US2683583A - Blade attachment - Google Patents

Description

2 Sheets--Shee'l'l 1 G. J. Hun-:BNERQ JR., Er AL BLADE ATTACHMENT July 13, 1954 Filed sept. 1, 1948 1N VENOR 5.

wertig. Berufen July l31954 G. J. HUEBNER, JR., Er AL w 2,683,583

BLADE ATTACHMENT Filed Sept. l, 1948 2 Sheets-Sheet 2 Patented July 13, 1954 UNITED it'iNT OFFICE BLADE ATTACHMENT Application September 1, 1948, Serial No. 47,174

3 Claims.

The present invention relates to blading, and more particularly to blading of the side entry type for use in elastic iiuid utilizing apparatus and has for an object the provision of an improved fastening means for blading of this character.

Another object of the invention is to provide novel securing means for retaining a side entry blade in its mating rotor groove, which securing means can be released and the blade removed without necessarily aifecting the securing means for all other blades in its row.

Still another object of the invention is to provide novel securing means for side entry blades of elastic fluid utilizing apparatus, which securing means can be released to permit removal of and re-insertion of any desired blade without disturbing the setting of adjacent blades.

A further object is to provide a blade attachment such that its carrier may bear the conguration of a large hollow cylinder or frustum and have thus imparted to it an inherent lightness along with a natural structural rigidity.

Still a further object is to produce a blade structure wherein the carrier lends itself to a single integral casting construction which is simplel and relatively cheap to produce.

Yet a further object is to produce blade structure susceptible of ready and easy insertion and removal.

Yet another object is to avoid the undue Weakening of the spindle through the formation therein of the spaces intended for the accommodation of the blades.

While blade-fastening means of the character hereinafter disclosed will be found useful in many situations and types of apparatus, it is particularly useful in compressor and turbine apparatus for gas turbine power plants.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings forming a part of this application in which:

Fig. 1 is a longitudinal view of apparatus embodying the present invention, portions of the apparatus being broken away for the sake of clearness;

Fig. 2 is a fragmentary plan view of a compressor drum showing a row of impeller blades partially broken out and flanked by the strips relieved to accommodate the companion guide vanes;

Fig. 3 is a fragmentary transverse section through the compressor drum shown in Fig. 2;

Fig. 4 is a fragmentary perspective View of the compressor drum shown in Figs. 2 and 3 and brings out details of the securing and locking arrangement provided for the blades;

Fig. 5 is a view similar to Fig. 3, but shows how the invention may be applied to a tapered drum; and

Fig. 6 is a perspective view of a moving blade as appears in the assembly showing of Fig. 5.

The phraseology or terminology employed herein is for the purpose of description and not of limitation and it is not intended to limit the invention claimed beyond the requirements of the prior art.

In the drawings there are illustrated by way of example, certain embodiments of the present invention as applied to the apparatus as will be described in connection with Figure 1. It may be used on a straight drum spindle, on a tapered drum spindle, or on a combination drum spindle. It will be understood that the invention may be applied to turbine blading as well as to compressor or other blading. As to the particulars cf Fig. 1, the power plant shown may comprise in general the outer casing structure it open from end to end and having a central core structure I I which may provide an annular flow passage i2 extending fore and aft with respect to the aircraft in which it is mounted. The central core structure Il may be supported by the casing structure along its longitudinal axis and may include a hollow fairing cone IL!- deiining with the forward or left end of the casing lli, as viewed in Fig. l, the inlet portion of the flow passage i2.

The core structure also includes on the spindle, the rotor Il of an axial flow compressor I8, the fixed blades of which may be carried by the casing lil, the rotor I9 of a turbine 2l, and a conical tailpiece 22 which may define with the rear end of the casing structure, a propulsion nozzle 23. The intermediate portion of the core structure between the compressor and the turbine may comprise an inner wall structure 21% which may house a shaft 25 connecting the turbine rotor i9 and compressor rotor li and delines with the casing l@ an annular combustion chamber 216. The shaft 25 may be journalled in suitable bearings 25a carried by the outer casing.

The power plant may operate substantially as follows: Air may enter the casing IQ at the inlet of the iiow passage l2, may be compressed by the compressor, and may now into a diffuser or convergent portion 35 of the now passage which effects a further compression of the air. The hot gases or motive fluid comprising the products of combustion and the excess air heated by the combustion, on leaving the combustion chamber 26 may be directed by xed guide vanes or nozzles 38 of the turbine 2| into the blade passage of the turbine rotor I9. The spent gases leaving the turbine may be discharged through the propulsion nozzle 23 at a high velocity so that the remaining energy in the motive fluid is available to propel the aircraft.

The present invention is particularly concerned with the novel means employed for preventing axial displacement of the compressor and/or turbine blades with respect to their mounting grooves in their rotor drum.

With reference to Figs. 2 to 4 inclusive, there is shown a rotor drum such as may be employed in the straight portions of the spindle just described. The blade portion of the blading proper,` as shown, is purely fanciful and happens to be in the form of an impeller vane assembly. rThe invention may also be applied to a turbine bucket which maybe carried, for instance, 'on the straightturbine drum of Figure 1.

The blade portions 40,'42, and 4t, Ias shown, are'fadapted to t on a cylindrical strip or segmenti incorporated on the'face of the com'- pressor drum. This strip :it may be flanked by two'congruent strips o'r segments'll and 5B whichv may vbefated 01T plain.' The blade-holding strip may .be provided, however, .at its periphery with radiating teeth 52, 5t, and, which may carry at their tip or crest, transverse' lugs shown at 58.

Successive teeth suchias54 and 56 therebymay dene transverse T-slots having an enlarged groove portion B and a narrow neck-like -portion 62. lThese slots penetrate from the plane represented by the crest of the' teeth down to a depth which may be on a lower level with the plain'lstrips such as at 46. This groove or slot is frequently referred to in the elastic fluid industries as being of the keyholetype.

As may be observed vparticularly in Fig. 2, theselgrooves while extending generally in an axial direction may be inclined somewhat to the longitudinal axis of the spindle -They may be cut so as to have straight walls, yet they do not` affordstraight side entry even though they are opento side entry of a description. `The blade proper :i2 may be observed to comprise a vane assembly or blade portion S and a root throat portion The throat portion G6 may terminate in an enlarged end flange 58 givingit in effect a T appearance, adaptedto be 'received by the groove 6U.

As Yto its manufacture,'each`blade may, for example; be milled from a solid-piece of steel, bronze, Monel, stellite or other metal. The cross sectional form of the blades andthe manner-in which they are tanged linto slots" inthe rotor drum are not necessarily new.V -Since their slots arefinclined -at an acute angleto the length of thestrip, the blades are adaptedv for insertion in side entry at an oblique angle; The blade may beplaced in the'recess or relieved area represented by strip 45 Aand then forced at an angle to the spindle axis into 'the counterpart slot.- The lugs 58 provide a centripetal shoulder arrangement whereby the roots and blades are secured against'centrifugal forcesacting on'them' during operation.

To prevent axial shiftof the blades'once installed, ller rings suchas at I0 andlZ may be provided.V VThese rings-may-consist Aof at'strips. equal'in thickness approximately. to the working` depth `of the bladeslots justdescribed. .The

filler-rings may be adapted-to t in the bottom-.

of the recess formed by 45 and may comprise a series of arcuate segments. As appears in Fig. 2, the segments may abut one another and depending on their length expose a suitable number of blades to insertion or removal upon being detached.

The particular segments shown in Fig. 3 have been provided with an aperture '.'8 adapted to register with a tapped bere SEB provided in strip Sil 4The segment may be fastened to the cylindrical strip 5G by a detachable screw means, such as shown at 32, or some other common expedient. In order to remove one of the blades the filler segment of the ring on either side as involved, maybe removed and the blade quickly slipped out into the open over strip 5G. Then a new blade may be 4inserted and the segment re-installed. These i'llier rings serve not only to lock the blades in place but provide a smooth surface to define and direct the flow of the fluid passing through theturbine. This attachment, perfectly suitable for use on a turbine rotor, may be used too throughout an entire compressor rotor, the idea also being that the outer casing Walls will be tapered inwardly to accommodate the region of the shorter blades as in the diffuser area.

For another application of the invention, shownin Figs. 5 and 6 is a tapered type drum. This particular adaptation may be employed as well in a combination straight-tapered drum for a compressor or in a turbine rotor where diierentstages of blading are used. In any case, the outer-housing Sii may have an axially straight configuration while the drum may have a flare imparted to it in order to accommodate the diminishing sized blades The blade represented at 85 happens to incorporate the impellern type. It comprises a vane assembly or blade portion 88' which may be adapted to fit in a holding strip'or segment 92 formed in the face of the rotor drum. Segment S2 may be flanged on either side by -a segmentor strip Si) and 94 which provide-an outwardly facing plain cylindrical surface. Strip 953 may be seen to have a stepped relation to strips 92 and 915, with strip Sil lying at the unrelieved end of the slot and strip 92 and on level with the tip.

The actual slot and root arrangement is similar in detail to structure previously described. Along the base circle of the blade holding slot is aligned the surface of strip 99. Provided for each one of these sections such as S and S2 may be a transverse ange or rib 96 to provide for centrifugal and other forces exerted on the drum duringoperation. On the step S4 may be seen a Wedge-shaped nller ring 9S. Since access to the step gli is substantially unobstructed, this ring S8 is preferably of unitary form and may be inserted as one piece over the teeth of strip 92 and onto the step.

The wedge-shaped llers 98 and H33. are arranged to present a frusto conical surface such as will" converge with casing 815. The surface may be of regular selected pitch and is preferably smooth. Pitched in with this conguration there may be provided a baiile 84 mounted on the'blade assembly 88." The wedges and baffle may. cooperate to present a regular inclined surfaceanddirect the-gas into a path of decreasing or increasing-girth as the case may be. The baille lli may have its edges |05 trimmed on a bias'the samer aslis the root portion of the blade whereby `it may-be inserted/into position'at the samer angle asis thebladeJU-This inclination of course is related to and dependent upon the angle of incidence at which the blade portions are designed to be set. The edge |05 of the baille is adapted to abut the bailie of the blade next succeeding and present an uninterrupted ring around the rotor drum. Only a small change in the conguration of the actual blade portion may be all that is necessary to convert this saine structure into an ordinary turbine bucket. The baille in that instance will provide means for expanding the gases in going from one blade stage to the next.

It will be observed that such an attachment as is used on the tapered rotor is not susceptible of blade insertion from either side as was the straight rotor, although side entry may be used. In assemblage the annular ring on the higher step succeeding will preferably be positioned and then the blade inserted from the plain portion of the lower level nextl preceding. The blade will then abut against nller rings on either side and/or the higher strip such as at 94 on the higher side depending of course on whether the slot has been extended by undercutting a small distance beneath the ller S8. The blades may thus be firmly locked in place with no opportunity for axial slip or dislodgement.

In practice the present invention may be found to be highly desirable for use in attaching blades to spindles comprising turbine and blower rotors, and the like, operating at high speeds since it makes possible the mounting of the blades therein without localized weakening of the spindle. The spindle is provided with individual slots for the blades which may therefore be placed in assembled position or removed when required without disturbing adjacent blades. Moreover, each blade being inserted in an individual slot, the peripheral portion of the spindle may remain uniformly strong. No part of the slot serving to accommodate a blade is subjected to the wear occasioned by the repeated. insertion of blades into and the moving thereof through a single slot as is the case in many structures of this type. The

blades will therefore retain their initial ts With- -1 in the slots indenitely.

What is claimed is:

l. In a gas turbine power plant incorporating elastic fluid utilizing apparatus having an annular ilow passage defined by the combination of a cylindrical outer casing, a hollow rotor having a tapered segment in the outer face, the rotor comprising a succession of stepped cylindrical strips on said tapered segment alternating with conjoined strips integral therewith having straight grooves at the periphery disposed at acute angles to the length oi the respective strip, said grooves extending across said strip from one end to the other end thereof, and a number or moving blades having roots inserted in said grooves, with generally sloping deiiecting bailles secured to said blades and adapted to divide said blades into at least two sections located radially outward of each other, the baffles defining a generally predetermined pitch cone, and a number oi moving wedge fillers bearing circumierentially on the stepped cylindrical strips, the fillers of successive stepped strips presenting their' Wedge faces in general conformity with said pitch cone and pitching with the appertaining baffles of the included blades to form said tapered segment.

2. For use in elastic fluid utilizing apparatus of the axial now type, the combination with a hollow rotor having thereabout a succession of integral coaxial annular strips of limited width and each bearing through slots extending diagonally from one lateral side of the strip to the other side and undercutting centripetal shoulders thereon, the successive strips being separated by a plain spacing segment of the same limited width but recessed radially below the succeeding strip, of a plurality of blades having enlarged roots received in said slots with the enlarged roots engaging the centripetal shoulders, the root of each blade when assembled being substantially coextensive with the strip to which it is mounted and as incident to being assembled being receivable on the immediately preceding adjacent segment whereby for assemblage it may occupy the recess afforded by said adjacent segment preparatory to entry into the root-receiving slot thereof, and a unitary ring constituting filler means detachably occupying the recess offered by each segment, the width of the iiller means being substantially the same as said limited width in common to the strips and segments, said unitary ring constituting said iiller means being adapted to flank the blades abutting them generally on each side.

3. For use in elastic fluid utilizing apparatus of the axial ow type, the combination with a hollow rotor having thereabout a succession of integral coaxial annular strips of limited Width and each bearing through slots extending diagonally from one side of the strip to the other and undercutting centripetal shoulders, the successive strips being separated by a plain spacing segment of the same limited width but recessed radially below the succeeding strip, of a plurality of blades having enlarged roots received in said slots with the enlarged roots engaging the centripetal shoulders, the root of each blade being when assembled, substantially coextensive with the width of its root-receiving strip and as incident to assembly being receivable on the immediately preceding adjacent segment whereby for assemblage it may occupy the recess afforded by said adjacent segment preparatory to entry into the root-receiving slot therefor, and ller means detachably occupying the recess aiforded by each segment, the Width of the ller means being substantially the same as said limited width in common to the strips and segments, said filler means being adapted to flank the blades abutting them generally on each side and comprising a unitary nat ring of substantially the same depth of thickness as its recess and adapted to slide over the strip preceding for installation onto and removal from its segment.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,160,281 Price May 30, 1939 2,279,258 Allen et al Apr. 7, 1942 2,317,338 Rydmark Apr. 20, 1943 2,415,847 Redding Feb. 18, 1947 2,452,782 McLeod et al. Nov. 2, 1948 FOREIGN PATENTS Number Country Date 22,536 Great Britain Oct. 12, 1906 172,769 Germany July 11, 1906 537,121 Great Britain June 10, 1941 OTHER REFERENCES Flight, article entitled, Mamba Unmasked, March 18, 1948, pgs. b to h (p. c only is relied on).

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