Patent Application
20130287588
This disclosure relates, in general, to gas turbine engines and in particular to fan blades for turbines of such turbine engines.
At least one known gas turbine engine assembly includes a fan assembly that is mounted upstream from a core gas turbine engine. During operation, airflow discharged from the fan assembly is channeled downstream to the core gas turbine engine where the airflow is further compressed. The compressed airflow is then channeled into a combustor, mixed with fuel, and ignited to generate hot combustion gases. The combustion gases are then channeled to a turbine which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight.
The referenced fan blade assemblies may include fan blades having root portions which are connected to a rotor such that the rotor rotates in response to gases being directed toward the fan blades. In typical currently used fan blades, an airfoil shape of a fan blade is designed to yield optimum performance at a single operating or flight cycle point, which may be highly inefficient at other design points of importance. For example, such a blade design may be more efficient at one rotating speed relative to another.
There are also examples of prior fan blades including those that have mid chord regions that change in shape from a C-shaped cross-section to an S-shaped cross-section by an unsymmetric arrangement of fibers subjected to in-plane loads during operation. Such blades are constructed to bend at the mid-chord region of the blade to move from the C-shape to the S-shape.
There is a continuing need for blades which provide for more efficient operation of a turbine system of which they are a part.
The present system provides, in one aspect, a fan blade for a turbine system which includes a root portion connectable to a rotating member of a turbine system and airfoil portion having a morphable portion on an edge of the airfoil portion. The morphable portion includes a plurality of layers aligned unsymmetrically relative to each other in a thickness direction and changes in shape in response to a change in a speed of the airfoil portion.
The present technique provides, in a second aspect, a method for use in operating a turbine including rotating a rotor connected to a plurality of fan blades and changing a speed of the rotor to cause a change in a shape of a morphable portion on an edge of an airfoil of a first fan blade of the plurality of fan blades. The morphable portion is formed by a plurality of layers aligned unsymmetrically relative to each other in a thickness direction.
The present system provides, in a third aspect, a fan blade for a turbine system which includes a root portion connectable to a rotating member of a turbine system. An airfoil portion has a shape changing portion on an edge of the airfoil portion and a remainder. The shape changing portion includes a different weight distribution relative to the remainder. The shape changing portion changes shape in response to a change in a rotational speed of the airfoil portion.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention will be readily understood from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings in which:
In accordance with the principles of the present system and techniques, turbine blade systems for use in gas turbine engines for aircraft engines are provided.
Fan assembly 12 includes a plurality of fan blades 24 extending radially outward from a rotor disk 26. Gas turbine engine assembly 10 has an intake side 28 and an exhaust side 18. Fan assembly 12, booster 22, and turbine 131 are coupled together by a first rotor shaft 31, and compressor 14 and turbine 30 are coupled together by a second rotor shaft 32. In operation, air flows through fan assembly 12 and a first portion of the airflow is channeled through booster 22. The compressed air that is discharged from booster 22 is channeled through compressor 14 wherein the airflow is further compressed and delivered to combustor 16. Hot products of combustion (not shown in
A first blade 140 of plurality of fan blades 24 is depicted in
Blade 140 in one embodiment is a composite fan blade constructed as a solid, hollow internal cavity or filled internal cavity with a low density material. In one example blade 140 includes a morphable portion 100, located on the trailing edge of airfoil portion 180 at or near outer edge 101, which is configured to change in shape based on the speed the blade is moving during operation and thus the surface pressure applied by its immediate environment (e.g., gases in the area of fan assembly 12) and centrifugal forces due to the rotation.
The change of the shape of morphable portion 100 relative to remainder 110 allows for the airfoil shape to be optimized at two or more operating cycle points thereby increasing the aerodynamic efficiency of the fan (i.e., plurality of fan blades 20 connected to rotor disk 26), which in turn lowers the specific fuel consumption of the gas turbine engine. For example, morphable portion 100 may have a first shape at a low or cruising speed (e.g., 2291 rpm) and a changed shape at a higher speed present (e.g., 2655 rpm at maximum takeoff conditions). For example, in a chordwise cross-section, an initial shape may be singly curved with a relatively high curvature while the morphed shape is singly curved with a relatively low curvature.
Laminated structures using composite materials may be used to construct fan blades (e.g., blade 140) exhibiting various coupling behaviors such as bending and twisting deflections in the direction perpendicular to the loading in the presence of in-plane and bending loads. Such coupling properties of laminated composite structures may be used to change an airfoil shape (e.g., of blade 140). By tailoring the ply layup in the composite structure both in terms of unsymmetric and/or multi-material ply orientations and the region where these ply orientations occur, the airfoil shape can be morphed (e.g., morphable portion 100) as a function of a centrifugal force which is a function of the rotational speed of the fan blade (e.g., of blade 140). The centrifugal force provides an in-plane load that may cause a fan blade with a coupling behavior to change its shape. Also, the bending load induced by the centrifugal force (or in-plane load) when the fan blade (e.g., blade 140) rotates takes on a significant role in morphing the airfoil. Therefore, the initial shape of the airfoil in the spanwise direction prior to changing its shape may be optimized in addition to the unsymmetric ply layup.
Further, the airfoil shape change (e.g., change in shape of blade 140) can be achieved by tailoring the ply layup in the composite fan blade (e.g., in morphable portion 100) laminated structure through one or a combination of the following methods: 1) unsymmetric ply layup through a thickness of a laminated structure, 2) a ply layup using two or more distinct materials, i.e., multi-material laminated structure, and 3) intentionally changing the weight distribution at various locations of the fan blade. A region or regions of the fan blade or the entire fan blade may be designed in this manner to achieve a desired airfoil shape change.
Blade 140 may be formed by the application/or lamination of a plurality of continuous, unidirectional fiber reinforced matrix material layers. The orientation of each layer or ply is typically defined as the direction of the continuous, unidirectional fibers. For example, blade 140 may be formed of carbon fibers, glass fibers, boron fibers, or a combination of these materials.
Morphable portion 100 may be formed of a plurality of layers whose ply orientations are unsymmetrical through the thickness of the blade while the remainder 110 of blade 140, e.g., all of blade 140 except morphable portion 100, may be formed of a plurality of layers whose ply orientations are symmetrical through the thickness of the blade. Such symmetry and unsymmetry through the thickness of the blade may be about an imaginary center line of the thickness of the blade such that an equal distribution of material of the blade is present between such center line and the corresponding outer surface of the blade in the case of a symmetric arrangement. In contrast, in the case of an unsymmetric arrangement, a different amount of material may be present between such a center line and the corresponding outer surface of the blade on one side of such center line. Thus, the layers of morphable portion 100 in a thickness direction may be arranged differently (e.g., layer(s) of the morphable portion may be longitudinally aligned at an angle relative to each other). Further, the individual layers of morphable portion 100 and remainder 110 could be formed of a same material or the different layers could be formed of a mix of the same and/or different materials in the thickness direction.
In one example depicted in
In contrast to the unsymmetrical alignment of layers in
Further, adjacent layers of morphable portion 100 and remainder 110 could abut one another and could have longitudinal fibers aligned relative to each other or such adjacent portions could be misaligned relative to each other. Such alignment and/or misalignment could be present through the thickness of the layers of the morphable portion and remainder abutting each other.
Further, the layers of morphable portion 100 and remainder 110 could be aligned in any number of ways to allow morphable portion 100 to change its shape based on the centrifugal force applied thereto due to the rotation thereof and surface pressure thereto (e.g., pressure due to the gas surrounding portion 100). Also, morphable portion 100 and/or remainder 110 could have various layers aligned or misaligned relative to one another within such morphable portion and/or remainder 110 to provide a change in shape or resistance to such a change as desired. Moreover, the layers of morphable portion 100 and remainder 110 could have varying thicknesses to provide such a desired change in shape. Also, the ratio of the surface area and/or volume of morphable portion 100 and remainder 110 may also be controlled to provide a desired performance of blade 140 in response to a rotating speed thereof and surface pressure thereto.
The initial shape of an airfoil (e.g., airfoil portion 180) prior to changing shape may be optimized such that the bending loads (or moments) are favorable to induce morphing of a fan blade (e.g., blade 140). Unsymmetric ply layups including multi-material systems and varying weight distributions may be optimized such that in-plane load from centrifugal forces due to blade (e.g., blade 140) rotation and the induced bending moments drive the initial airfoil shape (e.g., blade 140 thereof) to change. In a chordwise cross-section, an initial shape of a blade (e.g., blade 140) may be singly curved with a relatively high curvature while the morphed shape is singly curved with a relatively low curvature.
Further, as described, blade 140 may change shape from a more curved C-shape to a less curved C-shape in response to an increased rotational speed. The shape change occurs in trailing edge region of the blade or in both the leading and trailing edge regions of the blade and not at the mid-chord region of the blade. An example of such a trailing edge is depicted in
It would be understood by one of ordinary skill in the art that a fan blade (e.g., fan blade 140 and any of fan blades 24) could include a morphable portion (e.g., morphable portion 100) at various locations including the leading and trailing edges of the blades at various radial locations relative to a root connectable to a rotor of a fan assembly, (e.g., fan assembly 12).
In another example, a fan blade may be formed of materials having different densities or rigidities to provide a desired change in shape to the blade in response to the centrifugal force (or in-plane load) when the fan blade rotates. Further, the weight distribution of the blade could be manipulated otherwise to provide a desired shape change and performance in operation. Such changes in density, materials, or weight distribution could be done in various portions (e.g., shape changing portions) which could be located at a leading edge, trailing edge or at other locations on a blade. Examples of blades with portions of different weigh distributions are depicted in
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
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 have 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 language of the claims.
