US3694104A

US3694104A - Turbomachinery blade

Info

Publication number: US3694104A
Application number: US78714A
Authority: US
Inventors: John R Erwin
Original assignee: Garrett Corp
Current assignee: Garrett Corp
Priority date: 1970-10-07
Filing date: 1970-10-07
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26

Abstract

This turbomachinery blade has an internal frame or strut made of plastic-impregnated fibers and covered with a thin metal sheath. The frame has sections extending spanwise with the fiber rovings wound under tension which is maintained while the plastic is being cured. The sheath may be made in one or more sections to receive the assembled frame structure the parts being adhesively or otherwise joined into a unit. The frame sections have the fibers passed around mandrels to form loop type openings at the hub end for receiving pins by which the blades are retained in the hub or on a rotor disc. When the blades are assembled with a disc to form a rotor, suitable spacers are inserted between them to provide the platforms or inner boundaries for the air or gas passages.

Description

United States Patent Erwin [4 Sept. 26, 1972 TURBOMACHINERY BLADE 3,051,436 8/1962 Kent et a1. ..4l6/244 A [72] Inventor: John Erwin, Paradise valley, 2,980,395 4/1961 Rubbra et a1 ..416/217 FOREIGN PATENTS OR APPLICATIONS [73] Assignee: The Garrett Corporation, Los An- 687 507 2/l953 England 416/217 geles, Calif.

[22] Filed: Oc1, 7, 1970 Primary Examiner-Everette A. Powell, Jr.

Attorney-Herschel C. Omohundro, John N. Hazel- [21] Appl' wood, Jack D. Puffer and Albert]. Miller [52 US. Cl. ..416/217, 416/226, 416/230, [57] A RA T Int Cl l This turbomachinery blade has an internal frame or I I u I s s I l n u u I u u u q l l s I I o I e I s I u I v u 1 s l s s u v -u [58] Fleld of Search "416/ with a thin metal sheath. The frame has sections extending spanwise with the fiber rovings wound under tension which is maintained while the plastic is being [56] References Cited cured. The sheath may be made in one or more sec- UNITED STATES PATENTS tions to receive the assembledframe structure the parts being adhesively or otherwise joined Into a unit. 3,333,642 8/1967 Kee ..416/229 The frame Sections have the fibers passed around 2,175,204 10/1939 Lougheed ..416/230 mandrels to form 100p type openings at the hub end 2,929,755 3/1960 Porter ..416/229 for receiving i by which the blades are retained in 2,635,848 4/1953 McDowell ..4l6/217 the hub or on a rotor u w the blades are assem 3,476,484 11/1969 Brunsch ..416/230 bled with a disc to form a rotor, Suitable Spacers are 3,167,129 1/1965 81111112 ..416/226 inserted between them to provide h platforms or 2,920,866 l/1960 Sp urrIer ..416/223 inner boundaries for the air or gas passages 2,916,808 12/1959 Wilkes ..416/233 1,452,602 4/1923 Herr ..416/217 18 Claims, 7 Drawing Figures PATENTED 8EP26 I972 3,894,104

SHEET 2 OF 3 j/v VENTOE- TURBOMACHINERY BLADE SUMMARY OF THE INVENTION This invention relates generally to turbomachinery and is more particularly directed to the formation of blades used inc compressor rotors, turbine wheels, and bypass fans.

Primarily the invention is concerned with a composite blade construction and method of making the same, the blade having a composite internal frame structure or strut made of plastic-impregnated fibers and a thin metallic cover or sheath to protect the composite frame from corrosion, erosion, and foreign ob ject damage.

The present invention is directed to the formation of a composite blade wherein an internal frame structure or strut is made of sections so shaped that the fibers used to reinforce the plastic are wound under tension in a spanwise direction and such tension can be maintained while the plastic or resin is cured, the shape of the sections also being such that they may be fitted together to provide the blade with a desired form and to receive a protective covering or sheath composed of metal or other wear and damage-resisting material.

One object of the invention is to so shape the frame sections that the finished blade will be relatively light in weight but will have requisite strength through properly located webs to reinforce the relatively thin side-wall construction.

An object also of the invention is to form an airfoilshaped blade from a plurality of frame sections, of V and/or modified U-shaped cross section, which can be readily fabricated, cured, and inspected. before assembly, these frame sections then being treated with an adhesive, fitted together, inserted in an internally treated sheath and all parts bonded together by applying pressure and curing the adhesive to form a completed unitary blade. By bonding the frame sections together into a strut and bonding a thin metallic sheath or skin to such strut the skin will be prevented from fluttering, buckling, and/or wrinkling under stresses or other forces applied to the blade during use of the rotor equipped therewith.

Another object is to arrange the frame sections mentioned in the preceding paragraph so that the apices of certain vee sections are disposed at the leading and trailing edge portions of the blade, the frame sections also having pin receiving loops or openings at the hub ends arranged so that the axes of the openings extend substantially parallel to the mean line of the blades adjacent the hub and blade retaining pins can be inserted into the openingsfrom the front and rear sides of the rotor disc to which the blades are being attached.

A still further object is to so form the frame sections mentioned in the two preceding paragraphs that considerable overlapping of parts of the frame sections will be secured during assembly of the frame structure whereby ample adhesive receiving and contacting surfaces will insure a good bonding together of the parts.

Other objects and advantages of the invention will be apparent from the following description of one embodiment of the invention illustrated in detail in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a turbomachinery blade formed in accordance with the invention;

FIG. 2 is a horizontal sectional view taken through the blade shown in FIG. 1 on the plane indicated by the line II-II of such figure;

FiG. 3 is a partial transverse sectional view through the rim of a rotor to which the blade of FIGS. 1 and 2 has been attached the section being taken on the mean lines of the blade and developed to better show the construction.

FIG. 4 is a sectional view taken through the rotor on the plane indicated by the line lV-lV of FIG. 3.

FIG. 5 is a transverse sectional view similar to FIG. 3 taken through the rotor on the plane indicated by the line V-V of FIG. 4.

FIG. 6 is a horizontal sectional view taken through the cover of sheath of the blade prior to the application thereof to the frame structure; and

FIG. 7 is a perspective view of an insert employed between adjacent blades to provide a platform or air passage wall at the blade root.

Referring more particularly to the drawings the completed blade is designated by the numeral 10. This blade may be of many shapes depending upon its function, the blade illustrated being an axial flow fan or compressor blade with a curved airfoil configuration. It has a tip end 11, a hub end 12, a leading edge 13 and a trailing edge 14 connected by pressure or concave and suction or convex surfaces, 15 and 16, respectively. The hub end 12 is formed with a plurality of loop-like portions 17 for the reception of pins employed to retain the blade 10 on a disc 18 in the formation of a rotor.

As shown more particularly in FIG. 2, the blade 10 includes an internal frame or strut structure 20 and a cover skin or sheath 21 of thin metal or other suitable material which will protect the frame structure from corrosion, erosion, and foreign object damage.

Frame structure 20 is composed of a plurality of individually formed sections 22-26, fabricated from plastic-impregnated fibers wound on suitable forms and cured, then assembled to complete the airfoil shaped frame or strut.

Sections 22 to 26, inclusive, extend spanwise of the blade and are shaped to permit the fiber rovings to be wound under spanwise tension which is maintained during the plastic curing operation to give the finished frame maximum strength consistent with minimum weight. This method of construction also facilitates the inspection of the parts prior to assembly into the completed frame structure. Sections 22 and 25 are disposed at the leading and trailing edge portions of the assembled blade and as illustrated in FIG. 2 have V- shaped cross-sectional forms.

Sections

23 and 24 are located between the sections 22 and 25 and have modified U-shape cross-sections. The reasons for the particular shapes selected will be apparent from the following description of the method of making the frame sections. In winding the frame sections suitable forms (not shown) must be employed; these forms will permit the fiber rovings to be grouped and oriented to provide the corresponding pressure and suction wall frame portions and to be wound around a mandrel at the hub end to form the loop portions 17. The fiber rovings are either wound under tension or the forms are arranged to apply tension to the fibers while the plastic with which they have been impregnated is being cured. In this manner the fibers will remain in tension after ouring even though the tip ends of the frame sections may be trimmed to finished blade size.

After the frame sections 22 to 26, inclusive, have been cured and removed from the forms they may be inspected and if satisfactory then fitted together to complete the inner frame structure of the blade. It will be noted that the

frame sections

23 and 24 are shaped to fit between the ends of the legs of the V-shaped sections 22 and 25. The ends of the legs of

sections

23 and 24 are butted together, as at 27, after the I-shaped section 26 is positioned therebetween. This arrangement provides considerable overlapping of surfaces which may be previously coated with suitable adhesive, resin, or heat-cured plastic. The assembled frame can then be clamped together between suitable dies and heated to cure the adhesive, resin, or plastic. The bases of the U- shaped sections and the stem of .the l-shaped section provide reinforcing webs between the concave and convex walls.

To complete the blade, the frame structure is then covered with a metal skin by inserting the frame in a previously formed sheath or by applying a sectional sheath thereto and suitably joining the sections Sheath 21 maybe made in a number of different ways, the sheath illustrated having a leading edge portion 28 of V-shaped cross-section and

sheets

30 and 31 which form the concave and convex wall surfaces, butt-joined to the legs of the vee section 28 as at 32. By this construction the skin or sheath may be provided with a thicker leading edge portion which will reinforce the final blade in the region where foreign object damage, erosion, or corrosion is most apt to occur. It will also apply such extra strength without introducing any unbalanced region to the rotor. The

sheets

30 and 31 may be left separate at the blade trailing edge until the frame structure has been inserted after which these edges may be suitably joined. If found more feasible the trailing edge portions of

sheets

30 and 31 may be joined and the frame structure inserted into the sheath from the hub end. As shown in FIGS. 3 and 4 this end of the protective outer cover or sheath is separated into prongs 33, one for each of the loop-like portions 17 of the

frame sections

22, 23, 24, and 25. The hub ends of the

sheets

30 and 31 are turned under the loop portions 17 of the frame sections and suitably joined to form the prongs 33. To insure proper bonding between the frame or strut and the skin, the latter may be chemically or mechanically treated on the inner side to provide a roughened surface for receiving the adhesive.

From FIG. 3 it will be noted that the rim portion of the disc 18 has a series of circumferentially extending grooves 34 formed therein. The. formation of the grooves provides the rim with

flanges

35 and 36 at the upstream and downstream sides, respectively, of the disc. A rib 37 is also provided between adjacent grooves. The grooves 34 receive the prongs 33 and the blades are secured in assembled relationship with the disc by inserting retaining pins 38 from the sides of the disc into holes in the

flanges

35, 36, the ribs 37 and the openings in the prongs 33 aligned therewith. When the blades and disc are employed to make a compressor rotor the flange 36 at the downstream side of the wheel is of greater length than the flange 35. A reverse arrangement is employed when a turbine wheel is formed. The flanges may be of the same length in certain rotors such as are used in ducted fans. When one flange is longer the frame sections and consequently the finished blade at the corresponding side of the rotor may be shorter from the tip to the hub end. This arrangement offsets the retaining pins at one side of the rotor from those at the other side and thus avoids interference between the retaining pins or holes. The strength of the disc is preserved in this manner. One feature of the invention is to arrange the axes of the eyes or openings in the hub ends of the frame sections substantially parallel and in radial registration with the mean line of the corresponding portion of the blade. In other words frame sections 22 and 23 form the leading edge and adjacent portions of the blade and the axes of the openings in the loops at the hub ends of these sections are substantially parallel and in radial registration with the mean line of this part of the blade. The holes for the retaining pins 38 will be angularly disposed relative to the rotor axis but since the pins will be in substantially radial registration with the mean line 10A of the blade the fiber rovings will extend (see FIG. 4) in a substantially straight line from one side of the frame section down to and around the pin and in a straight line back up the other side of the frame section. There will thus be no slack in the fibers which could give and distort the blade under centrifugal during high speed rotor operation.

To complete the air or gas passages between the blades at the hub of the rotor, curved plate-like inserts 39 may be disposed and secured between adjoining blades. Top walls 40 of inserts 39 provide the platforms which extend between the peripheries of the

flanges

35 and 36. End edges 41 and 42 of top wall 40 fit the

flanges

35 and 36 respectively of the disc rim while side edges 43 and 44 are curved to closely fit the concave and convex wall surfaces, respectively, of a pair of adjacent blades. Inserts 39 are secured in place in a manner similar to the blades by inserting retaining pins 45 through aligned holes in the

flanges

35, 36, ribs 37 and the legs 46 depending from the under side of the wall 40.

Pins

38 and 45 have been illustrated with threaded portions to retain them in place in the rotor disc. It is obvious that any other suitable retaining means could be employed. 7

One of the features of the invention is the formation of a rotor for turbomachinery by providing the disc part 18 and attaching blade elements as described above thereto. As mentioned previously the rim of the disk is turned to provide the annular grooves 34 between

flanges

35, 36 and ribs 37. The flanges and ribs have holes drilled from the sides of the disc at predetermined angles for alignment with other holes formed in prongs 33 at the hub ends of the composite blades 10 and in lugs 46 on the undersides of spacers 39. With this manner of construction a compact unitary rotor of minimum weight and high endurance will result.

What is claimed is:

l. A blade for turbomachinery comprising:

a. a substantially hollow internal frame structure composed of a plurality of sections formed of plastic-impregnated fibers extending spanwise and wound under tension oriented spanwise of the blade; and

b. a thin metal outer cover secured to and enclosing the frame structure, said frame structure and outer cover providing said blade with an airfoil shape.

2. The blade for turbomachinery of claim 1 in which the sections of the internal frame structure extend spanwise of the blade.

3. The blade for turbomachinery of claim 2 in which certain sections of the internal frame structure have interfitting overlapping portions.

4. The blade for turbomachinery of claim 1 in which the assembled sections of the internal frame structure provide the latter with an airfoil shape.

5. The blade for turbomachinery of claim 1 in which the assembled sections of the internal frame structure a hollow airfoil shape reinforced at intervals spaced chordwise of the blade with webs extending between pressure and suction side walls.

6. The blade for turbomachinery of claim 1 which at least part of the sections have the hub ends formed by passing the tensioned fibers around a mandrel to form a loop-type opening for receiving a blade retaining pin.

7. The blade for turbomachinery of claim 6 in which predetermined sections have the openings thereof located at different distances from the tip end of the section to receive a plurality of blade retaining pins disposed in an offset relationship.

8. The blade for turbomachinery of claim 6 in which the mandrels around which the fibers are passed to form the retaining pin receiving openings are arranged to dispose the axes of the openings in a direction generally parallel to the mean line of the finished blade and make the fibers extend from the blade forming portion to the loop forming portion with a minimum of curvature.

9. The blade for turbomachinery of claim 8 in which the axes of the openings of frame sections adjacent the leading edge portion of the blade are aligned generally with the mean line of the blade at the leading edge portion thereof adjacent the hub end. i

10. The blade for turbomachinery of claim 8 in which the axes of the openings of frame sections adjacent the trailing edge portion of the blade are aligned generally with the mean line of the blade at the trailing edge portion thereof adjacent the hub end.

11. The blade for turbomachinery of claim 8 in which the axes of the openings of frame sections ad- 5 jacent the leading and trailing edge portions of the blades are aligned generally with the mean line of the blade at the leading and trailing edge portions respectively thereof adjacent the hub end.

12. The blade for turbomachinery of claim 11 in which blade retaining pins are adapted to be inserted from opposite edges of the blade.

13. The blade for turbomachinery of claim 7 in which the frame sections adjacent one edge of the blade have the openings thereof disposed a greater distance from the tip end of the section than the openings of the frame sections adjacent the other edge of the blade.

14. The blade for turbomachinery of claim 6 in which the thin metal outer layer extends around the blade retaining pin receiving loops.

15. The blade for turbomachinery of claim 2 which the edge forming sections of the frame structure have substantially V-shaped cross-sections.-

16. The blade for turbomachinery of claim 15 in which the intermediate blade forming sections of the frame structure have substantially U-shaped cross-sectrons.

17. The blade for turbomachinery of claim 16 in which the frame structure sections with the V-shaped cross-sections are arranged to form the leading and trailingredges of the blade. u

18. he blade for turbomachinery of claim 17 in which the frame structure sections with the U-shaped cross-sections are disposed with the base ends of the U shape between the legs of the vee shape of the other sections.

Claims

1. A blade for turbomachinery comprising: a. a substantially hollow internal frame structure composed of a plurality of sections formed of plastic-impregnated fibers extending spanwise and wound under tension oriented spanwise of the blade; and b. a thin metal outer cover secured to and enclosing the frame structure, said frame structure and outer cover providing said blade with an airfoil shape.

9. The blade for turbomachinery of claim 8 in which the axes of the openings of frame sections adjacent the leading edge portion of the blade are aligned generally with the mean line of the blade at the leading edge portion thereof adjacent the hub end.

11. The blade for turbomachinery of claim 8 in which the axes of the openings of frame sections adjacent the leading and trailing edge portions of the blades are aligned generally with the mean line of the blade at the leading and trailing edge portions respectively thereof adjacent the hub end.

15. The blade for turbomachinery of claim 2 which the edge forming sections of the frame structure have substantially V-shaped cross-sections.

16. The blade for turbomachinery of claim 15 in which the intermediate blade forming sections of the frame structure have substantially U-shaped cross-sections.

17. The blade for turbomachinery of claim 16 in which the frame structure sections with the V-shaped cross-sections are arranged to form the leading and trailing edges of the blade.

18. The blade for turbomachinery of claim 17 in which the frame structure sections with the U-shaped cross-sections are disposed with the base ends of the U shape between the legs of the vee shape of the other sections.