Patent Application
20200158341
The present invention relates generally to the use of Ceramic Matrix Composite (CMC) liners in a gas turbine engine combustor and, in particular, to the mounting of such CMC liners to the dome and cowl of the combustor so as to accommodate differences in thermal growth therebetween.
It will be appreciated that the use of non-traditional high temperature materials, such as Ceramic Matrix Composites (CMC), are being studied and utilized as structural components in gas turbine engines. There is particular interest, for example, in making combustor components which are exposed to extreme temperatures from such material in order to improve the operational capability and durability of the engine. However, substitution of materials having higher temperature capabilities than metals has been difficult in light of the widely disparate coefficients of thermal expansion when different materials are used in adjacent components of the combustor. This mismatch can result in binding with adjacent components and subsequent failure unless sufficient clearance is available.
Accordingly, various schemes have been employed to address problems that are associated with mating parts having differing thermal expansion properties. As seen in U.S. Pat. No. 5,291,732 to Halila, U.S. Pat. No. 5,291,733 to Halila, and U.S. Pat. No. 5,285,632 to Halila, an arrangement is disclosed which permits a metal heat shield to be mounted to a liner made of CMC so that radial expansion therebetween is accommodated. This involves positioning a plurality of circumferentially spaced mount pins through openings in the heat shield and liner so that the liner is able to move relative to the heat shield.
U.S. Pat. No. 6,397,603 to Edmondson et al. also discloses a combustor having a liner made of Ceramic Matrix Composite materials, where the liner is mated with an intermediate liner dome support member in order to accommodate differential thermal expansion without undue stress on the liner. The Edmondson et al. patent further includes the ability to regulate part of the cooling air flow through the interface joint.
While each of the aforementioned patents reveals mounting arrangements for a CMC liner which are useful for their particular combustor designs, none involve a liner made of CMC materials being connected directly to the dome and cowl portions of the combustor in a single mounting arrangement. Thus, it would be desirable for a simple mounting assembly to be developed for a liner having a different coefficient of thermal expansion than the components to which it is mated. It would also be desirable for such mounting assembly to be efficiently sized such that clearances with adjacent hardware are not required.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
A combustor for a gas turbine engine is generally provided. In one embodiment, the combustor comprises: a liner comprising a ceramic matrix composite material and having a forward end and an aft end; an annular dome comprising a metal and defining an annular slot within its end defined between an outer arm and an inner arm; a feather seal extending from an annularly exterior surface of the annular dome to an annularly exterior surface of the liner; and a plurality of pin members. The forward end of the liner defines a plurality of fingers and a plurality of axial slots, and is fitted between the outer arm and the inner arm within the annular slot. Each pin member extending through an aperture in the feather seal, through an aperture in the outer arm of the annular dome, through an opening defined by the liner, and through an aperture in the inner arm of the annular dome.
A gas turbine engine is also generally provided, which comprises a compressor; a combustor; and a turbine. The combustor generally comprises: a liner comprising a ceramic matrix composite material and having a forward end and an aft end; an annular dome comprising a metal and defining an annular slot within its end defined between an outer arm and an inner arm; a feather seal extending from an annularly exterior surface of the annular dome to an annularly exterior surface of the liner; and a plurality of pin members. The forward end of the liner defines a plurality of fingers and a plurality of axial slots, and is fitted between an outer arm and an inner arm within the annular slot. Each pin member extending through an aperture in the feather seal, through an aperture in the outer arm of the annular dome, through an opening defined by the liner, and through an aperture in the inner arm of the annular dome.
A liner of a combustor is also generally provided. In one embodiment, the liner comprises a ceramic matrix composite material, with the liner having a forward end that defines a plurality of fingers and a plurality of axial slots.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. 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.
As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.
The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.
Referring now to the drawings,
It should be appreciated that each turbine 28, 30 may generally include one or more turbine stages, with each stage including a turbine nozzle (not shown in
Additionally, as shown in
It should be appreciated by those of ordinary skill in the art that the fan casing 40 may be configured to be supported relative to the core engine 14 by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes 42. As such, the fan casing 40 may enclose the fan rotor 38 and its corresponding fan rotor blades 44. Moreover, a downstream section 46 of the fan casing 40 may extend over an outer portion of the core engine 14 so as to define a secondary, or by-pass, airflow conduit 48 that provides additional propulsive jet thrust.
During operation of the engine 10, it should be appreciated that an initial air flow (indicated by arrow 50) may enter the engine 10 through an associated inlet 52 of the fan casing 40. The air flow 50 then passes through the fan blades 44 and splits into a first compressed air flow (indicated by arrow 54) that moves through conduit 48 and a second compressed air flow (indicated by arrow 56) which enters the booster compressor 22. The pressure of the second compressed air flow 56 is then increased and enters the high pressure compressor 24 (as indicated by arrow 58). After mixing with fuel and being combusted within the combustor 26, the combustion products 60 exit the combustor 26 and flow through the first turbine 28. Thereafter, the combustion products 60 flow through the second turbine 32 and exit the exhaust nozzle 36 to provide thrust for the engine 10.
Referring now to
As shown, the combustor assembly 100 generally includes an inner liner 102 extending between and aft end 104 and a forward end 106 generally along the axial direction, as well as an outer liner 108 also extending between and aft end 110 and a forward end 112 generally along the axial direction. The inner and outer liners 102, 108 together at least partially define a combustion chamber 114 therebetween. The inner and outer liners 102, 108 are each attached to an annular dome 111. More particularly, the combustor assembly 100 includes an inner portion 116 of the annular dome 111 attached to the forward end 106 of the inner liner 102 and an outer portion 118 of the annular dome 111 attached to the forward end 112 of the outer liner 108. As will be discussed in greater detail below, the inner and outer portions 116, 118 of the annular dome 111 each include an enclosed surface 120 defining an annular slot 122 for receipt of the forward ends 106, 112 of the respective inner and outer liners 102, 108.
The combustor assembly 100 further includes a plurality of fuel and air mixers 124 spaced along a circumferential direction within the outer portion 118 of the annular dome 111. More particularly, the plurality of fuel air mixers 124 are disposed between the outer portion 118 of the annular dome 111 and the inner portion 116 of the annular dome 111 along the radial direction. Compressed air from the compressor section of the turbofan engine 10 flows into or through the fuel air mixers 124, where the compressed air is mixed with fuel and ignited to create the combustion gases within the combustion chamber 114. The inner and outer domes 116, 118 are configured to assist in providing such a flow of compressed air from the compressor section into or through the fuel air mixers 124. For example, the outer portion 118 of the annular dome 111 includes an outer cowl 126 at a forward end 128 and the inner portion 116 of the annular dome 111 similarly includes an inner cowl 130 at a forward end 132. The outer cowl 126 and inner cowl 130 may assist in directing the flow of compressed air from the compressor section 26 into or through one or more of the fuel air mixers 124.
Moreover, the inner and outer domes 116, 118 can each include attachment portions configured to assist in mounting the combustor assembly 100 within the turbofan engine 10. For example, the outer portion 118 of the annular dome 111 can include an attachment extension configured to be mounted to an outer combustor casing and the inner portion 116 of the annular dome 111 can include a similar attachment extension configured to attach to an annular support member within the turbofan engine 10. In certain exemplary embodiments, the inner portion 116 of the annular dome 111 may be formed integrally as a single annular component, and similarly, the outer portion 118 of the annular dome 111 may also be formed integrally as a single annular component. It should be appreciated, however, that in other exemplary embodiments, the inner portion 116 of the annular dome 111 and/or the outer portion 118 of the annular dome 111 may be formed by one or more components joined in any suitable manner. For example, with reference to the outer portion 118 of the annular dome 111, in certain exemplary embodiments, the outer cowl 126 may be formed separately from the outer portion 118 of the annular dome 111 and attached to outer portion 118 of the annular dome 111 using, e.g., a welding process. Similarly, any attachment extension may also be formed separately from the outer dam 118 and attached to the outer portion 118 of the annular dome 111 using, e.g., a welding process. Additionally, or alternatively, the inner portion 116 of the annular dome 111 may have a similar configuration.
Referring still to
For the embodiment depicted, the inner liner 102 and outer liner 108 are each comprised of a ceramic matrix composite (CMC) material, which is a non-metallic material having high temperature capability. Exemplary CMC materials utilized for such liners 102, 108 may include silicon carbide, silicon, silica or alumina matrix materials and combinations thereof. Ceramic fibers may be embedded within the matrix, such as oxidation stable reinforcing fibers including monofilaments like sapphire and silicon carbide (e.g., Textron's SCS-6), as well as rovings and yarn including silicon carbide (e.g., Nippon Carbon's NICALON®, Ube Industries' TYRANNO®, and Dow Corning's SYLRAMIC®), alumina silicates (e.g., Nextel's 440 and 480), and chopped whiskers and fibers (e.g., Nextel's 440 and SAFFIL®), and optionally ceramic particles (e.g., oxides of Si, Al, Zr, Y and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite and montmorillonite). CMC materials may have coefficients of thermal expansion in the range of about 1.3×10−6 in/in/° F. to about 3.5×106 in/in/° F. in a temperature of approximately 1000-1200° F.
By contrast, the inner portion 116 of the annular dome 111 and outer portion 118 of the annular dome 111, including the inner cowl 130 and outer cowl 126, respectively, may be formed of a metal, such as a nickel-based superalloy (having a coefficient of thermal expansion of about 8.3-8.5×10−6 in/in/° F. in a temperature of approximately 1000-1200° F.) or cobalt-based superalloy (having a coefficient of thermal expansion of about 7.8-8.1×106 in/in/° F. in a temperature of approximately 1000-1200° F.). Thus, the inner and outer liners 102, 108 may be better able to handle the extreme temperature environment presented in the combustion chamber 114. However, attaching the inner and outer liners 102, 108 to the respective inner and outer domes 116, 118 presents a problem due to the differing mechanical characteristics of the components. Accordingly, as will be discussed below, a specially designed mounting assembly 144 is utilized to attach the forward end 106 of the inner liner 102 to the inner portion 116 of the annular dome 111, as well as to attach the forward end 112 of the outer liner 108 to the outer portion 118 of the annular dome 111. The mounting assemblies 144 are configured to accommodate the relative thermal expansion between the inner and outer domes 116, 118 and the inner and outer liners 102, 108, respectively, along the radial direction.
Referring now particularly to
For the embodiment depicted, the mounting assembly 144 includes a pin member 166 and an optional bushing 168 that extend through apertures 201, 203 defined in the outer arm 200 and the inner arm 202, respectively. The pin member 166 includes a head 170 and a nut 174 is attached to a distal end of the pin member 166. In certain exemplary embodiments, the pin member 166 may be configured as a bolt and the nut 174 may be rotatably engaged with the pin member 166 for tightening the mounting assembly 144. Alternatively, however, in other exemplary embodiments, the pen member 166 and nut 174 may have any other suitable configuration. For example, in other exemplary embodiments, the pin 166 may include a body 172 defining a substantially smooth cylindrical shape in the nut 174 may be configured as a clip. Additionally, the bushing 168 is generally cylindrical in shape and positioned around the pin member 166.
Referring to
Referring again to
In particular embodiments, the outer liner 108 defines a tapered portion 211. That is, the outer liner 108 has a thickness in its body portion 213 that is greater than the thickness of the fingers 113 and/or at its forward end 112. In the embodiment shown in
Each pin member 166 extends through an aperture in the feather seal 211, through an aperture in the outer arm 200 of the annular dome 118, through an axial slot 109 in the outer liner 108, and through an aperture in the inner arm 202 of the annular dome 118 to secure the components together. The number of pin members 166 annularly securing the outer annular dome 118 may be the same as the number of slots 109 (i.e., one pin member 166 extending through each slot 109); may be less than the number of slots 109; or more than the number of slots 109. That is, the plurality of axial slots 109 can be greater in number than the plurality of pin members 116, to allow for radial expansion and contraction of the outer liner 108 in certain embodiments. However, in other embodiments, the plurality of axial slots 109 can be lesser in number than the plurality of pin members 116 (e.g., when using wider and/or longer fingers, more than 1 pin member 166 may be utilized per finger).
A combustor in accordance with an exemplary embodiment of the present disclosure assembly having a cap positioned over an inner liner or an outer liner may be capable of controlling an airflow from a relatively high pressure plenum or a relatively high pressure inner passage into a combustion chamber through an attachment point between the inner or outer liners and an inner or outer dome. Moreover, such a combustor assembly may be capable of controlling an airflow from a relatively high pressure plenum or a relatively high pressure inner passage into a combustion chamber through an attachment point between the inner or outer liners and an inner or outer dome while still accommodating a relative thermal expansion between the inner or outer liners and inner or outer domes.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
