BACKGROUND
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 pressijre
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 fnst and second rotor disks are joined to the compressor by a
corresponding rotor shaft for powering the con:q)ressor 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 multistage
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 con:q)ressor 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
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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. Thismayoccur 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,
^ k 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.
^ SUMMARY
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
therefi-om, 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
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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 multimaterial
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
j
f k first material, the second airfoil portion extending from the first airfoil portion in a radial
direction, the second airfoil portion having a cavity receiving tiie interlock feature, the
first airfoil and the second airfoil portions defining an interlock region wherein the
i
interlock feature and the interlock cavity are disposed.
All of the above outlined features are to be imderstood 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 fiirther reading of the entire specification, claims,
and drawings included herewith.
BRIEF DESCRIPTION OF THE ILLUSTRATIONS
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 conjimction with the accompanying drawings, wherein:
FIG. 1 is a side-section small view of an exemplary turbine engine.
•
FIG. 2 is a side view of a fan rotor assembly.
FIG. 3 is a section view of the exemplary multi-material airfoil with an
interlock feature.
4
•
FIG. 4 is an isometric view of an exemplary parent portion of the multi-material
airfoil.
FIG. 5 is a section view of an exemplary multi-material airfoil with interiock
feature.
FIG. 6 is a side view of an exemplary interiock feature further depicting fibrous
material used to fonn the interiock features.
DETAILED DESCRIPTION
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 fi"om 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 fiirther 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
JA (CMC). Other materials may be 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 fi-ont 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.
Referring now to FIGS. 1-6, various embodiments depict apparatuses and
methods for providing for a mechanical interlock feature for multi-material airfoil. The I
airfoil may use any plurality of locations of a turbine engine including, but not limited to f
;
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the turbine, compressor, turbofan, and other locations. Additionally, the multi-material is
also utilized in other airfoil embodiments such as wing, blade, propeller or other locations
on an airplane, wind turbine or marine or industrial use.
Referring initially to FIG. 1, a schematic side section view of a gas turbine
engine 10 is shown having an engine inlet end 12, a compressor 14, a combustor 16 and a
multi-stage high pressure turbine 20. The gas turbine engine 10 may be used for aviation,
power generation, industrial, marine or the like. Depending on the usage, the engine inlet
end 12 may alternatively contain multi-stage compressors rather than a fan. The gas
turbine 10 is axis-symmetrical about engine axis 26 or high pressure shaft 24 so that
J ^ various engine components rotate thereabout. In operation air enters through the air inlet
end 12 of the engine 10 and moves through at least one stage of compression where the
air pressure is increased and directed to the combmtor 16. The compressed air is mixed
with fuel and burned providing the hot combustion gas which exits the combustor 16
toward the high pressure turbine 20. At the high pressure turbine 20, energy is extracted
from the hot combustion gas causing rotation of turbine blades which in turn cause
rotation of the shaft 24. The shaft 24 passes toward the front of the engine to continue
rotation of the one or more compressor stages 14, a turbo fan 18 or inlet fan blades,
depending on the turbine design.
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. I
Referring still to FIG. 1, the inlet 12 includes a turbofan 18 having a plurality of
blades. The turbofan 18 is connected by shaft 28 to the low pressure turbine 19 and
creates thrust for the turbine engine 10. Although discussed with respect to the various
blades of the turbine 19, the multi-material airfoil may be utilized with various airfoils
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within the turbine engine 10. Additionally, the multi-material blade may be utilized with
various airfoils associated with structures other than the turbine engine as well.
Referring now to FIG. 2, a side view of a single fan blade 30 is depicted
connected to a rotor disc 32. Although a fan blade is shown and described, other
components utilized in the airfoil shape may utilize the described multi-material interiock
feature 52 (FIG. 3). The fan blade or aufoil further includes a parent material or a first
portion 34 and a wrap material or second portion 36. The rotor disc 32 is connected to a
shaft, such as a high pressure shaft 24 (FIG. 1) or a low pressure shaft 28 (FIG. 1). The
rotor disc 32 rotates with the rotation of the shaft causing rotation of the airfoils 30. The
^ ^ blade or airfoil 30 includes a root portion which is connected to a, for example, rotor
assembly within the compressor 20, the turbofan 18 or the turbine 20 of the turbine
engine 10. For example, the root may be received in the cavity of a rotor disk 32 or may
utilize other mechanical connection with the rotor.
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 nonmetal)
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 sulfime), polyethersulfbne 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
nimiber 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
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chordwise, spanwise, oblique directions or combinations thereof through each or muhiple
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 FIG. 2.
fjP The airfoil 30 further includes a pressiire side 31 and a suction side 33 (FIG. 3)
wherein the distance from a leading edge 38 to a trailing edge 40 across the suction side
is typically longer than the distance from the leading edge to the trailing edge 32 across
the pressure side. In a gas turbme compressor application, the turbine blade 30 rotates in
a direction such that the pressiu'e side passes a reference point before the suction side
passes the same reference point. In a steam turbine application the airfoil may rotate in a
direction such that the suction side passes a reference point before the pressure side
passes the same reference point.
The fan blade 30 further comprises a leading edge 38, an interlock region 50 for
the pressiu-e 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 sohd, hollow, partially
j ^ 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.
Referring now to FIG. 3, a section view of the fan blade 30 is depicted in the
interlock region 50 is clearly shown in a direction perpendicular to that shown in FIG. 2.
The fan blade 30 depicts the parent material 34 and the wrap material 36 as well as the
interlock region 50. Within the interlock region 50, an interlock feature 52 is provided.
According to one exemplary embodiment, the interlock feature 52 comprises an inverted i
dovetail 54 extending radially upwardly from the parent 34. The inverted dovetail 54 is
integrally formed with the parent 34 and the wrap 36 comprises a cavity 56 which is
s
8 !
integrally fonned to receive the interlock feature 52. The cavity 56 may have a
corresponding shape to that of the interlock feature 52. Accordingly, as shown in the
exemplary embodiment, the cavity 56 also comprises a female inverted dovetail shape to
receive the corresponding male feature of the parent 34.
As additionally shown in FIG. 3, a cladding 70 is utilized on either or both
sides of the blade. The cladding 70 may be formed of various materials which are similar
or dissimilar from the parent 34 and the wrap 36. The cladding 70 may be attached by
fastening, adhesives or various other maimers. Additionally, it should be understood that
the cladding 70 is optional and therefore may or may not be utilized depending on the
^ k application.
Referring now to FIG. 4, an isometric view of a parent 34 as seen from the
leading edge 38 to trailing edge 40. The interlock feature 52 is shown having an upper
thickness 58 which varies between the leading edge 38 and the trailing edge 40. The
thickness at 58 may be engineered depending on the anticipated loading occurring along
the point of the parent material at the interlock region 50 (FIG. 3). The thickness 58 may
vary also with the curvature of the blade 30.
Referring now to FIG. 5, a sectional view of the parent 34 is depicted with the
wrap 36 shown in broken line. The mechanical interlock feature 52, comprises the
exemplary inverted dovetail 54. In this view various design parameters are depicted
around the interlock feature 52. As previously described, width or thickness 58 may vary
^ between the leading edge 38 and trailing edge 40 of the blade 30 or parent 34. Adjacent
dimension 80 may be designed based on the total weight of the wrap material 36.
Similarly, angled surfaces 84, having angles theta (D), are shown extending from the
lower portion of the interlock feature 52 arid measured from a vertical line shown
adjacent each of these surfaces. Angle theta (D) is sized to allow for greatest shear !
interface load between the parent 34 and the wrap 36. A neck thickness 82 is shown at
the bottom of the dovetail which is also sized based on total weight of the wrap material
36 under a rotational load. Specific sizing of the interlock angles and resulting
thicknesses will be material dependent such as to utilize each materials capability. The
9
interlock feature 52 may be formed by continuously adding layers of composite material
to build the inverted dovetail 54, for example, to a desired size.
Referring now to FIG. 6, an additional side sectional view of the parent
material 34 is depicted. One feature utilized at the instant embodiment may be
continuous fibers 90 extending firom the parent material 34 into the interlock feature 52.
The continuous fibers 90 extending fi-om the parent material 34 into the interlocking
feature 52 increase shear strength and tensile strength for the interlock feature 52, which
in some embodiments comprises the inverted dovetail 54.
While multiple inventive embodiments have been described and illustrated
1 ^ 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 config\irations will depend
upon the specific application or appUcations 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,
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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 imderstood to control
over dictionary definitions, defmitions in docimients incorporated by reference, and/or
ordinary meanings of the defined terms. The indefinite articles "a" and "an," as used
J ^ herein in the specification and in the claims, imless clearly indicated to the contrary,
should be imderstood 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 conjxmctively 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 o f and "consisting
essentially o f 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.
F
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We Claims :
1. A mechanical interlock for a multi-material airfoil, comprising:
a first airfoil portion connectable to a rotor disk, said first airfoil portion being
formed of a first material;
said first airfoil portion having an interlock feature extending therefrom;
^ a second airfoil portion connected to said interlock feature of said first airfoil
portion, said second airfoil portion extending from said first airfoil portion in a
radial direction;
said second airfoil portion fomfied of at least a partially dissimilar material.
2. The mechanical interlock for a multi-material airfoil of Claim 1 wherein said first
material is a first composite.
3. The mechanical interlock of Claim 2 wherein one of said interlock feature is an
inverted dovetail.
4. The mechanical interlock of Claim 3 wherein said first material includes a plurality
of continuous fibers extending from a lower portion of said first airfoil portion into
^ said inverted dovetail.
5. The mechanical interlock of Claim 1 wherein said second airfoil portion is a
second composite dissimilar from said first composite.
6. The mechanical interlock of Claim 1 wherein said second airfoil portion is one of
a cast-able foam or a polyurethane.
7. The mechanical interlock of Claim 1 further comprising a cladding material
f
overlapping said first airfoil portion and said second airfoil portion.
8. A mechanical interiock for a multi-material airfoil, comprising: ^
a leading edge, a trailing edge, a shank end and an opposed tip; >
12
a parent connectable to a rotor disk, said parent being formed of a first
material and liaving an interiocl< feature extending in a radial upward
direction;
a wrap being formed of at least a partially different material than said first
material, said wrap defining said opposed tip;
said wrap having a cavity for receiving said interlock feature;
said wrap extending from said parent in a radial direction.
9. The mechanical interlock of Claim 8, said interlock feature being an inverted
w dovetail.
10. The mechanical interlock of Claim 9, said inverted dovetail having angled
surfaces.
11. The mechanical interlock of Claim 9, said inverted dovetail having a varying
thickness extending along a length of said airfoil.
12. The mechanical interlock of Claim 8, said interlock feature having continuous
fibers integrally formed between the parent material and the dovetail.
13. The mechanical interlock of Claim 8, said parent material and said wrap
material being differing materials.
14. The mechanical interlock of Claim 8 further comprising a cladding between said
^ parent material and said wrap material.
15. A mechanical interlock for a multi-material airfoil, comprising:
a first airfoil portion formed of a first material and having an interlock feature
extending in a radially upward direction;
a second airfoil portion fomied of a second material wherein said second
material is at least partially different than said first material, said second airfoil
portion extending from said first airfoil portion in a radial direction;
said second airfoil portion having a cavity receiving said interlock feature;
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said first airfoil and said second airfoil portions defining an interlock region
wherein said interlock feature and said Interlock cavity are disposed.
16. The mechanical interlock of Claim 15, said interlock feature being an Inverted
dovetail.
17. The mechanical interlock of Claim 16, said first material including continuous
fibers extending from a radially lower end of said first airfoil portion into said
interlock feature.
18. The mechanical interlock of Claim 15, said first material and said second material
being composite materials.
19. The mechanical interiock of Claim 15 further comprising a cladding extending
across said interiock region.
20. The mechanical interiock of Claim 15 wherein characteristics of said interiock
feature may be varied in a spanwise direction.