BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of the part span shroud on a fan blisk, according to an embodiment of the invention.
FIG. 2 is an alternative view of the fan blisk of FIG. 1.
FIG. 3A is a perspective view of an alternate welding configuration on the part span shroud of a fan blisk according to the embodiments of the invention.
FIG. 3B is a front view of the part span shroud of FIG. 3A.
FIG. 4 is a perspective view of an alternate embodiment of the invention.
FIG. 5 is an alternate view of the embodiment of FIG. 4.
FIG. 6 is an alternate view of the embodiment of FIG. 4.
FIG. 7 is an illustration of an alternate embodiment of a part span shroud welding configuration.
FIG. 8 is an illustration of the present invention with only one weld connection.
FIG. 9 is an illustration of the present invention with a weld connection substantially parallel to the shroud interface.
FIG. 10A is an illustration of the present invention where the airfoils are attached in pairs.
FIG. 10B is an alternate view of FIG. 10A where the shroud segments are connected before the airfoils are attached to the blisk.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1, 2, 3A and 3B illustrate various embodiments of the present invention. The present invention is directed to a part span shrouded blisk 10 that increases the stability of a fan blade while decreasing the overall weight associated with higher stability blisks. FIG. 1 shows a blisk 10 according to an embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed substantially parallel to each other and in areas of lower stress on the part span shroud. The part span shroud segments 18 are secured with the weld connections 20 such that the weld connections are in a full line of sight and closer to the airfoils 16. The weld connections at this location on the shroud segments 18 provides a clear line of sight for implementing the weld connection, which creates an easier installation and implementation of the shroud segments 18 and weld connections 20 on the airfoils 16.
FIG. 2 shows a prospective view of the blisk 10 according to an embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed at approximately halfway between the airfoils 16. With the weld connection 20 placed at this location, the weld is away from the fillet where the airfoil 16 meets the part span shroud. FIG. 3A shows another prospective view a blisk 10 according to an embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed between the airfoils 16 such that the weld connections 20 are substantially parallel to each other, but offset from the center of the area between the airfoils 16 to facilitate the weld process. FIG. 3B shows a front view of a blisk 10 configuration according to one embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed where the shroud segments 18 attach to the airfoils 16.
Referring to FIGS. 1, 2, 3A and 3B, the blisk 10 includes a disk 12 or disk body, and a plurality of circumferentially spaced apart blade airfoils 16 extending integrally radially outwardly from the disk 12. A plurality of shroud segments 18 are disposed circumferentially radially between the blade airfoils 16, and connect thereto to increase the aeromechanic stability of the blades 16 on the blisk 10. A welded connection 20 secures each of the plurality of shroud segments 18 to the blade airfoils 16 and to the other shroud segments 18. The weld connections 20 on the shroud segments 18 may include attachments resulting from welding processes including but not limited to, electron beam welding, laser welding, friction stir welding, induction welding, solid state welding and diffusion bonding and are located on the shroud segments 18 to avoid high stress areas. In addition, a plurality of coated wear surfaces 22 are disposed between the shroud segments 18 to prevent excessive wear on the shroud segments 18. The excessive wear on the shroud segments 18 can occur during operation of the blisk, when vibrations caused by the rotation of the disk 12 and blades 16, causing the shroud segments 18 to rub against each other. The disk 12, airfoils 16, shroud segments 18 and weld connections 20 collectively form an integral or one-piece assembly.
FIGS. 4, 5 and 6 are side views of a portion of a blisk 10 according to another embodiment of the present invention with the part span shroud segments 18 connected to the blades 16. FIG. 4 shows a front view of a blisk 10 configuration according to one embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed where the shroud segments 18 attach to the airfoils 16. FIG. 5 shows an angled front view of a blisk 10 configuration according to one embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed where the shroud segments 18 attach to the airfoils 16. FIG. 6 shows a rear view of a blisk 10 configuration according to one embodiment of the invention showing shroud segments 18 disposed between airfoils 16 with weld connections 20 disposed where the shroud segments 18 attach to the airfoils 16. The blisk 10 includes in accordance with the present invention a plurality of discrete part-span shroud segments 18 each disposed circumferentially between and bridging a respective pair of blade airfoils 16. The welded connections 20 of the shroud segments 18 to the blade airfoils 16 are disposed in areas that avoid the high stress areas of the shroud segments 18.
One embodiment of the present invention includes a method for making the blisk 10 according to the present invention by attaching the blade airfoils 16 to the disk 12 first, and then securing the shroud segments 18 to the blade airfoils 16 after the airfoils 16 are secured. The blade airfoils 16 may be attached to the disk 12 by any suitable attachment method known in the art, including but not limited to translation friction welding, electron beam welding, induction welding, solid state welding and forming the disk 12 and airfoil from the same piece of material. The blade airfoils 16 and the shroud segments 18 may be attached by a weld connection 20 with a modified shroud interface orientation, which provides a more producible weld during the assembly of the present invention. Another suitable location for the weld connection 20 on the shroud 18 may be closer to the airfoils 16, which provides better interfaces with the adjacent shroud, and provides better shroud-to-shroud interface alignment.
An alternate embodiment of the present invention is where the shroud segments 18 are integral with the blade airfoils 16. The blade airfoils 16 are secured to the disk with translational friction welding or any other suitable attachment process. The shroud segments 18 are coated with a coating known in the art for blade airfoil 16 surfaces. For example, the coating may be made of tungsten carbide, or may be a brazed on wear pad. This embodiment may also include having every other shroud segment 18 split into a plurality of shroud segments, preferably two segments. The blades 16 are then secured one at a time to the disk with translational friction weld connections. The adjacent blades 16 need to be elastically bent out of the way during the translational friction weld process to avoid interference. While no shroud welds are necessary for this configuration, alternatively, induction welding or some other joining method may be used to attach the integral blade to the blisk hub.
Another alternate embodiment of the present invention is shown in FIG. 7, where the blade airfoils 16 have two sections, a first section 24 and a second section 26, with a connection junction 28 between the two. Each of the first section 24 and second section 26 being airfoil components, when joined at the connection junction 28 forming a full airfoil. The first section 24 of the airfoils 16 is attached to the disk 12 or machined integral with the disk 12 first. Then the part span shroud segments 18 are attached to the first section of the airfoils 16, then the second section 26 of the airfoils 16 are attached last. The attachments are made by machining the first section 24 of the blades 16 and the shroud segments 18 to the disk 12, then using a weld connection 20 to attach the second section 26 of the blade airfoils 16. Another attachment used for this embodiment is to machine the first section 24 of the blade 16, then using weld connections 20 for securing the shroud segments 18 and the second sections 26 of the blade. This process is repeated around the disk 12 to form a blisk. This embodiment allows for easy attachment of the shroud segments by conventional welding techniques.
Yet another embodiment of the present invention is shown in FIG. 8, where only one weld connection 20 is applied to the shroud segments 18. The weld connection 20 is applied substantially perpendicular to the edge of the shroud segment 18. A gap clearance must be maintained from the adjacent shroud 18 without the weld connection during application of the weld 20. The shroud segment 18 without the weld may be either removed or deflected during the welding process if necessary. The gap clearance provides clearance from the adjacent airfoil and shroud during translation friction welding the airfoil 16 to the hub.
Another embodiment of the present invention is shown in FIG. 9, where a weld connection 20 is placed on the shroud 18 substantially perpendicular to the airfoil 16. The weld 20 is substantially parallel to the shroud interface between the shroud segments 18. Line 90 illustrates the direction of translation for the translation friction weld process of this configuration. The airfoils 16 may be deflected during the weld process for clearance from the adjacent airfoil. This configuration assumes a tolerance substantially perpendicular to the axis of translation of the shroud 18 and avoids welds in the shroud.
FIG. 10A illustrates another alternative configuration of the present invention. The airfoils 16 are attached to the disk 12 in pairs, or two at a time. The shroud segments 18 are coated with a wear coating at every other interface only since the blade airfoils 16 are attached two at a time. In addition, every other shroud segment 18 has a clearance gap for the translational friction weld clearance. The shroud 18 is only disposed there to avoid aeromechanic excitation from non-uniform wake disturbance. The shroud segments 18 are joined before the pair of blade airfoils 16 are attached to the disk 12, as shown in FIG. 10B.
Another embodiment of the present invention is to utilize weld connections 20 for the shroud segments 18 and the blade airfoils 16, but leaving gaps between the shroud segments. The shroud-to-shroud gap has an assembled wear surface between the two shroud pieces. This shroud-to-shroud gap provides damping during blade vibrations and prevents hoop stresses that occur in when the shrouds are connected as a continuous ring. The wear surfaces 22 are secured after the shroud segments 18 and blade airfoils 16 have been secured. This is repeated around the disk 12 to form the blisk 10.
Yet another embodiment of the present invention is to leave a gap between the shroud segments 18 and assembling a type of wear surface 22 to fit in the gap. This embodiment provides the option for not using a weld connection 22 to secure the shroud 18 to the blade airfoil 16. This embodiment provides the stiffness the airfoils require for operation, and also increases the first flex frequency. In addition, the gap provides blade-to-blade damping that reduces stresses in the shroud and blade airfoils 16. Also, the process of leaving the gap between the shroud 18 and then later assembling the wear surface in the gap provides easier assembly of the apparatus, as the shrouds 18 are not in danger of making contact with one another during the welding process.
Another embodiment of the present invention is to machine the entire blisk 10 apparatus from one material, using no weld connections 20. The blisk 10 is manufactured from a metal material such as titanium or any other suitable metal material. The shrouds 18 can be machined integrally to the airfoils as one solid piece, and form a continuous ring. In this embodiment, a wear surface 22 may be omitted. In addition, the shroud 18 could be machined as one solid piece, but each shroud segment 18 may have a gap where the gap is sufficiently large to ensure that the edges of the shroud 18 do not contact each other. A wear surface 22 can also be used that is assembled to fit into the gap between the shroud segments 18 to provide damping. As in the other embodiments, the gap eliminates any hoop stresses on the shrouds 18 and blade airfoils 16. The shroud 18 provides aeromechanical stiffness to the blade airfoils 16. Machining the blisk 10 from a single solid piece eliminates the need for wear surfaces 22.
Another embodiment of the present invention would be to construct the part span shrouded blisk 10 using composite materials and composite manufacturing techniques. The blisk 10 may be constructed of natural fiber substrates, fiberglass substrates, open cell foams, closed cell foams, vinyl, and any other suitable composite. The composite manufacturing techniques may include resin transfer molding, filament winding, autoclaving, pultrusion, hot pressing, wet layup, carbon pyrolysis, braiding or any other suitable technique. Characterization capabilities include ultrasonics, acoustic emission, X-radiography, infrared thermography, eddy current, thermal analysis, microscopy and any other suitable characterization. Composite materials performance is evaluated with a comprehensive array of testing equipment such as servo-hydraulic and screw-driven load frames, a high-rate servo-hydraulic load frame with high speed laser flash video recording, high temperature creep frames, an instrumented drop-weight impact tester, environmentally-controlled wear testers, a vacuum-ready flywheel spin chamber and any other suitable evaluation method or system.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Patent Application
20080089788
