Patent ID: 12247580

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure.

The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein.

The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

The term “at least one of” in the context of, e.g., “at least one of A, B, and C” refers only A, only B, only C, or any combination of A, B, and C.

The terms “forward” and “aft” refer to relative positions within a gas turbine engine, pump, or vehicle, and refer to the normal operational attitude of the gas turbine engine, pump, or vehicle. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust.

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

As used in this application, stating that any part (e.g., a layer, film, area, region, or plate) is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween.

As used herein, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referenced by the connection reference and/or relative movement between those elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and/or in fixed relation to each other. As used herein, stating that any part is in “contact” with another part is defined to mean that there is no intermediate part between the two parts.

Unless specifically stated otherwise, descriptors such as “first,” “second,” “third,” etc., are used herein without imputing or otherwise indicating any meaning of priority, physical order, arrangement in a list, and/or ordering in any way, but are merely used as labels and/or arbitrary names to distinguish elements for ease of understanding the disclosed examples. In some examples, the descriptor “first” may be used to refer to an element in the detailed description, while the same element may be referred to in a claim with a different descriptor such as “second” or “third.” In such instances, it should be understood that such descriptors are used merely for identifying those elements distinctly that might, for example, otherwise share a same name.

Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a ten percent margin.

Here and throughout the specification and 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.

Engine designers continue to push for more fuel efficient, higher thrust, and quieter turbofan engines that produce less carbon dioxide emissions. Achieving such desired performance goals may consequently increase the thrust loads acting on particular engine components, such as, for example, the ball (thrust) bearings of a high pressure (HP) spool. Minimizing such loads presents certain challenges, including deterioration of certain components and reduced lifespan of certain components.

The inventors of the present disclosure developed architectures for turbofan engines, specifically the compressor portion thereof. Particularly, the inventors proceeded in the manner of designing turbofan engines with given dimensional characteristics in the compressor portion; redesigning the compressor portion to achieve particular characteristics with respect to reducing the thrust loads acting on the HP ball (thrust) bearings, improving the rotor life capability and hence providing higher compressor discharge temperatures (T3) and pressures (P3), reducing the overall engine weight, improving dynamics, and improving compressor load path stiffness for aft regions thereof; and rechecking the thrust loads, exit temperatures, and load path stiffness that resulted from the redesigned compressor during the design of several different types of turbofan engines, including the turbofan engine described below with reference toFIG.1.

During the course of this practice of studying/evaluating various compressor characteristics, and dimensional characteristics of compressor components considered feasible for best satisfying mission requirements, the inventors unexpectedly discovered that a certain relationship exists between cavity height, vane height, and flowpath hub radius in the aft stages of the compressor, and the flow of air at the exit stages of the compressor. This relationship is captured by a forward load reduction, which represents an indicator of an amount of load acting on the HP spool thrust bearings due to the introduction of a diverging load path with respect to the flowpath hub for the aft stages of the compressor.

Referring now to the drawings,FIG.1provides a schematic cross-sectional view of a turbofan engine100according to an example embodiment of the present disclosure. For the depicted embodiment ofFIG.1, the turbofan engine100is an aeronautical, high-bypass turbofan engine configured mountable to an aircraft, such as, for example, in an under-wing configuration. As shown, the turbofan engine100defines an axial direction A, a radial direction R, and a circumferential direction C. The axial direction A extends parallel to or coaxial with a longitudinal centerline102defined by the turbofan engine100.

The turbofan engine100includes a fan section104and a core turbine engine106disposed downstream of the fan section104. The core turbine engine106includes an engine cowl108that defines an annular core inlet110. The engine cowl108encases, in a serial flow relationship, a compressor section112including a first booster (e.g., an LP compressor114) and a second booster (e.g., an HP compressor116), a combustion section118, a turbine section120including a first turbine (e.g., an HP turbine122) and a second turbine (e.g., an LP turbine124), and an exhaust section126. The compressor section112, combustion section118, turbine section120, and exhaust section126together define a core air flowpath132through the core turbine engine106.

An HP shaft128drivingly connects the HP turbine122to the HP compressor116. An LP shaft130drivingly connects the LP turbine124to the LP compressor114. The HP shaft128, the rotating components of the HP compressor116that are mechanically coupled with the HP shaft128, and the rotating components of the HP turbine122that are mechanically coupled with the HP shaft128collectively form a high pressure spool, or HP spool131. The LP shaft130, the rotating components of the LP compressor114that are mechanically coupled with the LP shaft130, and the rotating components of the LP turbine124that are mechanically coupled with the LP shaft130collectively form a low pressure spool, or LP spool133.

The fan section104includes a fan assembly138having a fan134mechanically coupled with a fan rotor140. The fan134has a plurality of fan blades136circumferentially-spaced apart from one another. As depicted, the fan blades136extend outward from the fan rotor140along the radial direction R. A power gearbox142mechanically couples the LP spool133and the fan rotor140. The power gearbox142may also be called a main gearbox. The power gearbox142includes a plurality of gears for stepping down the rotational speed of the LP shaft130to provide a more efficient rotational fan speed of the fan134. In other example embodiments, the fan blades136of the fan134can be mechanically coupled with a suitable actuation member configured to pitch the fan blades136about respective pitch axes, such as, for example, in unison. In some alternative embodiments, the turbofan engine100does not include the power gearbox142. In such alternative embodiments, the fan134can be directly mechanically coupled with the LP shaft130, such as, for example, in a direct drive configuration.

Referring still toFIG.1, the fan rotor140and hubs of the fan blades136are covered by a rotatable spinner144aerodynamically contoured to promote an airflow through the plurality of fan blades136. Additionally, the fan section104includes an annular fan casing145and an outer nacelle146connected to the fan casing145. The fan casing145and the outer nacelle146both circumferentially surround the fan134and/or at least a portion of the core turbine engine106. The fan casing145and the outer nacelle146are supported relative to the core turbine engine106by a plurality of circumferentially-spaced outlet guide vanes148. A downstream section150of the nacelle146extends over an outer portion of the core turbine engine106so as to define a bypass passage152therebetween.

During operation of the turbofan engine100, a volume of air154enters the turbofan engine100through an associated inlet156of the nacelle146and/or fan section104. As the volume of air154passes across the fan blades136, a first portion of air158is directed or routed into the bypass passage152and a second portion of air160is directed or routed into the annular core inlet110. The pressure of the second portion of air160is progressively increased as it flows downstream through the LP compressor114and HP compressor116. Particularly, the LP compressor114includes sequential stages of LP compressor stator vanes182and LP compressor blades184that progressively compress the second portion of air160. The LP compressor blades184are mechanically coupled to the LP shaft130. Similarly, the HP compressor116includes sequential stages of HP compressor vanes186and HP compressor blades188that progressively compress the second portion of air160even further. The HP compressor blades188are mechanically coupled to the HP shaft128. Additional details regarding the various components of the LP compressor114and the HP compressor116will be described in greater detail hereinbelow. The compressed second portion of air160is then discharged from the compressor section112into the combustion section118.

The compressed second portion of air160discharged from the compressor section112mixes with fuel and is burned within a combustor of the combustion section118to provide combustion gases162. The combustion gases162are routed from the combustion section118along a hot gas path174of the core air flowpath132through the HP turbine122where a portion of thermal and/or kinetic energy from the combustion gases162is extracted via sequential stages of HP turbine stator vanes164and HP turbine blades166. The HP turbine blades166are mechanically coupled to the HP shaft128. Thus, when the HP turbine blades166extract energy from the combustion gases162, the HP shaft128rotates, thereby supporting operation of the HP compressor116. The combustion gases162are routed through the LP turbine124where a second portion of thermal and kinetic energy is extracted from the combustion gases162via sequential stages of LP turbine stator vanes168and LP turbine blades170. The LP turbine blades170are coupled to the LP shaft130. Thus, when the LP turbine blades170extract energy from the combustion gases162, the LP shaft130rotates and supports operation of the LP compressor114, as well as the fan134by way of the power gearbox142.

The combustion gases162exit the LP turbine124and are exhausted from the core turbine engine106through the exhaust section126to provide propulsive thrust. Simultaneously, the pressure of the first portion of air158is substantially increased as the first portion of air158is routed through the bypass passage152before the first portion of air158is exhausted from a fan nozzle exhaust section172of the turbofan engine100, also providing propulsive thrust. The HP turbine122, the LP turbine124, and the exhaust section126at least partially define the hot gas path174.

It will be appreciated that the turbofan engine100depicted inFIG.1is provided by way of example, and that in other example embodiments, the turbofan engine100has other configurations. Additionally, or alternatively, aspects of the present disclosure may be utilized with other suitable aeronautical turbofan engines, a turboshaft engine, and turboprop engine.

Referring now toFIG.2A, a schematic, cross-sectional view of a portion of the compressor section112and a portion of the combustion section118of the turbofan engine100ofFIG.1is provided. More specifically,FIG.2Adepicts an aft end of the HP compressor116of the compressor section112and a portion of the combustion section118. However, it should be appreciated that the various components described herein can be included in other compressor sections of the turbofan engine100, including the LP compressor114and/or an intermediate pressure (IP) compressor in 3 spool gas turbine engines.

Referring toFIGS.1and2A-2B, and as noted above, during operation of the turbofan engine100, an airflow through the core air flowpath132of the turbofan engine100is sequentially compressed as it flows through the compressor section112, or more specifically, as it flows through the LP compressor114and the HP compressor116. The compressed air from the compressor section112is then provided to the combustion section118, wherein at least a portion of the compressed air is mixed with fuel and burned to create the combustion gases162. The combustion gases162flow from the combustion section118to the turbine section120, and more specifically, sequentially through the HP turbine122and the LP turbine124, for the embodiment depicted, driving the HP turbine122and the LP turbine124. The HP spool131is drivingly coupled to both the HP turbine122and the HP compressor116.

Referring particularly toFIG.2A, the HP compressor116includes a plurality of compressor stages202a-202e(collectively, compressor stages202), with each of the compressor stages202including, for example, a plurality of the HP compressor blades188and a rotor206. While five compressor stages202are depicted inFIG.2A, the HP compressor116includes greater than or fewer than five stages in other embodiments. Each of the various compressor stages202is drivingly coupled to the HP spool131, such that the HP turbine122(FIG.1) may drive the HP compressor116through the HP spool131. Amongst the plurality of compressor stages202of HP compressor116, is an aft-most stage202alocated at an aft end200of the HP compressor116.

The aft-most stage202aprovides compressed air to the combustion section118. More specifically, for the embodiment depicted inFIG.2A, the combustion section118includes a diffuser230, an inner combustor casing232, and a combustor assembly234. Further, the combustion section118defines a diffuser cavity236, with the diffuser230located downstream of the compressor stages202of the HP compressor116and upstream of the diffuser cavity236, such that compressed air from the aft-most stage202ais provided to the diffuser cavity236through the diffuser230. The compressed air within the diffuser cavity236is, in turn, provided to the combustor assembly234, where the compressed air is mixed with fuel and burned to generate the combustion gases162. As is depicted inFIG.2A, the combustor assembly234generally includes a fuel nozzle240, an inner liner242, and an outer liner244, with the inner liner242and the outer liner244together forming a combustion chamber250.

It should be appreciated that the combustor assembly234is configured as a suitable assembly for the turbofan engine100(FIG.1). For example, in certain embodiments, the combustor assembly234is configured as an annular combustor assembly, a can combustor assembly, or a cannular combustor assembly.

Referring still toFIG.2A, as previously noted, the HP spool131is drivingly connected to the HP compressor116. For the embodiment depicted, the HP spool131generally includes a central spool section including a central spool member208, which may also be referred to herein as an inner circumferential support structure. The central spool member208extends, for the embodiment depicted inFIG.2A, generally along the axial direction A at a location radially inward of the combustor assembly234of the combustion section118. In addition, the central spool member208is coupled to or formed integrally with one or more spacer arms210located forward of the central spool member208. The one or more spacer arms210, for the embodiment depicted, also extend generally along the axial direction A. Together, the central spool member208and the one or more spacer arms210may form an inner circumferential support structure209of the HP compressor116.

Still referring toFIG.2A, the aft-most stage202aof the HP compressor116represents a final stage of the HP compressor116when traversing the HP compressor116from fore to aft positions in the axial direction A. One or more forward stages202b-202elocated forward of the aft-most stage202ainclude, for example, a first forward stage202b, a second forward stage202c, a third forward stage202d, and a fourth forward stage202e. Each one of the compressor stages202a-202fincludes corresponding ones of the HP compressor vanes186and the HP compressor blades188. That is, the aft-most stage202aincludes an aft-most vane186a(e.g., a first vane) and a first compressor blade188a, the first forward stage202bincludes a second vane186band a second compressor blade188b, the second forward stage202cincludes a third vane186cand a third compressor blade188c, the third forward stage202dincludes a fourth vane186dand a fourth compressor blade188d, and the fourth forward stage202eincludes a fifth vane186eand a fifth compressor blade188e, and so forth (e.g., a sixth vane186fand a sixth compressor blade188f, etc.).

The HP compressor116further includes an outer casing204, which may also be referred to herein as an outer circumferential support structure. The outer casing204may extend generally in the axial direction A radially outward of the inner circumferential support structure209. In some embodiments, the outer casing204and the inner circumferential support structure209are positioned around a central axis, such as, for example, the longitudinal centerline102of the turbofan engine100(FIG.1). That is, the inner circumferential support structure209is positioned radially outward of the longitudinal centerline102(FIG.1), and the outer casing204is spaced radially outward of the inner circumferential support structure209, as depicted inFIG.2A.

Referring toFIGS.2A and2B, the various vanes186of the compressor generally extend inwardly a distance in the radial direction R from the outer casing204. Each one of the various vanes186extends from the outer casing204at a location that is between adjacent compressor blades188. For example, the aft-most vane186amay extend from the outer casing204at a location that is between the first compressor blade188aand the second compressor blade188b. In addition, the various vanes186extend towards the inner circumferential support structure209, particularly one of the one or more spacer arms210thereof. In embodiments, one or more components are disposed between the vanes186and the corresponding spacer arms210, such as, for example, an inner platform282, a seal support structure284, a seal structure286, and/or one or more seal teeth260, as described in greater detail herein.

Referring particularly toFIG.2B, each of the vanes186(e.g., the aft-most vane186a, the second vane186b, etc.) includes a root262, a tip264, a leading edge268, and a trailing edge266. The root262of each vane186represents a radially outward extent of the vane186at a connection point with the outer casing204. That is, the root262of each vane186is the part (e.g., end) of the vane186that contacts the outer casing204. The tip264of each vane186represents a radially inward extent of the vane186. That is, the tip264of each vane186is the part (e.g., end) of the vane that is closest to the corresponding spacer arm210. The leading edge268of each vane186represents an edge of the vane186that extends from the root262to the tip264and is a forward-most edge of the vane186generally in the axial direction (e.g., an edge that receives fluid flowing through the HP compressor116, as described herein). The trailing edge266of each vane186represents an edge of the vane186that extends from the root262to the tip264and is an aft-most edge of the vane186generally in the axial direction. As such, the trailing edge266and the leading edge268are opposite one another. In some embodiments, the trailing edge266and the leading edge268are parallel or substantially parallel to one another. In other embodiments, the trailing edge266and the leading edge268are not parallel to one another.

As depicted inFIG.2B, each of the vanes186defines a first point272and a second point274. The first point272represents the intersection of the tip264of the vane186with the trailing edge266of the vane186. The second point274represents an intersection of the root262of the vane186with the trailing edge266of the vane186.

As noted herein, one or more components may be disposed between the tip264of each vane186and the corresponding spacer arm210, including, for example, the inner platform282, the seal support structure284, the seal structure286, and/or the one or more seal teeth260. In embodiments, the inner platform282, the seal support structure284, the seal structure286, and the one or more seal teeth260appear in serial order from the tip264to the corresponding spacer arm210, with the inner platform282, the seal support structure284, and the seal structure286coupled to one another and the tip264of each vane186and the one or more seal teeth disposed on a radially outer surface294of the spacer arm210.

The inner platform282is a component that defines a flow path. That is, fluid (e.g., air) movement through each of the compressor stages202(FIG.2A) occurs via the flow path defined by the inner platform282. The inner platform282is coupled to and extends inward along the radial direction R from the tip264of the vane186. As will be appreciated, the inner platform282has a shape and surface features that are not necessarily limited to the shape and surface features disclosed in the examples. For example, the inner platform282may be shaped to correspond to a shape of the tip264of the vane186and/or may be shaped to flare outward in the axial direction A relative to a width of the vane186(e.g., a dimension extending from the leading edge268to the trailing edge266of the vane186). Each inner platform282may be different relative to the other inner platforms282in shape, size, and configuration, or may be substantially the same as the other inner platforms282in shape, size, and configuration.

The inner platform282further defines an area past which air of the core air flowpath132(FIG.1) flows. The specific dimensional aspects of the inner platform282, as described in greater detail herein, directs the air from the core air flowpath132(FIG.1) in a particular manner. While the flowpath hub is still maintained, an angle of a high-pressure aft cone arm reduces with respect to the longitudinal centerline102(FIG.1), which enables better life for various components.

The seal support structure284is generally a component coupled to and disposed inward in the radial direction R of the inner platform282. The seal support structure supports the seal structure286thereon. The seal structure286is generally any component that prevents or minimizes fluid leakage from the flow path defined by the inner platform282. That is, the seal structure286functions to maintain fluid flow within the flow path defined by the inner platform282. In the embodiment depicted inFIG.2B, the seal structure286is an abradable honeycomb seal. That is, the seal structure286is a machined component having individual chambers that create a pressure drop to slow leakage and/or disrupt circumferential flow around the HP shaft128(FIG.1). The seal structure286forms a seal with the seal teeth260that are disposed on the radially outer surface294of the spacer arm210.

It should be appreciated that the seal structure286depicted inFIG.2Bis not limited to an abradable honeycomb seal. For example, in other embodiments, the seal structure286is a bridge seal, a stick-type seal, a box-type seal, an attached seal ring housing, a foil seal, a brush seal, an advanced aspirating seal, or the like. In some embodiments, the seal structure286is selected depending on the size of an inter stage seal (ISS) cavity defined by the spacer arm210, adjacent rotors206and the outer casing204.

Referring now toFIGS.3A-3D, various illustrative seal structures located within the aft-most stage202aof the HP compressor116are depicted. More specifically,FIG.3Adepicts a bridge seal302coupled to the inner platform282at a location that is inward in the radial diction R relative to the inner platform282. That is, the bridge seal302extends generally in the axial direction A and is held in place on either end thereof by adjacent rotors206such that the bridge seal302forms a seal with the inner platform282of aft-most vane186ato maintain fluid flow within the flow path defined by the inner platform282. As is depicted inFIG.3A, the bridge seal302is positioned a distance from the spacer arm210in the radial direction R and does not contact the spacer arm210. Use of the bridge seal302allows for the aft-most vane186ato provide sealing functionality at a reduced size relative to other seal structures. As a result, the bridge seal302also reduces or eliminates windage losses in forward and aft wheelspace cavities. As depicted inFIG.3A, the aft-most vane186aincludes the inner platform282and is abradable. In other embodiments, the bridge seal302is formed as a bridge arm connecting the adjacent rotors206, which allows for the aft-most vane186ato act as a cantilever vane. In some embodiments, and as depicted inFIG.3A, use of the bridge seal302eliminates the use of seal teeth in the aft-most stage202a.

Referring now toFIG.3B, a stick-type seal housing304may be implemented between the inner platform282and the seal teeth260. That is, the stick-type seal housing304may be coupled to and extend inward along the radial direction R from the inner platform282and contact the one or more seal teeth260positioned on the radially outer surface294of the spacer arm210to seal the aft-most vane186a. For high temperature cycles, a cast vane segment may be utilized. The stick-type seal housing304enables an integral casting of vanes to form segments, including a platform and a seal.

Referring now toFIG.3C, a box-type seal housing306may be implemented between the inner platform282and the one or more seal teeth260. That is, the box-type seal housing306may be coupled to and extend inward along the radial direction R from the inner platform282and contact the one or more seal teeth260positioned on the radially outer surface294of the spacer arm210to seal the aft-most vane186a. Use of such a box structure may be particularly used in embodiments with a high ISS cavity area, as the box structure provides a seal in the cavity with minimal weight impact relative to other sealing structures.

Referring now toFIG.3D, an attached seal ring housing308may be implemented between the tip264of the aft-most vane186aand the one or more seal teeth260. That is, the attached seal ring housing308may be coupled to and extend inward along the radial direction R from the tip264of the aft-most vane186aand contact the one or more seal teeth260positioned on the radially outer surface294of the spacer arm210to seal the aft-most vane186a. The attached seal ring housing308may be used in lieu of the platform described herein with respect to other sealing structures. The attached seal ring housing308may include a seal and shroud that is fixed to the aft-most vane186a(e.g., riveted to the aft-most vane186a). Because embodiments utilizing the attached seal ring housing308omits the platform described elsewhere herein, the attached seal ring housing308may further define the flow path. Use of the attached seal ring housing308may improve vane-to-vane circumferential leakage relative to other sealing components.

It should be appreciated that while various seal structures described herein are particularly depicted with respect to the aft-most stage202a, such seals may also be used in other stages without departing from the scope of the present disclosure.

Referring again toFIGS.2A and2B, the spacer arms210are generally positioned a distance inward from the outer casing204in the radial direction R to define spaces for each of the compressor stages202, including the vanes186and the HP compressor blades188thereof. The spacer arm210of the aft-most stage202adefines-points292that are centrally located at an intersection of the spacer arm210with each rotor206bounding the aft-most stage202a. As will be described in greater detail herein, a first line291drawn through both points292forms an angle θ with a second line293that is parallel to the longitudinal centerline102(e.g., in some embodiments, extending through at least one midpoint290located equidistant from the trailing edge266and the leading edge268at the root262of a vane186). The angle θ may be referred to as a spacer angle. It should be understood that since each spacer arm210may have a different slope, each compressor stage202may have a corresponding spacer angle that is different from a spacer angle of an adjacent or nearby spacer arm. As such, the angle θ depicted inFIG.2Bis referred to as the spacer angle for the aft-most stage202a.

As previously noted herein, the spacer arms210includes the radially outer surface294and the radially inner surface296. The radially inner surface296is opposite the radially outer surface294. The radially outer surface294of the spacer arms210generally faces the vanes186and, in some embodiments, supports the one or more seal teeth260coupled thereto. The spacer arms210generally define a thickness in the radial direction R between the radially outer surface294and the radially inner surface296. In addition, the spacer arms210define a midpoint211on the radially inner surface296that is located equidistant between adjacent points292, as depicted inFIG.2B.

As will be described in further detail herein, a first radial distance Ch is defined by a distance in the radial direction R between the first point272and the midpoint211on the radially inner surface296of the corresponding spacer arm210. That is, the first radial distance Ch represents a distance that includes all of the components disposed between the tip264of the vane186and the corresponding spacer arm210, including, in some examples, the inner platform282, the seal support structure284, the seal structure286, the one or more seal teeth260, and the thickness of the spacer arm210. This first radial distance Ch may also be referred to as a cavity height. As will also be described in further detail herein, a second radial distance Vh is defined by a distance in the radial direction R between the first point272and the second point274. The second radial distance Vh also represents a height of the vane186and may be referred to as a vane height. Further, with reference toFIG.2A, a third radial distance Rh is defined by a distance in the radial direction R between the first point272and the longitudinal centerline102of the engine.

Referring now toFIGS.4A-4B, a stator delivery system that enables cooled cooling air passage to an area forward of the rotor206of the aft-most stage202avia hole passages present on the rotor206above a rotor rim is depicted. The inner combustor casing232of the combustion section118also forms in part a compressor discharge pressure seal412, such that the HP spool131forms the compressor discharge pressure seal412with the inner combustor casing232of the combustion section118. As is depicted inFIGS.4A and4B, the inner combustor casing232forms a stator portion414of the compressor discharge pressure seal412and the HP spool131forms a rotor portion416of the compressor discharge pressure seal412(the rotor portion416being rotatable relative to the stator portion414). The stator portion414generally includes a seal pad418and the rotor portion416generally includes a plurality of seal teeth420configured to form a seal with the seal pad418.

The compressor discharge pressure seal412depicted inFIGS.4A-4Bis a labyrinth seal. However, it should be appreciated that in other illustrative embodiments, the compressor discharge pressure seal412can have another suitable configuration. For example, in alternative illustrative embodiments, the compressor discharge pressure seal412is configured as a brush seal, an aspirating seal, or the like.

Referring still toFIGS.4A-4B, the inner combustor casing232generally includes a structural portion425and a seal flow separator426. The seal flow separator426extends from the structural portion425of the inner combustor casing232to define in part an air flow path430with the HP spool131, and more specifically with the central spool member208. Notably, the inner combustor casing232further defines in part an air cavity427positioned inward of the structural portion425along the radial direction R, and the seal flow separator426separates the compressor discharge pressure seal412from the air cavity427.

Referring particularly toFIG.4B, which depicts an aft-most stage blisk, the turbofan engine100(FIG.1) generally defines at least in part the air flow path430. The air flow path430is positioned at least in part between the HP spool131and the inner combustor casing232, and, more specifically, for the embodiment shown, is defined at least in part by the inner combustor casing232and the seal flow separator426.

Further, for the embodiment depicted inFIG.4B, the air flow path430further extends past, or through, the compressor discharge pressure seal412and is in fluid communication with the core air flowpath132of the turbofan engine100. More specifically, in the embodiment depicted, the air flow path430is in fluid communication with the core air flowpath132at the HP compressor116. More specifically, still, in the embodiment depicted, the air flow path430is in fluid communication with the core air flowpath132at a location downstream of the aft-most stage202aand upstream of the diffuser230.

As noted, the embodiments ofFIGS.4A-4Bintroduce holes415in the stator portion414to allow for cooling air. Cooling air is introduced into the inner combustor casing232through conduit from an external location (not depicted). The holes415in the stator portion414locate air into the cavity above (e.g., outward in the radial direction R) the seal pad418and direct the air into the cavity directly aft of the aft-most stage rotor206. InFIG.4B, the cooling air is directed into the cavity directly aft of the aft-most stage rotor206via an inducer in the seal flow separator426. In other embodiments, the cooling air can also be directed into the cavity directly aft of the aft-most stage rotor206via hole features432in a pedestal portion434of the aft-most stage rotor206.

The aft-most stage202adepicted inFIG.4Bincludes a blisk. That is, the aft most-stage includes a disk with integral/welded blades instead of other forms of blade to disk attachment, such as axial or circumferential dovetail, bolted, or pinned. These are different combinations/types of blade attachments that can be used interchangeably at the aft-most stage202aor any other stage of the HP compressor. Use of a blisk represents an assembly having the lightest weight due to absence of attachment features like dovetails/pins.

In some embodiments, the spacer arm210is a single, continuous structure formed as part of the inner circumferential support structure209(FIG.2A). However, in other embodiments, the spacer arm210includes more than one component to provide additional benefits, such as, for example, higher torque transfer, use of lower spacer arm radii, and/or length reduction. For example, as depicted inFIGS.5A and5B, the spacer arm210may include a first portion210aand a second portion210b.

As particularly depicted inFIG.5A, the first portion210aand the second portion210bof the spacer arm210may be joined together via a curvic coupling502that extends in the axial direction A between the first portion210aand the second portion210b. The curvic coupling502is generally a ring of face splines or radial teeth disposed on the first portion210aof the spacer arm210that interlock with a corresponding ring of space splines or radial teeth disposed the second portion210bof the spacer arm210to couple the first portion210aand the second portion210btogether. Use of the curvic coupling502may allow for higher torque transfer capability of the spacer arm210relative to spacer arms that do not incorporate a curvic coupling.

As particularly depicted inFIG.5B, the first portion210aand the second portion210bof the spacer arm210may be joined together via a welded joint504. The welded joint504is generally a point where the first portion210aand the second portion210bcontact one another and are held together via welds. Use of the welded joint504may allow for lower torque transfer capability of the spacer arm210relative to spacer arms that do not incorporate a welded joint.

While not depicted inFIGS.5A and5B, the first portion210aand the second portion210bof the spacer arm210are coupled via a weld joint in some embodiments. Use of a weld joint may realize a machining benefit in that a radius of the spacer arm can be reduced, which enables easier tool access between adjacent rotors206in the axial direction A (e.g., for the purposes of cleaning or the like).

As alluded to earlier, the inventors discovered, unexpectedly during the course of engine design, that a relationship exists between the relative dimensions of components within the aft-most stage of the HP compressor116in directing the HPC load path, while at the same time maintaining the flowpath hub per aero requirements. In addition, the inventors discovered that the angle of the high-pressure aft cone arm (the spacer angle θ described herein) is reduced with respect to the engine center line relative to conventionally shaped components and enabling a longer life for the component. The inventors further discovered that, by tuning the relative dimensions of components of the aft-most stages of the HP compressor116, the forward thrust loads acting on the HP spool thrust bearing could be reduced, a higher compressor discharge temperature T3 can be enabled with existing materials, overall engine weight could be reduced, structural dynamics associated with operation of the high speed (HP) shaft are improved, and at least a 15% improvement in the compressor load path stiffness in the aft regions thereof were observed. As a result, an improvement in fuel burn was also realized.

The higher compressor discharge temperature T3 realized by the inventors is directly relatable to the improvements in compressor characteristics and performance. Lowering and smoothing of the rotor mechanical load path helps solve issues relating to weight, life, and dynamics. Lowering and smoothing of the load path also enables performance improvements in the form of higher operating temperatures. While larger wheelspace cavities cause some performance loss due to windage, the losses are more than offset by the benefits that are realized.

With reference now toFIGS.1through6B, various relationships between operational and architectural characteristics of a turbofan engine and measured load path characteristics are depicted inFIGS.6A and6Band shown in the Tables below, particularly with respect to the various features shown and described with respect toFIGS.2A-2B,3A-3B,4A-4D, and5A-5B. These relationships will be explained in the context of the turbofan engine100ofFIG.1(and particularly the HP compressor116ofFIG.2A), but as will be appreciated, these relationships are applicable to turbofans having different configurations.

As noted herein, the HP compressor116is particularly designed such that the aft-most stage202athereof includes an aft-most vane186ahaving particular dimensional characteristics and particular positioning relative to other components, particularly the radially inner surface296of the spacer arm210. Specifically, the components of the aft-most stage202aare sized and positioned such that the first radial distance Ch in the radial direction R between the first point272and a line extending in the axial direction through the midpoint211on the radially inner surface296of the corresponding spacer arm210, which is parallel to the longitudinal centerline102of the turbofan engine100(e.g., a cavity height), can be expressed relative to the second radial distance Vh in the radial direction R between the first point272and a line extending in the axial direction through the second point274parallel to the longitudinal centerline102(e.g., a vane height) as expression (1):

ChVh(1)

With respect to the aft-most vane186a, expression (1) above represents a radial length of the aft-most vane186aand a distance between the tip264of the aft-most vane186aand the radially inner surface296of the spacer arm210of the compressor. It was found that certain values for expression (1) uniquely identify the advantageous load path noted herein, considering both the penalties and benefits associated with having the divergent flowpath defined by this relationship. Values for expression (1) that result in the advantageous load path through the compressor are between 0.95 and 5.1, and more particularly, between 0.97 and 3.6. Table 1 below depicts a corrected exit flow of fluid from the HP compressor116under takeoff conditions (in pound mass per second or lbm/sec), which is expressed as W3R, that is observed when the aft-most vane186aincludes dimensional characteristics and spacing according to expression (1):

TABLE 1Measured corrected flowEngineCh (inch)Vh (inch)ChVhW3R(lbm/sec)Rh (inch)ChVh*RhW3⁢R0.5% LR10.5250.5530.953.36.73.517%21.4780.5532.673.36.79.8828%31.9480.5533.523.36.713.0240%42.3480.5534.253.36.715.6949%52.4880.5534.503.36.716.6353%60.5860.6170.954.47.93.578%71.6220.6172.634.47.99.8736%82.1720.6173.524.47.913.2252%92.8420.6174.614.47.917.3071%103.1470.6175.104.47.919.1580%110.6280.6610.954.56.73.0018%121.4030.6612.124.56.76.7135%131.8730.6612.834.56.78.9547%142.2730.6613.444.56.710.8756%152.9750.6614.504.56.714.2275%160.8110.8540.959.211.63.639%172.2930.8542.699.211.610.2642%183.1130.8543.659.211.613.9361%193.8130.8544.479.211.617.0676%204.3530.8545.109.211.619.4788%210.8720.9180.9511.313.83.917%222.9630.9183.2311.313.813.2854%234.0630.9184.4311.313.818.2179%244.6630.9185.0811.313.820.9091%254.1290.9184.5011.313.818.5181%

The corrected exit flow of fluid from the HP compressor116under takeoff conditions (W3R) can be expressed according to Expression (2):

W3⁢R=W3⁢(T3518.67)0.5P314.696(2)
where W3represents a physical flow of fluid out of the HP compressor116at an exit thereof, T3represents a total temperature (in Rankine) of the fluid at the exit of the HP compressor116, and P3represents a total pressure of the fluid at the exit of the HP compressor116.

Also depicted in Table 1 above is the compressor characteristic referred to in the example as Rh, which represents a radius of the first point272with respect to the longitudinal centerline102of the engine. % LR as depicted in Table 1 above is the determined percentage of load reduction as measured at the HP spool thrust bearing, which is also depicted graphically inFIG.6A. The inventors discovered, as is evident inFIG.6A, that the percentage of load reduction generally increases as the Ch/Vh of expression (1) increases.

Further, the inventors found that the spacer angle θ formed from an intersection of the line passing through points292and a line parallel to the longitudinal centerline102of the engine can vary from between 0° and 45°, and more particularly between 0° and 25°.

In other embodiments, the components of the aft-most stage202aare sized and positioned such that the first radial distance Ch in the radial direction R between the first point272and a line extending in the axial direction through the midpoint211, which is parallel to the longitudinal centerline102of the turbofan engine100, can be expressed relative to the second radial distance Vh in the radial direction R between the first point272and the second point274and the corrected flow of fluid from the HP compressor116(in lbm/sec) W3Ras expression (3):

ChVh*RhW3⁢R0.5(3)

Expression (3) above expresses a particular radial length of the aft-most vane186aand distance between the aft-most vane186aand the spacer arm210of the compressor having an advantageous load path noted herein. Values for expression (3) that result in the advantageous load path of the compressor are between 3.0 and 21.0, and more particularly, between 3.0 and 15.

The percentage of load reduction measured at the HP spool thrust bearing is depicted graphically atFIG.6B. The inventors discovered, as is evident inFIG.6B, that the percentage of load reduction generally increases as the value of expression (3) increases.

Further, the spacer angle θ formed from an intersection of the line passing through points292and a line parallel to the longitudinal centerline102of the engine is between 0° and 45°, and more particularly between 0° and 25°.

With the characteristics noted above, the inventors discovered that, as Ch/Vh increases, the divergence of the load-path with respect to the flowpath hub increases, leading to improvement in the form of increased rotor-stator cavity areas, thereby enabling greater aft thrust load generation to reduce the net forward load and reduced centrifugal stresses for the spacer arms, which can lead to improved rotor life for the spacers. In addition, the more particular value combination of Ch/Vh leads to an improved dynamics mode margin and stability due to smoother load-path with improved stiffness.

Further, the inventors discovered that, after Ch/Vh and the spacer angle θ crosses a particular limit, the net rotor thrust would start reversing from the forward to aft direction, and the dynamics stability would also start to deteriorate, which is not acceptable.

Dimensional aspects of the aft-most stator according to expression (3) above are particularly advantageous to address operating condition changes such as variation of the compressor pressure ratio effects.

The inventors also realized various other effects of incorporating features described with respect toFIGS.3A-3D,4A-4B, and5A-5B. Specifically, introduction of a cooling flow of air using the structures depicted inFIGS.4A-4Ballows for directing cooled cooling air to the compressor stages, which improves rotor life. Further, introduction of the various seals described and depicted with respect toFIGS.3A-3Dallows for the tall cavities described herein while at the same time maintaining clearances and stiffness of seals. The seals further improve rotor life, improve acoustic margins, and reduces rotor thrust, which enables better life for architectures. In addition, introduction of a coupling as described with respect toFIGS.5A and5Ballows for improved torque transfer.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

This written description uses examples to disclose the present 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 may include other examples that occur to those skilled in the art. Such other examples are intended to be 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.

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

A compressor, comprising: an outer circumferential support structure and an inner circumferential support structure, the outer and inner circumferential support structures positioned concentrically around a central axis; and an aft-most stage comprising a vane extending radially inward from the outer circumferential support structure, an axial length of the aft-most stage being defined by a spacer arm of the inner circumferential support structure, wherein the vane comprises a root, a tip, and a trailing edge extending between the root and the tip, the root positioned at the outer circumferential support structure, and wherein a ratio of (1) a first radial distance between a first point located at an intersection of the tip of the vane and the trailing edge to a radially inner wall of the spacer arm of the inner circumferential support structure to (2) a second radial distance between the first point and a second point located at an intersection of the root of the vane and the trailing edge is between 0.95 and 5.1.

The compressor according to the previous clause, wherein the ratio is between 0.97 and 3.6.

The compressor according to any one of the previous clauses, further comprising one or more forward stages positioned forward of the aft-most stage, each one of the one or more forward stages comprising a vane having a root extending from the outer circumferential support structure, and a tip, an axial length of each one of the one or more forward stages being defined by additional spacer arms of the inner circumferential support structure.

The compressor according to any one of the previous clauses, wherein an arrangement of a first line extending through intersection points of the spacer arm between adjacent rotors forms an angle with a second line parallel to a longitudinal centerline and wherein the angle is between 0° and 45°.

The compressor according to any one of the previous clauses, wherein the angle is between 0° and 25°.

The compressor according to any one of the previous clauses, further comprising an aft most stage seal positioned adjacent to the tip of the vane.

The compressor according to any one of the previous clauses, wherein the aft most stage seal is a bridge seal, a stick-type seal housing, a box-type seal housing, or incorporates an attached seal ring.

The compressor according to any one of the previous clauses, wherein the spacer arm comprises a first portion and a second portion, the first portion coupled to the second portion via a curvic coupling, a friction joint, or a weld joint

The compressor according to any one of the previous clauses, further comprising a blisk positioned aft of the aft-most stage.

The compressor according to any one of the previous clauses, further comprising a stator delivery system positioned aft of the aft-most stage.

A compressor, comprising: an outer circumferential support structure and an inner circumferential support structure, the outer and inner circumferential support structures positioned concentrically around a central axis; and an aft-most stage comprising a vane extending radially inward from the outer circumferential support structure, an axial length of the aft-most stage being defined by a spacer arm of the inner circumferential support structure, wherein the vane comprises a root, a tip, and a trailing edge extending between the root and the tip, the root positioned at the outer circumferential support structure, a flowpath hub radius defined between the longitudinal centerline and the vane tip wherein relative dimensions of the vane are defined by

ChVh*RhW3⁢R0.5,
where Ch represents a first radial distance between a first point located at an intersection of the tip of the vane and the trailing edge to a radially inner wall of the spacer arm of the inner circumferential support structure, Vh represents a second radial distance between the first point and a second point located at an intersection of the root of the vane and the trailing edge and Rh (in inches) represents a third radial distance between the first point and the longitudinal centerline, and W3Rrepresents a corrected flow of a fluid out of the compressor as defined by:

W3⁢R=W3*(T3518.67)0.5P314.696,
where W3represents a physical flow of the fluid at a compressor exit, T3represents a total temperature of the fluid at the compressor exit in Rankine, and P3represents a total pressure of the fluid at the compressor exit in pounds per square inch absolute (psia).

The compressor according to any one of the previous clauses, wherein

ChVh*RhW3⁢R0.5
is between 3.0 and 21.0 or

ChVh*RhW3⁢R0.5
is between 3.0 and 15.0.

The compressor according to any one of the previous clauses, further comprising one or more forward stages positioned forward of the aft-most stage, each one of the one or more forward stages comprising a vane having a root extending from the outer circumferential support structure, and a tip, an axial length of each one of the one or more forward stages being defined by additional spacer arms of the inner circumferential support structure.

The compressor according to any one of the previous clauses, wherein an arrangement of a first line extending through intersection points of the spacer arm between adjacent rotors forms an angle with a second line parallel to a longitudinal centerline and wherein the angle is between 0° and 45°.

The compressor according to any one of the previous clauses, wherein the angle is between 0° and 25°.

The compressor according to any one of the previous clauses, further comprising an aft most stage seal positioned adjacent to the tip of the vane.

The compressor according to any one of the previous clauses, wherein the seal is a bridge seal, a stick-type seal housing, a box-type seal housing, or incorporates an attached seal ring.

The compressor according to any one of the previous clauses, wherein the spacer arm comprises a first portion and a second portion, the first portion coupled to the second portion via a curvic coupling, a friction joint, or a weld joint.

The compressor according to any one of the previous clauses, further comprising a blisk positioned aft of the aft-most stage.

The compressor according to any one of the previous clauses, further comprising a stator delivery system positioned aft of the aft-most stage.