RU2315868C1 - Device for fastening blades of rotor wheels of axial-flow turbomachine - Google Patents

Abstract

FIELD: mechanical engineering; turbomachines.

SUBSTANCE: proposed device for fastening blades of rotor wheel of axial-flow turbomachine has disk, blades sealing ring, U-shaped split ring and lock. Blades are installed in longitudinal slots of disk by their roots provided with radial-axial catches. Sealing ring is installed on disk with thrusting by outer radial bead both against rim part of disk and against roots of blades. Outer radial bead of sealing ring is fitted in catches of blade roots. Sealing ring engages through inner radial bead with bead of disk radially pointed to longitudinal axis. Beads of sealing ring and disk are mated through cylindrical bodies and enclosed by U-shaped ring with radial cut communicating with slot. U-shaped ring engages with lock made in form of part of C-shaped ring arranged between disk and U-shaped split ring. Projection made on side surface of said radial bead of sealing ring pointed to disk is fitted in additional slot of radial bead of disk and slot of U-shaped split ring which are registered. Projection of sealing ring and cylindrical surfaces of U-shaped split ring are enclosed by lock.

EFFECT: provision of reliable locking of blades turbomachine operating at high temperature, centrifugal and gas dynamic loads, increased strength of construction and facilitated assembling and disassembling.

4 cl, 22 dwg

Description

The claimed technical solution relates to gas turbine technology, namely to gas turbine engines, in particular to the impellers of axial turbines with the fixation of their working blades in the axial direction.

The impeller of an axial gas turbine is known (see the description and figures for the patent of the Russian Federation No. 1077380, class IPC F01D 5/32, publication 21.06.93).

In the longitudinal grooves of its disk, the blades are fixed from moving along the longitudinal axis of the wheel with a split U-shaped sealing ring with a groove in inner diameter, covering the shoulder of the disk directed to the axis. An outer diameter ring is inserted into an annular groove composed of individual grooves in the blades and open to the axis of the disk. A liner is installed in the section of the sealing retaining ring as a fragment of the retaining ring of the same U-shaped cross section.

The liner and the retaining ring are held by the collar of the disk, and its outer diameter is included in the annular groove formed by the grooves of the blades. In the liner and the collar of the turbine disk, combined holes are made, into which a latch-pin is inserted that holds the liner in the circumferential direction. This device successfully operates in turbines of sufficient size.

A device for attaching blades from axial displacement in an axial gas turbine wheel is known (see the description and figures for patent analogues of General Electric, USA No. 4171930, CL NKI 416-220 R, CL IPC F01D 5/30, same France No. 2413543 , Germany No. 2842095, Great Britain No. 2012007).

For all variants of the known solution, a common split ring with a U-shaped cross section facing the open side radially from the longitudinal axis of the wheel is common.

In the embodiment closest to the claimed combination of essential features and technical result, a lock in the form of a part of a U-shaped ring is also installed in the direct groove of the retaining ring.

In the annular groove on the outer side of the shoulder of the sealing ring and the groove on the inside of one of the walls of the U-shaped retainer, a spring lock in the form of a plate is introduced.

The known device is not technologically advanced, especially for rotors of turbines of small engines, where it can be generally impossible due to the need for proportional reduction of all its components.

The impeller of an axial turbomachine is also known (see the description of the patent of the Russian Federation No. 2241834, IPC ⁷ F01D 5/30, application date December 30, 2002, published December 30, 2004).

The working blades according to the patent of the Russian Federation No. 22181834 in the disk of the wheel from the rearward movement are mounted with an emphasis by the rear end of the shank in the o-ring, and from the forward movement with the focus of the shank protrusions in the rim of the disk.

The sealing ring and disc have each annular collar. The shoulders are directed towards the longitudinal axis of the wheel and are enclosed by the walls of the U-shaped retaining ring. To install the latch, fixed with a flat lock, the wall of the U-shaped ring between the shoulder of the disk and its blade has a through radial groove.

The groove in its direct projection is connected with a diagonal cut in another wall of the U-shaped ring. The latch is made in the form of a plate according to the size of the groove, fixed by a lock, which is inserted between the disk and the U-shaped ring and bent to the inner diameter of the ring.

The known device successfully and reliably operates in an aircraft medium-power turboprop engine, close to the task, the totality of the technical results achieved and the commonality of essential features.

The technical solution described is adopted as a prototype.

The author took into account the constructive commonality of essential features with the possibility of their improvement and further development of the technical results of the known device for fixing the blades in the turbine impeller when solving a more complex problem in relation to highly loaded turbines.

The complication of the problem is caused by the fact that in the wheels of highly loaded turbines, it is often necessary to install two working blades in each longitudinal groove of the disk. This manages to reduce the level of dynamic stresses in the structural elements of the blades, in particular by damping.

The author was faced with the task of creating such a device for fixing the blades of the impeller of an axial turbomachine, in which, if necessary, installing pairwise working blades in each groove of the disk, fixing them in the axial direction, it would be possible to obtain a certain aggregate technical result, consisting of several logically interrelated technical results .

The main technical result, as in the prototype, is to obtain reliable fixation of the blades, but installed in pairs in each groove of the disk of the wheel of a turbomachine, operating under conditions of high temperatures and loads from both centrifugal and gas-dynamic forces.

At the same time, it is necessary to ensure the concomitant technical result - by optimizing the design, increase the strength of its parts. This requirement is also exacerbated if, in each groove of the wheel disk operating in the field of high axial, centrifugal and temperature loads, the blades are installed in pairs.

The need for these measures is explained by the fact that, in modern turbines, the plane of symmetry of the longitudinal groove of the disk, as a rule, is made at an angle to the axis of rotation, and one blade from a pair in the groove tends to move forward, and the other backward.

In operation, twin blades, making oscillating movements, act on the sealing ring in the circumferential direction, and this effect is much greater than in wheels with single blades.

As the operating experience of such rotors shows, the result of this effect is the displacement of the sealing ring in an angle, which is preceded by the destruction of the elements fixing the ring in the circumferential direction.

In addition, in small-sized turbines, requirements for manufacturability, assembly and disassembly, as well as for reducing the number of parts, increase.

Such interrelated technical results, including, in particular, and preventing the displacement of the sealing ring in the impeller of the axial turbomachine, can be achieved as follows.

The known device for mounting blades in the impeller of an axial turbomachine, in which improvements are made, contains a disk, rotor blades installed in the longitudinal grooves of the disk with their shanks having radial-axial hooks, a sealing ring mounted on the disk with a stop with its outer shoulder as in the rim part the disk, and in the shanks of the working blades and conjugated by its internal radial shoulder with a radially directed to the axis of the shoulder of the disk.

Moreover, the said collars of the sealing ring and the disk are joined by cylindrical bodies and surrounded by a U-shaped ring having a diagonal cut and a groove connected with it, interconnected with a lock located between the disk and the U-shaped ring.

Improvements are as follows.

The fixing of the blades in the axial direction is provided by the emphasis of the sealing ring with its outer radial shoulder in the shanks of the blades and the location of this shoulder in the hooks on the shanks of the working blades.

For fixing in the circumferential direction of the U-shaped split ring relative to the disk and the sealing ring, an additional protrusion is made on the side surface of the inner radial shoulder of the sealing ring mating with the shoulder of the disk.

The protrusion is placed simultaneously in the combined additional groove of the specified collar of the disk and the groove of the U-shaped split ring.

The ends of the split U-shaped retaining ring are kept from sagging by means of a lock covering the surface of said protrusion on the sealing ring and the cylindrical surfaces of the split ring.

This is done as follows.

On the inner cylindrical surface of the U-shaped split ring, a fixative sample is made, divided by the mentioned diagonal cut.

The specified protrusion on the o-ring is blocked by the middle part of the lock introduced between the disk and the U-ring, which is made in the form of a part of a C-shaped ring.

The radially lower end part of the lock is interconnected simultaneously with the inner cylindrical surface of the U-shaped split ring and the fixation sample divided by the diagonal cut on it.

The upper end part of the lock covers the jointly indicated protrusion of the sealing ring and the shoulder of the U-shaped split ring facing both sides of the groove.

For fixing in the circumferential direction of the sealing ring on the specified lateral surface of its inner radial collar facing the collar of the disk, and perpendicular to it, cylindrical bodies are placed in the form of bosses inserted into mating slots in said collar of the disk.

To improve the manufacturability of the assembly-disassembly of the device for impellers of small turbines on the outer radial shoulder of the sealing ring, samples were made between the aforementioned hooks on the shanks of the blades.

The claimed technical solution is illustrated by drawings, where:

- figure 1 shows a longitudinal section of the rim of the impeller of the turbine in assembled form;

- figure 2 shows a fragment of the impeller of the turbine in dimetry;

- figure 3 is an enlarged element G of a split U-shaped ring in place of an oblique cut;

- figure 4 is an enlarged element B, which shows the relative position of the elements of the split U-shaped and O-rings, as well as the disk in the assembled turbine wheel;

- figure 5 shows in dimetry the individual components of the wheels of the turbomachine, including a pair of rotor blades combined for installation in one common groove of the disk, a sealing ring, a split U-shaped retaining ring and its lock;

- Fig.6 shows in dimetry a fragment of the sealing ring from the side of its fit to the disk and blades;

- Fig.7 shows one embodiment of the sealing ring also from the side of contact with the disk and blades;

- Fig.8 is an image in dimetry of a part of a split U-shaped retaining ring in place of a direct groove and a diagonal cut from the side facing the disk;

- figure 9 shows the image in diameter of a fragment of a U-shaped split retaining ring from the side of its inner cylindrical surface with a locking sample for the deformable element of the lock;

- figure 10 is given in dimetric lock to hold the ends of the U-shaped ring;

- 11, 12 shows the steps of setting the blades and the sealing ring in the case of assembling the wheel with the sealing ring in the embodiment presented in Fig.6;

- FIGS. 13, 14, 15, 16 show the steps for installing the rotor blades and the sealing ring in the case of assembling the wheel with the sealing ring in the embodiment of it shown in FIG. 7;

- Fig.17 shows the finally installed working blades and the sealing ring;

- FIGS. 18, 19, 20, 21, 22 show the steps for installing a U-shaped split ring and a lock holding the ends of the split ring from sagging.

The impeller (Fig. 1, 2) of the turbomachine contains left 1 and right 2 working blades installed with their Christmas shanks, respectively, 3, 4, two in each Christmas groove 5 of the disk 6. Each of the working blades 1, 2 has rear shanks 3, 4 hooks 7, 8, respectively (Figs. 1, 5).

Behind, with an emphasis on the rim of the disk 6, a sealing ring 9 is installed, having a radial annular collar 10 inserted into the hooks 7, 8 of the working blades 1, 2, keeping them from moving in the longitudinal direction (Fig. 1, 2, 6, 7 )

When performing the sealing ring 9, as in Fig. 7, the radial shoulder 10 is made by divided samples 11 into sections according to the number of pairs of blades 1, 2. In the assembled wheel, each such section of the shoulder 10 is included in a pair of hooks 7, 8 (Fig. 1, 16 )

In parallel to the shoulder 10 is a radial protrusion 12, covering the hooks 7, 8, providing a smooth outer surface of the turbine wheel (Fig. 1).

The sealing ring 9 also has an annular shoulder 13, directed radially to the axis of rotation (figures 1, 6, 7). On the side surface of the shoulder 13 facing the disk 6, there are several bosses 14 and one protrusion 15.

On the rim of the disk 6 there is an annular shoulder 16, directed radially to the axis of rotation. On the shoulder 16 there are several grooves 17 open to the axis of rotation and one wide groove 18 (see figure 5). The grooves 17 in number and angular arrangement are made in response to the bosses 14 of the sealing ring 9, and the groove 18 is a response to the protrusion 15. The bosses 14 and the protrusion 15 of the sealing ring 9 mounted on the disk 6 are included in the grooves 17 and 18, respectively (Fig. 17).

Moreover, the bosses 14 are inserted into the grooves 17 with a minimum clearance and ensure the fixation of the sealing ring 9 in the circumferential direction. The dimensions of the groove 18 are selected larger than the protrusion 15 in order to exclude their contact.

Split U-shaped ring 20 (Fig, 9) covers the shoulder 16 of the disk 6 and the shoulder 13 of the sealing ring 9 with its vertically directed from the common longitudinal axis collars, outer 21 and inner 22 (Figs. 4, 21). The ring 20 fixes the sealing ring 9 in the longitudinal direction, which, in turn, by means of a collar 10 holds the locks 3.4 of the working blades 1, 2 (Fig. 1).

Split U-shaped ring 20 (Fig 3, 8, 9) has a narrow diagonal through cut 23.

On the inner collar 22 of the ring 20 (Fig. 8, 9), opposite the diagonal cut 23, there is a wide straight groove 24 with sides parallel to the radial plane of the ring 20.

On the inner cylindrical surface of the U-shaped ring 20, a sample 25 is made, divided by a diagonal cut 23 (Fig. 9).

The split U-shaped ring 20 is installed so that a straight groove 24 formed on its inner shoulder 22 faces the disk 6, located behind its shoulder 16 (Fig. 19, 20).

The parallel walls of the groove 24 are placed on both sides of the protrusion 15 belonging to the sealing ring 9, passing through the groove 18 of the shoulder 16 of the disk 6 (Fig. 20, element E). This achieves the fixation of the split ring 20 in the circumferential direction.

The lock 26 (figure 10) is a sector, mainly C-shaped in cross section, having an inner 27 and an outer collar 28, a vertical wall 29 and a deformable part 30.

The complete wheel (FIGS. 1, 21, 22) has a lock 26 located opposite the protrusion 15 of the sealing ring 9 and the groove 24 of the split ring 20.

The lock 26 is wider than the straight groove 24 of the split ring 20, so that its outer shoulder 28 covers not only the outer surface of the protrusion 15 of the sealing ring 9, but also the outer surface of the inner shoulder 22 of the ring 20 on both sides of the groove 24 (Fig. 19, 20, 21, 22). The inner collar 27 of the lock 26 covers the inner surface of the split ring 20. Thus, the ends of the split ring 20 are fixed from sagging.

Part 30 of the lock 26 is deformed inwardly (FIGS. 1, 22) into the sample 25 on the inner cylindrical surface of the U-ring 20, thereby securing the lock 26 in the circumferential direction.

There are two possibilities for assembling the impeller of a turbomachine with the claimed device for fixing the rotor blades, characterized by the initial stages regarding the setting of the rotor blades 1, 2 and the sealing ring 9.

The first method is applicable in the case of a gap between the Christmas groove 5 and the combined Christmas shanks 3, 4 of a pair of blades 1.2 over 0.1 mm. In this case, it is preferable that the wheel with a sealing ring 9 in the embodiment shown in Fig.6, that is, with a continuous outer collar 10. The distinctive initial stages of assembly of the wheel are presented in Fig.11, 12. The assembly begins with the installation of a pair of working blades 1, 2 their hooks 7, 8 on the shoulder 10 of the sealing ring 9, as shown in Fig.11.

Then, in this way, the entire set of working blades 1, 2 is installed and is held together with the sealing ring 9 by the technological device. The blades 1, 2 assembled with the sealing ring 9 are installed in a set in the Christmas grooves 5 of the disk 6 (see Fig. 12).

The second method of installing the working blades 1, 2 and the sealing ring 9 is shown in FIGS. 13, 14, 15, 16, it is preferable for the gaps between the Christmas groove 5 of the disk 6 and the combined Christmas shanks 3, 4 of the pair of blades 1, 2 less than 0.1 mm (wheels of small turbines), when the simultaneous installation of the entire set of working blades 1, 2 in the grooves 5 of the disk 6 is difficult. In this case, the set of blades 1, 2 is pre-installed in the grooves 5 of the disk 6 approximately half the width of the rim of the disk 6 (see Fig.13).

Presented in Fig.7, the sealing ring 9 with the shoulder 10, divided by samples 11 into sections, is installed so that the protruding sections of the shoulder 10 pass between the hooks 7, 8 of the Christmas shanks of the working blades 1, 2 (Fig.14, 15). Then, the sealing ring 9 is rotated about the axis so that each protruding section of the shoulder 10 is engaged with the hooks 7, 8 of the pair of working blades 1,2 (Fig. 16).

Further steps of assembling the turbine wheel are common and are presented in FIGS. 17, 18, 19, 20, 21, 22.

A set of working blades 1, 2 together with the sealing ring 9 are moved until the stop of the sealing ring 9 into the rim of the disk 6 (see Fig.17). In this case, the bosses 14 of the sealing ring 9 enter the grooves 17 in the shoulder 16 of the disk 6, not protruding above the surface 19 of the shoulder 16, while the protrusion 15, passing through the groove 18, protrudes above the surface 19 of the shoulder 16.

The installation of the split ring 20 and the lock 26 is shown in stages in FIGS. 18, 19, 20, 21, 22. When installing the split ring 20, a lock 26 is installed on its trailing part, as shown in FIG. 18.

The parallel walls of the direct groove 24 of the ring 20 are located on both sides of the protrusion 15 of the sealing ring 9 (see Fig. 19, 20), which ensures the fixation of the split ring 20 in the circumferential direction. Then the lock 26 moves along the arc and is installed opposite the protrusion 15 of the sealing ring 9 (see Fig.21, 22).

The collar 28 of the lock 26 external from the longitudinal axis of the device covers the outer surface of the protrusion 15 of the sealing ring 9, as well as the outer surface of the collar 22 of the ring 20 on both sides of the direct groove 24, which prevents the lock 26 from falling out.

The shoulder 27 of the lock 26, internal from the longitudinal axis, covers the inner surface of the ring 20. The deformable part 30 of the lock 26, which is opposite the sample 25 of the split ring 26, is deformed inside this sample (see Fig. 22), which ensures the lock 26 is secured in the circumferential direction.

The width of the lock 26 is greater than the width of the groove 24 of the split ring 20, which ensures that the outer shoulder 28 of the lock 26 covers not only the outer surface of the protrusion 15, but also both ends of the split ring 20 along the outer surface of the shoulder 22.

This, combined with the lower collar 27 of the lock 26 covering the ends of the split ring 20 along its inner surface, provides reliable fixation of the said ends against sagging.

The turbine wheel is finally assembled (see figures 1, 2, 21).

It should also be added that the presence of a shoulder 12 of the sealing ring 9, covering the hooks 7, 8 of the Christmas shanks 3, 4 of the working blades 1, 2, as well as the almost smooth outer surface of the split ring 20 minimize ventilation losses.

The design in the production of its parts is technological, and during assembly-disassembly does not cause any difficulties.

The temperature in the rim of the wheel in operation is 600 degrees Celsius. The highest stresses are noted in the sealing ring, in the radius of the centering collar to the vertical wall, but their value does not exceed 63 kg / mm ² , which is much less than the long-term strength limits of modern heat-resistant nickel alloys used for such parts of turbine rotors.

The high reliability of the inventive device at all normal engine operating conditions is confirmed by 150-hour tests of a full-size experimental prototype of the turbine wheel on an experimental AI222-25 type aviation gas turbine engine.

Claims (4)

1. The mounting device of the blades of the impeller of the axial turbomachine, containing the disk, the rotor blades installed in the longitudinal grooves of the disk with their shanks having radial-axial hooks, a sealing ring mounted on the disk with emphasis on its outer radial collar both in the rim of the disk and in the shanks of the working blades, and conjugated by its inner radial collar with radially directed to the longitudinal axis of the collar of the disk, and the said collars of the sealing ring and disk are joined by cylindrical bodies and covered by a U-shaped ring with a diagonal cut connected with a groove, which is interconnected with a lock placed between the disk and the U-shaped split ring, characterized in that the outer radial shoulder of the sealing ring is placed in the hooks of the shanks of the working blades, and on facing the disk a side surface of said inner radial collar of the sealing ring has a protrusion located in a combined additional groove of the radial collar of the disk and the groove of the U-shaped split ring, said protrusion and surface of cylindrical U-shaped split ring covered by a lock in the form of part of C-shaped cross section. 2. The attachment device for the blades of the impeller of an axial turbomachine according to claim 1, characterized in that the C-shaped lock between the disk and the U-shaped split ring is installed so that its middle part overlaps the protrusion on the inner radial collar of the sealing ring on both sides of the aforementioned the groove of the U-shaped split ring, made in the collar of the ring facing the disk, while the upper end part of the lock covers the joint protrusion and the outer surface of the specified shoulder of the U-shaped split ring on either side of its groove, while the lower end portion of the lock open interconnected with the inner cylindrical surface of the U-shaped split ring and formed thereon detent sample divided by said diagonal rezom. 3. The attachment device of the blades of the impeller of the axial turbomachine according to claim 1, characterized in that said cylindrical bodies that articulate the said radial collars of the disk and the sealing ring are made in the form of bosses on the side surface of the radial collar of the sealing ring facing the disk and inserted into the reciprocal grooves in the radial collar of the disk. 4. The attachment device of the blades of the impeller of the axial turbomachine according to claim 1, characterized in that on the said outer radial collar of the sealing ring, samples are made between these hooks on the shanks of the blades.

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