EP0222679A1

EP0222679A1 - A sideplate for turbine disk

Info

Publication number: EP0222679A1
Application number: EP86630162A
Authority: EP
Inventors: Thomas Alger Farrand; Kenneth Paul Cidela
Original assignee: United Technologies Corp
Current assignee: RTX Corp
Priority date: 1985-11-04
Filing date: 1986-11-04
Publication date: 1987-05-20
Also published as: EP0222679B1; JPS62118033A; DE222679T1; DE3662420D1

Abstract

sideplate for a turbine disk is secured to the disk by cooperating bayonet fastening means on the plate and disk, and the plate carries a seal adjacent to its inner periphery, and two pilot areas cooperating with the disk to maintain concentricity, an outer rim seal near the disk periphery, and the sideplate rests on the disk near the periphery to hold the blades in position and to direct the cooling air through the disk.

Description

Technical Field

The invention is a combination seal and sideplate for attachment to a turbine disk and serves as a spaced seal element, a sideplate for the disk to hold the blades in position and to direct cooling air into the blade roots and has its Own fastening means to eliminate the need for any bolt attachments of the device to the disk.

Background Art

The prior art has generally been an annular seal element carrying several knife-edge seals and bolted to the turbine disk as one element, and a separate plate also bolted to the disk to serve as the sideplate for holding the blades in axial position in the disk and for directing cooling air into the grooves for the blade roots. It has also been necessary to provide additional devices to guide cooling air from the seal element to the separate side plate. This has necessitated another annular device in addition to the many bolts and nuts necessary for holding the several plate elements in position. It is well known that bolt holes create stress concentrations and are undesirable in a high speed device like a turbine disk. The elimination of any bolt holes and bolts as retaining means is a desirable result. The necessity for attaching several plates each by a number of bolts and nuts also increases the cost of assembling the device as well as the number of parts used in creating the finished product.

Disclosure of Invention

According to the invention, a single annular plate for use against the side of the turbine disk has the necessary seal elements near its inner periphery and serves as a sideplate for preventing axial movement of the blade roots within a disk, and also has a means for guiding the cooling air from a point near the axis of the disk outwardly to and into the cooling spaces at the roots of the blades. Also, according to the invention, the attachment of the disk by a bayonet form of mount integral with the disk and plate avoids any bolting attachment. This, in turn, eliminates the necessity for bolt holes in either disk or plate. A feature of the invention is the use of a double snap fit between the plate and disk to tailor the load split between the two snap fits. The arrangement is also such that the device serves as a pump in increasing the cooling air pressure from the point where it is delivered to the device near the axis of the disk to the point where it enters the blade roots near to the periphery thereby increasing the flow of air through the bases of the slots in the disk.
The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings.
Brief Description of Drawings

Fig. 1 is a sectional view through a turbine disk and the plate thereon to show the cooperating structures and the method of attachment of the plate to the disk.
Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1.
Fig. 3 is a fragmentary perspective view of a modification.

Best Mode for Carrying Out the Invention

The invention is shown in conjunction with the first stage disk 10 of a multistage turbine rotor, and this disk has an annular attachment flange 12 extending forwardly and laterally therefrom near or at its center for attachment to the remainder of the rotor. Radially outward from the center of the disk is another lateral flange 14 to support a ring 16 carrying a plurality of knife-edge seals 17 cooperating with a fixed eeal ring 18. The plate 18 is supported by a fixed structure 20. The structure 20 also carries one or more tubes 22 through which cooling air is admitted to the space 24 radially outward from the ring 16 and flange 14. The structure 20 also carries another annular seal ring 25 surrounding and in spaced relation to the seal ring 18. The ring 16 is secured to the flange 14 by suitable bolts 26.
Outwardly beyond the flange 14 the disk has another axially extending flange 27 with an inturned rib 28 on the outer end. This inturned rib is notched at 29 so that the rib has evenly spaced elements 30 between the notches and forming part of a bayonet attachment by which to hold a sideplate 32 in position on the disk. The plate 32 has an outwardly extending flange 33 to cooperate with the inturned rib, and this outwardly extending flange has a recess 34 to receive the rib 28. The flange 33 has notches 36 therein corresponding in dimension to the projections 30 between the notches 29 on the rib 28. The notches 36 are spaced apart by projections 38 on the flange.
With this arrangement the plate is held against the disk by the bayonet at attachment which is activated by placing the plate with the projections 38 aligned with the notches 29, moving the plate axially against the disk and then turning the plate to align the notches in the disk and plate thereby placing the projections 38 in alignment with the projections 30 formed by the notches in the flange 27.
The inner diameter of the rib 28 is the same as the diameter of the bottom of the recess 34 so that there is a tight fit at this location to provide for piloting the plate on the disk and holding these parts in concentric relation. The notches 29 are cut deeply into the flange 27, as shown at 42, and the notches 36 are cut to the surface 44, as shown, so that cooling air may pass through the aligned notches to flow along the surface of the disk from the chamber 24 to a chamber 45 radially outward of the flange 27.
Radially inward of the flange 33 on the plate, the latter has an inner peripheral extension 46 that extends laterally out of the general plane of the plate and carries several outwardly extending spaced ribs 48 having on their outer ends knife-edge elements 50 to cooperate with the seal ring 25 above described to minimize air leakage from the chamber 24 at this location.
Radially outward from the bayonet connection, the disk 10 has an increasing thickness near its periphery to provide adequate dimension for the formation of slots 52 to receive the blade roots 54 therein as in conventional disk constructions. Where the disk becomes thicker, there is an axially extending flange 55 having an inwardly facing axial surface 56, and this axial surface cooperates with another axial surface 58 on a lateral flange 59 on the plate. These cooperating surfaces are nearly the same dimension radially to provide a second pilot for the plate on the disk. The preferable embodiment is to have the first pilot at the bayonet connection tight to maintain concentricity between plate and disk and then to adjust the dimension at this outer pilot to tailor the load split between these two locations under different conditions of operation. This is particularly desirable because of the thermal differences between plate and disk during operation, and the significant thermal dimension changes in the respective parts.
The flanges 55 and 59 have spaced notches 60 and 62 therethrough to allow for a flow of air past these flanges radially outward for cooling the blade roots.
The plate 32 extends radially outward beyond the flange 59 to overlie the disk between the flange and the blade roots and define a chamber 63 between it and the disk in this area. The plate then has a conical portion 64, and the outer periphery of the plate terminates in a radially extending portion 66 that overlies and is held against the surface of the plate and the blade root ends to prevent axial movement of the roots within the disk. This radial portion begins its contact with the disk at the outer edge of the conical portion at the point radially outward of the cooling air passages 67 provided at the base of each slot and located at the bottom of the blade root. These passages accept cooling air from the chamber 63 and serve for cooling the disk and the blade root by the flow of the cooling air through the disk.
Because of the arrangement of the air passages in the flanges 27 and 33 and also the flanges 55 and 59, they act as centrifugal pumps and raise the pressure of the air between the chambers 24 and 63 significantly to increase the cooling air flow through the disk.
The plate 32 has another axial flange 68 on the side remote from the disk and near the conical portion. This flange carries at its outer end an outwardly extending rib 70 cooperating with a fixed seal ring 72 adjacent to the disk.
The plate may have seal grooves 74 and 76 at opposite edges of the radial portion 66 to receive sealing wires 78 and 80. This will provide a tight seal between the plate and disk at these locations and prevent the escape of cooling air past this radial portion of the plate.
A modification shown in Fig. 3 may have vanes 82 mounted thereon adjacent to and on the side of the flange 33', and these vanes will serve to increase the pressure rise in the flow of air outwardly between plate and disk to increase the cooling effect on the periphery of the disk. These vanes may be integral with the plate, being machined therein, or may be attached thereto if desired. In many installations these vanes are unnecessary, but in particularly high performance turbines they may have added function in further increasing the pressure of the cooling air as it reaches the slots in a disk.
The side plate may be locked against turning on the side of the disk by a plurality of slots 84, Fig. 2 in the periphery of the disk or plate 32. These slots are in a position to be engaged by tangs 86 on the blade roots. The tangs and slots are so located that when the tangs engage the slots the projections 30 and 38 are in alignment axially and the slots 60 and 62 are also in alignment. This will assure retention of the side plate securely on the disk.
It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit and scope of this novel concept as defined by the following claims.

Claims

1. The combination with a turbine disk having a row of slots in its periphery, and blade roots in said slots,

of an annular plate eecured to one side of the disk, said plate having,

a slotted radially extending flange on one side thereof between its edges, and a slotted radially extending flange on the disk to cooperate therewith to provide a bayonet attachment of the plate to the disk, said plate also having,

another flange radially outward from said slotted flange and a cooperating flange on the disk, said flanges having cooperating surfaces to pilot the plate on the disk, said plate also.having,

an outer radial portion to overlie the portions of the disk having the slots therein to guide air from the space between the plate and disk into the slots and to retain the blade roots in position in the slots.

2. The combination as in claim 1 in which said plate also has a plurality of knife-edge ribs near the inner periphery on the side opposite to the flanges to provide a seal for the air adjacent the disk.

3. The combination as in claim 1 in which said slotted flanges have cooperating axially extending surfaces in contact with one another to maintain contact concentricity of the plate and disk, thereby providing a second piloting location between disk and plate.

4. The combination as in claim 1 in which the slots in the slotted flanges are deep enough when plate and disk are assembled to permit air flow past said flanges and to provide a pumping action on the air.

5. The combination as in claim 1 in which the cooperating flanges radially outward from the bayonet attachment device are slotted for the passage of air therethrough and to cause a pumping action on the air.

6. The combination as in claim 1 in which the slotted flanges are deep enough to cause a flow of air past said flanges and the cooperating flanges radially outward from the slotted flanges are also slotted for the passage of air therethrough.

7. The combination as in claim 1 in which said plate has a conical portion adjacent the outer radial portion to form a chamber for cooling air between the plate and disk and to direct cooling air into the slots.

8. A sideplate for use with a turbine disk, said disk having a flange on one side with a radial rib extending inwardly and having notches therein, said disk also having slots in its periphery with blade roots therein, and also having another flange on the same side as the first flange and located between said first flange and the blade root, said sideplate includings

a series of knife-edge seals located adjacent to the inner edge thereof and at one side of the plate,

a bayonet attachment device in the form of a projecting rib having slots therein located between the knife-edge seals and the outer periphery of the plate and in a position to align with and cooperate with the notched rib on the disk, and

an axially extending flange outwardly of the bayonet attachment structure and on the same side of the plate to cooperate with another flange on the disk for piloting the disk and plate, and a flat portion at the outer periphery of the plate to overlie the clotted portion of the disk and engage the blade roots therein.

9. A sideplate as in claim 8 in which the second flange on the disk and the axial extending flange outwardly of the bayonet device on the plate have cooperating axially extending surfaces by which the piloting of the plate and disk at this point is effected.

10. A sideplate as in claim 8 in which there is a conical portion in the disk between the flanges thereon and the flat portion to space the plate from the disk and provide a chamber between the plate and disk from which air reaches the slots, said conical portion terminating adjacent to the bases of the slots in the disk.