Patent Application
20140112796
1. Field of the Invention
The invention relates to gas turbine engine blades and, particularly, to composite blades.
2. Description of Related Art
Composite blades made from elongated filaments composited in a light-weight matrix have been developed for aircraft gas turbine engines. The blades are light-weight having high strength. The term composite has come to be defined as a material containing a reinforcement such as fibers or particles supported in a binder or matrix material. Many composites are used in the aerospace industry including both metallic and non-metallic composites. The composites used for the blades disclosed herein are made of a unidirectional tape material and an epoxy resin matrix. A discussion of this and other suitable materials may be found in the “Engineering Materials Handbook” by ASM INTERNATIONAL, 1987-1989 or later editions.
The composite blades disclosed herein are made from the non-metallic type made of a material containing a fiber such as a carbonaceous, silica, metal, metal oxide, or ceramic fiber embedded in a resin material such as Epoxy, PMR15, BMI, PEEU, etc. The fibers are unidirectionally aligned in a tape that is impregnated with a resin, formed into a part shape, and cured via an autoclaving process or press molding to form a light weight, stiff, relatively homogeneous article having laminates or plies within.
Composite fan blades have been developed for aircraft gas turbine engines to reduce weight and cost, particularly, for fan blades in larger engines. A large engine composite wide chord fan blades offer a significant weight savings over a large engine having standard chorded fan blades. Among the problems, all gas turbine engine blades face resonance or flexural modes. Large composite fan blades for high bypass ratio aircraft gas turbine engines with relatively wide diameter fans are faced with this problem. This is particularly true for the frequencies that cause the blade to experience first and second flexural airfoil modes.
It is highly desirable to provide light-weight and strong aircraft gas turbine engine fan blades that avoid passing through or experiencing assonance and flexural modes and, in particular, first and second flexural airfoil modes.
A gas turbine engine composite fan blade includes an airfoil having pressure and suction sides extending outwardly in a spanwise direction from a blade root of the blade along a span to a blade tip. A core section of the blade includes composite quasi-isotropic plies extending spanwise outwardly through the blade including the root and the airfoil towards the tip. One or more spars including a stack of uni-tape plies having a preferential 0 degree fiber orientation with respect to the span spanwise outwardly through the root and through a portion of the airfoil towards the tip.
The chordwise extending portion of the core section may be centered about a maximum thickness location of the airfoil. The spars may have a spanwise height, chordwise width, and spar thickness that avoids flexural airfoil modes such as first and second flexural airfoil modes. The one or more spars may include pressure and suction side spars sandwiching a chordwise extending portion of the core section in the airfoil which may be located near or along the pressure and suction sides respectively.
In one embodiment of the blade, the one or more spars include chordwise spaced apart upstream and downstream pressure side spars and chordwise spaced apart upstream and downstream suction side spars sandwiching a chordwise extending portion of the core section in the airfoil.
The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings where:
Illustrated in
The exemplary pressure and suction sides 41, 43 illustrated herein are concave and convex respectively. The airfoil 12 extends along a chord C between chordwise spaced apart leading and trailing edges LE, TE. Thickness T of the airfoil 12 varies in both chordwise and spanwise directions C, S and extends between pressure and suction sides 41, 43 of the blade 10 also referred to as convex and concave sides of the blade or airfoil. The airfoil 12 may be mounted on and be integral with a hub to form an integrally bladed rotor (IBR) or integrally with a disk in a BLISK configuration.
The plies 40 are generally all made from a unidirectional fiber filament ply material, preferably a tape, as it is often referred to, arranged generally in order of span and used to form a composite airfoil 12 as shown in
The composite fan blade 10 is made up of filament reinforced laminations 30 formed from a composite material lay-up 36 of different filament reinforced airfoil plies 40. The blade 10 uses filament reinforced laminations or plies with a filament orientation of 0 degrees, +P degrees, and −P degrees as illustrated in
Referring to
Referring to
The quasi-isotropic ply core section 50 generally include alternating plies of tape with different +P, 0, and −P fiber orientations. The pressure and suction side spars 54, 56 include uni-tape plies with a predominately 0 degree fiber orientation. An exemplary blade ply lay-up is disclosed in U.S. Pat. No. 5,375,978, entitled “Foreign Object Damage Resistant Composite Blade and Manufacture” to Evans, which issued Dec. 27, 1994, is assigned to the same assignee of this patent, and is incorporated herein by reference. The ply lay-up disclosed in U.S. Pat. No. 5,375,978 is referred to as a standard quasi-isotropic lay-up sequence of 0. degree, +45 degree, 0 degree, −45 degree fiber orientations with the plies having the numerous ply shapes.
The stacks 62 of the spars include uni-tape plies with a predominately 0 degree fiber orientation. A few of the plies may have another fiber orientation. An example is a stack having a total of 8 plies with 4 plies of 0 degree fiber orientation on both sides of two plies having +30 and a −30 degree plies. This ply layup may be represented or denoted by 0,0,0,0,+30,−30,0,0,0,0.
Referring to
The exemplary embodiment of the composite blade 10 illustrated herein includes one or more outer cover plies 66 around the core section 50, made of composite quasi-isotropic plies, and the pressure and suction side spars 54, 56. A leading edge metallic shield 68 is bonded around the leading edge LE. The shield is often referred to as metallic cladding.
Referring to
The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. While there have been described herein, what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein and, it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.
Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims:
