Patent Application
20150192023
Present embodiments generally relate to gas turbine engines. More particularly, but not by way of limitation, present embodiments relate to apparatuses and methods for providing a mechanical interlock feature for multi-material airfoils.
In turbine engines, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. These turbine stages extract energy from the combustion gases. A high pressure turbine includes a first stage nozzle and a rotor assembly including a disk and a plurality of turbine blades. The high pressure turbine first receives the hot combustion gases from the combustor and includes a first stage stator nozzle that directs the combustion gases downstream through a row of high pressure turbine rotor blades extending radially outwardly from a first rotor disk. In a two stage turbine, a second stage stator nozzle is positioned downstream of the first stage blades followed in turn by a row of second stage turbine blades extending radially outwardly from a second rotor disk. The stator nozzles direct the hot combustion gases in a manner to maximize extraction at the adjacent downstream turbine blades.
The first and second rotor disks are joined to the compressor by a corresponding rotor shaft for powering the compressor during operation. These are typically referred to as the high pressure turbine. The turbine engine may include a number of stages of static airfoils, commonly referred to as vanes, interspaced in the engine axial direction between rotating airfoils commonly referred to as blades. A multi-stage low pressure turbine follows the two stage high pressure turbine and is typically joined by a second shaft to a fan disposed upstream from the compressor in a typical turbofan aircraft engine configuration for powering an aircraft in flight.
As the combustion gases flow downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced. The combustion gas is used to power the compressor as well as a turbine output shaft for power and marine use or provide thrust in aviation usage. In this manner, fuel energy is converted to mechanical energy of the rotating shaft to power the compressor and supply compressed air needed to continue the process.
One desirable characteristics or design of gas turbine engines is to improve performance of airfoil structures. This may occur in a variety of fashions. One manner of improving airfoil performance is utilizing multi-material designs for the airfoil. This would allow specific benefit of differing moduli, density or ductility. It additionally allows optimization for extreme loading conditions such as impact conditions. However, while use of multi-materials would be desirable, the joining of these multi-materials via legacy techniques such as welding is often not possible based on the materials themselves. Other options such as traditional bond joints can be investigated. These typical bond or lap joints involve material interfaces that transfer load thru a bond shear interface. However, it is desirable to improve the typical shear or lap joints which are adhesively bonded together. It would further be desirable to improve the interface strength of the materials being combined to form the airfoil.
As may be seen by the foregoing, there is a need to optimize performance of airfoils. Additionally, there is a need to optimize blade designs to include lighter weight materials while providing requisite strength features needed for blades, airfoils and like components of a turbine engine or other construct using an airfoil design.
Some embodiments of the present disclosure involve a multi-material airfoil comprising a first airfoil portion connectable to a rotor disk, the first airfoil portion being formed of a first material, the first airfoil portion having an interlock feature extending therefrom, a second airfoil portion connected to the interlock feature of the first airfoil portion, the second airfoil portion extending from the first airfoil portion in a radial direction, the second airfoil portion formed of at least a partially dissimilar material.
According to some embodiments, a mechanical interlock for a multi-material airfoil comprises a leading edge, a trailing edge, a shank end and an opposed tip, a parent connectable to a rotor disk, the parent being formed of a first material and having an interlock feature extending in a radial upward direction, a wrap being formed of at least a partially different material than the first material, the wrap defining the opposed tip, the wrap having a cavity for receiving the interlock feature, the wrap extending from the parent in a radial direction.
According to still other embodiments, a mechanical interlock for a multi-material airfoil comprises a first airfoil portion formed of a first material and having an interlock feature extending in a radially upward direction, a second airfoil portion formed of a second material wherein the second material is at least partially different than the first material, the second airfoil portion extending from the first airfoil portion in a radial direction, the second airfoil portion having a cavity receiving the interlock feature, the first airfoil and the second airfoil portions defining an interlock region wherein the interlock feature and the interlock cavity are disposed.
All of the above outlined features are to be understood as exemplary only and many more features and objectives of the interlock feature of the multi-material airfoil may be gleaned from the disclosure herein. Therefore, no limiting interpretation of this summary is to be understood without further reading of the entire specification, claims, and drawings included herewith.
The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the shape changing airfoil will be better understood by reference to the following description of embodiments taken in conjunction with the accompanying drawings, wherein:
Reference now will be made in detail to embodiments provided, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not limitation of the disclosed embodiments. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to still yield further embodiments. Thus it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Present embodiments provide an airfoil which may be formed of various layers of material. For example, one material may be a polymeric matrix composite (PMC). According to a second embodiment, the material may be a ceramic matrix composite (CMC). Other materials may used, as described further herein, such as carbon based materials, for example, and therefore the description should not be considered limiting.
The terms fore and aft are used with respect to the engine axis and generally mean toward the front of the turbine engine or the rear of the turbine engine in the direction of the engine axis, respectively. The term radially is used generally to indicate a direction perpendicular to an engine axis.
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The axis-symmetrical shaft 24 extends through the turbine engine 10, from the forward end to an aft end. The shaft 24 is supported by bearings along its length. The shaft 24 may be hollow to allow rotation of a low pressure turbine shaft 28 therein. Both shafts 24, 28 may rotate about the centerline or axis 26 of the engine. During operation the shafts 24, 28 rotate along with other structures connected to the shafts such as the rotor assemblies of the turbine 20 and compressor 14 in order to create power or thrust depending on the area of use, for example power, industrial or aviation.
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Extending from the rotor disc 32 in a radial direction is the parent material or first portion 34. The parent includes a shank or lower end which is connected to the rotor disc 32 by the root. The parent material 34 may be formed from various materials such as metallic or composite material. The term composite material is defined to be a material having any (metal or non-metal) fiber filament embedded in any (metal or non-metal) matrix binder. The composite material is comprised of fiber filaments embedded in an epoxy (i.e. epoxy resin) matrix binder. Other choices for the fiber filaments in the composite material include, but are not limited to, glass fibers, aramid fibers, carbon fibers, and boron fibers and combinations thereof. Other choices for the matrix resin include, but are not limited to, bismaleimide, polyimide, polyetherimide, polyetherketone, poly(aryl sulfone), polyethersulfone and cyante ester and combinations thereof. The matrix may additionally include other materials to toughen or strengthen the final material. The airfoil 30 may be formed with multiple layers of composite material which build upon one another to form the desired shape of the airfoil 30. Although a number of layers are shown in the depicted embodiment, more layers or fewer layers may be utilized. According to one embodiment, the airfoil 30 may be formed of for example a polymeric matrix composite (PMC). According to other embodiments, carbon fibers, glass fibers or some combination thereof may be utilized and may be laid in the chordwise, spanwise, oblique directions or combinations thereof through each or multiple layers.
The wrap material 36 may be formed of castable material, such as castable foam, composite material or polyurethane. The wrap may for instance use any of the above listed materials as used with the parent material 34. These parent 34 and wrap 36 materials are however at least partially dissimilar and may be completely dissimilar. An interlock region 50 is found between the parent 34 and wrap 36 where the parent 34 and wrap 36 materials join together. The interlock region 50 is depicted between the broken lines in
The airfoil 30 further includes a pressure side 31 and a suction side 33 (
The fan blade 30 further comprises a leading edge 38, an interlock region 50 for the pressure blade 30 extends from a lower end or shank 42 near the rotor disc 32 upward to the lip or end 44 of the fan blade. The fan blade 30 may be solid, hollow, partially hollow, in whole or in part with some low density materials. The interlock region 50 defines an area where a mechanical interlock feature extends from the parent material 34 to the wrap material 36.
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While multiple inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the invent of embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
Examples are used to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the apparatus and/or method, including making and using any devices or systems and performing any incorporated methods. These examples are not intended to be exhaustive or to limit the disclosure to the precise steps and/or forms disclosed, and many modifications and variations are possible in light of the above teaching. Features described herein may be combined in any combination. Steps of a method described herein may be performed in any sequence that is physically possible.
All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.
It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
