Patent Application
20180156054
The technical field generally relates to turbine wheels, turbine engines including the turbine wheels, and methods of forming the turbine wheels, and more particularly relates to turbine wheels having improved seal plate sealing for bonded turbine blade/rotor disk configurations.
Gas turbine engines are generally known for use in a wide range of applications such as aircraft engines and auxiliary power units for aircraft. In a typical configuration, the gas turbine engine includes a turbine section having a plurality of sets or rows of stator vanes and turbine blades disposed in an alternating sequence along an axial length of a hot gas flow path of generally annular shape. The turbine blades are coupled to a main engine shaft through one or more rotor disks. Hot combustion gases are delivered from an engine combustor to the annular hot gas flow path, resulting in rotary driving of the turbine rotor disks which, in turn, drives the compressors and gearbox.
Advanced high performance gas turbine engines, such as high pressure turbines (HPTs) are constantly driven to achieve maximized thermodynamic efficiency, which is generally achieved by operating at higher rotor speeds and temperatures. In many gas turbine engine configurations, especially for HPTs, the turbine blades are mounted at the periphery of the one or more rotor disks through a mechanical connection, e.g., through a dovetail-type connection or the like. However, the mechanical properties of the rotor disks and turbine blades may be inadequate to sustain induced loads during operation, even with selection of special materials and engineered cooling schemes. This may be especially true as efforts are made to maximize thermodynamic efficiency by maximizing rotor speeds and operating temperatures.
One approach taken to maximize temperatures and load carrying capability in turbine blades and rotor disks, particularly in HPTs is to employ dissimilar materials for the rotor disks and the turbine blades while removing the stress concentrations associated to mechanical connections. The respective rotor disks and turbine blades, including the dissimilar materials, are directly bonded together as opposed to relying upon a mechanical connection. In one example, the turbine blades may be operatively connected to blade mounts, e.g., by casting the turbine blades and blade mounts together, or by brazing or welding the turbine blades to the blade mounts. The blade mounts may be operatively connected to each other forming a blade ring, such as by casting a plurality of blade mounts together or by brazing or welding blade mounts together. However, the creation of an integral bonded rotor requires the release of hoop stress attributable to the thermal gradients and rotation of the rotor disk. The hoop stress can be broken by slotting the blade ring and rotor disk after bonding the blade ring and rotor disk together.
In addition, it is often desirable to regulate the normal operating temperature of certain turbine components in order to prevent overheating. That is, while engine stator vanes and turbine blades are specially designed to function in the high temperature environment of the mainstream hot gas flow path, other turbine components such as the rotor disks are not generally designed to withstand such high temperatures. Accordingly, in many gas turbine engines, the volumetric space disposed radially inwardly or internally from the hot gas flow path includes a fore seal plate, and an aft seal plate is also generally disposed on an opposite side of the turbine wheel from the fore seal plate. The fore and aft seal plates form respective fore and aft rotating internal engine cavities around the rotor disk(s). The internal engine cavities are sealed from direct contact with the high temperature environment of the mainstream hot gas flow path, sometimes with a cooling air flow provided therethrough. When provided, the cooling air flow is normally obtained as a bleed flow from a compressor or compressor stage forming a portion of the gas turbine engine. The internal engine cavities enable a normal steady state temperature of the rotor disks and other internal engine components to be maintained at or below a temperature of the high temperature environment.
With bonded turbine blade/rotor disk configurations that are slotted to relieve hoop stress, sealing of the internal engine cavities is often imperfect, resulting in excessive intrusion of high temperature gas from the mainstream hot gas flow path into the internal engine cavities or an excessive use of parasitic cooling air. While attempts have been made to seal the internal engine cavities, the configuration of the slots can complicate complete sealing using seal plates.
Accordingly, it is desirable to provide turbine wheels, turbine engines including the turbine wheels, and methods of forming the turbine wheels having improved seal plate sealing for bonded turbine blade/rotor disk configurations. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
Turbine wheels, turbine engines, and methods of forming the turbine wheels are provided herein. In an embodiment, a turbine wheel includes a rotor disk and a plurality of turbine blades. Each turbine blade is operatively connected to the rotor disk through a blade mount and the blade mount is bonded to the rotor disk. The blade mount and the rotor disk have a fore surface on a higher pressure side of the blade mount and the rotor disk. The blade mount and the rotor disk further have an aft surface on a lower pressure side of the blade mount and the rotor disk. The blade mount includes a blade attachment surface that extends between and connects the fore surface and the aft surface of the blade mount. The turbine blade extends from the blade attachment surface. A gap is defined between adjacent blade mounts. The gap separates the blade mounts and extends into the rotor disk. The gap includes a pocket that has a fore opening in the fore surface. A pocket seal is disposed in the pocket.
In another embodiment, a turbine engine includes a turbine wheel and a fore seal plate. The turbine wheel includes a rotor disk and a plurality of turbine blades. Each turbine blade is operatively connected to the rotor disk through a blade mount and the blade mount is bonded to the rotor disk. The blade mount and the rotor disk have a fore surface on a higher pressure side of the blade mount and the rotor disk. The blade mount and the rotor disk further have an aft surface on a lower pressure side of the blade mount and the rotor disk. The blade mount includes a blade attachment surface that extends between and connects the fore surface and the aft surface of the blade mount. The turbine blade extends from the blade attachment surface. A gap is defined between adjacent blade mounts. The gap separates the blade mounts and extends into the rotor disk. The gap includes a pocket that has a fore opening in the fore surface. A pocket seal is disposed in the pocket. The fore seal plate has a fore plate edge abutting the blade mounts about a circumference of the turbine wheel.
In another embodiment, a method of forming a turbine wheel includes providing a turbine blade operatively connected to a blade mount and a plurality of blade mounts operatively connected to form a blade ring. The blade ring is bonded to a rotor disk, where the blade mounts and the rotor disk are formed from dissimilar materials that have different coefficients of thermal expansion. The blade ring and the rotor disk are slotted along a radius thereof to thereby form a gap between adjacent blade mounts. The gap separates the blade mounts and extends into the rotor disk. The gap includes a pre-formed pocket that is defined in and between adjacent blade mounts. The pocket has a fore opening in a fore surface of the blade mounts and, optionally, an aft opening in an aft surface of the blade mounts. A pocket seal is formed in the pocket through at least one of the fore opening or the aft opening.
The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the turbine wheels, turbine engines including the turbine wheels, and methods of forming the turbine wheels as described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
Embodiments of the present disclosure are generally directed to turbine wheels, turbine engines, and methods of forming the turbine wheels. For the sake of brevity, conventional techniques related to turbine engine design and fabrication may not be described in detail herein. Moreover, the various tasks and process steps described herein may be incorporated into a more comprehensive procedure or process having additional steps or functionality not described in detail herein. In particular, turbine wheels, turbine engines, and methods of forming turbine wheels are well-known and so, in the interest of brevity, many conventional steps will only be mentioned briefly herein or will be omitted entirely without providing the well-known process details.
The turbine wheel may be useful in any gas turbine engine, and may be particularly useful in high pressure turbine (HPT) engines or HPT sections of the gas turbine engines. The turbine wheel and turbine engines may be used in many industries including aerospace and industrial such as for applications including electricity generation, naval propulsion, pumping sets for gas and oil transmission, aircraft propulsion, automobile engines, and stationary power plants.
The turbine wheels, turbine engines, and methods of forming the turbine wheels as described herein provide improved seal plate sealing for bonded turbine blade/rotor disk configurations. In one example, the turbine wheel includes a plurality of turbine blades each operatively connected to a rotor disk through a blade mount. “Operatively connected,” as referred to herein, means that the referenced parts are connected by casting the parts together, by brazing or welding the parts together, or by otherwise bonding the parts together in the absence of a mechanical connection such as dovetails, keyhole connections, or the like where physical contours or frictional forces maintain the connection between the parts, The blade mounts, as referred to herein, are portions of the turbine wheel that include a single turbine blade and that are directly bonded to the rotor disk. The blade mounts and rotor disk are formed from dissimilar materials, i.e., materials having a different coefficient of thermal expansion, due to design and operating environment considerations. To form the turbine wheels, the blade mounts may be bonded or cast together to form a blade ring, followed by bonding the blade ring to the rotor disk. Due to bonding of the dissimilar materials, thermal gradients, and the rotation induced stress in the unbroken ring, hoop stress arises in the blade ring and the rotor disk. To relieve the hoop stress, the blade ring and the rotor disk are slotted along a radius thereof, i.e., a common radius of the rotor disk and the blade mount, to thereby form a gap between adjacent blade mounts, with the gap separating the blade mounts and extending into the rotor disk. The gap includes a pre-formed pocket defined in and between adjacent blade mounts to enable effective release of the hoop stress through slotting, with the pre-formed pocket formed prior to slotting. The pocket has a fore opening in a fore surface of the blade mounts and, optionally, an aft opening in an aft surface of the blade mounts. The turbine engine includes a fore seal plate having a fore plate edge abutting the blade mounts about the circumference of the turbine wheel. Given the presence of the fore opening in the pre-formed pocket, poor sealing of the fore plate edge to the blade mounts can result. Thus, a pocket seal is disposed in the pocket to assist with sealing of the fore plate edge to the blade mounts, thereby further isolating a cavity between the fore seal plate and the turbine wheel from an environment surrounding the turbine blades during operation of the turbine engine.
With reference to
In this example, the turbine engine 100 includes a fan section 102, a compressor section 104, a combustor section 106, a turbine section 108, and an exhaust section 110. The fan section 102 includes a fan 112 mounted on a rotor 114 that draws air into the gas turbine engine 100 and accelerates it. A fraction of the accelerated air exhausted from the fan 112 is directed through an outer (or first) bypass duct 116 and the remaining fraction of air exhausted from the fan 112 is directed into the compressor section 104. The outer bypass duct 116 is generally defined by an inner casing 118 and an outer casing 144. In the embodiment of
In the embodiment of
Referring to
Referring again to
The blade mount 20 and the rotor disk 26 have a fore surface 30 on the fore side of the turbine wheel 12, and the blade mount 20 and the rotor disk 26 have an aft surface 32 on the aft side of the turbine wheel 12. The fore surface 30 and the aft surface 32 are opposite and generally parallel to each other. The blade mount 20 further includes a blade attachment surface 34 that extends between and connects the fore surface 30 and the aft surface 32. The turbine blade 24 extends from the blade attachment surface 34 of each blade mount 20.
A gap 36 is defined between adjacent blade mounts 20. In one example, the gap 36 separates the blade mounts 20 and extends into the rotor disk 26. The gap 36, as referred to herein, is an interface between surfaces of adjacent blade mounts 20, and the surfaces of the adjacent blade mounts 20 may be in direct physical contact at various points therealong, but are not bonded to each other. The gap 36 may be formed by slotting a blade ring of blade mounts 20 after bonding the blade ring to the rotor disk 26 during formation of the turbine wheel 12 to release hoop stress. The gap 36 includes a pocket 38 that has a fore opening 40 in the fore surface 30. An opening into the pocket 38, as referred to herein, is a cavity through which seal material can effectively be moved into the pocket. In embodiments and as shown in
Referring again to
In embodiments and as shown in
In embodiments, a pocket seal 52 is disposed in the pocket 38. For example, the pocket seal 52 is at least disposed along the radially outward surface 46, thereby effectively sealing the gap 36 at the radially outward surface 46. However, it is to be appreciated that the pocket seal 52 may fill the entire pocket 38. In embodiments and as shown in
In embodiments, the pocket seal 52 is formed in the pocket 38 through at least one of the fore opening 40 or the aft opening 42. For example, the pocket seal 52 may be formed by inserting a wire into the pocket 38, blowing a powdered metal into the pocket 38, spraying molten metal into the pocket, or the like. The pocket seal 52 may include metal, i.e., a material with properties characteristic of a metal such as malleability. However, it is to be appreciated that the pocket seal 52 may be formed from any material that can conform to the radially outward surface 46 under centripetal force and heat while resisting breakdown. For example, in embodiments, the pocket seal 52 is formed from L605, Haynes 188, or Hastelloy X.
In the embodiment shown in
In another embodiment of a turbine engine 200 and referring to
In another embodiment of a turbine engine 300 and referring to
In another embodiment of a turbine engine 400 and referring to
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims.
