sources 74. The ejector 68 operates using high-pressure gas and low-pressure gas associated with the venturi section 69 (Figure 3) to enable the fluid injection system 38 to extract and / or inject fluid using the fluid line 50 and the injection port 54. Accordingly, in certain embodiments, the injection port 54 can be used as an injection port or an extraction port, and the fluid line 50 can be used as an injection line or an extraction line. Various details of the ejector 68 will be described later.

[0021] The manifold 70 can include a fluid injection manifold configured to distribute various fluids from the fluid source 74 to the injectors or injection ports 54. In certain embodiments, the manifold 70 can further include a fluid extraction manifold coupled to the ejector 68 and one or more sets of ports 54 (e.g., extraction ports). Also, a valve 72 is coupled to the fluid line 50 and the manifold 70 to effect control of the distribution of fluid to the injectors or injection ports 54 by the fluid injection system 38.

[0022] In the illustrated embodiment, the exhaust portion 24 includes an exhaust passage 84 (e.g., an annular exhaust passage), an inner wall 86 (e.g., an inner annular wall, an inner exhaust wall) disposed radially along the exhaust passage 84, and an outer wall 88 (e.g., an outer annular wall, an outer exhaust wall) disposed radially outside the inner wall 86 and along the exhaust passage 84. Further, the inner wall 86 and the outer wall 88 can define an exhaust diffuser (or an exhaust diffuser portion) of the exhaust portion 24, and the cross-sectional area of the exhaust diffuser increases so that the exhaust pressure can be reduced and the exhaust flow can be diffused. The exhaust portion 24 also includes a chamber 89 (e.g., an annular chamber, an annular exhaust chamber), and the chamber 89 is disposed between the inner wall 86 and the outer wall 88 in the radial direction and downstream of the final stage blade 91 (or a set of final stage blades) of the turbine 22 in the axial direction.

[0023] In certain embodiments, the exhaust section 24 also includes one or more struts 90 (e.g., diffuser struts of the exhaust diffuser section). The struts 90 can include main struts 92 (e.g., main structure support struts) and / or auxiliary struts 93. In the illustrated embodiment, the main struts 92 and the auxiliary struts 93 extend radially 34 from the inner wall 86 to the outer wall 88. In certain embodiments, the main struts 92 and / or the auxiliary struts 93 may extend only partially between the inner wall 86 and the outer wall 88, or may extend over the entire length between the inner wall 86 and the outer wall 88. For example, the main strut 92 can extend over the entire length between the inner wall 86 and the outer wall 88, while the auxiliary strut 93 can extend only partially (not over the entire length) between the inner wall 86 and the outer wall 88. In the following description, reference may be made only to the struts 90 (e.g., 92, 93), but the disclosed features of the fluid injection system 38 are intended to apply to any number of struts 90 (at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, or more struts 92, 93, etc.). In the illustrated embodiment, the exhaust section 24 includes a manway 94 (e.g., a hollow radial manway structure that enables user access) fluidly coupled to a channel 96 disposed in the inner wall 86. The channel 96 is fluidly coupled to the chamber 89.

[0024] The fluid injection system 38 is configured to inject fluid 73 into the chamber 89 by a fluid injection port 54, as described in more detail herein. As described in further detail below, the injector or injection port 54 can include one or more sets of injection ports disposed on the inner wall 86, outer wall 88, struts 90 (e.g., 92, 93), or any combination thereof. For example, the injector or injection port 54 can include one or more sets of injection ports 54 circumferentially disposed in a circumferential direction 36 about the longitudinal axis 34, and each set of injection ports 54 is disposed at a different axial position along the longitudinal axis 34 (e.g., the first set at the first axial position, the second set at the second axial position, etc.). By other examples, the aforementioned sets of injection ports 54 can be disposed on the inner wall 86 and / or outer wall 88 in the downstream side of the turbine 22 or in a low-pressure turbine stage (e.g., the final turbine stage), disposed in the exhaust portion 24 between the final turbine stage and the strut 90, disposed on the strut 90, circumferentially disposed between the struts 90, or any combination thereof. Accordingly, the injection port 54 can be disposed at different radial positions (such as an inner radius along the inner wall 86, an outer radius along the outer wall 88, or one or more intermediate radial positions along the strut 90 between the inner wall 86 and the outer wall 88, etc.).

[0025] In some embodiments, each strut 90 can include any number of injection ports 54 (e.g., at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more injection ports) distributed uniformly or non-uniformly in the radial direction 34 between the inner wall 86 and the outer wall 88. In some embodiments, the injection ports 54 may be angled at an acute angle or perpendicular to a surface or wall (e.g., the inner wall 86, the outer wall 88, or the wall of the strut 90). For example, the angle of the injection port 54 may be less than, equal to, or greater than 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, or 90 degrees with respect to an adjacent surface or wall, or a value plus or minus 5 degrees with respect to these angles. The injection ports 54 can be directed in the upstream direction, downstream direction, and / or crosswise direction with respect to the downstream direction of the exhaust flow flowing through the turbine 22 and the exhaust section 24. For example, the position, angle, and direction of the injector or injection port 54 can be selected to particularly interfere with, suppress, or disrupt the reverse flow (or recirculation) of the exhaust gas associated with large-scale vortex structures in the flow, thereby suppressing or preventing the formation of rotational stall cells in the turbine 22. Various aspects of the fluid injection system 38 will be described later.

[0026] Furthermore, the controller 56 controls the fluid injection system 38 based on the operating conditions of the turbine system 10 such that the formation of rotating stall cells in the turbine 22 can be suppressed or prevented. For example, the controller 56 can selectively activate or initiate fluid injection by the fluid injection system 38 when the operating conditions of the turbine system 10 indicate low flow conditions or other conditions that cause the formation of rotating stall cells (e.g., low flow conditions associated with partial load or transient conditions (e.g., startup, shutdown, or other transient behavior) of the turbine system 10). In some embodiments, the controller 56 can receive sensor feedback indicating low flow, reverse flow, vibration, or other conditions indicating rotating stall from the turbine 22 and / or the exhaust section 24. As another example, the controller 56 can selectively reduce the flow rate of fluid injection by the fluid injection system 38, selectively adjust so that fluid injection does not operate, or stop fluid injection when the operating conditions of the turbine system 10 indicate normal flow conditions or other conditions that do not cause the formation of rotating stall cells (e.g., high flow conditions or regular flow conditions associated with full load conditions or steady state conditions of the turbine system 10). The controller 56 can selectively control the injection of fluid into various ports 54 and / or the extraction of fluid from various ports 54 depending on the severity of the operating conditions that cause rotating stall.

[0027] FIG. 3 is a side cross-sectional view taken along line 3-3 of one embodiment of the gas turbine engine 12 of FIG. 2, showing the injection of fluid into the turbine 22 and the exhaust section 24 by the fluid injection system 38 of FIG. 2. In the illustrated embodiment, the fluid injection system 38 includes fluid lines 50 (e.g., fluid lines 120, 122, 124, 126, 128, and 130) fluidly coupled to a plurality of fluid sources 74 (e.g., external gas 132 and compressor bleed gas 82). The fluid lines 50 can be fluid introduction lines or fluid supply lines, fluid extraction lines or fluid withdrawal lines, or combinations thereof. The illustrated embodiment shows an external gas 132 and a compressor bleed gas 82, but it should be recognized that combinations of one or more of the fluid sources 74 described herein can be coupled to the fluid injection system 38. Specifically, the external gas 132 can be air 76, an inert gas 78, or another gas 80, as described above with reference to FIG. 2. The fluid lines 50 are fluidly coupled to fluid injection ports 54. The fluid injection ports 54 include an inner port 134, outer ports 136 (e.g., outer ports 138, 140, 142, and 144), and strut ports 146 (e.g., strut ports 148, 150, 152, and 154) disposed on the main strut 92, the auxiliary strut 93, or both struts.

[0028] In the illustrated embodiment, fluid line 120 is fluidly coupled to the duct 94 of the exhaust section 24. The duct 94 is fluidly coupled to a channel 96 disposed in the inner wall 86. As shown, the channel 96 is fluidly coupled to an inner port 134 integrally disposed in the inner wall 86. The inner port 134 is disposed downstream (e.g., on the downstream side in the longitudinal direction 32) of the downstream edge 156 of the final stage blade 91 of the turbine 22 (e.g., on the downstream side of the final turbine stage). The inner port 134 is configured to introduce (e.g., inject) fluid 73 into the chamber 89. The inner port 134 may also be described as a radially inner port, an inner radius port, an inner wall port, or an inner hub port. The inner port 134 can include one or a plurality of sets of a plurality of inner ports 134 spaced apart from each other circumferentially about the longitudinal axis 32 at a common axial position, and each set of the plurality of inner ports 134 can be disposed at a different axial position. For example, each set of the plurality of inner ports 134 can include at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 500 or more inner ports 134 spaced evenly or unevenly in the circumferential arrangement. The inner port 134 may be angled at an acute angle or perpendicular to the inner wall 86 and / or the longitudinal axis 32.

[0029] In the illustrated embodiment, the inner port 134 is disposed at a position downstream by an axial distance 158 from the downstream end 156 of the final stage blade 91. As shown, the distance 158 is within the range of the axial distance 160 with respect to the axial distance 162 (e.g., total distance or spacing) that extends downstream from the downstream edge 156 of the final stage blade 91 towards the upstream edge 164 of the strut 90 of the exhaust portion 24. When the range of the axial distance 160 is measured as a percentage of the axial distance 162 in the downstream direction from the downstream edge 156, the range of the axial distance 160 can be about 5 - 95 percent, 10 - 90 percent, 15 - 85 percent, 20 - 80 percent, 25 - 75 percent, 30 - 70 percent, 35 - 65 percent, or 40 - 60 percent. In a particular embodiment, the first set of inner ports 134 (e.g., a set of inner ports arranged circumferentially) can be disposed at the first axial distance 158, the second set of inner ports 134 (e.g., a set of inner ports arranged circumferentially) can be disposed at the second axial distance 158, the third set of inner ports 134 (e.g., a set of inner ports arranged circumferentially) can be disposed at the third axial distance 158, the fourth set of inner ports 134 (e.g., a set of inner ports arranged circumferentially) can be disposed at the fourth axial distance 158, and so on. These different distances 158 can be distances that gradually increase at a uniform or non-uniform interval from the downstream end 156 of the final turbine blade 91. During operation, when the fluid 73 is introduced through the inner port 134, the formation of rotating stall cells (e.g., stall cells caused by hub vortices) in the chamber 89 adjacent to the turbine 22 (e.g., the final turbine stage) is alleviated.

[0030] In the illustrated embodiment, the fluid introduction line 122 is fluidly coupled to the outer port 138. As shown, the outer port 138 is integrally disposed in the outer wall 88 and is disposed downstream of the downstream edge 156 of the final stage blade 91. The outer port 138 can include one or more sets of the outer ports (e.g., a set of outer ports arranged circumferentially) at one or more respective axial distances (such as the axial distance from the downstream edge 156 of the final stage blade 91). Similar to the inner port 134, the outer port 138 can be spaced apart at a position of one or more axial distances between the downstream edge 156 of the final stage blade 91 and the upstream edge 164 of the strut 90. In a particular embodiment, the range of the axial distance of the outer port 138 can be the same as the range described above with reference to the inner port 134. The outer port 138 is configured to introduce the fluid 73 from the outer wall 88 into the chamber 89. It should be recognized that introducing the fluid 73 through the outer port 138 alleviates the formation of rotating stall (e.g., hub vortex stall) in the chamber 89 on the downstream side of the turbine 22.

[0031] In the illustrated embodiment, fluid lines 124, 126, and 128 are each fluidly coupled to outer ports 140, 142, and 144. As shown, outer port 140 is integrally disposed in outer wall 88 and is located at an axial position between vane 166 of the second-to-last stage of turbine 22 and blade 168 of the second-to-last stage of turbine 22. Outer port 140 is configured to introduce or inject fluid into the second-to-last toroidal chamber 174 located at an axial position between vane 166 of the second-to-last stage and blade 168 of the second-to-last stage. Further, outer port 142 is integrally disposed in outer wall 88 and is located at an axial position between blade 168 of the second-to-last stage of turbine 22 and final stage vane 170. Further, outer port 144 is integrally disposed in outer wall 88 and is located at an axial position between final stage vane 170 and final stage blade 91. In the illustrated embodiment, each outer port 136 is shown as being independently controllable through valve 172 (e.g., valve 72), and fluid can be introduced into turbine 22 and / or exhaust section 24 by any combination of outer ports 138, 140, 142, or 144. It should be recognized that introducing fluid 73 through outer ports 140, 142, and 144 alleviates the formation of rotating stall (e.g., toroidal vortex stall) in turbine chamber 174 (e.g., toroidal chamber) located between blades 45 and vanes 46 of turbine 22. Further, it should be recognized that outer port 136 may include any combination of outer ports 138, 140, 142, and 144.

[0032] Outer ports 138, 140, 142, and 144 can be described as radially outer ports, outer radial ports, or outer wall ports. Outer ports 138, 140, 142, and 144 can include one or more sets of a plurality of outer ports spaced from each other circumferentially about longitudinal axis 32 at a common axial position, and each set of the plurality of outer ports can be arranged at a different axial position. For example, each set of the plurality of outer ports 138, 140, 142, and 144 can include at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 500, or more outer ports spaced evenly or unevenly in the circumferential arrangement. Outer ports 138, 140, 142, and 144 can be angled at an acute angle or perpendicular to outer wall 88 and / or longitudinal axis 32.

[0033] In the illustrated embodiment, fluid line 130 is disposed within strut 90 (e.g., main strut 92, auxiliary strut 93) and is fluidly coupled to strut port 146. As shown, strut port 146 is integrally disposed at the front end portion 176 (e.g., upstream end portion) of strut 90. Strut port 146 is configured to introduce fluid 73 into chamber 89 from the front end portion 176 of strut 90. In the illustrated embodiment, strut port 146 is disposed at a position radially lower than or within a radial height 178 (e.g., a radial threshold or radial range) relative to inner wall 86. In certain embodiments, radial height 178 is less than half of the total height 180 (e.g., total radius or radial length) of strut 90 extending from inner wall 86 to outer wall 88. When fluid 73 is introduced through strut port 146, the formation of rotational stall (e.g., hub vortex stall) in chamber 89 downstream of turbine 22 is alleviated. Strut port 146 is described in further detail herein.

[0034] The fluid injection port 54 can include any combination of the inner port 134, the outer port 136, and the strut port 146. For example, in certain embodiments, the fluid injection system 38 includes the inner port 134 and the strut port 146, but the outer port 136 can be omitted. In certain embodiments, the controller 56 can be configured to independently control the flow of fluid to the inner port 134, the outer port 136, and the strut port 146, simultaneously and / or sequentially, based on operating conditions. The operating conditions can include an operating mode (e.g., steady state, full load, partial load, or transient (e.g., startup, shutdown, etc.)) or sensor feedback (e.g., pressure, flow rate, flow velocity, flow direction, etc.). For example, the sensor feedback can indicate a flow reversal and / or a stall condition.

[0035] In the illustrated embodiment, the ejector 68 is fluidly coupled to the chamber 89 through a fluid line 182 coupled to the outer wall 88. As described above, the ejector 68 can operate using high-pressure gas and low-pressure gas associated with the venturi section 69 so that the fluid injection system 38 can extract and / or inject fluid. In the illustrated embodiment, the ejector 68 includes an annular body portion 184 along a central axis 186, and the annular body portion 184 includes an axial fluid inlet 188, a radial fluid inlet 190, an axial fluid outlet 192, and a venturi section 69 between the axial fluid inlet 188 and the axial fluid outlet 192. The venturi section 69 includes an annular converging wall or passage 194, an annular diverging wall or passage 196, and an annular throat 198 between the passage 194 and the passage 196. The ejector 68 is configured to receive a high-pressure flow (e.g., working fluid or drive fluid) through the axial fluid inlet 188 and a low-pressure flow (e.g., driven fluid or suction fluid) through the radial fluid inlet 190. In the illustrated embodiment, the high-pressure flow can be the compressor bleed gas 82, but other high-pressure gases may be used with the ejector 68. The low-pressure flow can be the exhaust gas in one or more regions of the turbine 22 and / or the exhaust section 24 that are prone to stall (such as the portion along the outer wall 88 between the final stage blade 91 and the strut 92).

[0036] Accordingly, in the illustrated embodiment, the ejector 68 is configured to extract a portion of the exhaust gas from the chamber 89 between the turbine 22 and the exhaust section 24 by using the compressor bleed gas 82 as a high-pressure stream. For example, the compressor bleed gas 82 can be used in combination with the ejector 68 to generate a suction force and suck the exhaust gas from the chamber 89. The ejector 68 can also output a fluid (e.g., a mixed stream of exhaust gas and compressor bleed flow) to another location within the exhaust section 24 (such as downstream of the strut 90). In a particular embodiment, in addition to introducing fluid through the inner port 134, the outer port 136, and / or the strut port 146 using the ejector 68, sucking or removing the exhaust gas is controlled independently of the introduction of the fluid, thereby reducing or eliminating reverse flow and stall conditions of the flow.

[0037] FIG. 4 is a cross-sectional view taken along line 4-4 of an embodiment of the gas turbine engine 12 of FIG. 3, showing that the fluid injection ports 54 are disposed at the upstream portion 200 (e.g., the front end portion) of a plurality of main struts 92 of the gas turbine engine 12 and are also disposed on the inner wall 86 and the outer wall 88 of the gas turbine engine 12. In the illustrated embodiment, the fluid injection system 38 includes an inner port 134 disposed on the inner wall 86 (e.g., the inner annular wall) and an outer port 136 disposed on the outer wall 88 (e.g., the outer annular wall). In some embodiments, the inner port 134 is configured to introduce the fluid 73 into the chamber 89 by injecting the fluid 73 radially outward (e.g., in the radially outward direction) through the inner port 134. Additionally or alternatively, the outer port 136 is configured to introduce the fluid 73 into the chamber 89 by injecting the fluid 73 radially inward (e.g., in the radially inward direction) through the outer port 136. In the illustrated embodiment, the inner port 134 is circumferentially angled in a direction opposite to the direction of rotation of the turbine blades (e.g., the direction of rotating stall motion). For example, when the blades rotate in the circumferential direction 36 (e.g., counterclockwise as shown), the inner port 134 can be angled in the clockwise direction, and vice versa. In certain embodiments, the outer port 136 can further be circumferentially angled in a direction opposite to the direction of rotation of the blades. The circumferential angle of the inner port 134 is described in more detail herein.

[0038] In the illustrated embodiment, the fluid injection system 38 of the exhaust section 24 includes a strut port 146 (e.g., main strut port 202) integrally disposed in an upstream portion 200 of a main strut 92 (e.g., exhaust strut, diffuser strut). As shown, the fluid injection system 38 is configured to inject fluid 73 into the chamber 89 through the main strut port 202. As shown, the main strut 92 extends radially from the inner wall 86 to the outer wall 88. In the illustrated embodiment, each main strut 92 includes four main strut ports 202 disposed in a radially inner portion 204 of the upstream portion 200 (e.g., front end portion) of the main strut 92. In certain embodiments, the main strut 92 can include more or fewer than four main strut ports 202 (e.g., 1, 2, 3, 5, 6, 7, 8, 9, 10, or more). As described in more detail herein, the main strut ports 202 are angled with respect to the longitudinal axis (e.g., radial axis) of the main strut 92. In the illustrated embodiment, each main strut 92 is shown as having the same number of strut ports 146, but the number of strut ports 146 may vary between the main struts 92.

[0039] In the illustrated embodiment, the fluid injection system 38 of the exhaust section 24 includes a strut port 146 (e.g., auxiliary strut port 206) integrally disposed at an upstream portion 205 (e.g., front end portion) of an auxiliary strut 93 (e.g., auxiliary exhaust strut, auxiliary diffuser strut). As shown, the auxiliary strut 93 extends radially 34 from the inner wall 86 to the outer wall 88 of the gas turbine engine 12 and is circumferentially offset from the main strut 92 (e.g., spaced apart circumferentially 36). In certain embodiments, the auxiliary circumferential thickness 208 of the auxiliary strut 93 can be thinner than the circumferential thickness 210 of the main strut 92 in the circumferential direction 36. However, in some embodiments, the auxiliary circumferential thickness 208 may be equal to or thicker than the main strut circumferential thickness 210.

[0040] As shown, the fluid injection system 38 is configured to inject fluid 73 into the chamber 89 through the auxiliary strut port 206. In the illustrated embodiment, each auxiliary strut 93 includes four auxiliary strut ports 206 disposed at a radially inner portion 208 of the upstream portion 205 (e.g., auxiliary front end) of the auxiliary strut 93. As will be described in more detail herein, the auxiliary strut ports 206 are angled with respect to the longitudinal axis of the auxiliary strut 93. In certain embodiments, the auxiliary strut 93 can include more or fewer than four auxiliary strut ports 206 (e.g., 1, 2, 3, 5, 6, 7, 8, 9, 10, or more ports). In the illustrated embodiment, each auxiliary strut 93 is shown as having the same number of auxiliary strut ports 206, but the number of auxiliary strut ports 206 may vary between the auxiliary struts 93.

[0041] In the illustrated embodiment, the inner port 134, the outer port 134, and the strut port 146 are shown to be arranged at uniform intervals. However, it should be recognized that in certain embodiments, these ports may be arranged at non-uniform intervals. Additionally or alternatively, in certain embodiments, the fluid injection system 38 may include more or fewer inner ports 134, outer ports 134, and / or strut ports 146 than shown in the illustrated embodiment.

[0042] FIG. 5 is a cross-sectional view taken along line 5-5 of an embodiment of the main strut 92 and the auxiliary strut 93 of FIG. 3, showing the fluid injection ports 54 disposed at the upstream portions 200 of the main strut 92 and 205 of the auxiliary strut 93. In the illustrated embodiment, the main strut 92 includes a nose portion 230 of the upstream portion 200, a central portion 232, a central support 234 disposed in the central portion 232, and a trailing edge portion 236 of the downstream portion 235. As shown, the nose portion 230 of the upstream portion 200 includes one or more main strut ports 202 disposed in the nose wall 238 of the nose portion 230, and the main strut ports 202 are fluidly coupled to the fluid channel 237 (e.g., a radial fluid passage) of the nose portion 230. In the illustrated embodiment, the auxiliary strut 93 includes a fluid channel 239 (e.g., a radial fluid passage) disposed at the upstream portion 205 of the auxiliary strut 93. The fluid channel 239 can be configured to flow the fluid 73 in the radial direction 34 to the auxiliary strut port 206.

[0043] In the illustrated embodiment, the auxiliary longitudinal length 241 (e.g., axial length) of the auxiliary strut 93 is shorter than the longitudinal length 243 (e.g., axial length) of the main strut 92 in the axial direction 32. For example, the auxiliary longitudinal length 241 may be longer than, or equal to, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 percent of the longitudinal length 243. In a particular embodiment, the auxiliary longitudinal length 241 can be substantially equal to the longitudinal length 243.

[0044] In the illustrated embodiment, the longitudinal central axis 242 passes through the main strut 92 from the leading edge 244 to the trailing edge of the trailing edge portion 236. The longitudinal central axis 242 intersects the leading edge 244 at the central upstream end or the first intersection. Each main strut port 202 includes a central axis 240 that is angled with respect to the longitudinal central axis 242 of the main strut 92. In a particular embodiment, the angle 245 between the central axis 240 and the longitudinal central axis 242 can be a value from 0 degrees to 80 degrees. For example, the angle 245 may be an angle smaller than, or equal to, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 degrees. In the illustrated embodiment, the central axis 240 is offset from the longitudinal central axis 242 at the leading edge 244 of the nose portion 230 of the main strut 92. In the illustrated embodiment, the central axis 240 is substantially perpendicular to the tangent line 246 of the nose wall 238 at the second intersection 248 between the central axis 240 and the nose wall 238 (i.e., the main strut port 202 is perpendicular to the surface of the nose wall 238 at the position of the main strut port 202). In a particular embodiment, the central axis 240 may not be perpendicular to the tangent line 246 (i.e., the main strut port 202 may be oriented at an angle other than 90 degrees with respect to the surface of the nose wall 238).

[0045] In the illustrated embodiment, the auxiliary longitudinal central axis 250 passes through the auxiliary strut 93 from the leading edge 252 to the trailing edge on the side opposite the leading edge. The longitudinal central axis 250 intersects the leading edge 252 at the central upstream end or the first intersection point. Each auxiliary strut port 206 includes an auxiliary central axis 249 that is angled with respect to the auxiliary longitudinal central axis 250 of the auxiliary strut 93. As shown, the auxiliary longitudinal central axis 250 is substantially parallel to the longitudinal central axis 242. In a particular embodiment, the angle 251 between the auxiliary central axis 249 and the auxiliary longitudinal central axis 250 can be a value from 0 degrees to 80 degrees. For example, the angle 245 can be an angle less than 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, or 80 degrees, or an equal angle. In the illustrated embodiment, the auxiliary central axis 249 is offset from the auxiliary longitudinal central axis 250 at the leading edge 252 of the auxiliary strut 93. In the illustrated embodiment, the auxiliary central axis 249 is substantially perpendicular to the tangent line 286 of the outer surface 254 at the second intersection point 258 of the auxiliary central axis 248 and the outer surface 254 (i.e., the auxiliary strut port 206 is perpendicular to the surface of the upstream portion 205 at the position of the auxiliary strut port 206). In a particular embodiment, the auxiliary central axis 249 may not be perpendicular to the tangent line 256 (i.e., the auxiliary strut port 206 may be oriented at an angle other than 90 degrees with respect to the surface of the upstream portion 205).

[0046] In certain embodiments, the controller 56 can independently control the flow to the main strut port 202 and the auxiliary strut port 206. That is, the main strut port 202 and the auxiliary strut port 206 can be controlled to inject fluid simultaneously or at different times in response to operating conditions and sensor feedback indicating a need to reduce reverse flow and / or stall conditions. In certain embodiments, when the flow is introduced through the inner exhaust wall 86 or the outer exhaust wall 88, the main strut port 202, the auxiliary strut port 206, or both ports can be omitted. For example, in some embodiments, the exhaust section 24 includes struts for both the main strut 92 and the auxiliary strut 93, the main strut 92 does not include the main strut port 202, but the auxiliary strut 93 can include the auxiliary strut port 206.

[0047] FIG. 6 is a cross-sectional view taken along line 6-6 of one embodiment of the strut 90 (e.g., main strut 92, auxiliary strut 93) of FIG. 4, showing independent control of the introduction of fluid by each fluid injection port. In the illustrated embodiment, the strut 90 includes a strut port 146 (e.g., main strut port, auxiliary strut port). The strut ports 146 are each fluidly coupled to a separate fluid channel 288 (e.g., fluid channels 290, 292, 294, 296). The fluid channels 288 are disposed within the interior 291 of the strut 90. In the illustrated embodiment, the fluid channels 288 extend from the front wall 297 (e.g., nose wall) of the strut 90 to the outer wall 88 (e.g., outer exhaust wall) of the gas turbine engine 12. In certain embodiments, the fluid channels 288 may extend from the front wall 297 to the inner wall 86 of the gas turbine engine 12.

[0048] In the illustrated embodiment, each fluid channel 288 is coupled to a valve 298 (e.g., valves 300, 302, 304, and 306). As shown, a plurality of valves 298 (e.g., valve 72 in FIG. 2) are fluidly coupled to a fluid source 74 and communicatively coupled to a controller 56, which is configured to independently control each valve of the plurality of valves 298 (only the coupling between the controller 56 and the valve 306 is shown for simplicity). In certain embodiments, the controller 56 can be configured to set different flow rates for each valve of the plurality of valves 298. For example, the controller 56 can control the valve 306 such that fluid 73 flows through the fluid channel 296 and is introduced into the chamber 89 at a high flow rate through the strut port 154. The controller 56 can be configured to vary the flow rate of the fluid 73 for each strut port 146. That is, the controller 56 can control the valve 298 such that the flow rate at which the fluid 73 is injected into the chamber 89 decreases (i.e., decreases radially outward) from the strut port 154 toward the strut port 148. In certain embodiments, the controller 56 can control the valve 298 such that the flow rate at which the fluid 73 is injected into the chamber 89 increases (i.e., increases radially outward) from the strut port 154 toward the strut port 148. As shown, each of the plurality of strut ports 146 (e.g., strut ports 148, 150, 152, and 154) is disposed at a different radial distance from the inner wall 86. During operation, the controller 56 is configured to selectively control the valves 298 (e.g., valves 300, 302, 304, and 306) to regulate the flow of fluid at different radial distances through different strut ports 146.

[0049] In the illustrated embodiment, each strut port 146 is fluidly coupled to a separate fluid channel 288. In certain embodiments, the fluid channel 288 can be fluidly coupled to a plurality of strut ports 146. For example, one fluid channel 288 can be fluidly coupled to strut ports 148 and 150, and another fluid channel 288 can be fluidly coupled to strut ports 152 and 154. In certain embodiments, each strut port 146 may be fluidly coupled to the same fluid channel 288. The illustrated embodiment shows four strut ports 146, four fluid channels 288, and four valves 298, but it should be recognized that the main strut 92 can include more than four or fewer than four strut ports 146, fluid channels 288, and / or valves 298 (e.g., one, two, three, four, five, six, seven, eight, nine, ten, or more ports, channels, and / or valves). The embodiments described herein with respect to the independent control of the strut ports 146 can be applied to the main strut, auxiliary strut, or both struts.

[0050] FIG. 7 is a cross-sectional view of an embodiment of the fluid injection ports 54 of the inner wall 86 or the outer wall 88 as seen along line 7-7 of FIG. 4, showing the manner in which a manifold 70 (e.g., an annular manifold, a fluid manifold) is fluidly coupled to each set or each row 332 of fluid injection ports 54 (e.g., the circumferential arrangement of the ports at a particular axial position). In the illustrated embodiment, each manifold 70 (e.g., fluid manifolds 334, 336, and 338) is fluidly coupled to a separate set or a separate row 332 of fluid injection ports 54 (e.g., rows 340, 342, and 344). In the illustrated embodiment, each row 332 of fluid injection ports 54 extends circumferentially 36 about the central axis of rotation of the gas turbine engine 12. As shown, a plurality of rows 332 are axially spaced from each other in the longitudinal direction 32 of the gas turbine engine 12. Each manifold 70 is fluidly coupled to each fluid injection port 54 belonging to a particular row 332. For example, fluid manifold 334 can be fluidly coupled to row 340, fluid manifold 336 can be coupled to row 342, and fluid manifold 338 can be coupled to row 344.

[0051] In the illustrated embodiment, each row 332 is fluidly coupled to a separate row valve 346 (e.g., row valves 348, 350, and 352). The row valves 346 are communicatively coupled to the controller 56. The controller 56 is configured to independently control the injection of fluid 73 through the fluid injection ports 54 of each row 332 into the chamber 89. The controller 56 can be configured to vary (e.g., increase or decrease) the flow rate of the fluid 73 for each row 332. That is, the controller 56 can control the row valves 346 such that the flow rate of the fluid 73 injected into the chamber 89 decreases from row 340 to row 344. In a particular embodiment, the controller 56 can control the row valves 346 such that the flow rate of the fluid 73 injected into the chamber 89 increases from row 340 to row 344. The fluid injection ports 54 in the illustrated embodiment can include inner ports 134, outer ports 136, or both.

[0052] FIG. 8 is a cross-sectional view taken along line 8-8 of one embodiment of row 342 of fluid injection ports 54 of FIG. 7, showing how each fluid injection port 54 is angled circumferentially in the circumferential direction 36. In the illustrated embodiment, the fluid injection ports 54 (e.g., fluid injection ports 362, 364, and 366) are disposed in a wall 368 (e.g., inner wall 86, outer wall 88). As shown, the port central axes 370 of the fluid injection ports 54 (e.g., port central axes 372, 374, and 376) have an angle 378 (e.g., angles 380, 382, and 384) with respect to the radial axis 386. The radial axis 386 extends from the central axis of rotation of the gas turbine engine 12 to the intersection 394 (e.g., intersections 396, 398, and 400) of the radial axis 386, the port central axis 370, and the surface 402 (e.g., inner surface, outer surface) of the wall 368. In a particular embodiment, the fluid injection ports 54 are angled in a direction opposite to the direction of rotation of the turbine blade (e.g., the direction of rotating stall). For example, when the turbine blade rotates as indicated by arrow 403 with respect to the circumferential direction 36, the fluid injection ports 54 are angled in the circumferential direction 36 opposite to arrow 403, whereby the fluid 73 can be directed in an angular direction 405 having a circumferential component. The fluid introduction ports 54 can be angled in the circumferential direction 36 either clockwise or counterclockwise. In a particular embodiment, the angle 378 can be an angle in the range of 0 degrees to 80 degrees. For example, the angle 378 can be an angle less than 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, or 80 degrees, or an angle equal to these angles.

[0053] In the illustrated embodiment, each fluid injection port 54 includes an inlet portion 404 (e.g., inlet portions 406, 408, and 410) and an outlet portion 412 (e.g., outlet portions 414, 416, and 418). As shown, by angling the port central axis 370, the outlet portion 412 is circumferentially shifted relative to the inlet portion 404. In the illustrated embodiment, the fluid injection port 54 includes side surfaces 420 (e.g., side surfaces 422, 424, and 426). The side surfaces can have a uniform cross-section 428 extending from the inlet portion 404 to the outlet portion 412. For example, the cross-section 428 can be circular, elliptical, square, rectangular, etc. In the illustrated embodiment, the cross-section 428 linearly translates along the port central axis 370 from the inlet portion 404 to the outlet portion 412, showing how the fluid injection port 54 is formed. In certain embodiments, the fluid injection port 54 may be curved. That is, the cross-section 428 may translate along a curve extending from the inlet portion 404 to the outlet portion 412.

[0054] FIG. 9 is a side cross-sectional view of an embodiment of a steam turbine engine 440 cut along the longitudinal axis 32, showing an embodiment of a fluid injection system 38. In the illustrated embodiment, the fluid injection system 38 includes fluid lines 442 (e.g., fluid introduction lines 446, 448, 450) fluidly coupled to a steam source 452 and an external auxiliary boiler 454. In the illustrated embodiment, the steam source 452 and the external auxiliary boiler 454 are shown, but combinations of one or more of the fluid sources described herein can be used. The fluid line 442 is fluidly coupled to a fluid injection port 456. The fluid injection port 456 includes an inner port 458 and outer ports 460 (e.g., outer ports 462, 464, 466).

[0055] In the illustrated embodiment, the inner port 458 is disposed downstream by a distance 468 from the downstream edge 470 of the final stage blade 472. As shown, the distance 468 is included within a distance 474 that ranges from 1 / 4 to 1 / 2 of the width 476 that extends from the downstream edge 470 of the final stage blade 472 to the rear wall 478 of the steam turbine engine 440. In a particular embodiment, the inner port 458 can include one or more axial port rows (e.g., an annular port row). It should be appreciated that introducing fluid 73 through the inner port 458 alleviates the formation of rotational stall (e.g., hub vortex stall) in the chamber 480 downstream of the turbine 482 of the steam turbine engine 440.

[0056] In the illustrated embodiment, the fluid introduction line 446 is fluidly coupled to the outer port 462. As shown, the outer port 462 is integrally disposed in the outer wall 484 and is disposed downstream of the downstream edge 470 of the final stage blade 472. The outer port 462 can include one or more axial port rows (e.g., an annular port row). The outer port 462 is configured to introduce the fluid 73 from the outer wall 484 into the chamber 480. It should be appreciated that introducing fluid 73 through the outer port 462 alleviates the formation of rotational stall (e.g., hub vortex stall) in the chamber 480 downstream of the turbine 482.

[0057] In the illustrated embodiment, fluid lines 448 and 450 are fluidly coupled to outer ports 464 and 466, respectively. As shown, outer port 464 is integrally disposed in outer wall 484 and is axially disposed between the penultimate stage blade 486 of turbine 482 and the ultimate stage vane 488 of turbine 482. Outer port 464 is configured to introduce fluid 73 into the penultimate toroidal chamber 490 axially disposed between the penultimate stage blade 486 and the final stage vane 488 of turbine 482. Further, outer port 466 is integrally disposed in outer wall 484 and is axially disposed between the final stage vane 488 and the final stage blade 472 of turbine 482. Outer port 466 is configured to introduce fluid 73 into the final toroidal chamber 491 axially disposed between the final stage vane 488 and the final stage blade 472 of turbine 482.

[0058] In the illustrated embodiment, each outer port 460 is independently controllable via a valve 492 coupled to controller 56, and fluid can be introduced into turbine 482 and / or chamber 480 in any combination of outer ports 462, 464, and 466. Introduction of fluid 73 through outer ports 462, 464, and 466 alleviates the formation of rotating stall (e.g., toroidal vortex stall) in toroidal chambers 490 and 491 (e.g., turbine chambers) and chamber 480. Further, the plurality of outer ports 460 can be in any combination of outer ports 462, 464, and 466. Although outer ports 462, 464, 466 may be referred to herein as a single outer port, it should be understood that a plurality of circumferentially disposed outer ports 462, 464, 466 can be used.

[0059] FIG. 10 is a schematic cross-sectional view taken along line 10-10 of FIG. 3 of an embodiment of the stall alleviation system of FIG. 2. In the illustrated embodiment, the cutting plane of the cross-section is orthogonal to the radial direction 34, and the cutting plane of the cross-section intersects the final stage vanes 170 of the turbine 22, the final stage blades 91 of the turbine 22, and the main struts 92 of the exhaust section 24. As shown, the fluid 73 is injected (e.g., introduced) through one or more fluid injection ports 136 (e.g., the outer ports 144 referenced in FIG. 3) disposed downstream of the axial position of the final stage vanes 170 and upstream of the axial position of the final stage blades 91, and the fluid 73 is injected axially between the final stage vanes 170 and the final stage blades 91. Further, one or more fluid injection ports 498 are configured to inject the fluid 73 in the circumferential direction 175 (e.g., the direction opposite to the blade rotation direction of the final stage blades 91). In a particular embodiment, one or more fluid injection ports 498 can include the fluid injection ports 136, 144 of FIG. 3. The injected fluid 73 acts on the reverse flow 500 of the exhaust gas, thereby changing the reverse flow 500 in the direction 175. The reverse flow 502 with the changed direction is sufficiently aligned with the trailing edge portion 504 of the final stage vanes 170. When the fluid 73 is injected in the direction 175, the reverse flow 502 with the changed direction is sufficiently aligned with the outer contour 506 of the final stage vanes 170, whereby the turbulent flow that could originally occur due to the reverse flow 121 (e.g., the reverse flow with an unchanged direction) contacting the final stage vanes 170 with sufficient orthogonality is alleviated.

[0060] As described herein, injecting fluid 73 through outer port 144 between final stage vane 170 and final stage blade 91 can mitigate the formation of a toroidal vortex between final stage vane 170 and final stage blade 91. Any number of outer ports 498 can be disposed between final stage vane 170 and final stage blade 91. For example, 2, 3, 4, 5, 6, 7, 9, 15, 20, 30, 50, 100, or more outer ports 498 can be disposed between final stage vane 170 and final stage blade 91. Similar to the inner ports, outer ports 498 can be axially aligned within turbine 22. In certain embodiments, referring to FIG. 3, outer port 498 can be disposed longitudinally (e.g., axially) as outer port 142 between the penultimate stage blade 168 and the final stage vane 170, as outer port 140 between the penultimate stage vane 166 and the penultimate stage blade 168, or as an outer port between any suitable blade and vane of turbine 22. As shown in FIG. 3, turbine 22 can also include one or more inner ports 134 disposed longitudinally (e.g., axially) between the final stage vane 170 and the final stage blade 91 of turbine 22 for injecting fluid 73 between the final stage vane 170 and the final stage blade 91. In certain embodiments, one or more inner ports 134 can be disposed at the same axial position as outer port 136.

[0061] The technical effects of the disclosed embodiments include the ability to mitigate the formation of rotating stall cells in a turbine section, such as in the exhaust section of a gas turbine engine or a steam turbine. In particular, the disclosed embodiments block the forward and / or reverse flow of the exhaust gas, thereby reducing the velocity gradient of the shear layer disposed immediately downstream of the final stage blade of each turbine. For example, in one embodiment, the inner fluid injection ports disposed on the inner wall of the exhaust section of the turbine are configured to inject fluid into the path of the reverse flow of the exhaust gas, whereby the velocity of the reverse flow is reduced before the reverse flow reaches the final stage blade. Further, the strut fluid injection ports disposed upstream of the main diffuser strut and / or the auxiliary diffuser strut inject fluid into the path of the exhaust gas when the exhaust gas is blocked by the strut and changes from forward flow to reverse flow. Similar to the inner fluid injection ports, the strut fluid injection ports reduce the velocity of the reverse flow before the reverse flow reaches the final stage blade, thereby reducing the velocity gradient of the shear layer.

[0062] The subject matter described in detail above can be defined by the following embodiments. [Embodiment 1] The system includes a turbine exhaust section located downstream of the turbine. The turbine exhaust section includes an exhaust flow path. The turbine exhaust section also includes an inner wall disposed radially along the exhaust flow path. The turbine exhaust section further includes an outer wall disposed radially outside the inner wall along the exhaust flow path. The system includes a fluid injection system configured to inject fluid into a chamber disposed radially between the inner wall and the outer wall through a plurality of inner ports disposed on the inner wall. The plurality of inner ports are disposed downstream of the downstream edge of the final stage blade of the turbine. [Embodiment 2] The system according to Embodiment 1, wherein the plurality of inner ports are disposed at a distance downstream of the downstream edge of the final stage blade of the expansion turbine, and the distance is a value between 25 percent and 50 percent of the width from the downstream edge of the final stage blade to the upstream edge of the strut of the turbine exhaust section. [Embodiment 3] The fluid injection system according to Embodiment 1 or 2, which is configured to inject fluid into the chamber through a plurality of first outer ports arranged on the outer wall. [Embodiment 4] The fluid injection system according to any one of Embodiments 1 to 3, which is configured to inject fluid into a turbine chamber arranged radially between the inner wall and the outer wall and axially between the vanes and blades of the turbine through a plurality of second outer ports integrally arranged on the outer wall. [Embodiment 5] The system according to any one of Embodiments 1 to 4, wherein the central axis of one of the plurality of inner ports is circumferentially angled with respect to a radial axis extending from the longitudinal central axis of the turbine exhaust portion to the central axis of the inner port. [Embodiment 6] The fluid injection system according to any one of Embodiments 1 to 5, which includes an ejector fluid-coupled to one or more fluid ports of the outer wall, and the ejector is configured to suck exhaust gas from the chamber. [Embodiment 7] The system according to any one of Embodiments 1 to 16, wherein the fluid includes extraction gas from the compressor of the turbine, external gas, inert gas, or a combination thereof. [Embodiment 8] The system includes a turbine exhaust portion. The turbine exhaust portion includes an exhaust flow path, an inner wall arranged radially along the exhaust flow path, an outer wall arranged radially outside the inner wall along the exhaust flow path, and struts extending radially from the inner wall to the outer wall. The system also includes a fluid injection system configured to inject fluid into a chamber arranged radially between the inner wall and the outer wall through a plurality of ports arranged at the front end portion of the struts. The plurality of ports are arranged on the downstream side of the downstream edge of the final turbine blade of the turbine. [Embodiment 9] The plurality of ports are arranged in the radially inner part of the front end portion of the strut, and the central axis of one of the plurality of ports is angled with respect to the longitudinal central axis of the strut. The system according to any one of Embodiments 1 to 8. [Embodiment 10] The system according to any one of Embodiments 1 to 9, including auxiliary struts extending from the inner wall toward the outer wall. [Embodiment 11] The auxiliary strut is circumferentially offset with respect to the strut, and the fluid injection system is configured to inject the fluid into the chamber through a plurality of auxiliary ports arranged at the auxiliary front end portion of the auxiliary strut. The system according to any one of Embodiments 1 to 10. [Embodiment 12] The plurality of auxiliary ports are arranged in the auxiliary radially inner part of the auxiliary front end portion of the auxiliary strut, and the auxiliary central axis of one of the plurality of auxiliary ports is angled with respect to the auxiliary longitudinal central axis of the auxiliary strut. The system according to any one of Embodiments 1 to 11. [Embodiment 13] The central axis of the plurality of ports is offset from the longitudinal central axis of the strut, the auxiliary central axis is offset from the auxiliary longitudinal central axis of the auxiliary strut, or both axes of the central axis and the auxiliary central axis are offset from the longitudinal central axis and the auxiliary longitudinal central axis, respectively. The system according to any one of Embodiments 1 to 12. [Embodiment 14] The fluid injection system includes a controller configured to independently control the flow to different ports among the plurality of ports to inject the fluid into the chamber, independently control the flow to different auxiliary ports among the plurality of auxiliary ports to inject the fluid into the chamber, or perform both injections, according to any one of Embodiments 1 to 13. [Embodiment 15] The system includes a turbine exhaust section located downstream of the turbine. The turbine exhaust section includes an exhaust flow path, an inner wall arranged radially along the exhaust flow path, and an outer wall arranged radially outside the inner wall along the exhaust flow path. The system also includes a fluid injection system. The fluid injection system includes a fluid supply section configured to supply one or more fluids to the turbine exhaust section. The fluid injection system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor, the instructions being for controlling the injection of one or more fluids into a chamber arranged radially between the inner wall and the outer wall through a plurality of inner ports integrally formed in the inner wall. The plurality of inner ports are arranged downstream of the downstream edge of the final stage blade of the turbine. [Embodiment 16] The fluid injection system according to claim 1 is configured to inject one or more fluids into the chamber through a plurality of first outer ports arranged on the outer wall. [Embodiment 17] The fluid injection system is configured to inject one or more fluids radially between the inner wall and the outer wall and axially between the vanes and blades of the turbine through a plurality of second outer ports integrally arranged on the outer wall, according to any one of Embodiments 1 to 16. [Embodiment 18] The plurality of inner ports, the plurality of first outer ports, the plurality of second outer ports, or combinations thereof include a plurality of rows of ports circumferentially arranged at different axial positions, and the controller independently controls injecting one or more fluids through each of the plurality of rows. The system according to any one of Embodiments 1 to 17. [Embodiment 19] The fluid injection system includes an ejector fluidly coupled to one or more fluid ports of the outer wall, and the ejector is configured to suck exhaust gas from the chamber. The system according to any one of Embodiments 1 to 18. [Embodiment 20] The controller is configured to control injection of one or more fluids, control suction of exhaust gas from the chamber independently of injection of one or more fluids, or control both through a plurality of inner ports, a plurality of first outer ports, a plurality of second outer ports, or combinations thereof. The system of any of the preceding clauses.

[0063] In this specification, embodiments are used to disclose the present invention including the best mode, and enable anyone skilled in the art to practice the present invention, including manufacturing and using any device or system and performing any incorporated method. The patentable scope of the present invention is defined by the claims and can include other embodiments conceivable by those skilled in the art. Such other embodiments are intended to be included in the claims if they have structural elements that do not differ from the literal language of the claims or include equivalent structural elements that do not substantially differ from the literal language of the claims.

Description of Reference Numerals

[0064] 12 Gas turbine engine

Claims

1. A stall mitigation system (11) for a gas turbine engine (12), the system (11) comprising: A turbine exhaust section (24) located downstream of an expansion turbine (22), the turbine exhaust section (24) comprising: An exhaust flow path (84); An inner wall (86) arranged radially along the exhaust flow path (84), the inner wall (86) defining a plurality of inner ports (54, 134); and An outer wall (88) arranged radially outside the inner wall (86) along the exhaust flow path (84); The turbine exhaust section (24); and A fluid injection system (38) configured to inject a fluid (73) into a chamber (89) arranged radially between the inner wall (86) and the outer wall (88) through the plurality of inner ports (54, 134). Including The plurality of inner ports (54, 134) are arranged downstream of the downstream edge (156) of the final stage blade (91) of the expansion turbine (22), the system (11).

2. The plurality of inner ports (54, 134) are arranged at a distance downstream of the downstream edge (156) of the final stage blade (91) of the expansion turbine (22), the distance being a value between 25% and 50% of the width from the downstream edge (156) of the final stage blade (91) to the upstream edge (164) of the strut (90) of the turbine exhaust section (24), the system (11) according to claim 1.

3. The fluid injection system (38) is configured to inject the fluid (73) into the chamber (89) through a plurality of first outer ports (136) arranged on the outer wall (88), the system (11) according to claim 1.

4. The fluid injection system (38) is configured to inject the fluid (73) into a turbine chamber (174) arranged radially between the inner wall (86) and the outer wall (88) and axially between the vanes (46) and the blades (45) of the expansion turbine (22) through a plurality of second outer ports (140, 142, 144) integrally arranged on the outer wall (88), the system (11) according to claim 3.

5. A controller (56) having a processor (58), a memory (60), and instructions (62) stored in the memory (60) and executable by the processor (58). The system (11) according to claim 4, wherein the instructions are for independently controlling the injection of the fluid (73) into a chamber (89) radially disposed between the inner wall (86) and the outer wall (88) through the plurality of inner ports (134), the first plurality of outer ports (136), and the second plurality of outer ports (140, 142, 144). 。

6. The plurality of inner ports (134), the plurality of first outer ports (136), the plurality of second outer ports (140, 142, 144), or combinations thereof include a plurality of rows (332) of ports circumferentially disposed at different axial positions. The controller (56) independently controls the injection of the fluid (73) through each row (340, 342, 344) of the plurality of rows (332). controls the suction of exhaust gas from the chamber (89) independently of the injection of the fluid (73), or performs both controls The system (11) according to claim 5, wherein the system is configured as such.

7. The central axis (370) of one of the plurality of inner ports (134) of the plurality of inner ports (134) is circumferentially angled with respect to a radial axis (386) extending from the longitudinal central axis of the turbine exhaust section (24) to the central axis (370) of the inner port (134). The system (11) according to claim 1.

8. The fluid injection system (38) includes an ejector (68) fluidly coupled to one or more fluid ports (136) of the outer wall (88), and the ejector (68) is configured to suck exhaust gas from the chamber (89). The system (11) according to claim 1.

9. The fluid (73) includes bleed gas (82) from a compressor (18) of the gas turbine engine (12), external gas (132), inert gas (78), or combinations thereof. The system (11) according to claim 1.

10. A stall mitigation system (11) for a gas turbine engine (12), the system (11) is a turbine exhaust section (24), an exhaust flow path (84), An inner wall (86) arranged radially along the exhaust flow path (84), An outer wall (88) arranged radially outside the inner wall (86) along the exhaust flow path (84), and Struts (90, 92) extending radially from the inner wall (86) to the outer wall (88) A turbine exhaust section (24) including, and A fluid injection system (38) configured to inject fluid (73) into a chamber (89) arranged radially between the inner wall (86) and the outer wall (88) through a plurality of ports (146) arranged at the front end portions (176) of the struts (90, 92), wherein the plurality of ports (146) are arranged downstream of the downstream edge (470) of the last turbine blade (91, 472) of the expansion turbine (22). Fluid injection system (38) Including, system (11). **Claim 11** The plurality of ports (146) are arranged in the radially inner portions (204, 208) of the front end portions (176) of the struts (90, 92), and the central axis of one of the plurality of ports is angled with respect to the longitudinal central axis of the struts (90, 92). The system (11) according to claim 10. **Claim 12** Including an auxiliary strut (93) extending from the inner wall (86) towards the outer wall (88), the auxiliary strut (93) being circumferentially offset with respect to the strut (90), and the fluid injection system (38) is configured to inject the fluid (73) into the chamber (89) through a plurality of auxiliary ports (146, 206) arranged at the auxiliary front end portion (205) of the auxiliary strut (93). The system (11) according to claim 10. **Claim 13** The plurality of auxiliary ports (146, 206) are arranged in the auxiliary radially inner portion (208) of the auxiliary front end portion (205) of the auxiliary strut (93), and the auxiliary central axis (249) of one of the plurality of auxiliary ports is angled with respect to the auxiliary longitudinal central axis (250) of the auxiliary strut (93). The system (11) according to claim 12. **Claim 14** The central axis (240) of the plurality of ports (146) is offset from the longitudinal central axis (242) of the struts (90, 92). The auxiliary central axis (249) is offset from the auxiliary longitudinal central axis (250) of the auxiliary strut (93), or The axes of both the central axis (240) and the auxiliary central axis (249) are each offset from the longitudinal central axis (242) and the auxiliary longitudinal central axis (250), the system (11) according to claim 13. **Claim 15** The fluid injection system (38) independently controls the flow to different ports among the plurality of ports (146) to inject the fluid (73) into the chamber (89), independently controls the flow to different auxiliary ports among the plurality of auxiliary ports (146, 206) to inject the fluid (73) into the chamber (89), or both injections The system (11) according to claim 12, comprising a controller (56) configured to perform.

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