Passive flow modulation device

Abstract

A passive flow modulation device for a machine defining an axial direction and a radial direction, the passive flow modulation device comprising: a first ring having a first coefficient of thermal expansion; a second ring disposed coaxially with the first ring and at least partially positioned radially inward of the first ring, spaced apart from the first ring in the axial direction, or both, the first ring, the second ring, or both at least partially defining one or more passages, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion to passively modulate a size of the one or more passages during operation.

Description

TECHNICAL FIELD

[0001] Generally, the present disclosure relates to passive flow modulation devices, such as airflow inducers for gas turbine engines. BACKGROUND

[0002] Gas turbine engines generally include turbine and rotor assemblies. Gas turbine engines, such as turbofan engines, can be used for aircraft propulsion. In the case of turbofan engines, the rotor assembly can be configured as a fan assembly.

[0003] Existing gas turbine engines generally include various fluid management systems for managing airflow used in conjunction with thermal energy management. For example, during operation of the engine, different portions of the engine experience a significant amount of thermal energy.

[0004] In particular, rotating components, such as high pressure turbine rotors, often experience high thermal energy levels during different operating modes of the engine. Existing cooling systems provide a cooling airflow to the high pressure turbine rotor to provide a cooling function. The inventors of the present disclosure have discovered that it can be difficult to maintain a desired temperature level and pressure ratio of the cooling airflow provided to the high pressure turbine rotor, and thus improvements that address these issues would be welcomed in the art. BRIEF DESCRIPTION OF DRAWINGS

[0005] A complete and enabling disclosure of the present disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification, which is to be taken in conjunction with the appended drawings, wherein:

[0006] Figure 1 is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary aspect of the present disclosure.

[0007] Figure 2 is an enlarged cross-sectional view of a portion of a gas turbine engine in accordance with an exemplary aspect of the present disclosure, and illustrates an inducer assembly.

[0008] Figure 3 is a further enlarged cross-sectional view of a portion of a gas turbine engine in accordance with an exemplary aspect of the present disclosure, and illustrates an inducer assembly.

[0009] Figure 4 is a cross-sectional view of an inducer assembly in accordance with an exemplary aspect of the present disclosure, taken along line Figure 3 3-3 in FIG. 3.

[0010] Figure 5 is a cross-sectional view of an alternative inducer assembly in accordance with an exemplary aspect of the present disclosure.

[0011] Figure 6 is a cross-sectional view of an alternative inducer assembly in accordance with an exemplary aspect of the present disclosure, taken along line Figure 5alternative cross-sectional view taken at 6-6 in FIG. 6.

[0012] Figure 7 flow diagram of a method of modulating a cooling air flow through an inducer assembly in accordance with example aspects of the present disclosure. Figure 5 second alternative cross-sectional view taken at 7-7 in FIG. 7.

[0013] Figure 8 flow diagram of a method of modulating a cooling air flow through an inducer assembly in accordance with example aspects of the present disclosure.

[0014] Figure 9 enlarged cross-sectional view of a portion of a gas turbine engine in accordance with example aspects of the present disclosure, and showing an alternative inducer assembly.

[0015] Figure 10 enlarged cross-sectional view of a portion of a gas turbine engine in accordance with example aspects of the present disclosure, and showing an axial inducer assembly.

[0016] Figure 11 enlarged cross-sectional view of a radial inducer assembly in a first position in accordance with example aspects of the present disclosure.

[0017] Figure 12 enlarged cross-sectional view of an axial inducer assembly in a second position in accordance with example aspects of the present disclosure.

[0018] Figure 13 flow diagram of a method of modulating a cooling air flow through an axial inducer assembly in accordance with example aspects of the present disclosure.

[0019] Figure 14 isolated cross-sectional view of a first axial inducer assembly in accordance with example aspects of the present disclosure.

[0020] Figure 15 isolated cross-sectional view of a second axial inducer assembly in accordance with example aspects of the present disclosure.

[0021] Figure 16 isolated cross-sectional view of a third axial inducer assembly in accordance with example aspects of the present disclosure.

[0022] Figure 17 isolated cross-sectional view of a fourth axial inducer assembly in accordance with example aspects of the present disclosure.

[0023] Figure 18 enlarged cross-sectional view of a portion of a turbine section of a gas turbine engine in accordance with example aspects of the present disclosure, and showing an inducer assembly.

[0024] Figure 19 enlarged cross-sectional view of a portion of a turbine section of a gas turbine engine in accordance with example aspects of the present disclosure, and showing an inducer assembly.Figure 18 Independent cross-sectional view of an axial inducer assembly. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to the presently preferred embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations

[0026] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, unless otherwise explicitly provided herein, none of the examples described herein is

[0027] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall relate to the embodiments as they are oriented in the drawing

[0028] As used herein, the terms "first", "second", and "third" can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0029] The terms "forward" and "aft" refer to relative positions within a gas turbine engine or vehicle and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, with respect to a gas turbine engine, forward refers to a position closer to the engine inlet and aft refers to a position closer to the engine nozzle or exhaust.

[0030] The terms "upstream" and "downstream" refer to the relative direction with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows.

[0031] Unless otherwise stated herein, the terms "coupled", "fixed", "attached to" and like terms means both direct coupling, fixation, or attachment and indirect coupling, fixation or attachment through one or more intermediary

[0032] The singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise.

[0033] As used throughout the specification and claims, approximate language is applied to modify any quantitative representation that can permit variations 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,” “approximately,” and “substantially,” is not limited to the precise value specified. In at least some instances, the approximate language can correspond to the precision of an instrument used to measure the value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, the approximate language can refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins can apply to individual values, either end point or both end points defining a range of values, and / or a margin of a range between end points.

[0034] Throughout this document and in the claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0035] The term “turbomachine” or “turbomachinery” refers 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 generate a torque output.

[0036] The term “gas turbine engine” refers to an engine having a turbomachine as all or a portion of its power source. Example gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and the like, as well as hybrid-electric versions of one or more of these engines.

[0037] 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 example embodiments, a 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.

[0038] The terms “low” and “high,” or their respective comparative forms (e.g., more “low” and more “high,” where applicable), when used in conjunction with a compressor, turbine, shaft, or spool component, and the like, each refer to relative speeds within an engine, unless otherwise specified. For example, a “low turbine” or “low speed turbine” defines a component that is configured to operate at a lower rotational speed (e.g., maximum allowable rotational speed) than a “high turbine” or “high speed turbine” at the location of the engine.

[0039] Aspects of the present disclosure present methods and assemblies for passively modulating air flow through an inducer of a gas turbine engine.

[0040] In a first embodiment, the present disclosure presents a differentially variable area radial inducer that passively modulates the cooling flow to a high pressure turbine, for example to the first stage rotor blades of a high pressure turbine blade. For example, an outer ring having a high coefficient of thermal expansion, for example a material such as metal, is assembled with an inner ring having a low coefficient of thermal expansion, for example a material such as ceramic matrix composite. When assembled, the two rings form discrete, radially configured flow passages that act as an inducer for the cooling air flow delivered to the high pressure turbine. During operation, the difference in coefficient of thermal expansion causes the outer ring to grow faster than the inner ring, thereby opening flow areas between the rings in response to an increase in temperature of the airflow through the rings.

[0041] In a second embodiment, the present disclosure presents a differentially variable area radial inducer that passively modulates the cooling flow to a high pressure turbine. In particular, a first side wall plate having a high coefficient of thermal expansion, for example a material such as metal, bounds one side of a circumferentially disposed set of nozzle vanes of the inducer, while a second side wall plate having a low coefficient of thermal expansion, for example a material such as ceramic matrix composite, bounds the other side of the set of nozzle vanes. The first side wall plate having a high coefficient of thermal expansion has a circle of pins, each pin connected to a nozzle vane. The second side wall plate having a low coefficient of thermal expansion has a circle of pins, each pin also connected to a nozzle vane. As the temperature of the airflow through the two rings increases, the first side wall plate (having a high coefficient of thermal expansion) radially outgrows the second side wall plate (having a low coefficient of thermal expansion), thereby rotating the nozzle vanes open and increasing the throat area of the inducer.

[0042] These two passive temperature driven inducer configurations reduce the flow through the inducer, providing the benefit of maintaining a maximum inducer pressure ratio, resulting in improved specific fuel consumption.

[0043] Reference will now be made to the drawings wherein like numerals refer to like components throughout the several figures, Figure 1 is a schematic cross-sectional view of a propulsion system 10 in accordance with an example embodiment of the present disclosure. More specifically, for Figure 1 embodiments of the present disclosure, the propulsion system 10 includes a gas turbine engine, referred to herein as a “turbofan engine 12.” In one example, the turbofan engine 12 can be a high-bypass turbofan jet engine. As Figure 1 shown, the turbofan engine 12 defines an axial direction A (extending parallel to an axial centerline 14 provided for reference) and a radial direction R. Generally, the turbofan engine 12 includes a fan section 16 and a turbine section 18 disposed downstream from the fan section 16.

[0044] The depicted exemplary turbine 18 generally includes a substantially tubular outer casing 20 that defines an annular inlet 22. The casing 20 encloses, in serial flow order / relationship: a compressor section including a booster or low pressure compressor 24 ("LP compressor 24") and a high pressure compressor 26 ("HP compressor 26"); a combustion section 28; and a turbine section including a high pressure turbine 30 ("HP turbine 30") and a low pressure turbine 32 ("LP turbine 32"). A high pressure shaft or spool 34 ("HP spool 34") drivingly connects the HP turbine 30 to the HP compressor 26. A low pressure shaft or spool 36 ("LP spool 36") drivingly connects the LP turbine 32 to the LP compressor 24.

[0045] For the depicted embodiment, the fan section 16 includes a variable pitch fan 38 having a plurality of fan blades 40 coupled to a disk 42 in a spaced apart manner. As shown, the fan blades 40 extend outwardly from the disk 42 in a generally radial direction R. Each fan blade 40 is rotatable relative to the disk 42 about a pitch axis P by virtue of the fan blades 40 being operatively coupled to a suitable actuation member 44 that is configured to, for example, uniformly collectively change the pitch of the fan blades 40. The fan blades 40, disk 42, and actuation member 44 are rotatable together about the axial centerline 14 by the LP spool 36 across a power gear box 46. The power gear box 46 includes a plurality of gears for reducing the rotational speed of the LP spool 36 to a more efficient rotational fan speed.

[0046] Still referring to Figure 1 the exemplary embodiment, the disk 42 is covered by a rotatable front hub 48 that is aerodynamically shaped to facilitate airflow through the plurality of fan blades 40. Further, the fan section 16 includes an annular fan casing or outer nacelle 50 that circumferentially surrounds at least a portion of the variable pitch fan 38 and / or the turbine 18. It should be appreciated that, in some embodiments, the nacelle 50 is configured to be supported relative to the turbine 18 by a plurality of circumferentially spaced apart outlet guide vanes 52. Further, a downstream section 54 of the nacelle 50 extends over an outer portion of the turbine 18 so as to define a bypass airflow passage 56 therebetween.

[0047] During operation of turbofan engine 12, a volume of air 58 enters turbofan engine 12 through nacelle 50 and / or associated inlet 60 of fan section 16. As volume of air 58 passes through fan blades 40, a first portion of air 58, as indicated by arrow 62, is directed or routed into bypass airflow passage 56, and a second portion of air 58, as indicated by arrow 64, is directed or routed into LP compressor 24. The ratio between first portion of air 62 and second portion of air 64 is generally referred to as the bypass ratio. The pressure of second portion of air 64 then increases as it is directed through high pressure (HP) compressor 26 and into combustion section 28, where it mixes with fuel and combusts to provide combustion gases 66. Combustion gases 66 are then directed through HP turbine 30 and LP turbine 32, where a portion of the thermal and / or kinetic energy from combustion gases 66 is extracted.

[0048] The combustion gases 66 are then directed through the combustion section 28 of the turbine 18 to provide propulsive thrust. Simultaneously, the pressure of the first portion of air 62 is significantly increased as it is directed through the bypass airflow passage 56 before being discharged from the fan nozzle exhaust section 68 of the turbofan engine 12, also providing propulsive thrust.

[0049] Furthermore, as schematically depicted, the turbofan engine 12 also includes various auxiliary systems to assist in the operation of the turbofan engine 12 and / or an aircraft incorporating the turbofan engine 12. For example, as will be discussed in greater detail below, the turbofan engine 12 includes a compressor cooling air ("CCA") system 72 for providing air from one or both of the HP compressor 26 or the LP compressor 24 to one or both of the HP turbine 30 or the LP turbine 32. The CCA system 72 may include ducting and a CCA heat exchanger. The ducting may receive airflow from the compressor section and provide this airflow to the CCA heat exchanger for cooling. The cooled airflow may then be provided to, for example, the turbine section to cool various components of the turbine section. Furthermore, the turbofan engine 12 includes an active thermal clearance control ("ACC") system 74 for cooling the turbine section casing to maintain clearances between the various turbine rotor blades and the turbine casing within a desired range under various engine operating conditions. Although not depicted, the ACC system 74 may similarly include ducting for receiving airflow and providing this airflow to the ACC heat exchanger.

[0050] However, it should be understood that Figure 1The turbofan engine 12 depicted in FIG. 1 is merely an example, and in other exemplary embodiments, aspects of the present disclosure may additionally or alternatively be applied to any other suitable gas turbine engine. For example, in other exemplary embodiments, the turbofan engine 12 may alternatively be any other suitable aviation gas turbine engine, such as a turbojet engine, a turboshaft engine, a turboprop engine, etc. Furthermore, in other exemplary embodiments, the turbofan engine 12 may include any other suitable number and / or configuration of shafts, spools, compressors, turbines, etc.; may be configured as a direct drive engine (e.g., without including a power gearbox 46); may be a fixed pitch fan; may be a non-ducted turbofan engine (without including a nacelle 50); etc.

[0051] Now refer to Figure 2 , Figure 2 is a turbine 18 of a turbofan engine 12 according to an exemplary aspect of the present disclosure (see, e.g., Figure 1 ) and showing the inducer assembly.

[0052] The turbofan engine 12 includes a combustor casing 76 . The combustor casing 76 is a casing or shell of hard material that surrounds and defines the outer surface of the combustion section 28 .

[0053] The turbofan engine 12 also includes a combustor 78. The combustor 78 is the portion of the turbine 18 that defines a cavity in which air and liquid fuel from the HP compressor are combusted to produce fuel for propulsion of the system 10 (see, e.g., Figure 1 )’s motivation.

[0054] The turbofan engine 12 also includes a passive flow modulation device. More specifically, for the depicted embodiment, the passive flow modulation device is configured as an inducer assembly 80. In certain exemplary embodiments, the inducer assembly 80 is configured to divert the cooling air flow to at least partially match the rotation of the rotor disk of the HP turbine 30. The cooling air flow can then be provided along the rotor disk to the first-stage turbine blades of the HP turbine 30. The inducer assembly 80 is discussed in further detail with respect to the remaining figures.

[0055] Turbofan engine 12 additionally includes a forward cavity 82 defined between combustion section 28 and HP turbine 30 .

[0056] In this example embodiment, the turbofan engine 12 includes a duct 84. The duct 84 is a conduit or tube configured to transport a flow of fluid therethrough. The turbofan engine 12 also includes a frame assembly 85 including a forward or forward frame 86 and an aft or aft frame 87. The frame assembly 85 is stationary relative to rotating components within the turbine 18. The frame assembly 85 is a solid, rigid frame within the turbine 18. The forward frame 86 is configured to be part of the duct 84. In certain example embodiments, the aft frame 87 is part of an inlet guide frame. The forward frame 86 and the aft frame 87 can be joined in any suitable manner. Additionally or alternatively, in other embodiments, the forward frame 86 and the aft frame 87 can be integrally formed as a single unitary component.

[0057] Referring now to Figure 3 , Figure 3 is a further enlarged cross-sectional view of a portion of the turbine 18 of the turbofan engine 12 according to example aspects of the present disclosure and shows the inducer assembly 80.

[0058] The turbofan engine 12 additionally includes a first seal 88, a second seal 90, and a third seal 92. The first seal 88 and the second seal 90 are fluid seals configured to prevent or minimize fluid flow therethrough. In certain example embodiments, the first seal 88 and the second seal 90 can include W-seals. For the illustrated embodiment, the forward frame 86 includes a first lip that houses the first seal 88 and a second lip that houses the second seal 90. The third seal 92 is another fluid seal. In example embodiments, the third seal 92 can include a rotary seal, such as a labyrinth seal.

[0059] As discussed above with respect to Figure 2 , the turbofan engine 12 provides an airflow 94 through the duct 84 during operation of the turbofan engine 12. The airflow 94 can be a CCA airflow from the CCA system 72.

[0060] The inducer assembly 80 includes a first ring 100 and a second ring 102 that is coaxially disposed with and spaced apart from the first ring 100. More specifically, the first ring 100 and the second ring 102 are each disposed about the axial centerline 14 of the turbofan engine 12. The first ring 100 of the inducer assembly 80 is mounted to the frame assembly, and more specifically to the aft frame 87. The first ring 100 is movably coupled to the frame assembly such that the first ring 100 is movable relative to the frame assembly in the radial direction R. In particular, for the illustrated embodiment, the first ring 100 is mounted via a plurality of pins 104. In this example embodiment, one pin 104 is shown. However, it should be appreciated that in other example embodiments, a plurality of pins 104 can be distributed along the circumference of the first ring 100. The pins 104 can also be referred to as spoke centering pins. With this construction, the first seal 88 is configured as a sliding seal that is configured to form an airflow seal between the frame assembly and the first ring 100, and more specifically between the forward frame 86 and the first ring 100, as the first ring 100 is moved relative to the frame assembly in the radial direction R, as described below.

[0061] In certain example embodiments, the inducer assembly 80 can be in fluid communication with the compressor section (e.g., the LP compressor 24 and the HP compressor 26) via the duct 84, and in fluid communication with the HP turbine 30 (see, e.g., Figure 1 ) via the forward cavity 82. For example, the turbofan engine 12 can include a source of cooling air in fluid communication with the inducer assembly 80, and the inducer assembly 80 can be configured to supply a flow of cooling air to the HP turbine 30 (see, e.g., Figure 1 ) of the turbine 18.

[0062] The first ring 100 and the second ring 102 are, for example, tubular rings of solid material. In certain example embodiments, the first ring 100 includes a material having a first coefficient of thermal expansion. More specifically, in at least certain example aspects, the material of the first ring 100 can include a metal, such as nickel or a nickel alloy. Additionally or alternatively, the first coefficient of thermal expansion can be 5 microinches per inch per degree Fahrenheit or greater (e.g., greater than or equal to 7 microinches per inch per degree Fahrenheit, such as less than or equal to 13 microinches per inch per degree Fahrenheit).

[0063] Similarly, the second ring 102 can include a material having a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion. In certain exemplary embodiments, the second coefficient of thermal expansion of the second ring 102 is less than the first coefficient of thermal expansion of the first ring 100. More specifically, in at least certain exemplary aspects, the material of the second ring 102 can include a non-metallic material, such as a ceramic matrix composite material, such as a silicon carbide material. Additionally or alternatively, the second coefficient of thermal expansion can be 5 microinches / (inch x degree Fahrenheit) or less (e.g., less than or equal to 4 microinches / (inch x degree Fahrenheit), such as less than or equal to 3 microinches / (inch x degree Fahrenheit), such as greater than 0 microinches / (inch x degree Fahrenheit)).

[0064] As about Figures 4-8 As further discussed, first ring 100 is configured to expand at a first rate in response to a change in thermal energy. Second ring 102 is configured to expand at a second rate in response to the same change in thermal energy. More specifically, in at least some exemplary aspects, the first rate of first ring 100 is greater than the second rate of second ring 102.

[0065] In certain exemplary embodiments, if the airflow 94 includes only airflow from a cooled cooling air source (e.g., a cooled cooling air heat exchanger of the CCA system 72), the inductor assembly 80 may serve as a safety mechanism to open or increase the flow area of ​​the inductor assembly 80 in the event that the CCA system 72 fails to deliver the expected amount of cooling (e.g., if the CCA heat exchanger is not receiving the expected amount of cooling due to a tube rupture, etc.), resulting in higher temperature air being delivered to the inductor assembly 80. In such an event that the CCA system 72 fails to deliver the expected amount of cooling to the inductor assembly 80, the flow area of ​​the inductor assembly 80 increases (in response to the airflow 94 having a higher temperature) and more cooling air may be delivered to the HP turbine 30 to protect the HP turbine 30.

[0066] Now refer to Figure 4 , Figure 4 According to an exemplary aspect of the present disclosure Figure 3 3-3 in the cross-sectional view of the inductor assembly 80. For example, Figure 4 The cross-sectional view provided in FIG. 8 is taken from the forward direction of the inducer assembly 80 relative to the turbofan engine 12 (e.g., as Figure 3 left as shown) and rearward (e.g., as Figure 3 As seen from the front and back view points (shown to the right). Figure 4 , the axial direction A and the axial centerline 14 are shown into the page, and the radial direction R is shown pointing in an upward direction (eg, pointing away from the axial centerline 14 ).

[0067] In the exemplary embodiment, second ring 102 is disposed inwardly of first ring 100 in radial direction R. First ring 100 and second ring 102 may be concentric with each other. First ring 100 and / or second ring 102 may be coaxial with each other and / or with axial centerline 14 of turbofan engine 12.

[0068] The first ring 100 defines an inner surface 105. The inner surface 105 is the inner surface along the radial direction R of the first ring 100. The second ring defines an outer surface 106. The outer surface 106 is the outer surface along the radial direction R of the second ring 102. The first ring 100 includes first threads 108 provided along the inner surface 105 along the radial direction R of the first ring 100. The second ring 102 includes second threads 110 provided along the outer surface 106 along the radial direction R of the second ring 102. The first threads 108 of the first ring 100 are threadedly engaged with the second threads of the second ring 102.

[0069] In certain exemplary embodiments, the inducer assembly 80 defines one or more channels 112. More specifically, in at least certain exemplary aspects, the second ring 102 is spaced apart from the first ring 100 to define one or more channels 112 therebetween. In particular, for the illustrated embodiment, the one or more channels 112 include a plurality of channels 112 defined between the first ring 100 and the second ring 102. For example, each channel 112 can be defined in part by a radially facing end surface of one of the second threads 110, in part by a discrete portion of the inner surface 105, and further in part by a sidewall of an adjacent piece or tooth of the first thread 108. Figure 4 In the illustrated embodiment, less than a full circumferential portion of the first ring 100 and the second ring 102 is shown. However, it should be understood that the first ring 100 and the second ring 102 of the inductor assembly 80 extend the entire circumference to form a continuous, full 360° ring. It should be understood that the plurality of channels 112 may be collectively defined and referred to as flow channels.

[0070] In certain exemplary embodiments, the plurality of channels 112 of the inducer assembly 80 are configured to direct the airflow 94 in the axial direction A (see, e.g., Figure 3 ) through channel 112. More specifically, although Figure 4 108 and 110 define a helical shape along the axial direction A. In this manner, the first and second rings 100, 102 of the inducer assembly 80 and the plurality of passages 112 defined therebetween may function to turn the airflow 94 to introduce a circumferential direction into the airflow 94 to facilitate providing the airflow 94 to rotating components of the turbofan engine 12, such as HP turbine rotor blades.

[0071] The passages 112 together define a flow area through which the airflow 94 (see, e.g., FIG. 1) passes as the airflow 94 passes through the inducer assembly 80 and to the forward cavity 82. As the airflow 94 passes through the passages 112 of the inducer assembly 80, thermal energy is transferred between the airflow 94 and the first ring 100 and between the airflow 94 and the second ring 102. Figure 3

[0072] Due to the mismatch in the coefficient of thermal expansion between the first ring 100 and the second ring 102, the first ring 100 and the second ring 102 expand or contract at different rates in response to the changes and transfers of thermal energy. As the first ring 100 and the second ring 102 expand or contract at different rates, the size of the passages 112 increases or decreases, respectively, thereby changing the flow area of the passages 112 through which the airflow 94 is able to flow. As the flow area of the passages 112 increases or decreases, the amount of airflow 94 is modulated, thereby changing the amount of airflow 94 that is ultimately delivered to the HP turbine 30 (e.g., via the forward cavity 82, see, e.g., FIG. 1). Figure 3

[0073] The operation of the inducer assembly 80 will now be described. As will be appreciated from the above description and the following description, the inducer assembly 80 is configured as a thermally driven flow metering device and / or a differential variable area radial inducer that passively modulates the airflow 94 (e.g., cooling flow) to a turbine rotor (e.g., the first stage rotor blades of the HP turbine 30). The configuration of the disclosed inducer assembly 80 can provide the benefit of reducing the pressure loss across the turbomachine 18 and reducing the amount of cooling air (e.g., airflow 94) required to sufficiently cool the rotor blades of the HP turbine 30 during different operating modes (e.g., taxi, takeoff, cruise, etc.) of an aircraft incorporating the propulsion system 10.

[0074] Referring now to Figure 5 , wherein like numbers refer to like or similar elements discussed with respect to Figure 4 , Figure 5 is a cross-sectional view of an alternative inducer assembly according to example aspects of the present disclosure. In particular, Figure 5 illustrates an inducer assembly 80' having a first ring 100' and a second ring 102'. Reference is also made to Figure 6 , Figure 6 is an alternative cross-sectional view of the inducer assembly 80' taken along line 6-6 in Figure 5 . As described herein, Figure 6 is discussed in conjunction with Figure 5 .

[0075] In Figure 5 , the axial direction A is shown as coming out of the page, the radial direction R is shown as pointing in an upward direction, and the circumferential direction C is shown as bending left and right. In Figure 6 ​​In this example embodiment, the circumferential direction C is shown as in and out of the page, the radial direction R is shown as pointing in an upward direction, and the axial direction A is shown as left and right.

[0076] In this example embodiment, the inducer assembly 80' includes a first ring 100' and a second ring 102' having a different configuration than the first ring 100 and the second ring 102 shown in Figure 4 . The first ring 100' also includes an inner surface 105 and a first thread 108. Likewise, the second ring 102' includes an outer surface 106 and a second thread 110.

[0077] In certain example embodiments, the first thread 108 and the second thread 110 can include a stepped / constructed along the cross-sectional cutting direction. More particularly, in at least certain example aspects, the first thread 108 and the second thread 110 can each include two steps that respectively engage with the corresponding two steps of the second thread 110 and the first thread.

[0078] Here in Figure 5 , the passages 112 are defined by the first thread 108 and the second thread 110 and are disposed between adjacent pairs of the first thread 108 and the second thread 110 along the circumferential direction C of the inducer assembly 80'. The formation of the passages 112 of the inducer assembly 80' differs from the passages 112 of the inducer 80 shown in Figure 4 . For example, in Figure 4 , the passages 112 of the inducer 80 are primarily defined between the radial end face of the first thread 108 and the outer surface 106 of the second ring 102, or between the radial end face of the second thread 110 and the inner surface 105 of the first ring 100 (see, e.g., Figure 4 ).

[0079] Referring back to the inducer assembly 80' of Figure 5 , in certain example embodiments, the plurality of passages (e.g., all of the passages 112 extending around 360° of the inducer assembly 80') can define a flow area of the inducer assembly 80'. Additionally or alternatively, the flow area of the inducer assembly 80' can also include any space or gap defined between the steps of the first thread 108 and the second thread 110 along the radial direction R (as well as along the circumferential direction C). In certain example embodiments, the plurality of passages 112 of the inducer assembly 80' are configured to direct the airflow 94 through the passages 112 in the axial direction A and are further configured to introduce the circumferential direction into the airflow 94 (see, e.g., Figure 3 ) so as to facilitate the provision of the airflow 94 to rotating components of the turbofan engine 12, such as the HP turbine rotor blades (see Figure 6 below).

[0080] Each passage 112 defines a dimension H Rand size W C . Size H R is the height of one of the channels 112 and is defined by the distance in the radial direction R from the inner surface 105 to the outer surface 106 .

[0081] In an exemplary embodiment, dimension W C is the width of one of the channels 112 and may be defined by the arcuate distance between the side 114 of the first thread 108 and the side 116 of the second thread 110 adjacent to the first thread 108, dimension W. C Extends / or originates from the side 116. However, it should be understood that in other exemplary embodiments, the dimension W C The dimension W may be defined as the straight-line distance between the side surface 114 of the first thread 108 and the side surface 116 of the second thread 110 adjacent to the first thread 108 along a direction perpendicular to the radial direction R (e.g., along a secant line that intersects the side surface 114 of the first thread 108 at the midpoint of the side surface 114 and intersects the side surface 116 of the second thread 110 at the midpoint of the side surface 116). C Extending / starting from the side 116 .

[0082] In certain exemplary embodiments, a plurality of channels (e.g., all channels 112 extending 360° around the inductor assembly 80′) may define a flow region of the inductor assembly 80′. Additionally or alternatively, the flow region of the inductor assembly 80′ may also include any spaces or gaps defined between steps of the first and second threads 108, 110 in the radial direction R (as well as in the circumferential direction C).

[0083] With the above reference Figure 4 Similar to the described embodiments, the first ring 100' and the second ring 102' of the inducer assembly 80' have different coefficients of thermal expansion and, therefore, different growth rates in response to the same transfer of thermal energy into or out of the first ring 100' and the second ring 102'. In certain exemplary embodiments, because the coefficient of thermal expansion of the first ring 100' is greater than the coefficient of thermal expansion of the second ring 102', the first ring 100' grows / expands (and contracts / retracts) at a faster rate than the second ring 102'. Due to this thermal mismatch between the materials of the first ring 100' and the second ring 102', as the first ring 100' and the second ring 102' absorb thermal energy, the flow area of ​​the inducer assembly 80' increases as the first ring 100' moves away from the second ring 102' in the radial direction R. More specifically, in at least certain exemplary aspects, the dimension H R As the first ring 100' and the second ring 102' absorb heat energy, the dimension W increases. CThe size of the passages 112 can also increase as the first ring 100' and the second ring 102' absorb thermal energy. In another example embodiment, the size of any space or gap defined between the steps of the first thread 108 and the second thread 110 in the radial direction R (as well as in the circumferential direction C) can also increase as the first ring 100' and the second ring 102' absorb thermal energy.

[0084] It should be appreciated that, in certain example embodiments, as thermal energy is transferred away from the first ring 100' and the second ring 102' (e.g., to the airflow 94 passing through the inducer assembly 80'), the first ring 100' contracts in the radial direction R and becomes closer to the second ring 102'. As the first ring 100' and the second ring 102' contract (the first ring 100' contracts at a faster rate due to the mismatch in the coefficient of thermal expansion), the size of the passages 112 decreases, resulting in a decrease in the flow area of the inducer assembly 80'. More particularly, in at least certain example aspects, the size H R The size of the passages 112 can also decrease as the first ring 100' and the second ring 102' transfer thermal energy. Additionally or alternatively, the size of any space or gap defined between the steps of the first thread 108 and the second thread 110 in the radial direction R (as well as in the circumferential direction C) can also decrease as the first ring 100' and the second ring 102' transfer thermal energy. C The size of the passages 112 can also decrease as the first ring 100' and the second ring 102' transfer thermal energy. Additionally or alternatively, the size of any space or gap defined between the steps of the first thread 108 and the second thread 110 in the radial direction R (as well as in the circumferential direction C) can also decrease as the first ring 100' and the second ring 102' transfer thermal energy.

[0085] As such, as the temperature of the airflow 94 passing through the inducer assembly 80' and being delivered to the rotor blades of the HP turbine 30 increases, the flow area of the inducer assembly 80' increases, thereby providing an increased amount of airflow 94 to the HP turbine 30 for cooling purposes. Conversely, as the temperature of the airflow 94 passing through the inducer assembly 80' and being delivered to the rotor blades of the HP turbine 30 decreases, the flow area of the inducer assembly 80' decreases, thereby providing a decreased amount of airflow 94 to the HP turbine 30 for cooling purposes.

[0086] For example, in certain example embodiments, during a first operating condition (e.g., a low power operating condition), the airflow 94 can define a relatively low temperature, as the air source (e.g., a stage of a compressor) can provide relatively low temperature air as a starting point. With this configuration, the plurality of passages 112 can define a relatively small size. During a second operating condition (e.g., a high power operating condition), the airflow 94 can define a relatively high temperature, as the air source can provide relatively high temperature air as a starting point. This increase in the temperature of the airflow 94 can cause the first ring 100 to expand relative to the second ring 102, thereby increasing the size of the passages 112 and allowing more airflow 94 to cool the HP turbine 30 (which is typically hotter and requires more cooling during high power operating conditions as compared to low power operating conditions).

[0087] Further, the airflow 94 can define an even higher temperature during a third operating condition (e.g., a fault condition, whereby the airflow 94 is not properly cooled) as compared to the first and second operating conditions. This further increase in temperature of the airflow 94 can cause the first ring 100 to expand further relative to the second ring 102, thereby further increasing the size of the passage 112 and allowing more airflow 94 to cool the HP turbine 30. Although the airflow 94 is hotter in this third operating condition, the increase in volume allowed through the passage 112 can offset the decrease in cooling provided by the higher temperature until the fault condition can be remedied.

[0088] As provided herein, the passive and thermally driven flow metering device as the inducer assembly 80' can eliminate the need for actuators, valves, or tubes (e.g., associated with active flow control systems), thereby providing weight reduction benefits and improving combustor function. Further, the axial and passive control configuration of the proposed inducer assembly 80' (and inducer assembly 80) provides the benefit of maintaining a maximum pressure ratio at the inducer assembly 80', and more generally, improved specific fuel consumption of the propulsion system 10.

[0089] Reference is now made to Figure 7 , Figure 7 is a cross-sectional view taken along line 7-7 in Figure 5 Here, in Figure 7 , the radial direction R is shown as coming out of the page, the axial direction A is shown as pointing in the upward direction, and the circumferential direction C is shown as left to right.

[0090] In certain example embodiments, the first threads 108 and the second threads 110 can be angled tangentially relative to the axial direction A and the circumferential direction C, thereby defining a helical shape. As a result, the first threads 108 of the first ring 100' and the second threads 110 of the second ring 102' can form or define a passage 112 that is also angled tangentially, thereby defining a helical shape. This tangential angular configuration of the passage 112 enables the passage 112 to induce a tangential angular flow into the airflow 94 as the airflow 94 passes through the inducer assembly 80'.

[0091] Additionally or alternatively, the inducer assembly 80' can also include a shim plate 118. The shim plate 118 is a solid disk of material that includes circumferentially spaced apart slots 119. In this example embodiment, the shim plate 118 is disposed at a downstream (e.g., toward the top, as shown) end of the first and second rings 100', 102'. Figure 7

[0092] ​In certain example embodiments, the shroud 118 can be configured to block a selected portion or all of the airflow 94 flowing through the passages 112. For example, given a particular pressure or velocity of the airflow 94, the airflow 94 can have a small amount of momentum, in which case it can be desirable to minimize the pressure loss of the airflow 94 as it passes through the inducer assembly 80'. During operation, the position of the shroud 118 (e.g., rotation, circumferential, etc.) can be adjusted to cover more of the passages 112, thereby blocking more of the airflow 94 from flowing out of the passages 112. In this manner, the airflow 94 can be forced to turn through the smaller openings created by the shroud 118 or through other passages 112 that are not covered or blocked by the shroud 118. Thus, the shroud 118 can reduce low momentum leakage through the inducer assembly 80' and provide improved control of the flow area of the passages 112.

[0093] Reference is now made to Figure 8 , Figure 8 is a flowchart of a method 200 of modulating a flow of cooling air (e.g., the airflow 94) through a passive flow modulation device (e.g., through an inducer assembly (e.g., the inducer assembly 80 and / or the inducer assembly 80')) in accordance with example aspects of the present disclosure. In certain example embodiments, the method 200 includes a method of providing an airflow in the turbofan engine 12. As discussed herein, the inducer assembly 80 and its corresponding components are discussed with respect to the method 200. However, it should be understood that Figure 8 the method 200 depicted in FIG. 2 is by way of example only, and in other example embodiments, the method 200 can also involve the inducer assembly 80' and its corresponding components (e.g., the first ring 100' and the second ring 102', etc.).

[0094] The method 200 provides the airflow 94 to the inducer assembly 80 at 202. The method 200 provides transferring thermal energy between the airflow 94 and the first ring 100, between the airflow 94 and the second ring 102, or both, at 204.

[0095] In example embodiments, the step 204 of the method 200 can provide transferring thermal energy between the airflow 94 and the first ring 100 and between the airflow 94 and the second ring 102 at 206, thereby causing the first ring 100 to expand at a first rate in response to the transferring thermal energy between the airflow 94 and the first ring 100 and causing the second ring 102 to expand at a second rate in response to the transferring thermal energy between the airflow 94 and the second ring 102. More particularly, in at least certain example aspects, the first rate of the first ring 100 is greater than the second rate of the second ring 102.

[0096] In another exemplary embodiment, step 204 of method 200 may provide, at step 208 , changing the size of first ring 100 relative to the size of second ring 102 . In another exemplary embodiment, step 204 of method 200 may provide, at step 210 , passively modulating the amount of airflow 94 through passage 112 .

[0097] The method 200 , at 212 , provides directing the airflow 94 in the axial direction A of the turbofan engine 12 using the inducer assembly 80 .

[0098] Now refer to Figure 9 , Figure 9 is a turbofan engine 12 according to an exemplary aspect of the present disclosure (see e.g. Figure 2 ) and showing the diverter 120 upstream of the inducer assembly 80. Figure 9 The embodiments provided in Figure 3 The method described is constructed in essentially the same manner, but with the addition of a diverter 120 .

[0099] The flow divider 120 is a curved piece of solid material. In certain exemplary embodiments, the flow divider 120 can be curved about the axial centerline 14 (see, e.g., Figure 1 ) partially extended or fully extended 360 degrees. The flow splitter 120 is disposed in the duct 84 and can be mounted to the duct 84 or a portion of the frame assembly 85.

[0100] In certain exemplary embodiments, the flow splitter 120 is configured to create a temperature profile upstream of the inductor assembly 80. More specifically, in at least certain exemplary aspects, the flow splitter 120 is configured to separate or prevent (substantial) mixing of the first and second air streams 94A, 94B before they reach the first and second rings 100, 102.

[0101] In certain exemplary embodiments, the first airflow 94A may include air from the compressor section of the turbofan engine 12 (or more specifically, from the diffuser cavity (see FIG. Figure 3 ) air), while the second air stream 94B may include air from a heat exchanger (e.g., from the CCA system 72 (see e.g., Figure 1 )) of air.

[0102] First airflow 94A defines a first temperature and second airflow 94B defines a second temperature. During certain operating modes of propulsion system 10, the first temperature of first airflow 94A may be higher than the second temperature of second airflow 94B. Similarly, the difference between the first temperature of first airflow 94A and the second temperature of second airflow 94B may be of different magnitudes and at different rates of change during different operating modes of propulsion system 10 and during transitions between different operating modes.

[0103] In the exemplary embodiment, because first airflow 94A comprises a higher temperature than second airflow 94B, splitter 120 directs the higher temperature first airflow 94A to and through first ring 100, and splitter directs the lower temperature second airflow 94B to and through second ring 102. In other words, the hotter first airflow 94A will preferentially contact first ring 100, while the cooler second airflow 94B will preferentially contact second ring 102.

[0104] As such, the growth rate difference between the first ring 100 and the second ring 102 will be magnified because the first ring 100 already has a higher coefficient of thermal expansion than the second ring 102, and therefore, when exposed to the same amount of thermal energy transfer, the first ring 100 will already grow at a faster rate than the second ring 102. Here, by exposing the first ring 100 to a higher temperature gas stream (e.g., the first gas stream 94A), the first ring 100 will grow at a faster rate than the second ring 102 due to the higher amount of thermal energy transferred to the first ring 100 and the larger coefficient of thermal expansion and corresponding faster thermal growth rate of the first ring 100 relative to the second ring 102.

[0105] Now refer to Figure 10 , Figure 10 is a turbofan engine 12 according to an exemplary aspect of the present disclosure (see e.g. Figure 2 ) and showing the inducer assembly. Figure 10 The embodiments provided in Figure 3 For example, in the depicted embodiment, the turbofan engine 12 includes a passive flow modulation device, which is more specifically configured as an inducer assembly 280. However, unlike Figures 1 to 9 Compared to the inducer assembly 80 (which is generally configured as an axial inducer assembly), Figure 10 The exemplary inducer assembly 280 is generally configured as a radial inducer assembly.

[0106] For example, HP turbine 30 includes rotor blades 122. In the exemplary embodiment, rotor blades 122 are in fluid communication with inductor assembly 280 via forward cavity 82. Rotor blades 122 are disposed about axial centerline 14 of turbofan engine 12 (see, e.g., FIG.Figure 1 ) rotation. Additionally, the inducer assembly 280 is configured to deliver the airflow 94 to the rotor blades 122 of the HP turbine 30. More specifically, in at least certain example aspects, the inducer assembly 280 is structured to direct the airflow 94 through the inducer assembly 280 in the radial direction R while imparting a circumferential swirl to the airflow 94 to at least partially match the rotation of the rotor blades 122.

[0107] As will be discussed in further detail with respect to Figures 11-19 As will be discussed in further detail with respect to

[0108] Reference is now made to Figure 11 , Figure 11 An enlarged cross-sectional view of the inducer assembly 280 in a first position is provided in accordance with example aspects of the present disclosure.

[0109] The inducer assembly 280 includes a first ring 300 and a second ring 302. The first ring 300 and the second ring 302 are annular disks of solid material (e.g., annular shape, such as a rectangular annulus).

[0110] However, it should be appreciated that the term “ring” as used herein is a convenient term used to generally describe a structure that extends around an axis. The term “ring” does not require a perfectly circular shape, and can refer to any structure that extends around an axis and is capable of the functions described herein.

[0111] In certain example embodiments, the first ring 300 includes a material having a first coefficient of thermal expansion. More specifically, in at least certain example aspects, the material of the first ring 100 can include a metal, such as nickel or a nickel alloy. Additionally or alternatively, the first coefficient of thermal expansion can be 5 microinches per inch x degree Fahrenheit or greater (e.g., greater than or equal to 7 microinches per inch x degree Fahrenheit, such as less than or equal to 13 microinches per inch x degree Fahrenheit).

[0112] Likewise, the second ring 302 can include a material having a second coefficient of thermal expansion that is different than the first coefficient of thermal expansion. In certain example embodiments, the second coefficient of thermal expansion of the second ring 302 is less than the first coefficient of thermal expansion of the first ring 300. More specifically, in at least certain example aspects, the material of the second ring 102 can include a non-metallic material, such as a ceramic matrix composite, such as a silicon carbide material. Additionally or alternatively, the second coefficient of thermal expansion can be 5 microinches per inch x degree Fahrenheit or less (e.g., less than or equal to 4 microinches per inch x degree Fahrenheit, such as less than or equal to 3 microinches per inch x degree Fahrenheit, such as greater than 0 microinches per inch x degree Fahrenheit).

[0113] The first ring 300 is configured to expand at a first rate in response to a change in thermal energy. The second ring 302 is configured to expand at a second rate in response to the same change in thermal energy. More specifically, in at least certain example aspects, the first rate of the first ring 300 is greater than the second rate of the second ring 302.

[0114] In example embodiments, the first ring 300 is mounted and attached to the duct 84 of the turbofan engine 12 such that the first ring 300 is fixed tangentially relative to the axial centerline 14. In another example embodiment, the second ring 302 is mounted to the plurality of nozzle vanes 308 and is free to rotate tangentially relative to the axial centerline 14 (and relative to the first ring 300). Reference will be made to the following figures in describing this configuration in greater detail. Figures 14 to 17 This configuration is described in greater detail.

[0115] In certain example embodiments, the first ring 300 and the second ring 302 can be disposed in and mounted to an inner portion of the duct 84 (see, e.g., FIG. 1). Additionally, the first ring 300 can be connected to the plurality of nozzle vanes 308 via the plurality of first pins 304, and the second ring 302 can be connected to the plurality of nozzle vanes 308 via the plurality of second pins 306. In this manner, the plurality of nozzle vanes 308 can be rotatably coupled to the first ring 300 and the second ring 302. Figure 10 ) of the duct 84. Additionally, the first ring 300 can be connected to the plurality of nozzle vanes 308 via the plurality of first pins 304, and the second ring 302 can be connected to the plurality of nozzle vanes 308 via the plurality of second pins 306. In this manner, the plurality of nozzle vanes 308 can be rotatably coupled to the first ring 300 and the second ring 302.

[0116] The inducer assembly 280 additionally includes the first pins 304 and the second pins 306. The first pins 304 and the second pins 306 are pegs or rods of, e.g., solid material, that are configured to be inserted into corresponding receptacles or holes defined by the first ring 300 and the second ring 302, respectively. The first pins 304 are engaged with corresponding holes defined by and located in the first ring 300. The second pins 306 are engaged with corresponding holes defined by and located in the second ring 302. In example embodiments, with respect to a single nozzle vane 308 of the plurality of nozzle vanes 308, a first pin (of the first pins 304) is disposed outward in the radial direction R and is circumferentially offset from a second pin (of the second pins 306) along the circumferential direction C.

[0117] The first pins 304 and the second pins 306 define a distance Lpp. More specifically, the distance Lpp is defined by a pair of one of the first pins 304 and one of the second pins 306 that are mounted to a particular one of the nozzle vanes 308. The distance Lpp can be further defined as a projected distance between a center of one of the first pins 304 mounted to the particular nozzle vane 308 and a center of one of the second pins 306 mounted to the particular nozzle vane 308. The distance Lpp can determine how much the nozzle vanes 308 will rotate when the first ring 300 expands beyond the second ring 302 in response to the transfer of thermal energy between the airflow 94 and the first ring 300 and between the airflow 94 and the second ring 302.

[0118] As noted above, the inducer assembly 280 additionally includes nozzle vanes 308. The nozzle vanes 308 are louvers, paddles, or airfoils configured to direct fluid flow. In certain example embodiments, the nozzle vanes 308 are oriented in a position that is skewed or angled relative to the radial direction R. Each nozzle vane 308 is configured to rotate about one of the first pins 304 and one of the second pins 306. For example, as heat energy transfer between the airflow 94 and the first ring 300 and between the airflow 94 and the second ring 302 occurs, each of the nozzle vanes 308 will rotate as the first ring 300 grows (or shrinks) faster than the second ring 302. In this way, a second end of each nozzle vane 308 is rotatably engaged with the second ring 302 via one of the second pins 306.

[0119] The inducer assembly 280 defines a passage 312. More particularly, in at least certain example aspects, the passage 312 is defined in part by the first ring 300, the second ring 302, and the nozzle vanes 308.

[0120] The passage 312 defines a first throat area A T1 between adjacent nozzle vanes 308. It should be appreciated that the term “first throat area A T1 ” can refer to the throat area of a single passage 112 between two adjacent nozzle vanes 308, and the term “first throat area A T1 ” can also refer to a total amount of area equal to the sum of all first throat areas A T1 between each pair of adjacent nozzle vanes 308 extending around the entire 360° of the inducer assembly 280. In certain example embodiments, the size of the first throat area A T1 impacts or sets the amount, rate, and / or pressure of the airflow 94 that is able to pass through the passage 112.

[0121] In certain example embodiments, the distance Lpp can be tuned to provide a desired rotational performance of the nozzle vanes 308 depending on the throat area requirements of a particular engine. For example, in adjusting the distance Lpp, the variation of the first throat area A T1 (see, e.g., Figure 11 and 12 ) can be tuned to provide a reduced or increased amount of airflow 94 to the rotor blades 122 (see, e.g., Figure 10 ) of the HP turbine 30.

[0122] During operation of the propulsion system 10, as the temperature of the airflow 94 increases, the radial position of the first pin 304 disposed in the first ring 300 exceeds the radial position of the second pin 306 disposed in the second ring 302 in the radial direction R. As the radial position of the first pin 304 exceeds the radial position of the second pin 306, the nozzle vane 308 rotates in a more open position. As the nozzle vane 308 rotates open, the first throat area A T1 increases, thereby allowing a greater amount of airflow 94 to pass through the passage 112 (see, e.g., FIG. 3). Figure 12

[0123] Figure 12 is an enlarged cross-sectional view of the inducer assembly 80 in the second position, in accordance with example aspects of the present disclosure.

[0124] Here in Figure 12 , the first ring 300 and the second ring 302 are shown in the second position. More specifically, in at least certain example aspects, each of the nozzle vanes 308 is shown occupying a second rotational position that is different than the first rotational position shown in Figure 11 .

[0125] As shown in Figure 12 , adjacent nozzle vanes 308 now define a second throat area A T2 extending between the adjacent nozzle vanes 308. Figure 12 The second throat area A T2 shown in Figure 11 is greater than the first throat area A T1 shown in .

[0126] Figure 12 The rotation R2 of the second ring 302 is also shown in . The rotation R2 of the second ring 302 occurs when the first ring 300 and the second ring 302 expand in response to absorbing thermal energy from the airflow 94. In certain example embodiments, the rotation R2 of the second ring 302 occurs due to a fixed distance (e.g., pin-to-pin distance) between the first pin 304 and the second pin 306 mounted to a particular nozzle vane 308 causing the Lpp distance to be a fixed value. To maintain the pin-to-pin distance, the nozzle vane 308 pulls the second ring 302 in the tangential (or circumferential direction), causing the second ring 302 to rotate and increase the throat area (e.g., increase the size from the first throat area A T1 to the second throat area A T2 ).

[0127] Reference is now made to Figure 13 , Figure 13 is a flowchart of a method 400 of modulating a flow of cooling air through the inducer assembly 280, in accordance with example aspects of the present disclosure.

[0128] Method 400 provides, at 402, providing a gas stream 94 to an inducer assembly 280. Method 400 provides, at 404, transferring thermal energy between the gas stream 94 and the first ring 300, between the gas stream 94 and the second ring 302, or both. Step 404 of method 400 can provide, at step 406, transferring thermal energy from the gas stream 94 to the first ring 300.

[0129] Step 406 of method 400 can provide, at step 408, expanding the first ring 300 in response to transferring thermal energy between the gas stream 94 and the first ring 300. Step 406 of method 400 can provide, at step 410, moving a first pin of a plurality of first pins with the first ring 300 in response to expanding the first ring 300, wherein the first pin of the plurality of first pins is connected to a first end of a nozzle vane 308 of a plurality of nozzle vanes 308, wherein a second end of the nozzle vane 308 is rotatably engaged with the second ring 302, wherein a portion of the passage 312 is defined between the nozzle vane 308 and an adjacent nozzle vane 308. Step 406 of method 400 can provide, at step 412, pushing the first end of the nozzle vane 308 outward in the radial direction R with the first pin.

[0130] Step 406 of method 400 can provide, at step 414, rotating the nozzle vane 308 in response to the first end of the nozzle vane 308 being pushed outward in the radial direction R. Step 406 of method 400 can provide, at step 416, increasing a size of the portion of the passage 312 defined between the nozzle vane 308 and the adjacent nozzle vane 308 in response to rotating the nozzle vane 308. Step 406 of method 400 can provide, at step 418, increasing an amount of the gas stream 94 passing through the inducer assembly 280 in response to increasing the size of the portion of the passage 312 defined between the nozzle vane 308 and the adjacent nozzle vane 308.

[0131] Step 404 of method 400 can provide, at step 420, changing a size of the first ring 300 relative to a size of the second ring 302. Step 420 of method 400 can provide, at step 422, transferring thermal energy between the gas stream 94 and the first ring 300 and between the gas stream 94 and the second ring 302, thereby expanding the first ring 300 at a first rate in response to transferring thermal energy between the gas stream 94 and the first ring 300 and expanding the second ring 302 at a second rate in response to transferring thermal energy between the gas stream 94 and the second ring 302. In certain example embodiments, the first rate of the first ring 300 is greater than the second rate of the second ring 302. Step 420 of method 400 can provide, at step 424, adjusting a position of the plurality of nozzle vanes 308 in response to changing the size of the first ring 300 relative to the second ring 302.

[0132] Step 404 of the method 400 can provide for passively modulating the amount of airflow 94 through the passage 312 at step 426.

[0133] The method 400 provides for directing the airflow 94 with the inducer assembly 280 along the radial direction R of the turbofan engine 12 at 428. Step 428 of the method 400 can provide for directing the airflow 94 through the passage 312 with the plurality of nozzle vanes 308 disposed in the passage 312 at step 430.

[0134] Reference is now made to Figure 14 , Figure 14 is a cross-sectional view of a portion B of the first inducer assembly 80A from Figure 10 . Figure 14 The first inducer assembly 280A can be constructed in substantially the same manner as the inducer assembly 280 of Figures 10 to 12 . In addition to the elements discussed above (e.g., with respect to Figures 10-12 ), the first inducer assembly 280A includes a cavity 314 defined by a portion of the first ring 300 and a W-seal 316 disposed in the cavity 314.

[0135] Here, Figure 14 illustrates an exemplary arrangement and positioning of components of the first inducer assembly 280A. In certain exemplary embodiments, the first ring 300 can define a cavity 314 extending between a portion of the first ring 300 and the second ring 302.

[0136] The W-seal 316 is disposed between the portion of the first ring 300 and the portion of the second ring 302 to prevent fluid flow through the W-seal 316. More particularly, in at least certain exemplary aspects, the W-seal 316 can prevent fluid flow inwardly through the interface between the first ring 300 and the second ring 302. The W-seal 316 more particularly forms a sliding seal between the portion of the first ring 300 defining the cavity 314 and the second ring 302. Thus, it should be appreciated that in other embodiments, the W-seal 316 can be any other suitable sliding seal.

[0137] Further, it should be appreciated that although not depicted, each of the plurality of nozzle vanes 308 can include an endwall seal of the forward endwall, the aft endwall, or both. The endwall seal can include a recess in the forward endwall and / or the aft endwall with, for example, a pressure-loaded member (e.g., a piston rod). The pressure-loaded member can contact, for example, the first ring 300 and / or the second ring 302 or the duct 84. In this manner, the nozzle vane 308 can prevent or reduce airflow that bypasses the nozzle vane 308.

[0138] In exemplary embodiments, Figure 14Examples are provided in which the airflow 94 can include a stream of air from a single air source, or can include a mixed stream of air (e.g., a mixture of air from a compressor section and from the CCA system 72).

[0139] As described above, as thermal energy is transferred from the airflow 94 to the first and second rings 300, 302, the first and second rings 300, 302 thermally expand and grow outward in the radial direction R. However, due to a mismatch in the coefficient of thermal expansion between the materials of the first and second rings 300, 302, the first ring 300 grows / expands at a faster rate than the second ring 302. In response to the first ring 300 growing / expanding, the first pin 304 is pushed outward by the first ring 300 in the radial direction R. Likewise, in response to the second ring 302 growing / expanding, the second pin 306 is pushed outward in the radial direction R, albeit at a slower rate than the first pin 304 is pushed. Due to this mismatch in radial translation rates between the first and second pins 304, 306, the nozzle vane 308 rotates about both the first and second pins 304, 306. As the nozzle vane 308 rotates about the first and second pins 304, 306, the throat area between adjacent nozzles increases, allowing more airflow 94 to move through the openings (e.g., passages 112) between adjacent nozzle vanes 308.

[0140] Reference is now made to Figure 15 , Figure 15 is an enlarged cross-sectional view of a portion of a turbofan engine 12 according to example aspects of the present disclosure, and shows a flow splitter 320 upstream of the second inducer assembly 280B. Figure 15 The embodiments provided in the Figure 14 may be constructed in substantially the same manner as described with respect to but with the addition of the flow splitter 320.

[0141] The flow splitter 320 is a curved piece of, for example, solid material. In certain example embodiments, the flow splitter 320 can extend partially or fully 360° about the axial centerline 14 (see, e.g., Figure 1 ). The flow splitter 320 is disposed in the duct 84, and can be mounted to the duct 84 or a portion of the frame assembly 85 (see, e.g., Figures 9-10 ).

[0142] In certain example embodiments, the flow splitter 320 is disposed to create a temperature profile upstream of the second inducer assembly 280B. More particularly, in at least certain example aspects, the flow splitter 320 is disposed to separate or prevent the first and second airflows 94A, 94B from (substantially) mixing before the first and second airflows 94A, 94B reach the first and second rings 300, 302.

[0143] In certain example embodiments, the first airflow 94A can include air from a compressor section of the turbofan engine 12, while the second airflow can include air from a heat exchanger, such as from the CCA system 72 (see, e.g., FIG. 1). Figure 1

[0144] The first airflow 94A includes a first temperature and the second airflow 94B includes a second temperature. During certain operating modes of the propulsion system 10, the first temperature of the first airflow 94A can be higher than the second temperature of the second airflow 94B. Also, during different operating modes of the propulsion system 10, as well as during transitions between different operating modes, the difference between the first temperature of the first airflow 94A and the second temperature of the second airflow 94B can be at different magnitudes and at different rates of change.

[0145] In example embodiments, due to the first airflow 94A including a higher temperature than the second airflow 94B, the splitter 320 directs the higher temperature first airflow 94A to and through the first ring 300 of the second inducer assembly 280B before the first airflow 94A and the second airflow 94B are mixed together to form a cooler combined flow. In other words, the hotter first airflow 94A will preferentially contact the first ring 300 before the mixture of the first airflow 94A and the second airflow 94B contacts the second ring 302.

[0146] In another example embodiment, the second inducer assembly can be configured such that the second ring 302 is disposed on an opposite side of the axial direction A from the first ring 300 along the nozzle vane 308. In such example embodiments, due to the first airflow 94A including a higher temperature than the second airflow 94B, the splitter 320 directs the higher temperature first airflow 94A to and through the first ring 300 of the second inducer assembly 280B, and the splitter 320 directs the lower temperature second airflow 94B to and through the second ring 302. In other words, the hotter first airflow 94A will preferentially contact the first ring 300, while the cooler second airflow 94B will contact the second ring 302.

[0147] As such, the difference in growth rate between the first ring 300 and the second ring 302 will be amplified, as the first ring 300 already has a higher coefficient of thermal expansion than the second ring 302, and thus the first ring 300 has already grown at a faster rate than the second ring 302 when exposed to the same amount of heat energy transfer. Here, by exposing the first ring 300 to a higher temperature airflow (e.g., the first airflow 94A), the first ring 300 will grow at a faster rate than the second ring 302, due to the higher amount of heat energy being transferred to the first ring 300 and the larger coefficient of thermal expansion and corresponding faster rate of thermal growth of the first ring 300 relative to the second ring 302.

[0148] Referring now to​Figure 16 , Figure 16 is an isolated cross-sectional view of a third inducer assembly 280C according to example aspects of the present disclosure. Figure 16 The embodiments provided in the detailed description can be constructed in substantially the same manner as described with respect to Figure 14 but with the addition of an insulator 324.

[0149] As Figure 16 shown, the third inducer assembly 280C includes an insulator 324. The insulator layer 324 is an insulating layer or sheet configured to minimize the transfer of thermal energy therethrough. In certain example embodiments, the insulator 324 can include a honeycomb layer of material (e.g., a sheet of metal capped honeycomb or a ring of sheet metal having a honeycomb configuration). However, in other example embodiments, the insulator 324 can instead be any other suitable material having a higher thermal resistance than, for example, the material forming the duct 84.

[0150] In this example embodiment, the insulator 324 is disposed between the sidewall of the duct 84 and the nozzle vane 308. The first pin 304 and the second pin 306 can pass through the insulator 324 so as to engage with the sidewall of the duct 84.

[0151] During operation, the insulator 324 insulates the sidewall of the duct 84 from the transfer of thermal energy from the airflow 94 that would otherwise be transferred to the duct 84. This insulating function of the insulator 324 can alter (e.g., speed up or slow down) the thermal expansion of the duct 84, the first ring 300, and / or the second ring 302 by reducing the transfer of thermal energy from the airflow 94. In this way, the rate at which the open passage of the third inducer assembly is inhibited or amplified can be dampened or amplified based on the design intent and desired performance characteristics of the third inducer assembly 280C.

[0152] Reference is now made to Figure 17 , Figure 17 is an isolated cross-sectional view of a fourth inducer assembly 280D according to example aspects of the present disclosure. Figure 17 The embodiments provided in the detailed description can be constructed in substantially the same manner as described with respect to Figure 16 but with an alternative positioning of the insulator 324.

[0153] As Figure 17 shown, the insulator is positioned on the outer sidewall of the duct 84 (as compared to the positioning of the insulator 324 shown in Figure 16 along the inner sidewall of the duct 84).

[0154] In such example embodiments, the sidewall of the duct 84 is insulated from air outside of the duct 84 by the insulator 324. More particularly, in at least certain example aspects, the exterior of the duct 84 can be exposed to air from the compressor section (e.g., air from the seal cavity downstream of the compressor discharge pressure source). The insulator 324 insulates the sidewall of the duct 84 from the air from the compressor section by preventing the air from contacting the sidewall of the duct 84. In this manner, the amount of thermal energy transferred from the air outside of the duct 84 is reduced (relative to example embodiments without the insulator 324). This reduced rate of thermal energy transfer to the duct 84 will change the rate at which the first pin 304 and the second pin 306 move outward in the radial direction R, and thus change the rate at which the passage (e.g., passage 112 / 312) formed between adjacent nozzle vanes 308 opens.

[0155] For the illustrated embodiment, the insulator 324 is engaged with the surface of the duct 84. However, it should be appreciated that in other example embodiments, the insulator can be disposed on either side of the first ring 300 or the second ring 302.

[0156] It should be appreciated that in other example embodiments, the passive flow modulation devices of the present disclosure (e.g., one or more of the inducer assemblies 280 of the present disclosure) can be configured in any other suitable manner. For example, instead of being configured to increase the size of a passage (e.g., passage 312) to allow air flow therethrough in response to a temperature increase of the air flow therethrough, a passive flow modulation device can be configured to decrease the size of a passage (e.g., passage 312) to allow air flow therethrough in response to a temperature increase of the air flow therethrough. For example, with such a configuration, the first pin 304 rotatably coupled near the first end of the nozzle vane 308 (which can be the air flow inlet end) can be coupled to the second ring 302, while the second pin 306 rotatably coupled near the second end of the nozzle vane 308 (which can be the air flow outlet end) can be coupled to the first ring 300. The second ring 302 can be formed of a material having a coefficient of thermal expansion greater than the coefficient of thermal expansion of the material forming the first ring 300. In this manner, a temperature increase of the air flow through the passage will cause the second ring 302 to expand relative to the first ring 300 and decrease the size of the passage. Such a configuration can be useful, for example, when the passive flow modulation device is a passive valve in an exhaust duct that needs to close when the power of the engine is increased and the temperature of the exhaust air flow is increased.

[0157] Reference is now made to Figure 18 , Figure 18 is an enlarged cross-sectional view of a portion of the HP turbine 30 (see, e.g., Figure 2 ) of the turbofan engine 12 according to example aspects of the present disclosure, and shows an inducer assembly 480.

[0158] AsFigure 18 As shown, the HP turbine 30 includes rotor blades 122 and a stator 126. The stator 126 is a stationary component of the turbine 18 (e.g., a second stage stator) that is mounted to a non-rotating component of the turbofan engine 12.

[0159] The stator 126 includes stator blades 128. The stator blades 128 are airfoil portions of the stator 126. The stator 126 also includes a hub 130. The hub 130 is a base or platform of the stator 126 and is connected to radially inward ends of the stator blades 128. It should be appreciated that the hub 130 can extend circumferentially 360° about the axial centerline 14 of the propulsion system 10 (see, e.g., FIG. 1). The hub 130 of the stator 126 defines a cavity 132. The cavity 132 is a pocket or void formed within the hub 130. In example embodiments, the cavity 132 and the surrounding portion of the hub 130 that defines the cavity 132 can be referred to as a hub box or a nozzle hub box. Figure 1

[0160] The turbofan engine 12 defines a cavity 134. The cavity 134 is disposed inward from the hub 130 along the radial direction R and is partially defined by a seal 136. In example embodiments, the cavity 134 can be a rear cavity of a first stage rotor of the HP turbine 30. The cavity 134 is defined via the inducer assembly 480 and is in fluid communication with the cavity 132 through a passage of the inducer assembly 480. The seal 136 is a fluid seal, such as a labyrinth seal. The seal 136 is disposed along an inward surface of the hub 130 along the radial direction R. As the hub 130 is a stationary component of the turbofan engine 12, the seal 136 forms a sealing interface with a corresponding rotating component of the turbofan engine 12.

[0161] Similar to the inducer assemblies discussed above (e.g., the inducer assembly 280), the inducer assembly 480 includes a first ring 500 having a first coefficient of thermal expansion. The inducer assembly 480 also includes a second ring 502 having a second coefficient of thermal expansion. The inducer assembly 480 additionally includes a first pin 504 and a second pin 506. The first pin 504 extends between and is connected to the first ring 500 and the nozzle blade 508. The second pin 506 is connected to and extends between the second ring 502 and the nozzle blade 508.

[0162] The inducer assembly 480 also includes a nozzle blade 508. As described above with respect to the nozzle blade 308, the nozzle blade 508 is a baffle, paddle, or airfoil configured to direct a flow of fluid. In certain example embodiments, the inducer assembly 480 can include a plurality of nozzle blades 508 distributed circumferentially about the axial centerline 14 of the turbofan engine 12.

[0163] ​In this exemplary embodiment, the inductor assembly 480 includes a W-shaped seal 516 and an insulator 524 (see FIG. Figure 19 A W-shaped seal 516 is provided to form a sealing interface between the second ring 502 and a portion of the hub 130 .

[0164] Now refer to Figure 19 , Figure 19 According to an exemplary aspect of the present disclosure Figure 18 Isolated cross-sectional view of inducer assembly 480.

[0165] As shown there, hub 130 can include a seal 131. In the exemplary embodiment, seal 131 is coupled to a portion of hub 130 and first ring 500 and is configured to form a fluid seal therebetween.

[0166] In the exemplary embodiment, the inductor assembly 480 also includes an insulator 524. Figure 16 and Figure 17 Similar to the insulator 324 discussed above, the insulator 524 may be configured to insulate the first ring 500 (and / or the second ring 502 ) from the airflow 94 passing through the first ring 500 via the inducer assembly 480 , or from air passing through a side of the first ring 500 that is disposed on a side of the first ring 500 opposite the nozzle vanes 508 .

[0167] In the exemplary embodiment, during operation, air entering or exiting cavity 134 (e.g., HP turbine aft cavity air) contacts first ring 500. As the temperature of the air in contact with first ring 500 transfers thermal energy to first ring 500, first ring 500 expands, thereby pushing first pin 504 outward in radial direction R.

[0168] In response to the first pins 504 being pushed outward (and at a faster rate than the second pins 506 due to the thermal mismatch between the first coefficient of thermal expansion of the first ring 500 and the second coefficient of thermal expansion of the second ring 502), the nozzle vanes 508 rotate, thereby increasing the size of the throat area between adjacent nozzle vanes. In response to the nozzle vanes increasing the size of the throat area, the velocity of the airflow 94 through the inducer assembly 480 increases, resulting in an increase in the amount of airflow 94 turning the cavity 134.

[0169] In certain example embodiments, the hole disposed in the hub case of the nozzle (e.g., the forward dump hole) can be replaced with an embodiment of the disclosed inducer assembly 480, thereby minimizing ingestion from the upstream cavity (e.g., cavity 134). If the temperature of the air in the cavity 134 increases, the temperature of the first ring 500 will also increase, resulting in an increase in the throat area of the inducer assembly 480 and causing more airflow 94 to be delivered to the cavity 134. In this way, the inducer assembly 480 can function as a flow conditioning device and a safety mechanism for the hub 130 (e.g., hub case) of the stator 126.

[0170] As provided herein, the disclosed inducer assembly is discussed with respect to a turbofan engine. However, it should be understood that, Figure 1 The depicted turbofan engine 12 is merely an example, and in other example embodiments, aspects of the present disclosure can additionally or alternatively be applied to any other suitable gas turbine engine or industrial engine.

[0171] It should be understood that while the passive flow conditioning device is described herein in accordance with an inducer assembly (e.g., an axial inducer assembly or a radial inducer assembly), in other example embodiments, the passive flow conditioning device can be configured to function as any other suitable flow conditioning device. For example, in other embodiments, the passive flow conditioning device can be configured in a similar manner as one or more of the example inducer assemblies of Figures 3 to 6 It should be understood that while the passive flow conditioning device is described herein in accordance with an inducer assembly (e.g., an axial inducer assembly or a radial inducer assembly), in other example embodiments, the passive flow conditioning device can be configured to function as any other suitable flow conditioning device. For example, in other embodiments, the passive flow conditioning device can be configured in a similar manner as one or more of the example inducer assemblies of

[0172] Furthermore, it should be understood that while the passive flow conditioning device is described in accordance with use within a turbofan engine 12, in other example embodiments, the passive flow conditioning device can be used within any other suitable aeronautical gas turbine engine (e.g., a turboprop engine, a turbojet engine, a turboshaft engine, etc.), or further within any non-aeronautical gas turbine engine (e.g., a nautical gas turbine engine, a gas turbine engine for power generation (an industrial gas turbine engine), etc.).

[0173] Furthermore, it should also be understood that in other example embodiments, certain embodiments of the passive flow conditioning device can be used in any other suitable machine and are not limited to gas turbine engines. For example, embodiments of the passive flow conditioning device can be used in other internal combustion engines, elsewhere in a vehicle, etc.

[0174] Further, it should be appreciated that in yet another example embodiment, the arrangement of the second ring inside the first ring can be reversed, such that increasing the temperature of the first and second rings decreases the flow area. For example, if used as a valve incorporated into, for example, a pipe, where an increase in the temperature of the gas flow indicates a need to decrease the amount of gas flow required through the flow area, arranging the ring having the higher coefficient of thermal expansion inside the ring having the lower coefficient of thermal expansion can achieve such a goal.

[0175] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure 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 include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0176] Further aspects are provided by the subject matter of the following clauses:

[0177] A passive flow modulation device for a machine defining an axial direction and a radial direction, the passive flow modulation device comprising: a first ring having a first coefficient of thermal expansion; a second ring disposed coaxially with the first ring and at least partially positioned inside the first ring in the radial direction, spaced apart from the first ring in the axial direction, or both, the first ring, the second ring, or both at least partially defining one or more passages, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion to passively modulate a size of the one or more passages during operation.

[0178] The passive flow modulation device according to one or more of the clauses, wherein the machine is a gas turbine engine defining the radial direction, and wherein the second ring is positioned inside the first ring in the radial direction.

[0179] The passive flow modulation device according to one or more of the clauses, wherein the gas turbine engine further defines the axial direction, wherein the one or more passages are configured to direct a gas flow through the one or more passages in the axial direction.

[0180] The passive flow modulation device according to one or more of the preceding clauses, further comprising a seal, wherein the gas turbine engine comprises a frame assembly, wherein the first ring is configured to be movably coupled to the frame assembly such that the first ring is movable relative to the frame assembly in the radial direction, and wherein the seal is configured to form an airflow seal between the frame assembly and the first ring.

[0181] The passive flow modulation device according to one or more of the preceding clauses, wherein the seal is a first seal, and wherein the passive flow modulation device further comprises a second seal, wherein the second ring is configured to be coupled to the frame assembly such that the second ring is movable relative to the frame assembly in the radial direction, and wherein the second seal is configured to form an airflow seal between the frame assembly and the second ring.

[0182] The passive flow modulation device according to one or more of the preceding clauses, wherein the gas turbine engine comprises a turbomachine having a turbine, and wherein the passive flow modulation device is an inducer for directing and passively modulating a flow of cooling air to the turbine of the turbomachine.

[0183] The passive flow modulation device according to one or more of the preceding clauses, wherein the first ring comprises a first thread disposed along an inner surface in the radial direction, wherein the second ring comprises a second thread disposed along an outer surface in the radial direction, wherein the first thread of the first ring is engaged with the second thread of the second ring, and wherein the first thread and the second thread at least partially define the one or more channels.

[0184] The passive flow modulation device according to one or more of the preceding clauses, wherein the machine is a gas turbine engine defining the axial direction, wherein the first ring is spaced apart from the second ring in the axial direction, and wherein passive flow modulation device further comprises: a plurality of nozzle vanes disposed between and connected to the first ring and the second ring, wherein the one or more channels are further at least partially defined by the plurality of nozzle vanes.

[0185] The passive flow modulation device according to one or more of the preceding clauses, wherein each nozzle vane of the plurality of nozzle vanes is connected to one of the first ring or the second ring at a first end of the nozzle vane with a first pin, wherein each nozzle vane is connected to the other of the first ring or the second ring at a second end of the nozzle vane with a second pin, wherein the first pin is disposed outward in the radial direction and is circumferentially offset from the second pin.

[0186] The passive flow modulation device according to one or more of the preceding clauses, each pair of adjacent nozzle vanes defining a throat region, and wherein the second coefficient of thermal expansion is less than the first coefficient of thermal expansion to modulate a size of the throat region of each pair of adjacent airflow vanes.

[0187] The passive flow modulation device according to one or more of the preceding clauses, wherein the gas turbine engine includes a turbomachine having a turbine, and wherein the passive flow modulation device is an inducer to direct and passively modulate a flow of cooling air to the turbine of the turbomachine.

[0188] A method of providing an airflow in a gas turbine engine defining an axial centerline, the method comprising: providing the airflow to an inducer assembly, the inducer assembly including: a first ring having a first coefficient of thermal expansion; and a second ring disposed coaxially with the first ring, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion of the first ring, wherein a flow passage is at least partially defined between the first ring and the second ring, wherein the flow passage includes a flow area between the first ring and the second ring; transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or both, to change a size of the first ring relative to a size of the second ring and passively modulate an amount of the airflow through the flow passage.

[0189] The method according to one or more of the preceding clauses, wherein transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or both, to change a size of the first ring relative to a size of the second ring includes transferring thermal energy between the airflow and the first ring and between the airflow and the second ring to cause the first ring to expand at a first rate in response to transferring thermal energy between the airflow and the first ring and to cause the second ring to expand at a second rate in response to transferring thermal energy between the airflow and the second ring, wherein the first rate of the first ring is greater than the second rate of the second ring.

[0190] The method according to one or more of the preceding clauses, further comprising directing the airflow in an axial direction of the gas turbine engine with the inducer assembly, wherein the second ring is disposed inward of the first ring.

[0191] The method according to one or more of the preceding clauses, wherein the gas turbine engine defines a radial direction, and wherein the method further comprises directing the airflow in the radial direction of the gas turbine engine with the inducer assembly.

[0192] The method of one or more of the preceding clauses, wherein directing the airflow along the radial direction of the gas turbine engine with the inducer assembly includes directing the airflow through the flow passage with a plurality of nozzle vanes disposed in the flow passage.

[0193] The method of one or more of the preceding clauses, wherein transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or both, to change a size of the first ring relative to a size of the second ring includes adjusting a position of the plurality of nozzle vanes in response to changing the size of the first ring relative to the second ring.

[0194] The method of one or more of the preceding clauses, wherein transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or both, includes transferring thermal energy from the airflow to the first ring, wherein each nozzle vane of the plurality of nozzle vanes includes a first end and a second end, the method further comprising: in response to transferring thermal energy between the airflow and the first ring, expanding the first ring; in response to expanding the first ring, moving a first pin of a plurality of first pins with the first ring, wherein the first pin of the plurality of first pins is connected to the first end of a nozzle vane of the plurality of nozzle vanes, wherein the second end of the nozzle vane is rotatably engaged with the second ring, wherein a portion of the flow passage is defined between the nozzle vane and an adjacent nozzle vane; in response to the first pin of the plurality of first pins being connected to the first end of the nozzle vane, pushing the first end of the nozzle vane outward along the radial direction with the first pin; in response to the first end of the nozzle vane being pushed outward along the radial direction, rotating the nozzle vane; in response to rotating the nozzle vane, increasing a size of the portion of the flow passage defined between the nozzle vane and the adjacent nozzle vane; and in response to the size of the portion of the flow passage defined between the nozzle vane and the adjacent nozzle vane increasing, increasing an amount of the airflow through the inducer assembly.

[0195] A gas turbine engine comprising: a turbomachinery having, in serial flow order, a compressor section, a combustion section, and a turbine section; and an inducer assembly in fluid communication with the turbine section, the inducer assembly comprising: a first ring having a first coefficient of thermal expansion; a second ring disposed coaxially with the first ring and spaced apart from the first ring to at least partially define one or more passages therebetween, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion to passively modulate a size of the one or more passages during operation.

[0196] The gas turbine engine according to one or more of these clauses, further comprising a source of cooling air in fluid communication with the inducer assembly, wherein the inducer assembly is configured to supply a flow of cooling air to the turbine section of the turbine.

Claims

1. A passive flow modulation device for a machine defining an axial direction and a radial direction, characterized in that The passive flow modulation device comprises: a first ring having a first coefficient of thermal expansion; a second ring coaxially disposed with the first ring and positioned at least partially inwardly of the first ring in the radial direction, spaced apart from the first ring in the axial direction, or at least partially inwardly of the first ring in the radial direction and spaced apart from the first ring in the axial direction, the first ring, the second ring, or both the first and second rings at least partially defining one or more channels, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion to passively modulate a size of the one or more channels during operation.

2. The passive flow modulation device according to claim 1, characterized in that in, The machine is a gas turbine engine defining the radial direction, and wherein the second ring is positioned inwardly of the first ring in the radial direction.

3. The passive flow modulation device according to claim 2, characterized in that: in, The gas turbine engine further defines the axial direction, wherein the one or more passages are configured to direct airflow through the one or more passages in the axial direction.

4. The passive flow modulation device according to claim 2, characterized in that: Further including a seal, wherein the gas turbine engine includes a frame assembly, wherein the first ring is configured to be movably coupled to the frame assembly such that the first ring is movable in the radial direction relative to the frame assembly, and wherein the seal is configured to form an airflow seal between the frame assembly and the first ring.

5. The passive flow modulation device according to claim 4, characterized in that: in, The seal is a first seal, and wherein the passive flow modulation device further includes a second seal, wherein the second ring is constructed to be connected to the frame assembly so that the second ring can move in the radial direction relative to the frame assembly, and wherein the second seal is constructed to form an airflow seal between the frame assembly and the second ring.

6. The passive flow modulation device according to claim 2, characterized in that: in, The gas turbine engine includes a turbomachine having a turbine, and wherein the passive flow modulation device is an inducer for directing and passively modulating a flow of cooling air to the turbine of the turbomachine.

7. The passive flow modulation device according to claim 1, characterized in that: in, The first ring includes a first thread disposed along an inner surface in the radial direction, wherein the second ring includes a second thread disposed along an outer surface in the radial direction, wherein the first thread of the first ring engages with the second thread of the second ring, and wherein the first thread and the second thread at least partially define the one or more channels.

8. The passive flow modulation device according to claim 1, characterized in that: in, The machine is a gas turbine engine defining the axial direction, wherein the first ring is spaced apart from the second ring along the axial direction, and wherein the passive flow modulation device further comprises: A plurality of nozzle vanes are disposed between and connected to the first ring and the second ring, wherein the one or more passages are further defined at least in part by the plurality of nozzle vanes.

9. The passive flow modulation device according to claim 8, characterized in that: in, Each of the plurality of nozzle vanes is connected to one of the first ring or the second ring at a first end of the nozzle vane using a first pin, wherein each nozzle vane is connected to the other of the first ring or the second ring at a second end of the nozzle vane using a second pin, wherein the first pin is disposed outward in the radial direction and circumferentially offset from the second pin.

10. The passive flow modulation device according to claim 8, characterized in that: Each pair of adjacent nozzle vanes defines a throat region, and wherein the second coefficient of thermal expansion is less than the first coefficient of thermal expansion to modulate a size of the throat region of each pair of adjacent nozzle vanes.

11. The passive flow modulation device according to claim 8, characterized in that: in, The gas turbine engine includes a turbomachine having a turbine, and wherein the passive flow modulation device is an inducer for directing and passively modulating a flow of cooling air to the turbine of the turbomachine.

12. A method of providing airflow in a gas turbine engine, the gas turbine engine defining an axial centerline, characterized in that The method comprises: The airflow is provided to an inducer assembly, the inducer assembly comprising: a first ring having a first coefficient of thermal expansion; and a second ring, the second ring being coaxially arranged with the first ring, the second ring having a second thermal expansion coefficient smaller than the first thermal expansion coefficient of the first ring, wherein a flow passage is at least partially defined between the first ring and the second ring, wherein the flow passage includes a flow region between the first ring and the second ring; Thermal energy is transferred between the airflow and the first ring, between the airflow and the second ring, or between the airflow and the first ring and the second ring to change the size of the first ring relative to the size of the second ring and passively modulate the amount of the airflow through the flow channel.

13. The method according to claim 12, characterized in that in, Transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or between the airflow and the first ring and the second ring to change the size of the first ring relative to the size of the second ring includes transferring thermal energy between the airflow and the first ring and between the airflow and the second ring such that the first ring expands at a first rate in response to transferring thermal energy between the airflow and the first ring, and the second ring expands at a second rate in response to transferring thermal energy between the airflow and the second ring, wherein the first rate of the first ring is greater than the second rate of the second ring.

14. The method according to claim 12, characterized in that Further comprising directing the airflow in an axial direction of the gas turbine engine using the inducer assembly, wherein the second ring is disposed inwardly of the first ring.

15. The method according to claim 12, characterized in that in, The gas turbine engine defines a radial direction, and wherein the method further comprises: The airflow is directed in the radial direction of the gas turbine engine using the inducer assembly.

16. The method according to claim 15, characterized in that in, Directing the airflow in the radial direction of the gas turbine engine using the inducer assembly includes directing the airflow through the flow passage using a plurality of nozzle vanes disposed in the flow passage.

17. The method according to claim 16, characterized in that in, Transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or between the airflow and the first ring and the second ring to change a size of the first ring relative to a size of the second ring includes adjusting a position of the plurality of nozzle vanes in response to changing the size of the first ring relative to the second ring.

18. The method according to claim 16, characterized in that in, Transferring thermal energy between the airflow and the first ring, between the airflow and the second ring, or between the airflow and the first ring and between the airflow and the second ring includes transferring thermal energy from the airflow to the first ring, wherein each nozzle vane of the plurality of nozzle vanes includes a first end and a second end, the method further comprising: expanding the first ring in response to transferring thermal energy between the airflow and the first ring; in response to expanding the first ring, moving a plurality of first pins with the first ring, wherein each first pin of the plurality of first pins is connected to the first end of each nozzle vane of the plurality of nozzle vanes, wherein the second end of each nozzle vane is rotatably engaged with the second ring, wherein a portion of the flow passage is defined between each nozzle vane and an adjacent nozzle vane; pushing the first end of each nozzle vane outwardly in the radial direction using the plurality of first pins; rotating each nozzle vane in response to the first end of each nozzle vane being urged outward in the radial direction; In response to rotating each nozzle vane, increasing a size of the portion of the flow passage defined between each nozzle vane and the adjacent nozzle vane; and In response to an increase in a size of the portion of the flow passage defined between each nozzle vane and the adjacent nozzle vane, an amount of the airflow through the inducer assembly is increased.

19. A gas turbine engine, characterized in that: The gas turbine engine comprises: a turbomachine having a compressor section, a combustion section, and a turbine section arranged in series flow order; and an inducer assembly in fluid communication with the turbine section, the inducer assembly comprising: a first ring having a first coefficient of thermal expansion; a second ring coaxially disposed with the first ring and spaced apart from the first ring to at least partially define one or more channels therebetween, the second ring having a second coefficient of thermal expansion less than the first coefficient of thermal expansion to passively modulate a size of the one or more channels during operation.

20. The gas turbine engine according to claim 19, wherein Further included is a cooling air source in fluid communication with the inductor assembly, wherein the inductor assembly is configured to supply a cooling air flow to the turbine section of the turbomachine.

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