U.S. patent application number 13/176076 was filed with the patent office on 2013-01-10 for ceramic matrix composite components.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to David C. Jarmon, Jun Shi.
Application Number | 20130011271 13/176076 |
Document ID | / |
Family ID | 46458305 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130011271 |
Kind Code |
A1 |
Shi; Jun ; et al. |
January 10, 2013 |
CERAMIC MATRIX COMPOSITE COMPONENTS
Abstract
A CMC component has an integral airfoil and root portion formed
by a plurality of plies extending in a spanwise direction and an
external feature formed by a plurality of bent plies.
Inventors: |
Shi; Jun; (Glastonbury,
CT) ; Jarmon; David C.; (Kensington, CT) |
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
46458305 |
Appl. No.: |
13/176076 |
Filed: |
July 5, 2011 |
Current U.S.
Class: |
416/230 |
Current CPC
Class: |
F01D 5/28 20130101 |
Class at
Publication: |
416/230 |
International
Class: |
F01D 5/14 20060101
F01D005/14 |
Claims
1. A CMC component comprises an integral airfoil and root portion
having a core formed by a plurality of plies extending in a
spanwise direction and an external feature formed by a plurality of
plies bent with respect to said spanwise direction.
2. The CMC component according to claim 1, wherein said bent plies
are attached to an exterior portion of said component and form a
platform.
3. The CMC component according to claim 2, wherein said bent plies
each have a first portion which extends from the root portion to a
mid span portion of said airfoil and a bent portion at an angle to
said first portion.
4. The CMC component according to claim 2, wherein said bent plies
each have a first portion which extends along the root portion and
a bent portion at an angle to said first portion which form a
platform adjacent said root portion.
5. The CMC component according to claim 1, wherein said bent plies
comprises extensions of at least some of said plies forming said
integral airfoil and root portion, said extensions extending beyond
a tip portion of said airfoil portion, and wherein said external
feature comprises a tip shroud formed by said extensions.
6. The CMC component according to claim 5, wherein said tip shroud
is formed by a bent portion of said extensions and said bent
portion is bent at an angle to said spanwise direction.
7. The CMC component according to claim 6, wherein a first number
of said extensions are bent in a first direction and a second
number of said extensions are bent in a second direction opposed to
said first direction.
8. The CMC component according to claim 7, wherein said first
number of said extensions have a first tip portion which are at an
angle with respect to said first direction and said second number
of said extensions have a second tip portion which are at an angle
with respect to said second direction.
9. The CMC component according to claim 6, wherein said first
number of said extensions includes a plurality of extensions having
a bent tip portion extending in a third direction and a plurality
of extensions having a bent tip portion extending in a fourth
direction opposed to the third direction forming a split end
shroud.
10. The CMC component according to claim 9, wherein said second
number of said extensions includes a plurality of extensions having
a bent tip portion extending in said third direction and a
plurality of extensions having a bent tip portion extending in said
fourth direction opposed to the third direction forming said split
end shroud.
11. The CMC component according to claim 5, further comprising a
plurality of plies positioned on said extensions.
12. The CMC component of claim 11, wherein said plurality of plies
are attached to said extensions by one of stitching and
Z-pinning.
13. The CMC component of claim 1, wherein said component is a
turbine blade.
14. The CMC component of claim 1, wherein said component is a vane.
Description
BACKGROUND
[0001] The present disclosure is directed to a ceramic matrix
composite (CMC) components, such as a blade or vane, for use in a
gas turbine engine which is provided with a platform.
[0002] Ceramic matrix composites (CMCs) have been proposed for
application in the high temperature sections of gas turbine engines
because of their high strength in hot, corrosive, and oxidating
atmospheres. For high efficiency gas turbine engines, the gas
temperatures at the turbine section of the engine may be so high
that nickel based superalloy blades would need substantial cooling
to withstand the high gas temperatures.
[0003] Cooling turbine blades incurs engine efficiency penalties as
the cooling air bypasses the high pressure turbine. As a result of
this, less energy is extracted from the gas flow by the turbines.
Therefore, there is a desire to use high temperature materials such
as ceramic matrix composites (CMCs) for turbine blades and
eliminate the cooling requirements for metallic blades.
[0004] Turbine blades tend to have high aspect ratio, or long in
radial direction of the engine but narrow in the blade chord
direction. They also tend to be thin for best aerodynamic
performance. Such long, narrow and thin blades have low bending and
torsional stiffness and therefore have the propensity to vibrate
under unsteady aerodynamic pressure. The vibration could
potentially cause blade high cycle fatigue (HCF).
[0005] To prevent HCF induced fatigue of turbine blades, shrouds
are commonly added to the tip of the blades and sometimes to the
mid-span of the blades. The shrouds serve at least two purposes:
(1) stiffening the blades through centrifugal loading and contact
between the shrouds; and (2) adding damping through frictional
rubbing between the shrouds. The shrouds of metal turbine blades
are typically integrally cast with the blade airfoils, platforms
and roots.
SUMMARY
[0006] The present disclosure teaches a CMC turbine component
having a platform which has been strengthened for HCF
resistance.
[0007] In accordance with the present disclosure, there is provided
a CMC component which broadly comprises an integral airfoil and
root portion having a core formed by a plurality of plies extending
in a spanwise direction and an external feature formed by a
plurality of bent plies. The external feature may be a platform
located at different places on the blade.
[0008] Other details of the (CMC) blade are set forth in the
following detailed description and the accompanying drawings
wherein like reference numerals depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a CMC blade without a blade
root insert;
[0010] FIG. 2 is a perspective view of a CMC blade with a blade
root insert;
[0011] FIG. 3 is a side view of a blade without a platform at blade
tip;
[0012] FIG. 4 is a side view of a blade with platform at blade
tip;
[0013] FIG. 5 is a side view of a blade with end platforms;
[0014] FIG. 6 is a side view of a blade with split end
platforms;
[0015] FIG. 7 is a side view of a blade with a mid-span
platform;
[0016] FIG. 8 is a side view of a blade with a root end
platform;
[0017] FIG. 9 is a side view of a blade with added plies at the
blade tip; and
[0018] FIG. 10 is a sectional view of a blade with plies extending
from the root to the tip.
DETAILED DESCRIPTION
[0019] As used herein, the term "platform" means a platform which
can be at the blade tip, mid-span and root and a shroud such as a
blade tip platform.
[0020] Referring now to the drawings, FIG. 1 shows a CMC turbine
blade 10 having a tapered wedge geometry. As can be seen in the
Figure, the blade 10 has an airfoil portion 12 and a root portion
14 formed by plies 22 of a CMC material extending in a spanwise
direction. The CMC material forming the airfoil portion 12 and the
root portion 14 may be layers or plies 22 of two-dimensional ply
drop offs or a three dimensional weave. The turbine blade 10
differs from other composite turbine blades in that it does not
have a core formed from a material such as rigid foam.
[0021] FIG. 2 illustrates a turbine blade 20 having a root portion
14 with a ceramic core insert 16 and a surrounding CMC material 18
forming the blade root portion 14 and the airfoil portion 12.
[0022] FIG. 3 is a side view of an unshrouded blade 10, i.e.,
without a platform at its blade tip. The blade 10 may formed by a
plurality of plies 22 extending in a spanwise direction. The
airfoil portion 12 of the blade 10 typically has a curved pressure
side 21 and a curved suction side 23.
[0023] FIG. 4 is a side view of a CMC blade 10 having an integral
airfoil 12 and root portion 14 and where the core 19 of the blade
is formed by a plurality of plies 22 of a CMC material extending in
a spanwise direction. As can be seen from the figure, a tip shroud
30 is added. The tip shroud 30 may be formed by having a plurality
of the plies 22' extend beyond the tip portion 32 of the blade 10.
The extended plies or extensions 22' are bent with respect to the
spanwise direction of the blade 10. For example, the extended plies
22' may be bent by approximately ninety degrees so that the
extended plies are almost horizontal. As can be seen in FIG. 4, a
first portion of the extended plies or extensions 22' may be bent
in a first direction and a second portion of the extended plies or
extensions 22' may be bent in a second direction opposed to the
first direction.
[0024] Referring now to FIG. 5, there is shown a CMC blade 10
having an integral airfoil 12 and root portion 14 and where the
core 19 of the blade is formed by a plurality of plies 22 of a CMC
material. The blade 10 in this figure is provided with end
platforms 40 formed by a plurality of plies or extensions 22' which
extend beyond the tip portion 32 of the airfoil portion 12. Each of
the end platforms 40 may be formed by bending a portion of the
extended plies or extensions 22' with respect to the spanwise
direction of the blade 10. The extended plies or extensions 22' may
first be bent at an angle of approximately ninety degrees with
respect to the spanwise direction in either the first or second
direction. The tips 42 of the bent plies are then bent with respect
to the first and/or second direction so as to extend vertically
upwards, substantially in a spanwise direction. For example, the
tips 42 of the extended plies or extensions 22' may be bent by an
angle of approximately ninety degrees with respect to the first or
second direction. In another embodiment, the tips 42 of the bent
plies are bent with respect to the first and/or second direction so
as to extend vertically downwards, substantially in a spanwise
direction.
[0025] Referring now to FIG. 6, there is shown a blade 10 with
split end platforms 50 formed by the extended plies or extensions
22'. As before, the blade 10 is formed by a CMC material and has an
integral airfoil 12 and root portion 14. The blade 10 also has a
core 19 which is formed by a plurality of plies 22 of a CMC
material. The split end platforms 50 may be formed as in the
embodiment of FIG. 5 with the exception that the tips 52 of some of
the bent plies or extensions 22' and the tips 54 of other of the
bent plies or extensions 22' are bent in a third direction
approximately 90 degrees upwardly or in a fourth direction
approximately 90 degrees downwardly.
[0026] The end platform configurations shown in FIGS. 5 and 6
create contact area between blades and thereby increase the
stiffness and damping effect.
[0027] The same techniques can be used to add platforms at
different blade span locations. FIG. 7 illustrates an unshrouded
blade 10 having an integral airfoil 12 and root portion 14. The
integral airfoil 12 and root portion 14 have a core 19 formed by a
plurality of plies 22 of CMC material extending in a spanwise
direction. The blade 10 further has platforms 60 located
essentially at the mid span of the airfoil portion 12 of the blade
10. The platforms 60 are formed by a plurality of plies 62 of CMC
material having a first portion 64 extending in a spanwise
direction and a second portion 66 bent with respect to the spanwise
direction of the blade 10. The second portion 66 is bent outwardly
at an angle of approximately ninety degrees with respect to the
spanwise direction. FIG. 10 illustrates yet another blade 10 having
a mid-span platform 60. As can be seen, the plies 22 of CMC
material extend from the root portion 14 to the tip portion 61.
[0028] FIG. 8 illustrates an blade 10 having an integral airfoil 12
and root portion 14. The integral airfoil 12 and root portion 14
have a core 19 formed by a plurality of plies 22 of CMC material
extending in a spanwise direction. The blade 10 further has root
end platforms 70 formed by a plurality of plies 72 of a CMC
material having a first portion 74 extending along the root portion
14 and a second portion 76 bent with respect to the spanwise
direction. The second portion 76 may be bent outwardly at an angle
of approximately ninety degrees with respect to the spanwise
direction.
[0029] The plies 62 and 72 may be formed from the same CMC material
which is used to form the plies 22 of the core 19 of the blade 10.
They may be attached or joined to the plies 22 forming exterior
portions of the core 19 of the blade 10 using any suitable
technique for joining plies of ceramic matrix composite materials
together.
[0030] Due to centrifugal loading, the shrouds or platforms shown
in FIGS. 4-8 induce compressive stress at ply transition regions
(circled by dashed lines in these figures). The compressive
stresses impede delamination between the plies. However, the
manufacturing process may introduce defects in these transition
regions and lower the interlaminar tensile strength. To counter
such a potential reduction in interlaminar tensile strength,
through thickness stitching 79 can be added to these regions as
shown in FIG. 9. For embodiments where the shrouds 30 are located
at the blade tip 32, as in the embodiment of FIG. 4, extra plies 80
of CMC material can be added and bonded to the bent portions of the
extended plies. The extra plies 80 also help to stiffen the
blade.
[0031] For the shroud arrangement shown in FIG. 4, the edges 82 of
the shroud 30 could be shaped to maximize the effect of shroud
interlocking, which enhances stiffening and damping effect.
[0032] The fiber architecture and material selection for the CMC
blade designs described herein may be tailored to achieve the
required material properties for blade performance. Material
properties of importance include: in-plane tensile strength,
interlaminar tensile strength, interlaminar shear strength, elastic
modulus, thermal conductivity, and thermal expansion.
[0033] The blade to shroud/platform transition can be achieved by
forming the plies 22 of the core 19 from two dimensional ply layups
or an integrally woven three-dimensional fiber weave. Weaving can
be used to create a three dimensional architecture that divides
into two separate three dimensional architectures to create the
shroud/platform segments. The three-dimensional weaves can be
created on either a Doppie or Jacquard loom. The Jacquard loom has
the capability to create more complicated architectures since it
controls the placement of each fiber tow individually.
[0034] With regard to the added plies 80 shown in FIG. 9, the
additional plies 80 can be attached to two dimensional ply layups
by such methods as stitching and Z-pinning.
[0035] Referring now to FIG. 10, there is shown a blade having a
root portion 14 and a tip portion 61. As can be seen from the
figure, the plies 22 run from the root portion 14 to the tip 61 and
from a mid-spin platform 60.
[0036] The CMC blade-shroud/platform designs described herein can
be fabricated in a variety of CMC systems including: silicon
carbide/silicon carbide (SiC/SiC), melt infiltrated SiC/SiC,
SiC/silicon-nitrogen-carbon (SiC/SiNC), and oxide/oxide. A useful
fiber for the designs described herein is a high modulus SiC fiber
due to temperature and loading considerations. A variety of SiC
fibers can be used for reinforcement, including Sylramic, iBN
Sylramic, Hi-Nicalon, Hi-Nicalon Tupe S, CG Nicalon, and Tyranno
SA.
[0037] The blade-shroud/platform designs described herein provide
low vibration and additional high cycle fatigue strength.
[0038] While the present invention has been described into context
of a turbine blade, the same technology could be used to form other
turbine engine components such as a vane.
[0039] There is provided herein a shrouded CMC blade. While the
shrouded CMC blade has been described in the context of specific
embodiments and combination thereof, other unforeseen alternatives,
modifications, and variations may become apparent to those skilled
in the art having read the foregoing description. Accordingly, it
is intended to embrace those alternatives, modifications, and
variations as fall within the broad scope of the appended
claims.
* * * * *