US2972470A

US2972470A - Turbine construction

Info

Publication number: US2972470A
Application number: US771337A
Authority: US
Inventors: Hamilton L Mccormick
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1958-11-03
Filing date: 1958-11-03
Publication date: 1961-02-21
Anticipated expiration: 1978-02-21
Also published as: GB877708A

Description

Feb. 21, 1961 H. L. MCCORMICK 2,972,470

' TURBINE CONSTRUCTION Filed Nov. 3, 1958 2 SheetsSheet 1 X INVENTOR.

1961 H. L. MCCORMICK 2,972,470

TURBINE CONSTRUCTION I Filed Nov. 3, 1958 2 Sheets-Sheet 2 A T TOR/V5) TURBINE CONSTRUCTION Hamilton L. McCormick, Carmel, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Nov. s, 1958, Ser. No. 771,337

s Claims. (Cl. 25349 This invention relates to a turbine assembly for a gas turbine engine.

More specifically, this invention relates to the construction of a turbine in a manner to permit removal of the turbine blades therein without disassembly of the turbine rotor.

In many constructions of a turbine, upon rupture or breaking of any one of the turbine blades therein, it becomes necessary to disassemble the entire turbine in order to remove that particular blade. From a balancing stand point, once the turbine rotor is disassembled, the entire turbine must be rebalanced upon reassembly, which is an expensive and tedious procedure. I

This invention eliminates rebalancing of the turbine rotor by constructing the turbine in a manner such that any one or a number of the turbine blades therein may be removed without-disassembling the entire rotor. enables the manufacturer to replace the blade or blades with blades of equal weight, thereby maintaining the turbine balanced both statically and dynamically.

This invention accomplishes the above objective by mounting the turbine blades and'interstage spacers on the turbine disks or wheels and spacer disks by means of firtree inserts so as to permit axial sliding movement relative thereto. Furthermore, axial positioning flanges are provided on portions of the turbine blades, rotor wheels and interstage spacers, preventing axial movement in one or both directions. The construction is such that it is necessary to remove only one end connection to remove one or'a row of rotor blades from the assembly. With the one row removed, removal of the stator vanes, interstage spacers, and other stage turbine blades is easily accomplished upon removal of the corresponding portions of the engine casing.

Therefore, it is an object of this inventionto provide a turbine construction permitting removal of any of the rows of turbine blades without disassembly of the turbine rotor.

Other features, advantages and objects will become apparent by reference to the detailed description of the invention and to the drawings wherein there isshown the preferred embodiment of this invention.

In the drawings:

Figure l is a partial cross-sectional view of a turbine embodying this invention,

Figure 2 is a cross-sectional view on a reduced scale of a portion of the turbine of Figure 1 showing the turbine in partially disassembled condition,

'Figure 3 is a cross-sectional view of a detail viewed by passing a plane through the lines indicated by the arrows 3-3 in Figure 1, and

Figure 4 is a cross-sectional view similar to Figure 3 obtained by passing a plane through the lines indicated by the arrows 44 in Figure 1.

Referring now to the drawings and more particularly to Figure l, a turbine assembly is" shown comprising in general an outer turbine casing supporting a plurality of annular axially spaced stator vane assemblies 12, 14

and 16 cooperating with first, second and third stage an- This States Patent O nular rotor blade assemblies 20, 22 and 24 axially spaced from each other by annular interstage spacer assemblies 26 the turbine case comprises a plurality of axially aligned circular casing portions 32, 34 and 36 suitably connected together at their abutting flanged edges 40 and 42 by a plurality of circumferentially spaced bolts 44 (only one set shown). Supported from the casing sections by means to be described are the stator vane assemblies 12, 14 and 16, each consisting of an outer shroud ring 46, 48 and 50, respectively, to which are welded or otherwise suitably secured a plurality of circumferentially spaced stator vanes 52, secured at their tip portions to an inner shroud 54, 56 and 58, respectively. Each of the radially outer shrouds 46, 48 and 50 comprises a number of arcuate abutting sections, preferably six, for example. The radially inner shrouds 54, 56 and 58 of assemblies 12, 14 and 16 also each consist of six ribbed abuttingsegments of a shroud ring welded to the tips of each of the stator vanes, the segments together forming a substantially continuous annular surface. I

The stator vane assemblies are supported from and connected to the engine casing portions 32, 34 and 36 by suitable tongue and groove connections as shown formed on the casing portions and'outer shroud rings, the outer shroud rings 46 and 48 of assemblies 12 and 14 having interfitted therebetween a ring member 60 constituting the first stage rotor blade shroud ring. Ring member 60, and shroud rings 46 and 48 are secured in position and supported from the casing by a number of circumferentially spaced dowels 62.

Also supported from the engine casing 10 by an annular bulkhead 64 connected to an annular stepped'supporting strut 66 is the bearing 11 rotatably supporting the turbine drive shaft 30.

Referring now to the details of the turbine rotor cooperating with the stator vane assemblies, the rotor is of the axial flow type having three stages 20, 22 and 24 comprising rotor wheels or disks 68, 70 and 72, each having secured thereto at its outer periphery by conventional firtree insert and slot means 74 and 76, respectively (Figs. 24),'a number of circumferentially spaced rotor blades 78 provided with platforms 80. The hub portions 82, 84 and 86 of rotor wheels.68, 70 and 72 consist of axially aligned-stub sleeve shafts formed integral with the wheels, and abutting each other at adjacent edges.

Inserted between the first and second stage rotor sleeve shafts S2 and 84 is an. end flange 88 of the turbine drive shaft 30, the three sleeve shafts and drive shaft flange being fixedly secured together by a number of circumferentiallyspaced tie-bolts 90 insertable through suitable apertures therein. Although any number of tie-bolts may be used, preferably ten, for example, would be preferred in the construction shown.

The construction above described explains the manner of axially locating the stator vane assemblies, and the manner in which the stator vane and rotor blade assemblies are-located radially with respect to each other. The axial disk 94 has a similar tongue and; groove support connec tion 97 with the hubs s4 and 86. measures-rotation of the disks 92 and 94 with the turbine rotor upon tightening of the tie-bolts 90. The radially outer portion of each of the disks 92 and 94 is U or channel-shape as shown in Figure 2 and formed with a number of circumferentially spaced axially extending fir-tree slots 98. Cooperating with slots 98 are a plurality'of mating fir-t-ree inserts 99 provided on each of two axially spaced annular flanges 100 suitably secured to or formed integral with an annular rim 102, the slots and inserts being equal in size and numberrto the number of third stage rotor blade inserts 74 for removal purposes as will be described, and the rims 102 cooperating with the radial ribs of shroud rings 56 and 58 to form labyrinth motive fluid seals. Each of the rims 102 is provided with radially outwardly extending parallel flanges 104 and 106 adapted to abut the adjacent edges 108 and 110 of the platforms of the first and second and second and third stage turbine blades, respectively. The turbine rotor blade assemblies are thus axially spaced from each other by the spacer disk shroud rims 102.

Depending from each of the fir-tree formed rotor blade inserts 74 at its downstream edge as seen in Figures 3 and 4 is a flange 112 overhanging the edge of the rotor wheel with which it is associated for further axially locating the rotor blades, the flanges 113 on the third stage blade inserts 74 being somewhat larger and further extended for a purpose to be described hereinafter. The spacer disks 92 and 94 and rims 102 are likewise axially located in one direction with respect to each other by depending flange portions 114 secured to each ofthe fir-tree insert portions 99 on the downstream leg of tang portions 100 to overlap the annular leg 115 of the U-shaped spacer disks 92 and 94. To axially position the assembly at each end thereof, the first stage rotor wheel 68 has secured thereto by a number of circumferentially spaced bolts 116, the rotating portion 118 of an annular triple interstage labyrinth seal number 120 cooperating with a stationary portion 122 of the seal secured to bulkhead 64. Seal portion 118 is abutted at 124 by a depending flange 126 secured to the platform 80 of each of the turbine blades 78. At the downstream end of the the turbine assembly, the third stage rotor wheel 72 is provided at its downstream edge with an annular depending flange 132 of the same radially inward extent as flanges 113 on the turbine blade fir-tree'inserts 74. Connecting the flanges together to prevent axial movement between the stalk and the rotor wheel in either direction is an annular expanding type snap ring 134 provided with radial flanges 136 surounding the flanges 132' and 113. With the construction as described, the rotor blade and stator vane assemblies are both axially and. radially fixed with respect to each other.

The turbine rotor is assembled separately as a unit prior to insertion in the engine casing by axially aligning the three rotor wheels 68, 70 and 72, the spacer disks 92 and 94, and the extension 88 of the turbine drive shaft in the correct order, and joining them together by the tie-bolts 90; The individual rotor blades 78 of the first stage are then positioned in place by a meshing of the fir-tree inserts 74 with the slots 76 in the rotor wheel 68, the flange portions 126 on the blade platforms 80 abutting the seal portions 118, and the. flange 112 abutting the wheel 68 for axially locating the blades. Spacer rim 102 and flanges 100 are then slid into position on spacer disk 92 as shown so that flange 104 abuts, edges 108 of platforms 80, and flanges 114 abut the spacer disk 92. The second stage turbine blades arethen inserted into the second stage wheel 70 with each of the platform edges '110 abutting flange 106 and flanges 112 abutting wheel 70. Spacer rim 1'02 and tangs 100 are then. slid into engagement with spacer disk 94, with the flange 104 abutting platforms 88 of the second stage rotor blades and flanges 114 abutting spacer disk 94. Theinserts 74 of the third stage rotor blades 78 are then engaged with the fir-tree slots 76' of the wheel 72 and the

flanges

113 and 132 and flange and platform edges abutted. Finally, the expanding snap ring 134 is inserted to fasten the

flanges

113 and 132 together, and the turbine rotor assembly is complete. The rotor assembly is thus prevented from axial movement as seen in Figure 1 by the abutment of flange 126 on the blade platform 80 of the first stage turbine assembly 20 against the seal portion 118, the holding of the last stage turbine blade assembly from axial movement in either direction by the expanding snap ring 134, and the interstage spacer disk rims 102 axially positioning the first, second and third stage rotor blade assemblies. The assembled rotor is then balanced both statically and dynamically before being inserted in the engine casing.

The assembly of the eomplete turbine is then as follows. The turbine is assembly by placing the sections on end and building up as would be viewed from the bottom of Sheet 1 of the drawings. The circular casing section 32 together with the abutted segments of the first stage stator vane assembly 12, bulkhead 64, labyrinth seal portion 122 and bearing 11 are positioned in place. a

The assembled rotor is then slid into place with the turbine shaft 30 being inserted though bearing 11 to be rotatably supported thereby, and the rotating portion 118 of seal positioned in place adjacent seal portion 122. The first stage rotor blade shroud ring 60 is then placed in position on top of shroud 46 (as viewed from the bottom of Sheet 1 containing Figure 1) and located by dowels 62. The six segments of the second stage stator vane assembly -14 are then laid in place, and the engine casing section 34 is then-positioned in place; and bolted tov section 32. at 40- by suitable bolts (not shown). I The segments of the third stage stator vane assembly 16 are then mounted on casing 34, and the. final turbine casing section 36 is fitted over shroud 50 and secured to casing section 34 by bolts 44. The assembly of the entire turbine is then complete. It is to be noted that, as assembled, the substantially continuous fairing of the several stages consisting of the blade platforms 88 and the inner and outer'shroud rings of the stator vane assemblies provides a streamlined path for the flow of motive fluid through the turbine. Furthermore, thev labyrinth seals formed-bythe rims 102 and the inner shroud rings 56, and 58 cooperate with the labyrinth seal 120 and blade platforms to. prevent the hot, motive fluid from reaching the bearings and the radial inward portions of the turbine, which would be injurious thereto.

To disassemble, as seen partially in Figure 2, all that is necessary is to remove the expanding snap ring 134, slide the third stage rotor blades 78 axially, remove bolts 44, the casing section 36, and the third. stage stator vane assembly 16, axially move the second-third stage spacer rim 102, axially slide the second stage rotor blades 78, remove turbine casing 34 together with second stage stator vane assembly 14, axially remove the first-second stage spacer rim 102, and then remove the; first stage turbine blades 78. Thus, the blades or vanes of any stage may be removed without disassembling the turbine rotor.

From the foregoing it will be seen that this invention provides a turbine construction permitting the removal of any of the turbine blades without disassembly of the turbine rotor, thus maintaining the dynamic and static balance of the rotor. Any of therblades may be replaced with blades of equal'weight thus eliminating the necessity ofrebalancing the entire turbine assembly.

While the preferred embodiment of this invention has been illustrated in connectionwith a turbine of a gas turbine engine, it will be clear' to those skilled in the art that many modifications can be made thereto without departing from the scope of the invention.

I claimt 1. A turbine assembly for a turboma'chine having a stationary casing comprising a multi-disk turbine rotor, said rotor including a plurality of axially spaced and aligned turbine blade support disks thereon, a plurality of circumferentially spaced turbine blades axially slideably secured to each of said disks, annular spacer disks mounted on said rotor between said support disks, said spacer disks having axially extending spacing means axially slideably mounted thereon having their axial edges abutting adjacent turbine blades for axially locating said turbine blades with respect to each other, removeable means engaging one of said support disks and the said turbine blades associated therewith securing them together against axial movement therebetween in either direction, means between said blades and disks preventing axial relative movementin one direction, removal of said removeable means permitting axial removal of said turbine blades in the other direction without disassembly of said rotor.

2. A turbine assembly including a multi-staged axial flow type turbine rotor including a plurality of axially spaced and aligned turbine wheels, means securing said wheels together, a plurality of turbine blades axially slideably secured to each of said wheels, spacer means mounted on said wheels therebetween and having portions axially slideably secured thereto, means securing said blades to said wheels against axial movement in one direction, a stationary casing surrounding and enclosing said turbine blades and said rotor, said spacer means portions abutting the blades of axially adjacent stages for axially positioning said blades, means on said casing adjacent one end of said assembly abutting one stage of said blades, and removeable means at the other end of said assembly secured to one of said wheels and the blades associated therewith preventing axial move ment therebetween, removal of said removeable means and said casing permitting the slideable axial removal of said turbine blades and spacer portions from said wheels in the other direction.

3. An axial flow type turbine assembly comprising a stationary axially extending casing, a plurality of axially spaced and aligned rows of stator vanes removably secured to said casing, a plurality of axially spaced and aligned rows of turbine blades positioned between the rows of stator vanes for cooperation therewith, a turbine rotor comprising a plurality of axially spaced turbine wheels, means securing said wheels together, fastening means on said turbine blades and said wheels cooperating together for axially slideably securing said blades to said wheels, means between said blades and wheels axially locating said blades with respect to said wheels in one direction, spacer disks secured to and between said wheels having axially spaced portions axially slideably secured thereto having edges abutting the blades on axially adjacent wheels, and means removeably secured to one of said row of blades and one of said wheels preventing axial movement therebetween in either direction, removal of said last mentioned means and said casing permitting the axial removal of all of said turbine blades and said spacer disk portions in the other axial direction without disconnection of said turbine wheels.

4. A turbine assembly having a multi-staged axial flow rotor comprising a plurality of axially spaced and aligned turbine wheels, means securing said wheels together for simultaneous rotation, a plurality of turbine blades axially slideably secured to each of said wheels, spacer means secured to and between said wheels for rotation therewith, said spacer means having axially extending flanges axially slideably secured thereto and extending between axially adjacent blades for axially spacing the blades on one wheel with respect to the blades on an adjacent wheel, means on said blades and said wheels engageable with each other for removably securing said blades to said wheels and preventing axial movement therebetween in one direction, and means secured to the blades secured to one of said wheels and to said wheel preventing axial movement therebetween in both directions, removal of said last mentioned means permitting the axial removal of all of said turbine blades and spacer flanges in the other axial direction without disconnecting said turbine wheels.

5. A multi-stage axial flow turbine assembly including a removeable stationary axially extending casing having a plurality of axially spaced and aligned rows of stator vanes removably secured thereto, a turbine rotor having a plurality of axially spaced and aligned turbine wheels secured together for simultaneous rotation, a plurality of rows of circumferentially spaced turbine blades axially slideably secured to said wheels between said rows of stator vanes, a plurality of spacer support means secured to said wheels for rotation therewith and positioned axially therebetween, said support means having outer annular rims axially slideably secured thereto, said rims each having axially spaced edge portions abutting the blades of adjacent stages to axially locate said blades with respect to each other, means on said wheels and said rotor blades and said spacer means and said rims, respectively, engageable with each other for axially positioning said blades and wheels and spacer means and rims with respect to each other, and removeable means secured to the blades of one rotor row at one end of said assembly and to the rotor wheel associated therewith preventing axial relative movement therebetween in either direction, means on said casing abutting a rotor blade row at the opposite end of said assembly preventing axial movement of said wheels, blades and spacer rims in one direction, removal of said removeable means permitting axial removal of said turbine blades and rims in said other axial direction upon removal of said casing and said stator vanes without disassembly of said rotor.

References Cited in the file of this patent UNITED STATES PATENTS 880,479 Buck Feb. 25, 1908 2,241,782 Jendrassik May 13, 1941 2,656,147 Brownhill et al. Oct. 20, 1953 2,807,434 Zimmerman Sept. 24, 1957 FOREIGN PATENTS $86,561 Great Britain Mar. 24, 1947 1,061,411 France Novi25, 1953 1,158,244 France Jan. 20, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Nos 2372 470 February 21 1961 Hamilton L, McCormick lt is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

for number read member Column 3 line 37 read W assembled line column 4 line 1'6 for "assembly 24L for "though" read through Signed and sealed this 12th day of September 19610 (SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Commissioner of Patents Attesting Officer USCOM M- DC