CERAMIC MATRIX COMPOSITE COMPONENTS
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.
Latest UNITED TECHNOLOGIES CORPORATION Patents:
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.
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.
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.
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).
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.
SUMMARYThe present disclosure teaches a CMC turbine component having a platform which has been strengthened for HCF resistance.
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.
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.
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.
Referring now to the drawings,
Referring now to
Referring now to
The end platform configurations shown in
The same techniques can be used to add platforms at different blade span locations.
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.
Due to centrifugal loading, the shrouds or platforms shown in
For the shroud arrangement shown in
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.
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.
With regard to the added plies 80 shown in
Referring now to
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.
The blade-shroud/platform designs described herein provide low vibration and additional high cycle fatigue strength.
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.
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.
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.
Type: Application
Filed: Jul 5, 2011
Publication Date: Jan 10, 2013
Applicant: UNITED TECHNOLOGIES CORPORATION (Hartford, CT)
Inventors: Jun Shi (Glastonbury, CT), David C. Jarmon (Kensington, CT)
Application Number: 13/176,076
International Classification: F01D 5/14 (20060101);