Patent Application
20150345317
The present invention relates to a device for connecting two enclosures of a turbomachine to allow the establishment through said connecting device of circulation of a cooling fluid between said enclosures.
A turbomachine's turbine generally has an air circulation circuit between a supply enclosure at the low-pressure stator and the rotor of the low-pressure turbine. This air circulation circuit is established through connecting devices connecting two enclosures of a turbomachine to allow the establishment through said connecting device of cooling air circulation between said enclosures.
With reference to
The air circulation circuit typically passes through circulation channels provided in a vane 24 of the turbine nozzle 23. Part of the air is released into the gas circulation stream by orifices (not shown) formed near the trailing edges of the vane 24 of the turbine nozzle. Another part of the air passes through the circulation channel provided in the vane 24 of the turbine nozzle 23 to reach a second tubular connecting device 21 which allows the cooling air circuit to pass through the internal wall 26 of the turbine nozzle and the casing 27 of the stator to arrive at the flanges 28 of the low-pressure rotor so as to cool them.
This circulation circuit thus has two important functions, consisting of carrying the cooling air
from the high-pressure compressor to the vanes 24 of the turbine nozzle 23, and
from the turbine nozzle 23 to the flanges 28 of the low-pressure rotor.
The establishment of this air circulation circuit is made possible by means of two hollow tubular connecting devices which allow circulation of the air between two enclosures such as the supply enclosure and a channel provided in the vane 24 of the turbine nozzle 23.
These connecting devices also make it possible to absorb the relative displacements between the elements defining these enclosures, particularly in the case of vibration or thermal expansion.
Typically, these connecting devices take the form of connecting tubes with a so-called “dog bone” shape, having external sections enlarged at their ends by which the connecting tube cooperates with the wall elements of the enclosures which it connects, or with intermediate bushings connecting it to said elements. Patent application EP 1 538 306 has such devices.
The tubular connecting devices must in addition ensure a good seal in the connection that they constitute. Ensuring a good seat requires:
tight tolerances on the connecting device and the parts in contact therewith, and
implementing a coating at the contacts between the connecting device and the elements that it connects, for example the casing or the turbine nozzle sector.
Thus, to obtain a good sealing, it is also necessary to provide for good clamping at the contacts between the connecting device and the elements that it connects.
However, wear is noted, particularly in rotation, of these tubular connecting devices, due to the different constraints to which they are subjected during operation of the turbomachine, and even breakage of these devices. A structure that is altered, cracked or broken no longer allows these devices to ensure sealing of the air circulation circuit.
It is also possible to observe disengagements of these tubular connecting devices, for example following wear or upon breakage of a portion of the tubular connecting device, which then cannot ensure either the sealing of the air circulation circuit, but also the establishment of this air circulation circuit.
One general aim of the invention is to correct all or part of the shortcomings of the connecting devices of the prior art.
It proposes in particular a connecting device between two enclosures of a turbomachine to allow the establishment, through said connecting device, of a cooling fluid circulation between said enclosures, said connecting device including an outer tube having an opening extending over the entire length of said outer tube, said outer tube being shaped to cooperate with the wall elements of the enclosures which it connects by means of enlarged portion or of intermediate bushings, the connecting device also including an inner tube extending inside the outer tube.
Such a device has the advantage of being simple, low in cost, reliable, robust, having good resistance to wear and to allow sealing of the cooling air circulation circuit during passage thereof into the connecting device.
This device is advantageously completed by the following features, taken along or in any one of their technically possible combinations:
The invention also relates to a turbomachine comprising a connecting device according to the invention.
Other features, aims and advantages of the invention will appear from the description hereafter, which is purely illustrative and not limiting, and which must be read with reference to the appended drawings, among which:
a and 4b are perspective views of the outer tube and the inner tube, respectively;
a and 5b are section views, respectively of the outer tube and the inner tube;
a,
11
b and 11c show a connecting device according to one possible embodiment of the invention, wherein a shutter is positioned at the end of the opening of the outer tube;
With reference to
The outer tube 4 has an opening 3 extending over the entire length of said outer tube 2. This opening 3 is preferably a slot in the wall of the outer tube 2, but it can take other more complex forms, toothed for example, or diagonal, or zig-zag or in any other acceptable form whose function approaches that of a slot. The opening 3 of the outer tube 2 can be accomplished by cutting by electrical melting using a wire.
The width of the opening 3 must be sufficient to allow a limited deformation of the outer tube 2 so as to decrease the forces applied to the structure of the outer tube 2 during its use (shear, thermal expansion . . . ). However, the opening must not be too large, so as not to alter the structure of the outer tube 2. The presence of the opening 3 also allows a reduction in the dimensioning requirements of the outer tube 2.
It should be noted that the opening 3 of the outer tube 2 is preferably not covered by a joint due to the high temperatures to which the connecting device can be subjected, which can reach 500° C. In fact, the materials selected to constitute the tubes are chosen for their resistance to such temperatures. It is also possible to provide for a suitable coating such a cobalt deposit on the surfaces of the tubes.
Moreover, the connecting device being most often mounted in a blind manner inside orifices in the walls of the enclosures which it connects, there exists a non-negligible risk of damaging the sealing during assembly operations, with no possibility of verification.
Preferably, the connecting device is mounted sliding within the orifices in the walls of the enclosures which it connects, and axial retaining means allow it to be held in position. Various axial retaining means can be contemplated to prevent a connecting device from leaving the orifice wherein it is positioned. With reference to
To this end, in the embodiment shown, the outer tube 2 is shaped to cooperate with elements associated with said enclosures so as to keep the connecting device in position with respect to said enclosures. The outer tube presents a central cylindrical portion 4, enlarged portions 5 at its ends through which the outer tube 2 cooperates with the wall elements of the enclosures that it connects, or with intermediate bushings connecting it to said wall elements. In the example illustrated, the central cylindrical portion 4 has a constant circular section, while the circular section of its enlarged portions 5 at its ends varies like that of a portion of a sphere. The connections through which the connecting device is held in position with respect to the walls of the enclosures which it connects are thus linear annular connection.
The inner tube 6 is positioned inside the outer tube 2 and extends within said outer tube 2. The positioning of the inner tube 6 inside the outer tube 2 makes it possible to reinforce the connecting device. Moreover, the inner tube 6 makes it possible to ensure a sealing of the cooling air circuit which the connecting device makes it possible to establish between the two enclosures, this circuit being established through the internal tube 6. Thus, despite the opening along the outer tube 2 which allows relaxation of constraints, the losses of cooling air are limited.
The inner tube 6 is preferably formed to cooperate with the outer tube 2 so as to be held axially in position. In the example illustrated, the inner tube 6 has a cylindrical portion 9, enlarged portions 7 at its end through which the inner tube 6 cooperates with the outer tube 2. These enlarged portions 7 have here a spherical shape. Specific axial retaining members can also be provided for.
In addition, in the case of deterioration of the structural integrity of the outer tube 2, for example by chipping or breakage, the inner tube 6 will continue to ensure both a sealing for the air circuit, and reinforcement of the weakened outer tube 2. Consequently, resistance to wear of the connecting device is improved compared to a single tube.
The inner tube 6 can have an external cross-section of an extent that is smaller than the extent of the inner cross-section of the outer tube 2, so as to facilitate putting it in place. Preferably, the extent of the outer cross-section of the inner tube 6 is selected closest to the extent of the inner cross-section of the outer tube 2, so that the inner tube 6 is held by tight contact against said outer tube 2.
In one preferred embodiment, the inner tube 6 has an opening 7 extending over the entire length of said inner tube 6. Just as for the opening 3 of the outer tube, this is preferably a slot in the wall of the inner tube 6, but it can take other more complex forms, for example toothed, diagonal, zig-zag, or other acceptable forms the function whereof approaches that of a slot. The opening 7 of the inner tube 6 can also be accomplished by cutting by electrical melting with a wire.
The width of the opening 7 must be sufficient to allow limited deformation of the inner tube 6 so as to reduce the forces applied to the structure of the inner tube 6 during its use (shear, thermal expansion . . . ) or its positioning. However, the opening 7 must not be too large, so as not to alter the structure of the inner tube 6. The presence of the opening 7 also allows reducing the dimensioning requirements of the inner tube 6.
So as to retain the sealing in the air circulation circuit, the opening 7 of the inner tube 6 faces a solid portion of the outer tube 2. The opening 7 of the inner tube 6 is thus not facing the opening 3 of the outer tube 2. In this manner, the opening 7 of the inner tube 6 is blocked by the wall of the outer tube 2, ensuring a sealing for the air circuit. In
In order to prevent relative rotation between the inner and outer tubes, the connecting device can additionally also include means of retention against rotation for limiting a relative rotation between the inner tube 6 and the outer tube 2.
In the embodiment of
The anti-rotation protrusion 10 of the inner tube preferably has dimensions smaller than the opening 3 of the outer tube 2. For example, the length of the anti-rotation protrusion 10 is less than 80%, preferably 50% of the width of the opening 3 of the outer tube 2 at the place where said anti-rotation protrusion 10 is engaged in the opening 3 of the outer tube 2. The outer tube 2 thus retains the advantages obtained by its opening 3 as regards constraints. In addition, the fact of allowing a limited relative rotation between the inner tube 6 and the outer tube 2 also makes it possible to relax constraints, while still facilitating the placement of the inner tube 6 in the outer tube 2.
This anti-rotation protrusion 10 is preferably located on the inner tube 6 opposite the opening 7 of said inner tube 6, so as to retain a maximum shift between the respective openings of the inner and outer tubes, as illustrated in
In the embodiments illustrated by
In order to limit the relative rotation of the outer and inner tubes, it is also possible to provide that at least one of the outer tube 2 and the inner tube 6 has a polygonal and/or non-circular cross-section.
It should be noted that an outer tube 2 with a polygonal and/or non-circular section can make it possible to limit rotation of the connecting device with respect to the recess wherein it is placed.
a,
11
b and 11c show a connecting device according to one possible embodiment of the invention, wherein a shutter 13 is positioned at one end of the opening 3 of the outer tube 2. The shutter 13 thus makes it possible to improve the sealing of the connecting device by blocking the end of the opening 3.
The shutter 13 can be an integral part of the outer tube 2, in which case it is integral on one side of the wall of the outer tube 2 and continues on the other side of the opening 3 of which it obstructs the opening at the end of the outer tube 2, to cover the wall on the other side of the opening 3.
The shutter 13 can also be part of the inner tube 6, particularly of the anti-rotation protrusion 10 of the inner tube 6. The shutter 13 then also constitutes an axial retaining means between the inner tube 6 and the outer tube 2.
The linear annular connections make it possible to ensure a linear sealing so as to prevent air leaks between the connecting bushings 14, 15 and the outer tube 2. However, this configuration of the outer tube 2, called “dog bone,” is not the only configuration that makes it possible to obtain linear annular connections suitable for ensuring a linear sealing between the connecting device and the intermediate bushings 15, 16, and other configurations can be considered.
For example,
The excrescence 14a, 15a is continuous over the inner circumference of the bushing 14, 15 to which it belongs, and preferably takes the form of a ring of which the cross-section is partially circular.
The invention also relates to a turbomachine provided with a connecting device including the characteristics previously described.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1262880 | Dec 2012 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2013/053224 | 12/20/2013 | WO | 00 |
