Turbine blade assembly   

The subject invention was conceived under United States Government contract DE-FC26-05NT42643-DOE. The Federal Government may have certain rights to this invention.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbomachines. More specifically, the subject disclosure relates to turbine blade assemblies for turbomachines.

Turbine assemblies include a number of blades secured to a rotor. In some turbines, it is desirable for the blade to include an airfoil portion and a platform portion into which the airfoil portion is inserted, often in order to allow the airfoil portion and the platform portion to be formed from different materials. The combined airfoil/platform blade assembly is secured to the rotor via, for example, a conventional dovetail attachment.

Blade assemblies where the airfoil portion and the platform portion are of differing materials having differing mechanical and thermal characteristics that introduce thermal matching problems as well as issues regarding the mechanical integrity of the assembly. In such assemblies the airfoil portions are typically secured to the platform portions also via dovetails, often in an axial direction. This introduces leakage paths through the turbomachine, for which additional sealing structures must be introduced to control the leakage. As such, the part count and therefore cost of the turbomachine increases. The art would well receive a turbine blade assembly that is cost effective and does not greatly negatively impact leakage through the turbomachine.

According to one aspect of the invention, a blade assembly for a rotor includes an attachment section operably connectable to a rotor, and an airfoil section. At least one retainer extends in a substantially tangential direction at least partially through the airfoil section and the attachment section to secure the airfoil section to the attachment section.

According to another aspect of the invention, a method of assembling a rotor assembly includes inserting at least one retainer in a substantially tangential direction at least partially through an attachment section of a blade assembly and an airfoil section of the blade assembly, thereby securing the airfoil section to the attachment section. The blade assembly is then secured to a rotor.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

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 are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a partial plan view of an embodiment of a rotor assembly;

FIG. 2 is an exploded view of an embodiment of a blade assembly for a rotor assembly; and

FIG. 3 is a cross-sectional view of an embodiment of a blade assembly for a rotor assembly.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION

Shown in FIG. 1 is an embodiment of a rotor assembly 10 for, for example, a turbine of a turbomachine. The rotor assembly 10 includes a plurality of blade assemblies 12 secured to a rotor 14 at a periphery of the rotor 14 via, for example, a plurality of dovetail attachments 16.

Referring to the exploded view of FIG. 2, a blade assembly 12 includes an airfoil section 18 and an attachment section 20. The airfoil section 18 includes an airfoil 22 and, in some embodiments, a platform 24 which defines an annular flowpath of the rotor 14. The airfoil section 18 may be formed from a variety of materials, which are well suited to the high temperature environment in which many rotors 14 operate. For example, the airfoil section 18 may be formed from a ceramic matrix composite (CMC), or a single crystal alloy. The attachment section 20 is formed separately from the airfoil section 18 and may be formed from a material different than that utilized in the airfoil section 18. Since the environment of the attachment section 20 is not as high temperature as that of the airfoil section 18, lower cost metallic materials such as nickel alloys may be used. The attachment section 20 includes an attachment feature to secure the blade assembly to the rotor 14, which in some embodiments is the dovetail 16.

The attachment section 20 includes a web portion 26, which in some embodiments, extends in a substantially axial direction along the attachment section 20. The web portion 26 includes a pocket 28 into which a tab 30 of the airfoil section 18 is inserted. The pocket 28 includes one or more pocket holes 32 through at least one wall of the pocket 28. As shown in FIG. 2, in some embodiments the pocket hole 32 extends through an axially-extending sidewall 34 of the pocket 28. Although the embodiment of FIG. 2 includes one pocket hole 32, it is to be appreciated that two or more pocket holes 32 may be included. The tab 30 includes at least one tab hole 36 extending therethrough and substantially aligned with the one or more pocket holes 32. While the tab hole 36 and the pocket hole 32 shown in FIG. 2 are round, it is to be appreciated that the tab hole 36 and/or the pocket hole 32 may be other shapes, for example oval or angular.

One or more retainers, for example, blade pins 38 are included to secure the airfoil section 18 to the attachment section 20. Each blade pin 38 extends tangentially through the pocket hole 32 and at least partially through the tab hole 36. Referring now to FIG. 3, the blade pin 38 extends through the pocket hole 32 at a first sidewall 34 of the pocket 28 and through the tab hole 36. In this embodiment, a second sidewall 34 of the pocket is without a pocket hole 32 so that a tip 40 of the blade pin 38 does not pass entirely through the pocket 28. To prevent the blade pin 38 from being inadvertently removed, when the adjacent blade assembly 12 is installed in the rotor 14, the sidewall 34 of the adjacent blade assembly 12 may substantially abut a head 42 of the blade pin 38 to retain the blade pin 38 in the blade assembly 12. In other embodiments, the blade pin may be retained in the blade assembly 12 via a process such as welding, or other retention means. Further, the blade pin 38 may be assembled to the blade assembly 12 via a press fit. Even though a blade pin 38 is utilized in the illustrated embodiment of FIG. 3, it is to be appreciated that other means for securing the airfoil section 18 to the attachment section 20, including mechanical threaded fasteners, wedges, welding, and/or adhesives.

Referring again to FIG. 2, in some embodiments, the blade assembly 12 includes a bushing 44 installed into the pocket holes 32 and tab holes 36 prior to installing the blade pin 38. Use of the bushing 44 reduces hertz stresses on the blade assembly 12 in the area of the blade pin 38. As shown in FIGS. 2 and 3, a sleeve 46, comprising for example, a relatively soft material, is disposed between the tab 30 and the pocket 28. The sleeve 46 is utilized to reduce stresses and wear on the tab 30 and the pocket 28 at the interfaces between the tab 30 and the pocket 28.

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.