Passive valve assembly for a nozzle of a gas turbine engine

Abstract

A nozzle assembly for a gas turbine engine includes a nozzle having a first material defining a first coefficient of thermal expansion, the nozzle having an airfoil defining a fluid passage therein, an inlet wall defining a fluid inlet, the inlet wall fluidly connected to the fluid passage, and a passive valve assembly including an annular band including a second material having a second coefficient of thermal expansion less than the first coefficient of thermal expansion, such that the passive valve assembly is at least partially movable relative to the fluid inlet.

Description

TECHNICAL FIELD

[0001] The present subject matter relates generally to a passive valve assembly for a nozzle of a gas turbine engine. More particularly, the present subject matter relates to a passive valve assembly for a fluid variable area turbine nozzle of a gas turbine engine. BACKGROUND

[0002] Gas turbine engines are rotary engines that extract energy from a flow of combustion gases passing through the engine to rotating turbine blades.

[0003] Gas turbine engines generally have a compressor section that compresses a volume of air admitted into the engine, a combustor section that burns a mixture of compressed air and fuel to produce combustion gases that pass through the engine, and a turbine section that is driven by the combustion gases to drive the compressor section and produce thrust. A nozzle can be formed at a first stage of the turbine section downstream of the combustion section to direct flow from the combustor to the blades of the turbine section. The nozzle can comprise a throat of the engine, and engine performance can be limited by the nozzle. Accordingly, the configuration of the nozzle can be important in determining engine efficiency and thrust. BRIEF DESCRIPTION OF DRAWINGS

[0004] A complete and enabling disclosure of the application, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended drawings, in which:

[0005] Figure 1 is a schematic cross-sectional view of a gas turbine engine in accordance with one or more embodiments.

[0006] Figure 2 is a perspective view of a portion of a nozzle assembly in accordance with one or more embodiments.

[0007] Figure 3 is a perspective view of one nozzle section of a nozzle assembly schematically coupled to a compressor section by a passive valve assembly in accordance with one or more embodiments.

[0008] Figure 4 is Figure 3 a cross-sectional view of the nozzle section of

[0009] Figure 5 is Figure 3 a cross-sectional view of the nozzle section of

[0010] Figure 6 is Figure 3 a cross-sectional view of the nozzle section of

[0011] Figure 7 is a schematic cross-sectional view of a portion of a gas turbine engine showing a cooling flow path and a passive valve assembly according to one or more embodiments.

[0012] Figure 8 is a schematic cross-sectional view of a nozzle and passive valve assembly according to one or more embodiments.

[0013] Figure 9 is a schematic cross-sectional view of a nozzle and passive valve assembly including a piston ring seal according to one or more embodiments.

[0014] Figure 10A is a schematic cross-sectional view of a nozzle and passive valve assembly in a closed position according to one or more embodiments.

[0015] Figure 10B is a schematic cross-sectional view of a nozzle and passive valve assembly in an open position according to one or more embodiments.

[0016] Figure 11A is a schematic view from the rear in an axial direction of a nozzle and passive valve assembly in an open position according to one or more embodiments.

[0017] Figure 11B is a schematic view from the rear in an axial direction of a nozzle and passive valve assembly in a closed position according to one or more embodiments.

[0018] Figure 12 is a schematic view from the rear in an axial direction of a nozzle and passive valve assembly in an open position according to one or more embodiments, showing a cooling gas flow therethrough.

[0019] Figure 13 is a schematic cross-sectional view of a nozzle and passive valve assembly having a serrated lug according to one or more embodiments.

[0020] Figure 14 is a schematic cross-sectional view of a nozzle and passive valve assembly having a serrated lug with a seal according to one or more embodiments.

[0021] Figure 15A is a schematic view from the rear in an axial direction of a nozzle and passive valve assembly having a serrated lug in an open position according to one or more embodiments.

[0022] Figure 15B is a schematic view from the rear in an axial direction of a nozzle and passive valve assembly having a serrated lug in a closed position according to one or more embodiments.

[0023] Figure 15C is a schematic view of a nozzle and passive valve assembly with a sawtooth lug in a partially open position, viewed from the rear in an axial direction, according to one or more embodiments.

[0024] Figures 16A-16D is a schematic cross-sectional view of a passive valve assembly with a sawtooth lug developing from a highest temperature condition to a lowest temperature condition, according to one or more embodiments.

[0025] Figures 17A-17C is a schematic view of a nozzle and passive valve assembly with a sealing arm developing from a highest temperature condition to a lowest temperature condition, according to one or more embodiments.

[0026] Figure 18 is a schematic cross-sectional view of a passive valve assembly with a sealing arm in a closed position, according to one or more embodiments.

[0027] Figures 19A-19C is a schematic view of a nozzle and passive valve assembly, according to one or more embodiments.

[0028] The repeated use of reference characters in the present specification and drawings is intended to represent the same or similar features or elements of the disclosure. DETAILED DESCRIPTION

[0029] Reference will now be made in detail to aspects of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure and is not meant as a limitation thereto. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield still a further embodiment. Thus, it is intended that this disclosure cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0030] As used herein, the terms “first,” “second,” and “third” can be used interchangeably to distinguish one component from another and are not meant to signify location or importance of the individual components.

[0031] The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid path. For example, “upstream” refers to the direction from which fluid flows, and “downstream” refers to the direction to which fluid flows.

[0032] The terms “coupled,” “fixed,” “attached to” and the like, mean either a direct coupling, fixation, or attachment, as applicable, or an indirect coupling, fixation or attachment via one or more intermediary components or features, unless specifically stated to the contrary.

[0033] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0034] Approximating language is applied to modify any quantitative representation that could possibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about" and "substantially," does not limit the exact value, to the modified term or terms. In at least some instances, the approximating language can correspond to the precision with which instrument measurements are cited, or the precision inherent to the methods or machines employed in creating or manufacturing components and / or systems. For example, approximating language can include an

[0035] Ratios, concentrations, amounts, and other numerical data can be expressed or presented herein in a range format. The terms "range" and "span" are used herein to describe a range of values. The terms "range" and "span" are used interchangeably herein. Although the scope of the range is expressed in terms of "from" and "to" values (e.g., "from 1 to 10"), an explicit value that is outside the range (e.g., 0 or 11) can be included in the range. Similarly, the scope of a range that is expressed in terms of an upper value and a lower value (e.g., "from 1 to 10") can be included in the range, as well as explicit values that are outside the range (e.g., 0 or 11). Unless otherwise stated, the approximate language can indicate that the value could vary from the stated value by no more than 10% of the value.

[0036] The terms "turbomachine" or "turbomachinery" refer to a machine that includes one or more compressors, a heat generating section (e.g., a combustion section), and one or more turbines that together produce a torque output.

[0037] The term "gas turbine engine" refers to an engine having a turbomachine as all or a portion of its power source. Exemplary gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and the like, as well as hybrid versions of one or more of these engines.

[0038] The term "combustion section" refers to any heat addition system for a turbomachine. For example, the term combustion section can refer to a section that includes one or more of a deflagration combustion assembly, a rotating detonation combustion assembly, a pulse detonation combustion assembly, or other suitable heat addition assembly. In certain exemplary embodiments, the combustion section can include an annular combustor, a can combustor, a tubular combustor, a trapped vortex combustor (TVC), or other suitable combustion system, or combinations thereof.

[0039] The terms "low" and "high," or their respective comparative degrees (e.g., lower or higher, as applicable), when used in conjunction with a compressor, turbine, shaft, or spool component, or the like, each refer to a relative speed within the engine, unless otherwise specified. For example, "low turbine" or "low speed turbine" defines a component configured to operate at a lower rotational speed (e.g., maximum allowable rotational speed) than a "high turbine" or "high speed turbine" of the engine.

[0040] As used herein, ceramic matrix composite or "CMC" refers to a class of materials that include a reinforcing material (e.g., reinforcing fibers) surrounded by a ceramic matrix phase. Generally, the reinforcing fibers provide structural integrity to the ceramic matrix. Some examples of matrix materials for CMCs can include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, alumina (AI2O3), silica (SiO2), aluminosilicates, or mixtures thereof), or mixtures thereof. Optionally, ceramic particles (e.g., oxides of Si, Al, Zr, Y, and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite, and montmorillonite) can also be included within the CMC matrix.

[0041] Some examples of CMC reinforcing fibers include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), non-oxide carbon-based materials (e.g., carbon), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, alumina (AI2O3), silica (SiO2), aluminosilicates such as mullite, or mixtures thereof), or mixtures thereof.

[0042] Generally, specific CMCs can be referred to by their fiber type / matrix type combination. For example, C / SiC is carbon fiber reinforced silicon carbide; SiC / SiC is silicon carbide fiber reinforced silicon carbide, SiC / SiN is silicon carbide fiber reinforced silicon nitride; SiC / SiC-SiN is silicon carbide fiber reinforced silicon carbide / nitride matrix hybrid, etc. In other examples, CMCs can include a matrix and reinforcing fibers that include oxide-based materials, such as alumina (AI2O3), silica (SiO2), aluminosilicates, and mixtures thereof. Aluminosilicates can include crystalline materials, such as mullite (3AI2O3 2SiO2), as well as glassy aluminosilicates.

[0043] In certain embodiments, the reinforcing fibers can be bundled and / or coated prior to inclusion within the matrix. For example, fiber tows can form reinforcing tapes, such as unidirectional reinforcing tapes. Multiple tapes can be laid up together to form a preform component. The fiber tows can be impregnated with a slurry composition prior to forming the preform or after forming the preform. The preform can then be heat treated, such as cured or burned out, to produce a high char residue in the preform, as well as subsequent chemical treatment, such as silicon melt infiltration, to achieve the desired chemical composition of the component formed from the CMC material.

[0044] Such materials, along with certain monolithic ceramics (i.e., ceramic materials without reinforcing materials), are particularly suitable for high temperature applications. In addition, these ceramic materials are lighter in weight compared to superalloys, yet are able to provide strength and durability to components made therefrom. As such, there is currently consideration being given to using such materials for many gas turbine components used in the high temperature section of a gas turbine engine, such as airfoils (e.g., turbine and vane), combustors, shrouds, and other similar components, which would benefit from the lighter weight and higher temperature capability that these materials can provide.

[0045] Fluid variable area turbine nozzles can improve the performance of an engine by modifying the compressor operating line. Generally, having a higher compressor operating line in an engine under aircraft flight cruise conditions can improve efficiency. However, operability of the engine under high power conditions can require a relatively large open throat. High power conditions can include takeoff conditions, steep climb conditions, and any other conditions where relatively high thrust can be used. The throat can be set with consideration to the high power conditions that can result in less efficient cruise conditions. However, fluid variable area turbine nozzles can allow for improved efficiency during cruise conditions and operability under higher power conditions. While traditional variable area turbine nozzles mechanically change the throat depending on the operating conditions of the engine, the mechanical components required, such as actuators, seals, etc., can result in increased weight and mechanical complexity. In contrast, fluid variable area turbine nozzles can bleed air flow from the compressor section at a location downstream of the throat via bleed holes, which effectively increases the volume of air flow through the axial location of the throat without actually increasing the volume of air flow through the throat, allowing for greater flow through the engine. That is, the size of the throat can be adapted for cruise condition efficiency, and during high power conditions, air flow can be bled from the compressor section and out downstream of the throat to increase the volume of air flow through the axial location of the throat.

[0046] While an external valve with associated plumbing and controls can actively control the flow of air to the suction side passage for exhaust via the exhaust hole downstream of the throat, the associated components can add weight and cause controller and supply plumbing issues. In contrast, the passive valve assembly described herein can passively allow air flow to exhaust downstream of the throat when needed by configuring the passive valve assembly and outer band to open the cooling air flow inlet during high power conditions. During cruise conditions, the cooling air flow inlet can be closed by the passive valve assembly to optimize efficiency. The passive valve assembly described herein can eliminate the need for an active valve, controller, or plumbing, thereby reducing weight, cost, and complexity. It should be noted that the structures disclosed herein can be applicable to land-based gas turbine engines, such as land-based gas turbine power plants. While cruise and high power operation of an aircraft engine are mentioned herein, in a land-based gas turbine engine, cruise operation can correspond to partial speed / partial load operation, while high power operation can correspond to high speed / high load operation.

[0047] Referring to Figure 1 Engine 10 has a generally longitudinally extending axis or centerline 12 extending in an axial direction A of engine 10 from a forward end 14 to an aft end 16. Engine 10 also defines a radial direction R that is perpendicular to centerline 12 and a circumferential direction C that extends around centerline 12. Engine 10 can include a fan section 18 including a fan 20 in downstream serial flow relationship, a compressor section 22 including a booster or low pressure (LP) compressor 24 and a high pressure (HP) compressor 26, a combustion section 28 including a combustor 30, a turbine section 32 including a HP turbine 34 and a LP turbine 36, and an exhaust section 38.

[0048] Fan section 18 includes a fan casing 40 surrounding fan 20. Fan 20 includes a plurality of fan blades 42 arranged radially about centerline 12. HP compressor 26, combustor 30, and HP turbine 34 form a core 44 of engine 10 that produces combustion gases. Core 44 is surrounded by a core casing 46 that can be coupled with fan casing 40. Core casing 46 can be formed of metal.

[0049] A HP shaft or spool 48 coaxially disposed about centerline 12 of engine 10 drivingly connects HP turbine 34 to HP compressor 26. A LP shaft or spool 50 coaxially disposed about centerline 12 of engine 10 within a larger diameter annular HP spool 48 drivingly connects low pressure turbine 36 to low pressure compressor 24 and fan 20. According to one or more embodiments, high pressure and low pressure spools 48, 50 can have fixed shafts and gear connections. HP and LP spools 48, 50 can rotate about engine centerline 12 and be coupled to a plurality of rotatable elements that can collectively define a rotor 51.

[0050] The LP compressor 24 and the HP compressor 26 each include a plurality of compressor stages 52, 54 in which a set of compressor blades 56, 58 rotate relative to a corresponding set of static compressor vane 60, 62, also referred to as a nozzle 73, to compress or pressurize a fluid flow passing through the stage. The nozzle assembly 65 for the compressor section 22 can be formed as a set of annular nozzles or compressor vanes 60, 62 with one or more segments forming the annular nozzle assembly 65. In a single compressor stage 52, 54, a plurality of compressor blades 56, 58 can be arranged in a ring and can extend radially outward from a blade platform to a blade tip relative to the centerline 12, with a corresponding static compressor vane 60, 62 located upstream and adjacent to the rotating blade 56, 58. Figure 1 The number of blades, vanes, and compressor stages shown in FIG. 1 is for illustrative purposes only and is not intended to be limiting in any way. The engine 10 can include other numbers of blades, vanes, and compressor stages.

[0051] The blades 56, 58 for the compressor stages can be mounted to a disk 61 that is mounted to a corresponding one of the HP and LP shafts 48, 50, with each stage having its own disk 61. The vanes 60, 62 for the compressor stages can be mounted in a circumferential arrangement to the core casing 46.

[0052] The HP turbine 34 and the LP turbine 36 each include a plurality of turbine stages 64, 66 in which a set of turbine blades 68, 70 rotate relative to a corresponding set of static turbine vanes 72, 74, also referred to as a nozzle 73, to extract energy from a fluid flow passing through the stage. The turbine nozzle assembly 75 for the turbine section 32 can be formed as a set of annular nozzles or turbine vanes 72, 74 with one or more segments forming the annular nozzle assembly 75. In a single turbine stage 64, 66, a plurality of turbine blades 68, 70 can be arranged in a ring and can extend radially outward from a blade platform to a blade tip relative to the centerline 12, with a corresponding static turbine vane 72, 74 located upstream and adjacent to the rotating blade 68, 70. Figure 1 The number of blades, vanes, and turbine stages shown in FIG. 1 is for illustrative purposes only and is not intended to be limiting in any way. The engine 10 can include other numbers of blades, vanes, and turbine stages.

[0053] The blades 68, 70 for the turbine stages can be mounted to a disk 71 that is mounted to a corresponding one of the HP and LP spools 48, 50, with each stage having its own disk 71. The vanes 72, 74 for the compressor stages can be mounted in a circumferential arrangement to the core casing 46.

[0054] In addition to the rotor portion, the stationary portion of the engine 10, such as the static vanes 60, 62, 72, 74 in the compressor section 22 and turbine section 32, can be referred to individually or collectively as a stator 63. As such, the stator 63 can refer to the combination of non-rotating elements of the entire engine 10.

[0055] In operation, the airflow exiting the fan section 18 is split such that a portion of the airflow is directed into the LP compressor 24, which then supplies pressurized air 76 to the HP compressor 26, which further pressurizes the air. The pressurized air 76 from the HP compressor 26 is mixed with fuel in the combustor 30 and ignited, producing combustion gases. Some work is extracted from these gases by the HP turbine 34, which drives the HP compressor 26. The combustion gases are discharged into the LP turbine 36, which extracts additional work to drive the LP compressor 24, and the exhaust gases are ultimately exhausted from the engine 10 via the exhaust section 38. The drive of the LP turbine 36 drives the LP spool 50 to rotate the fan 20 and the LP compressor 24.

[0056] A portion of the pressurized airflow 76 can be extracted from the compressor section 22 as bleed air 77. The bleed air 77 can be extracted from the pressurized airflow 76 and provided to engine components that require cooling. The temperature of the pressurized airflow 76 exiting the combustor 30 is significantly elevated. Thus, cooling provided by the bleed air 77 can be beneficial to the operation of such engine components in an elevated temperature environment.

[0057] The remaining portion of the airflow 78 bypasses the LP compressor 24 and engine core 44 and is discharged from the engine 10 through a static vane row, and more specifically, through an outlet guide vane assembly 80 comprising a plurality of airfoil guide vanes 82 at a fan discharge side 84. More specifically, a circumferential row of radially extending airfoil guide vanes 82 are used adjacent to the fan section 18 to impart some directional control to the airflow 78.

[0058] Some of the air provided by the fan 20 can bypass the engine core 44 and be used to cool portions of the engine 10, such as hot portions, or to cool or power other aspects of the aircraft, or a combination thereof. In the case of a turbine engine, the hot portions of the engine are typically downstream of the combustor 30, such as the turbine section 32, with the HP turbine 34 typically being the hottest portion as it is directly downstream of the combustion section 28. Other sources of cooling fluid can be, but are not limited to, fluid discharged from the LP compressor 24 or the HP compressor 26.

[0059] Referring to Figure 2 A portion of the nozzle assembly 75 includes a circumferential arrangement of nozzles 73. The circumferential arrangement of nozzles 73 defines an annular structure of the nozzle assembly 75, which can surroundFigure 1 The engine centerline 12 is positioned. For example, the nozzle assembly 75 can be positioned at... Figure 1 The nozzle assembly 75 is located within the first stage of the HP turbine 34, immediately downstream of the combustion section 28. The nozzle assembly 75 can be positioned anywhere along the turbine or compressor section of the turbine engine. Alternatively, the nozzle assembly 75 can be positioned within a secondary cooling supply system, such as a deflector, accelerator, or turbine-loaded deflector. Each nozzle 73 includes an outer belt 92 and an inner belt 94, with two static impellers 72 extending between the outer belt 92 and the inner belt 94. For example, the nozzle 73 can be an uncooled nozzle without internal cooling from an external source, or a subsonic nozzle suitable for operation at subsonic flow rates. Although only four nozzles 73 are shown, multiple nozzles 73 can be arranged to form an annular nozzle assembly 75. A flow path 88 can be defined for the airflow passing through the nozzle assembly 75 between the upper belt 92 and the lower belt 94 via the impellers 72. The annular geometry of the nozzle assembly 75 defines the annular cross-sectional area of ​​the flow path 88.

[0060] See Figure 3 An exemplary turbine nozzle 73 is shown comprising two blades 72, which may be airfoils 98 having an outer wall 100 defining a pressure side 102 and a suction side 104 extending between a leading edge 106 and a trailing edge 108. While the illustration shows two blades 72 or airfoils 98 in a dual arrangement for each nozzle 73, it should be understood that any number of airfoils 98, such as one or more, can be provided in the nozzle. Furthermore, although the stationary blades 72 are described as airfoils 98, the embodiment is equally applicable to rotating blades, such as… Figure 1 The blades 68 and 70. Airfoils 98 are spaced apart from each other by a gap 110. Although the gap 110 is shown between the trailing edges 108 of the airfoils 98, the spacing between the airfoils 98 can vary depending on the variable thickness of the airfoils 98. The nozzle 73 is sized such that the airfoils 98 on adjacent nozzles 73 are separated from each other by the gap 110, such that all airfoils 98 in the annular nozzle assembly are equidistant from each other. In an alternative example, the nozzle assembly can be non-equidistant, such that the gap is variable along the nozzle assembly.

[0061] The interior 120 of the airfoil 98 is defined by the outer wall 100. One or more interior structures, such as ribs 122, can partition the interior 120 into interior passages 124. In one additional non-limiting example, the interior structures can be inserts for the nozzle 73. While three interior passages 124 are shown at each airfoil 98, any number, combination, or geometry of interior passages 124 can be defined within the airfoil 98 for a particular airfoil 98 or nozzle 73. Further, all airfoils 98 disposed in the nozzle 73 or nozzle assembly 75 can be identical, while the nozzle 73 can vary between different engine stages or axial positions. A set of bleed holes 126 can be provided in the outer wall 100. The bleed holes 126 can fluidly couple the interior 120 of each airfoil 98 to the exterior 128. In one non-limiting example, the bleed holes 126 can be film holes, providing a film along the outer surface of the airfoil 98. It can be appreciated that the bleed holes 126 need not be film holes, and can be any suitable hole provided in the outer wall 100.

[0062] A fluid supply line 130 can fluidly couple the compressor section 22 to at least one interior 120 of the airfoil 98. In one non-limiting example, the fluid supply line 130 can supply a flow of bleed air to the airfoil 98, although other fluids or fluid supplies are contemplated. While shown schematically, the fluid supply line 130 can be a hollow conduit, allowing fluid to pass through the interior of the conduit. Similarly, the conduit can be fluidly coupled to an interior passage 124 of the airfoil 98 to provide such a flow of fluid to the interior 120 of the airfoil 98. The fluid supply line 130 can be coupled to one interior passage 124 positioned adjacent the suction side 104, with the bleed holes 126 fluidly coupling the fluid supply line 130 to the exterior 128 of the airfoil 98. In such an example, the interior passage 124 can be fluidly sealed from the remainder of the interior 120 of the nozzle 73 and the exterior 128 of the nozzle 73, except through the bleed holes 126.

[0063] According to one or more embodiments, a plurality of passive valve assemblies 200 can be disposed along the fluid supply line 130. According to one or more embodiments, each airfoil 98 can have a respective passive valve assembly 200. Figures 3-6 The passive valve assembly 200, which is shown schematically, will be described in more detail Figures 7-19C with reference to Figures 3-6 While shown separate from the nozzle 73, according to one or more embodiments, the passive valve assembly 200 is formed on the nozzle 73. Further, as Figures 7-18 shown, in addition to Figures 3-6In addition to the illustrated structure, the nozzle 73 can further include a radially extending portion 250 with a cooling air inlet 251. The passive valve assembly 200 can selectively provide a fluid flow to the nozzle 73 through the fluid supply line 130. For example, in an open position, the passive valve assembly 200 can allow the fluid flow to pass from the compressor section 22 to the nozzle 73, while in a closed position, the passive valve assembly 200 can partially or completely block the fluid flow to the nozzle 73. In addition, the passive valve assembly 200 can move to a position between the open position and the closed position such that the fluid flow to the nozzle 73 can be varied. According to one or more embodiments, the passive valve assembly 200 can vary a flow area of the cooling air inlet 251.

[0064] Referring now to Figure 4 The throat 150 can be defined between the airfoils 98 as the shortest distance between the airfoils 98. Typically, the throat 150 is defined between the suction side 104 of one airfoil 98 and the trailing edge 108 of an adjacent airfoil 98, as illustrated. However, the present disclosure is not so limited and the throat 150 can be defined at any location between the airfoils 98, i.e., the shortest distance between the airfoils 98. The internal passage 124 can be defined as a leading edge passage 152, a trailing edge passage 152, and a suction side passage 156. The exhaust aperture 126 can be disposed in the suction side 104 to fluidly couple the suction side passage 156 to the exterior 128 of the nozzle 73. According to one or more embodiments, the exhaust aperture 126 can be positioned downstream of the throat 150. According to one or more embodiments, the exhaust aperture 126 can be positioned upstream of the trailing edge 108. According to one or more embodiments, the exhaust aperture 126 can be centrally located between the throat 150 and the trailing edge 108, equidistant from both. According to one or more embodiments, the exhaust aperture 126 can be centrally located between the root and the tip of the airfoil 98. The suction side passage 156 can be fluidly isolated from the remainder of the passages 152, 154 and the remainder of the interior 120 of the nozzle 73. The fluid supply line 130 can be fluidly coupled to the suction side passage 156 to exhaust fluid through the exhaust aperture 126 downstream of the throat 150. Accordingly, the fluid supply line 130, the passive valve assembly 200, and any interconnecting components coupled to the suction side passage 156 can be fluidly isolated from the remainder of the nozzle 73.

[0065] Referring now to Figure 5 During operation of the engine including the nozzle 73, fluid flow from the combustor 30 (see Figure 1The main stream 160 can be supplied to the nozzle 73. The main stream 160 can travel substantially in the axial direction A through the engine and the nozzle 73. In a non-limiting example, the main stream 160 can have a helical component, wherein the main stream 160 rotates circumferentially about the engine center and travels in the axial direction A. Streamlined flow 162 can be defined by the nozzle 73 between the airfoils 98, deflecting the main stream 160 as it passes through the nozzle 73. A boundary layer 164 can be formed along the suction side 104 of the airfoil 98, and streamlined edges 166 can be spaced apart from the boundary layer 164, representing the streamlined flow 162 exiting from the throat 150. The boundary layer 164 can be along the suction side 104 and can provide a small amount of obstruction at the throat 150, forming an effective throat that is slightly narrower than the actual throat 150. The effective throat restricts the flow through the engine, thus limiting the power and thrust generated by the engine. The dimensions of the throat 150 are set by balancing operability (e.g., maintaining adequate stall margin) and efficiency, which can be improved by reducing the size of the throat 150. Therefore, a narrowed throat due to boundary layers can negatively impact engine operation. Conditions such as stall margin and flow disturbances or flow adhesion through the nozzle 73 can limit the dimensions of the throat 150. It may be beneficial for the nozzle 73 to not allow too small or too large flow rates to prevent engine stalling or inefficiency. Therefore, the throat size is determined based on these constraints to remain within the stall range while maximizing efficiency. However, different operating conditions may place different demands on the engine. This single throat geometry may not be able to accommodate the varying needs of different operating conditions required by the engine during operation.

[0066] like Figure 5 As shown, when the passive valve assembly 200 is closed, the amount of fluid from the fluid supply line 130 to the suction-side passage 156 is restricted. Therefore, only a small amount or no flow exits through the exhaust port 126, and the size of the effective throat depends entirely or largely on the actual physical geometry of the nozzle 73 and the boundary layer 164 along the suction side 104. In this case, the flow through the nozzle 73 can be set by the relationship between the inlet pressure of the main flow 160, the pressure and dilution temperature at the throat 150, the size of the effective throat narrowing through the boundary layer 164, or a combination thereof. The pressure at the throat 150 is determined by the geometry of the nozzle 73 and the pressure of the streamlined flow 162 downstream of the throat 150, while the pressure of the streamlined flow 162 is determined by the rest of the engine downstream of the nozzle 73. The relationship between the pressure at the throat 150 and the pressure of the streamlined flow 162 downstream of the throat 150 is referred to as pressure recovery, where fluid diffusion leads to an increase in pressure at the throat 150 and downstream of the nozzle 73.

[0067] In the case of a rotating vane or other similar element, such as a deflector or accelerator, a throat can be defined between adjacent vanes or similar elements that define a throat. In this case, the internal passage can be fluidly coupled to the passive valve assembly 200 to regulate fluid flow to the vane or similar element.

[0068] As shown in FIG. 1, the passive valve assembly 200 is positioned in the throat 150 of the engine 10. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150 by regulating the flow of fluid through the nozzle 73. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the nozzle 73 by regulating the flow of fluid through the passive valve assembly 200. Figure 6 As shown in FIG. 1, the passive valve assembly 200 is positioned in the throat 150 of the engine 10. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150 by regulating the flow of fluid through the nozzle 73. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the nozzle 73 by regulating the flow of fluid through the passive valve assembly 200. Figure 5 As shown in FIG. 1, the passive valve assembly 200 is positioned in the throat 150 of the engine 10. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150 by regulating the flow of fluid through the nozzle 73. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the nozzle 73 by regulating the flow of fluid through the passive valve assembly 200. Figure 6 As shown in FIG. 1, the passive valve assembly 200 is positioned in the throat 150 of the engine 10. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150 by regulating the flow of fluid through the nozzle 73. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the nozzle 73 by regulating the flow of fluid through the passive valve assembly 200.

[0069] As shown in FIG. 1, the passive valve assembly 200 is positioned in the throat 150 of the engine 10. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the throat 150 by regulating the flow of fluid through the nozzle 73. The passive valve assembly 200 is positioned in the throat 150 to regulate the flow of fluid through the nozzle 73 by regulating the flow of fluid through the passive valve assembly 200.

[0070] The variability of the throat 150 can be controlled by the structure of the passive valve assembly 200. In a non-limiting example, the variability of the throat 150 can be controlled proportionally by the structure of the passive valve assembly 200. For example, the passive valve assembly 200 can be configured to open, partially open, or open when higher operational demands on the engine are required during takeoff or acceleration, effectively opening the throat 150 and allowing a greater flow through the generator 10. The passive valve assembly 200 can also be configured to close, at least partially close, or close when less operational demand is required (e.g., during idling or cruise phases of flight), which can improve engine efficiency. Furthermore, the passive valve assembly 200 can be configured to allow a variety of variable fluid flows into the nozzle 73, for example, based on different operating characteristics or demands of the engine 10, and thus suited to the specific needs of specific operating conditions of the engine 10. Therefore, the passive valve assembly 200 can allow discontinuous flow rates, not just open and closed positions.

[0071] With a set of blades defining the throat, the passive valve assembly 200 can regulate the flow to one or more blades to reduce cooling flow to increase performance as needed (e.g., during cruise) or to increase cooling flow during periods of higher operational demand (e.g., during takeoff and climb) to improve cooling. With blades, the passive valve assembly 200 can be configured to control the total cooling flow to the blades, and the balance between blade cooling and engine operability can be adapted to current engine operating conditions or needs. A set of orifices, similar to exhaust ports 126, can be provided on the blades downstream of the throat defined between two adjacent blades to improve control of the effective throat at the blades when regulating cooling. Without orifices, higher levels of blade flow could reduce the effective throat, negatively impacting engine operability. Utilizing orifices downstream of the throat can offset this effect over a wide range of operating conditions.

[0072] Figure 7 This is a schematic cross-sectional view of a portion of a gas turbine engine according to one or more embodiments, showing a cooling flow path 180 and a passive valve assembly 200. According to one or more embodiments, the cooling flow path 180 may pass through a fluid supply line 130. Figure 7 As shown, the cooling flow path 180 extends from the compressor section 22 of the engine 10 to the passive valve assembly 200 located outside the nozzle 73 in the radial direction R. According to one or more embodiments, the cooling flow path 180 may extend from the HP compressor 26. According to one or more embodiments, the cooling flow path 180 may extend downstream of the HP compressor 26. The passive valve assembly 200 can selectively allow cooling airflow from the cooling flow path 180 to enter the nozzle 73, which may discharge from the aforementioned exhaust port 126. Although Figures 2-7 Shown as including passive valve assembly 200, butFigures 2-7 The illustrated structure can alternatively include passive valve assembly 300 or passive valve assembly 400 described below. Alternatively, Figures 2-7 The illustrated structure can include a combination of two or more of passive valve assembly 200, passive valve assembly 300, and passive valve assembly 400. Further, it should be appreciated that while cooling flow path 180 is described as extending from an outlet of HP compressor 26 and around combustor 30, in other embodiments, cooling flow path 180 can tap the compressor section flow upstream of the HP compressor 26 outlet at any other suitable location.

[0073] Figure 8 is a schematic cross-sectional view of nozzle 73 and passive valve assembly 200 according to one or more embodiments. Nozzle 73 can include an airfoil 98 extending between an outer band 92 and an inner band 94. An inner casing 148 can be further disposed radially inward of inner band 94. As described above, airfoil 98 can include a leading edge 106 and a trailing edge 108, and can further include a leading edge passage 152, a trailing edge passage 154, and a suction side passage 156 formed therein. Suction side passage 156 is an example of a fluid passage defined within airfoil 98. Outer band 92 can include a leading edge inlet 93 opening to leading edge passage 152, while inner band 94 can include a trailing edge inlet 95 opening to trailing edge passage 154.

[0074] As Figure 8 illustrated, outer band 92 can include a radially extending portion 250 extending outward in radial direction R. Radially extending portion 250 can extend further outward in radial direction R as compared to portions of the outer band surrounding leading edge passage 152 and trailing edge passage 154. A cooling airflow inlet 251 can extend axially through a radially extending back wall of radially extending portion 250. The radially extending back wall is an example of an inlet wall, and cooling airflow inlet 251 is an example of a fluid inlet formed in the inlet wall. A radially extending connection passage 253 is further formed in radially extending portion 250, between radially extending front and back walls of radially extending portion 250, extending to suction side passage 156 of airfoil 98, such that connection passage 253 fluidly couples cooling airflow inlet 251 and suction side passage 156. According to one or more embodiments, connection passage 253 can extend continuously annularly around centerline 12 of engine 10. Alternatively, a plurality of separate connection passages 253 can be disposed around centerline 12 of engine 10, one for each airflow inlet 251 or group of airflow inlets 251.

[0075] Further, a passive valve assembly 200 can be provided on the outer band 92. The passive valve assembly 200 can include an annular band 210 attached to the outer band 92 via a biasing structure 220. According to one or more embodiments, the biasing structure 220 can be a fixed clip. According to one or more embodiments, the biasing element 220 can be, for example, a W-clip or any suitable structure for attaching the annular band 210 to the outer band 92. The biasing structure 220 can also exert an axial force in the forward direction to press the annular band 210 against the cooling airflow inlet 251. According to one or more embodiments, the biasing structure 220 can be attached to another portion of the outer band 92. While the outer band 92 can be formed of metal, the annular band 210 can be formed of a material having a lower coefficient of expansion than the outer band 92. For example, the annular band 210 can include or be of a ceramic matrix composite (CMC) material, which has a much lower coefficient of expansion than the outer band 92. Alternatively, the annular band 210 can be formed of a ceramic (such as silicon carbide), a metal (such as a titanium alloy or a titanium aluminide alloy), or any other material having a lower rate of expansion than the outer band 92.

[0076] According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion equal to or lower than 40% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion equal to or lower than 35% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion equal to or lower than 30% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion equal to or lower than 25% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion between 40% and 25% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion between 35% and 25% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion between 30% and 25% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion between 40% and 30% of the material of the outer band 92. According to one or more embodiments, the annular band 210 is formed of a material having a coefficient of thermal expansion between 35% and 30% of the material of the outer band 92.

[0077] Briefly referring to Figure 9 , a passive valve assembly 200 and a nozzle 73 according to another example embodiment of the present disclosure are provided. Figure 9 The nozzle 73 and passive valve assembly 200 shown in Figure 8 are similar to those shown in , except that a piston ring seal 230 is formed on a forward surface of the annular band 210. When the annular band 210 is positioned behind the cooling airflow inlet, the piston ring seal 230 forms a seal 230 against the cooling airflow inlet 251.

[0078] Referring now to Figure 10A and Figure 10B , according to one or more embodiments, a schematic cross-sectional view of the nozzle 73 and passive valve assembly 200 in the closed and open positions, respectively, is provided. As described above, the outer band 92 has a higher coefficient of thermal expansion than the annular band 210. Thus, as this section of the engine 10 heats up, the outer band 92 and its radially extending portion 250 expand radially at a faster rate than the annular band 210. Due to this difference in coefficient of thermal expansion, as the outer band 92 and annular band 210 heat up, the radially extending portion 250 and cooling airflow inlet 251 formed therein move radially outward relative to the annular band 210. As the temperature of the radially extending portion 250 and annular band 210 changes, the annular band 210 can move between a relative position in which the annular band 210 and cooling airflow inlet 251 partially or fully overlap and a relative position in which the annular band 210 and cooling airflow inlet 251 do not overlap at all. According to one or more embodiments, the leading surface of the annular band 210 can be equal to or larger in size than the cooling airflow inlet 251 such that the annular band 210 can fully close the cooling airflow inlet 251. Alternatively, the leading surface of the annular band 210 can be smaller in size than the cooling airflow inlet 251 such that the annular band 210 allows some airflow to pass through the cooling airflow inlet in the closed position. The biasing structure 220 can be configured to allow the annular band 210 to move relative to the outer band 92.

[0079] Figure 10A The closed position of the passive valve assembly 200 can occur, for example, during cruise operation of the engine 10 when the nozzle 73 and its surrounding components are relatively cool. In the example shown, the relative position of the annular band 210 to the cooling airflow inlet 251 allows only a small amount of cooling airflow 201 to pass through the cooling airflow inlet 251. The cooling airflow 201 is an example of a flow of fluid provided to the fluid passage. The small opening can maintain a backflow margin and minimize the nozzle flow area. Alternatively, in the closed position, the cooling airflow 201 through the cooling airflow inlet 251 can be completely blocked by the annular band 210. Figure 10A The open position of the passive valve assembly 200 can occur, for example, during high power conditions of the engine 10 when the nozzle 73 and its surrounding components are relatively hot. In the example shown, the relative position of the annular band 210 to the cooling airflow inlet 251 allows a large amount of cooling airflow 201 to pass through the cooling airflow inlet 251. The cooling airflow 201 is an example of a flow of fluid provided to the fluid passage. The large opening can maximize the nozzle flow area. Alternatively, in the open position, the cooling airflow 201 through the cooling airflow inlet 251 can be completely unblocked by the annular band 210. Figure 10B Figure 10A ​In the example shown, the relative position of the annular band 210 and the cooling airflow inlet 251 allows the cooling airflow 201 to freely pass through the cooling airflow inlet 251 to the suction side passage 156. As used herein, the "closed," "open" positions do not necessarily require the cooling airflow inlet 251 to be completely closed or completely open. It is noted that if the piston ring seal 230 is formed on the front surface of the annular band 210, the piston ring seal 230 blocks the cooling airflow 201 from flowing to the cooling airflow inlet 251 instead of or in addition to the annular band 210.

[0080] Referring to Figure 10A and Figure 10B , the leading edge cooling airflow 153 can enter the leading edge passage 152 through the leading edge inlet 93 and the trailing edge cooling airflow 155 can enter the trailing edge passage 154 through the trailing edge inlet 95 regardless of the temperature of the outer band 92 and the inner band 94. Alternatively, a valve assembly can also be provided to control the leading edge and trailing edge cooling airflows 153, 155. In one or more embodiments, a passive valve assembly 200 can be provided at the leading edge inlet 93 or the trailing edge inlet 95.

[0081] Figure 11A is a schematic view from the rear in the axial direction A of a nozzle and a passive valve assembly in an open position according to one or more embodiments, Figure 11B is a schematic view from the rear in the axial direction A of a nozzle and a passive valve assembly in a closed position according to one or more embodiments. In the example shown, Figure 11B In the closed position shown, when the outer band 92 and the annular band 210 are relatively cool, for example during cruise operation, the annular band 210 overlaps the cooling airflow inlet 251 in the axial direction A to allow only a small amount of the cooling airflow 201 to pass through the cooling airflow inlet 251. Alternatively, in the closed position, the cooling airflow 201 through the cooling airflow inlet 251 can be completely blocked by the annular band 210. In the example shown, Figure 11AThe relative position of the annular band 210 and the cooling airflow inlet 251 in the shown open position can allow the cooling airflow 201 to freely pass through the cooling airflow inlet 251 to the suction side passage 156. The outer band 92 can have a guide slot 261 formed therein and the annular band 210 can have a corresponding positioning pin 263 extending in the axial direction A that is inserted into the guide slot 261. As the outer band 92 and the annular band 210 expand and contract at different contraction rates relative to one another, the positioning pin 263 moves in the radial direction R within the guide slot 261 while the outer band 92 and the annular band 210 remain aligned in the circumferential direction C. As the temperature of the outer band 92 and the annular band 210 increases, the positioning pin 263 moves inward in the radial direction R within the guide slot 261 and as the temperature of the outer band 92 and the annular band 210 decreases, the positioning pin 263 moves outward in the radial direction R within the guide slot 261. It is noted that while the positioning pin 263 is described as moving within the guide slot 261 for ease of explanation, the guide slot 261 moves outward in the radial direction R at a faster rate than the positioning pin 263 when the outer band 92 and the annular band 210 are heated such that the positioning pin 263 moves inward relative to the guide slot 261. However, the positioning pin 263 also moves outward in the radial direction R relative to the centerline 12 of the engine 10 when heated, albeit at a slower rate than the guide slot 261. Further, if the annular band 210 has a relatively large height in the radial direction R, the guide slot 261 can be provided in the annular band 210 and the positioning pin 263 can be formed on the outer band 92.

[0082] Figure 12 is a schematic view from the rear in the axial direction of the nozzle 73 and the passive valve assembly 200 in the open position in accordance with one or more embodiments. When the passive valve assembly 200 is in the open position, the cooling airflow 201 enters the cooling airflow inlet 251 into the suction side passage 156 and then exits from the airfoil 98 via the exhaust holes 126 described above with respect to Figures 3-6 .

[0083] Figure 13 is a schematic cross-sectional view of the nozzle 73 and the passive valve assembly 300 in accordance with one or more embodiments. Figure 13 The outer band 92 shown is similar to Figures 8-12 the outer band shown, but the radial extension 250 can also include a bypass cooling hole 255. In accordance with one or more embodiments, the bypass cooling hole 255 can be provided in an axial wall connecting a radial extension front wall and a radial extension rear wall of the radial extension 250. The bypass cooling hole 255 can maintain a baseline flow through the suction side passage 156 and the exhaust holes 126 to maintain a backflow margin in the exhaust holes 126, a minimum level of component cooling, or a combination thereof. Although not shown, in Figures 8-12In one or more embodiments shown, a bypass cooling hole 255 can be formed in the radially extending portion 250. A passive valve assembly 300 can be provided on the outer band 92. The passive valve assembly 300 can include an annular band 310 attached to the outer band 92 via a biasing structure 320. According to one or more embodiments, the biasing structure 320 can be a fixed clip. The biasing structure 320 can be, for example, a W-clip or any suitable structure for attaching the annular band 310 to the outer band 92. The biasing structure 320 can further exert an axial force in the forward direction to press the annular band 310 against the cooling airflow inlet 251. According to one or more embodiments, the biasing structure 320 can be attached to another portion of the outer band 92. The annular band 310 can be formed of the same material as the annular band 210 described above. The annular band 310 can be formed of an annular portion 311 fixed to the biasing structure 320 and a sawtooth lug 313 extending outward in the radial direction R from the annular portion 311. In Figure 13 In the closed position of the passive valve assembly 300 shown, the sawtooth lug 313 overlaps the cooling airflow inlet 251 in the axial direction A to block the cooling airflow from entering the cooling airflow inlet 251. As Figure 14 As shown, a seal 330 can be formed on the forward surface of the sawtooth lug 313 for sealing the cooling airflow inlet 251 in the closed position.

[0084] Figure 15A 、 15B Figs. 15A, 15B, and 15C are schematic views of the nozzle 73 and the passive valve assembly 300 in the axial direction from the rear in the open, closed, and partially open positions, respectively, according to one or more embodiments. Figures 16A-16D Fig. 16 is a schematic cross-sectional view of the nozzle 73 and the passive valve assembly 300 developing from a highest temperature condition to a lowest temperature condition, according to one or more embodiments. The outer band 92 includes a guide slot 361 extending obliquely in the circumferential direction C and the radial direction R.

[0085] According to one or more embodiments, the guide slot 361 extends in a direction forming an angle Θ of 2-8 degrees with a tangent to the circumferential direction C. According to one or more embodiments, the guide slot 361 extends in a direction forming an angle Θ of 4-6 degrees with a tangent to the circumferential direction C. According to one or more embodiments, the guide slot 361 extends in a direction forming an angle Θ of 5 degrees with a tangent to the circumferential direction C.

[0086] The annular belt 310 includes a corresponding locating pin 363 extending in the axial direction A, which is inserted into a guide groove 361. As the outer belt 92 and the annular belt 310 expand and contract at different rates, the locating pin 363 moves in the guide groove 361, the inclined orientation of which forces the locating pin 363 and the annular belt 310 to rotate in the circumferential direction C while moving in the radial direction R. As the temperature of the outer belt 92 and the annular belt 310 increases, the locating pin 363 moves inward in the radial direction R and clockwise in the circumferential direction C within the guide groove 361 (when viewed from the rear in the axial direction A), and as the temperature of the outer belt 92 and the annular belt 310 decreases, the locating pin 363 moves outward in the radial direction R and counterclockwise in the circumferential direction C within the guide groove 361 (when viewed from the rear in the axial direction A).

[0087] Figure 15A and Figure 16A The open position shown may occur when the outer belt 92 and the annular belt 310 are at their highest temperatures, which may happen, for example, under high-power conditions. Due to its higher coefficient of thermal expansion, the outer belt 92 expands further outward than the annular belt 310, and the locating pin 363 is located at its innermost position within the guide groove 361. In this position, the serrated lug 313 is located on one side of the cooling airflow inlet 251 in the circumferential direction C, and the annular portion 311 is located inside the cooling airflow inlet 251 in the radial direction R. Therefore, the cooling airflow inlet 251 is open and allows cooling airflow to pass through. Thus, under high-temperature operation such as high-power conditions, a large amount of cooling airflow can be discharged from the exhaust port 126 downstream of the throat 150.

[0088] Figure 15B and 16C The closed position shown may occur when the outer belt 92 and the annular belt 310 are at intermediate temperatures, which could happen, for example, during cruise operation. Due to its higher coefficient of thermal expansion, the outer belt 92 contracts faster than the annular belt 310, and the locating pin 363 is positioned centrally within the guide groove 361. In this position, the serrated lug 313 overlaps with the cooling airflow inlet 251 in the axial direction A. Therefore, the cooling airflow inlet 251 is closed by the serrated lug 313, preventing cooling airflow from passing through. Thus, during intermediate temperature operation such as cruise operation, the only cooling airflow exiting from the exhaust port 126 downstream of the throat 150 may be the airflow passing through the bypass cooling port 255. Alternatively, the annular belt 310 may allow a small volume of cooling airflow into the closed cooling airflow inlet 251. While a non-limiting example of the serrated lug 313 and cooling airflow inlet 251 is shown, other shapes and arrangements of the serrated lug 313 and cooling airflow inlet 251 are possible.

[0089] Figure 16B The partially opened position shown appears inFigure 15A and Figure 16A the open position shown in Figure 15B and Figure 16C the closed position shown in Figure 16B Although

[0090] Figure 15C and 16D the partially open position shown in Figure 15C may occur when the outer band 92 and the annular band 310 are at their lowest temperatures, which can occur, for example, upon engine 10 start-up when cold. Due to the higher coefficient of thermal expansion, the outer band 92 contracts further inward than the annular band 310, positioning the pin 363 at the outermost position within the guide slot 361. In this position, the serrated lugs 313 are positioned to one side of the cooling airflow inlet 251 in the circumferential direction C, and the annular portion 311 is disposed radially inward of the cooling airflow inlet 251 in the radial direction R, although in Figure 10A the interior portion of the cooling airflow inlet 251 can overlap the exterior portion of the annular portion 311, such that the cooling airflow inlet 251 is only partially open. The partially open cooling airflow inlet 251 allows cooling airflow to pass therethrough, albeit in a smaller volume than

[0091] Figures 17A-17C is a schematic view of a nozzle and a passive valve assembly 400 according to one or more embodiments, viewed from the rear in the axial direction A, as the passive valve assembly 400 develops from a highest temperature condition to a lowest temperature condition, and Figure 18 is a cross-sectional view of a passive valve assembly 400 according to one or more embodiments, in a closed position, having an annular band 410 and a sealing arm 461.

[0092] According to one or more embodiments, the passive valve assembly 400 can include an annular band 410 and a seal arm 461 pivotably attached to the annular band 410 at a central location via a pivot pin 463 and rotatably attached to the outer band 92 at a first end via an actuation pin 465. The passive valve assembly 400 can further include a biasing structure 467 attached to a second end of the seal arm 461. According to one or more embodiments, the biasing structure 467 can be a spring clip. The annular band 410 can be formed of the same material as the annular band 210 described above. The seal arm 461 can be formed of any suitable material and, in one or more embodiments, includes or is formed of metal. Alternatively, the seal arm 461 can include or be formed of CMC.

[0093] The annular band 410 can be attached to the outer band 92 via a biasing structure 420. According to one or more embodiments, the biasing structure 420 can be a fixed clip. The biasing structure 420 can be, for example, a W-clip or any suitable structure for attaching the annular band 410 to the outer band 92. The biasing structure 420 can also exert an axial force in the forward direction to press the annular band 410 against the cooling airflow inlet 251. According to one or more embodiments, the biasing structure 420 can be attached to another portion of the outer band 92.

[0094] As the temperature of the outer band 92 and the annular band 410 changes, the outer band 92 expands or contracts at a faster rate than the annular band 410 due to its larger coefficient of expansion. As a result, the outer band 92 moves inward and outward relative to the annular band 410, and the first end of the seal arm 461 moves along the actuation pin 465 attached to the outer band 92. As the first end of the seal arm 461 moves relative to the annular band 410, the seal arm 461 pivots about the pivot pin 463, and the second end of the seal arm 461 moves inward and outward in the radial direction R.

[0095] Figure 17A The open position shown in FIG. 4B occurs when the outer band 92 and the annular band 410 are at the highest temperature, which can occur, for example, under high power conditions. Due to the higher coefficient of thermal expansion, the outer band 92 expands further outward than the annular band 410, and the first end of the seal arm 461 moves to an outer position via the actuation pin 465 through the expanded outer band 92, and the second end of the seal arm 461 pivots about the pivot pin 463 to an inner position. In this position, the second end of the seal arm is disposed inward of the cooling airflow inlet 251 in the radial direction R. Accordingly, the cooling airflow inlet 251 is open and allows cooling airflow to pass through. Thus, under high temperature operation such as high power conditions, a large amount of cooling airflow can be exhausted from the exhaust hole 126 downstream of the throat 150.

[0096] Figure 17B and Figure 18The partially open position shown in FIG. 6 can occur when the outer band 92 and the ring band 410 are at an intermediate temperature, which can occur, for example, during cruise operation. Due to the higher coefficient of thermal expansion, the outer band 92 shrinks at a faster rate than the ring band 410, and the first end of the seal arm 461 is moved to an intermediate position via the actuating pin 465 through the shrinking outer band 92, and the second end of the seal arm 461 is pivoted to an intermediate position about the pivot pin 463. In this position, the seal arm 461 overlaps the cooling airflow inlet 251 in the axial direction A. As a result, the cooling airflow inlet 251 is closed by the seal arm 461 or a seal 430 disposed on the front surface of the seal arm 461, and the passage of cooling airflow is blocked. Thus, the only cooling airflow that can be exhausted from the exhaust aperture 126 downstream of the throat 150 during an intermediate temperature operation such as cruise operation can be the cooling airflow that passes through the bypass cooling aperture 255. Alternatively, the ring band 410 can allow a small amount of cooling airflow to enter the cooling airflow inlet 251 in the closed position.

[0097] Although not shown, a similar partially open position can occur when the outer band 92 and the ring band 410 are at an intermediate temperature, which can occur, for example, during cruise operation. Due to the higher coefficient of thermal expansion, the outer band 92 shrinks at a faster rate than the ring band 410, and the first end of the seal arm 461 is moved to an intermediate position via the actuating pin 465 through the shrinking outer band 92, and the second end of the seal arm 461 is pivoted to an intermediate position about the pivot pin 463. In this position, the seal arm 461 overlaps the cooling airflow inlet 251 in the axial direction A. As a result, the cooling airflow inlet 251 is closed by the seal arm 461 or a seal 430 disposed on the front surface of the seal arm 461, and the passage of cooling airflow is blocked. Thus, the only cooling airflow that can be exhausted from the exhaust aperture 126 downstream of the throat 150 during an intermediate temperature operation such as cruise operation can be the cooling airflow that passes through the bypass cooling aperture 255. Alternatively, the ring band 410 can allow a small amount of cooling airflow to enter the cooling airflow inlet 251 in the closed position. Figure 16B Figure 17A The open position shown in FIG. 8 can occur between the partially open position shown in FIG. 6 and the closed position shown in FIG. 7, and can occur during normal climb operation that is slightly cooler than high power conditions. Figure 17B 18 The partially open position shown in FIG. 6 can occur when the outer band 92 and the ring band 410 are at an intermediate temperature, which can occur, for example, during cruise operation. Due to the higher coefficient of thermal expansion, the outer band 92 shrinks at a faster rate than the ring band 410, and the first end of the seal arm 461 is moved to an intermediate position via the actuating pin 465 through the shrinking outer band 92, and the second end of the seal arm 461 is pivoted to an intermediate position about the pivot pin 463. In this position, the seal arm 461 overlaps the cooling airflow inlet 251 in the axial direction A. As a result, the cooling airflow inlet 251 is closed by the seal arm 461 or a seal 430 disposed on the front surface of the seal arm 461, and the passage of cooling airflow is blocked. Thus, the only cooling airflow that can be exhausted from the exhaust aperture 126 downstream of the throat 150 during an intermediate temperature operation such as cruise operation can be the cooling airflow that passes through the bypass cooling aperture 255. Alternatively, the ring band 410 can allow a small amount of cooling airflow to enter the cooling airflow inlet 251 in the closed position.

[0098] Figure 17C The partially open position shown in FIG. 6 can occur when the outer band 92 and the ring band 410 are at an intermediate temperature, which can occur, for example, during cruise operation. Due to the higher coefficient of thermal expansion, the outer band 92 shrinks at a faster rate than the ring band 410, and the first end of the seal arm 461 is moved to an intermediate position via the actuating pin 465 through the shrinking outer band 92, and the second end of the seal arm 461 is pivoted to an intermediate position about the pivot pin 463. In this position, the seal arm 461 overlaps the cooling airflow inlet 251 in the axial direction A. As a result, the cooling airflow inlet 251 is closed by the seal arm 461 or a seal 430 disposed on the front surface of the seal arm 461, and the passage of cooling airflow is blocked. Thus, the only cooling airflow that can be exhausted from the exhaust aperture 126 downstream of the throat 150 during an intermediate temperature operation such as cruise operation can be the cooling airflow that passes through the bypass cooling aperture 255. Alternatively, the ring band 410 can allow a small amount of cooling airflow to enter the cooling airflow inlet 251 in the closed position.

[0099] The biasing structure 467 can bias the second end of the seal arm 461 inward in the radial direction R. If the seal arm 461, the pivot pin 463, the actuating pin 465, or any combination thereof fail, the biasing structure 467 can apply a force to the second end of the seal arm 461 in the radial direction R to hold the second end of the seal arm 461 in the inner position, such that the cooling airflow inlet 251 is held in the open position. Thus, under such conditions, the engine 10 can continue to operate at high power conditions. ​​

[0100] Figure 19A A flow inducer 500 is shown including a passive valve assembly 200 that receives a flow of air from a cooling flow path 180 from a compressor section 22 and selectively provides a cooling flow 201 to a nozzle 73 of the inducer 500. Figure 19B A flow inducer 500 is shown including a passive valve assembly 300 that receives a flow of air from a cooling flow path 180 from a compressor section 22 and selectively provides a cooling flow 201 to a nozzle 73 of the inducer 500. Figure 19C A flow inducer 500 is shown including a passive valve assembly 400 that receives a flow of air from a cooling flow path 180 from a compressor section 22 and selectively provides a cooling flow 201 to a nozzle 73 of the inducer 500. According to one or more embodiments, the flow inducer 500 having variable flow due to the passive valve assemblies 200, 300, 400 can control one or more cooling flows into the nozzle 73.

[0101] This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent

[0102] Further aspects provide the subject matter of the following clauses:

[0103] A nozzle assembly for a gas turbine engine, the nozzle assembly comprising: a nozzle comprising a first material defining a first coefficient of thermal expansion, the nozzle comprising an airfoil defining a fluid passage therein; an inlet wall defining a fluid inlet fluidly connected to the fluid passage; and a passive valve assembly comprising an annular band comprising a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion, such that the passive valve assembly is at least partially movable relative to the fluid inlet.

[0104] The nozzle assembly according to one or more of the clauses, wherein the passive valve assembly is configured to move between a closed position in which the fluid inlet is blocked by the passive valve assembly and an open position in which the fluid inlet is unblocked by the passive valve assembly.

[0105] The nozzle assembly according to one or more of these articles, wherein the passive valve assembly is configured to move to the closed position during cruise operation of the gas turbine engine.

[0106] The nozzle assembly according to one or more of these articles, wherein the nozzle is a first stage nozzle for a high pressure turbine of the gas turbine engine; and wherein the fluid passage of the airfoil is fluidly connected to an exhaust hole formed in an outer wall of the airfoil downstream of a throat of the gas turbine engine.

[0107] The nozzle assembly according to one or more of these articles, wherein the second material is a ceramic matrix composite.

[0108] The nozzle assembly according to one or more of these articles, wherein the second coefficient of thermal expansion is between 40% and 25% of the first coefficient of thermal expansion.

[0109] The nozzle assembly according to one or more of these articles, wherein the fluid inlet is configured to be fluidly connected to a compressor section of the gas turbine engine to receive a gas flow therefrom.

[0110] The nozzle assembly according to one or more of these articles, wherein the inlet wall is formed on an outer band of the nozzle.

[0111] The nozzle assembly according to one or more of these articles, wherein the inlet wall extends in a radial direction of the gas turbine engine; and wherein the fluid inlet extends in an axial direction of the gas turbine engine.

[0112] The nozzle assembly according to one or more of these articles, wherein a seal is disposed on the annular band; and wherein the seal is configured to block at least a portion of a fluid flow into the fluid inlet at a predetermined temperature.

[0113] The nozzle assembly according to one or more of these articles, wherein the seal is a piston ring seal.

[0114] The nozzle assembly according to one or more of these articles, wherein the nozzle defines a guide slot extending in a radial direction of the gas turbine engine; wherein a positioning pin is formed on the annular band and disposed in the guide slot; and wherein the positioning pin is configured to move within the guide slot in the radial direction as the nozzle expands or contracts relative to the annular band due to a difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion.

[0115] The nozzle assembly according to one or more of the clauses, wherein the annular band includes an annular portion and a lug; and wherein the lug is configured to block at least a portion of the fluid flow into the fluid inlet at a predetermined temperature.

[0116] The nozzle assembly according to one or more of the clauses, wherein the nozzle defines a guide slot extending obliquely in a radial direction and a circumferential direction of the gas turbine engine; wherein a positioning pin is formed on the annular band and disposed in the guide slot; and wherein, due to a difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion, the guide slot forces the positioning pin to move obliquely in the radial direction and the circumferential direction as the nozzle expands or contracts relative to the annular band.

[0117] The nozzle assembly according to one or more of the clauses, wherein the guide slot extends in a direction that forms an angle between 2 degrees and 8 degrees with a tangent to the circumferential direction.

[0118] The nozzle assembly according to one or more of the clauses, further comprising a seal arm disposed between the annular band and the inlet wall and having a first end and a second end; an actuation pin, wherein the first end of the seal arm is rotatably attached to the inlet wall via the actuation pin; and a pivot pin, wherein a portion of the seal arm between the first end and the second end is pivotably attached to the annular band via the pivot pin, and wherein the second end of the seal arm or a seal disposed on the second end of the seal arm is configured to block at least a portion of the fluid flow into the fluid inlet at a predetermined temperature.

[0119] The nozzle assembly according to one or more of the clauses, further comprising a biasing structure attached to the second end of the seal arm to bias the second end in a radial direction of the gas turbine engine.

[0120] The nozzle assembly according to one or more of the clauses, wherein the passive valve assembly is configured to move between a blocked position and an open position, and wherein the passive valve assembly reduces gas flow through the fluid inlet when in the blocked position relative to the open position.

[0121] A gas turbine engine comprising a nozzle assembly, the nozzle assembly comprising: a nozzle comprising a first material defining a first coefficient of thermal expansion, the nozzle comprising an airfoil defining a fluid passage therein; an inlet wall defining a fluid inlet, the fluid inlet fluidly connected to the fluid passage; and a passive valve assembly comprising an annular band, the annular band comprising a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion, such that the passive valve assembly is at least partially movable relative to the fluid inlet.

[0122] The gas turbine engine according to one or more of the clauses further comprising a compressor section; a combustor section downstream of the compressor section; and a turbine section downstream of the combustor section; wherein the nozzle is a first stage nozzle of the turbine section; and wherein the fluid inlet is fluidly coupled to the compressor section via a cooling flow path that bypasses the combustor section.

Claims

1. A nozzle assembly for a gas turbine engine, characterized by, The nozzle assembly includes: a nozzle including a first material defining a first coefficient of thermal expansion, the nozzle including an airfoil defining a fluid passage therein; an inlet wall defining a fluid inlet fluidly connected to the fluid passage; and a passive valve assembly including an annular band including a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion such that the passive valve assembly is at least partially movable relative to the fluid inlet.

2. The nozzle assembly of claim 1, wherein: wherein the passive valve assembly is configured to move between a closed position in which the fluid inlet is blocked by the passive valve assembly and an open position in which the fluid inlet is unblocked by the passive valve assembly.

3. The nozzle assembly of claim 2, wherein: wherein the passive valve assembly is configured to move to the closed position during cruise operation of the gas turbine engine.

4. The nozzle assembly of claim 1, wherein: the nozzle is a first stage nozzle for a high pressure turbine of the gas turbine engine; and wherein the fluid passage of the airfoil is fluidly connected to an exhaust hole formed in an outer wall of the airfoil downstream of a throat of the gas turbine engine.

5. The nozzle assembly of claim 1, wherein: wherein the second material is a ceramic matrix composite.

6. The nozzle assembly of claim 1, wherein: wherein the second coefficient of thermal expansion is between 40% and 25% of the first coefficient of thermal expansion.

7. The nozzle assembly of claim 1, wherein: wherein the fluid inlet is configured to be fluidly connected to a compressor section of the gas turbine engine to receive a flow of gas therefrom.

8. The nozzle assembly of claim 1, wherein: wherein the inlet wall is formed on an outer band of the nozzle.

9. The nozzle assembly of claim 1, wherein: wherein, the inlet wall extends in a radial direction of the gas turbine engine; and wherein the fluid inlet extends in an axial direction of the gas turbine engine.

10. The nozzle assembly of claim 1, wherein: wherein, a seal is disposed on the annular band; and wherein the seal is configured to block at least a portion of a flow of fluid into the fluid inlet at a predetermined temperature.

11. The nozzle assembly of claim 10, wherein: wherein, the seal is a piston ring seal.

12. The nozzle assembly of claim 1, wherein: wherein the nozzle defines a guide slot extending in a radial direction of the gas turbine engine; wherein a positioning pin is formed on the annular band and disposed in the guide slot; and wherein the positioning pin is configured to move within the guide slot in the radial direction as the nozzle expands or contracts relative to the annular band due to a difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion.

13. The nozzle assembly of claim 1, wherein: wherein, the annular band includes an annular portion and a lug; and wherein the lug is configured to block at least a portion of a fluid flow into the fluid inlet at a predetermined temperature.

14. The nozzle assembly of claim 13, wherein, wherein the nozzle defines a guide slot extending obliquely in a radial direction and a circumferential direction of the gas turbine engine; wherein a positioning pin is formed on the annular band and disposed in the guide slot; and wherein, due to a difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion, as the nozzle expands or contracts relative to the annular band, the guide slot forces the positioning pin to move obliquely in the radial direction and the circumferential direction.

15. The nozzle assembly of claim 14, wherein, wherein the guide slot extends in a direction that forms an angle between 2 degrees and 8 degrees with a tangent to the circumferential direction.

16. The nozzle assembly of claim 1, wherein, further comprising: a seal arm disposed between the annular band and the inlet wall and having a first end and a second end; an actuation pin, wherein the first end of the seal arm is rotatably attached to the inlet wall via the actuation pin; and a pivot pin, wherein a portion of the seal arm between the first end and the second end is pivotably attached to the annular band via the pivot pin, and wherein the second end of the seal arm or a seal disposed on the second end of the seal arm is configured to block at least a portion of a fluid flow into the fluid inlet at a predetermined temperature.

17. The nozzle assembly of claim 16, wherein, further comprising: a biasing structure attached to the second end of the seal arm to bias the second end in a radial direction of the gas turbine engine.

18. The nozzle assembly of claim 1, wherein, wherein the passive valve assembly is configured to move between a blocked position and an open position, and wherein the passive valve assembly reduces a flow of gas through the fluid inlet when in the blocked position relative to the open position.

19. A gas turbine engine characterized by, comprising: a nozzle assembly comprising: a nozzle comprising a first material defining a first coefficient of thermal expansion, the nozzle comprising an airfoil defining a fluid passage therein; an inlet wall defining a fluid inlet, the fluid inlet fluidly connected to the fluid passage; and a passive valve assembly comprising an annular band comprising a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being less than the first coefficient of thermal expansion, such that the passive valve assembly is at least partially movable relative to the fluid inlet.

20. The gas turbine engine of claim 19, wherein, further comprising: a compressor section; a combustor section downstream of the compressor section; and a turbine section downstream of the combustor section; wherein the nozzle is a first stage nozzle of the turbine section; and wherein the fluid inlet is fluidly coupled to the compressor section via a cooling flow path that bypasses the combustor section.

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