The invention relates to a turbine ring forming the outer shroud of the rotor of said turbine. The invention applies particularly to a high pressure turbine situated immediately downstream from the combustion chamber of an airplane turbojet. It relates more particularly to the interconnection and cooling of the sectors making up said turbine ring.
In a turbine of the kind mentioned above, driven by gas at very high temperature, the rotor rotates inside a stationary turbine ring constituted by a plurality of curved sectors that are united end to end circumferentially in order to form the rotor shroud. The temperature of the gas driving the blade wheel is such that the thermomechanical stresses that are created between the sectors can lead to deterioration, reducing the lifetime of such rings. Typically, small cracks and/or flaking can often be observed on the inside (or “hot”) face of the sectors, mainly in the vicinity of the connections between adjacent sectors.
To provide the ring with better sealing, reducing leaks of non-working air, and in order to prevent hot gas being reinserted, sealing systems are provided between such adjacent sectors, said systems comprising tongues that extend between the sectors and that are received in slots formed facing them in the adjacent radial faces of said sectors.
For example, a prior art sector 1 shown in
The invention thus provides firstly a turbine ring forming a rotor shroud, the ring being of the type constituted by a plurality of sectors interconnected end to end with interposed sealing systems comprising tongues extending between adjacent sectors, said tongues being housed in slots formed facing each other in adjacent radial faces of said sectors, wherein each sealing system is constituted by rectilinear tongues engaged in respective rectilinear slots in said radial faces.
The fact of making the sealing system from tongues that are straight simplifies making the slots and facilitates mounting the tongues therein. In addition, control over the positioning of the tongues is improved because of the bear against surfaces that are under better control since they are strictly linear. Overall, leakage sections are made smaller. A configuration with only three tongues is described below.
More particularly and advantageously, in the above-defined turbine ring, each sealing system comprises a first tongue and a second tongue extending in a chevron configuration on the inside of said radial faces, said tongues being engaged in rectilinear slots of said radial faces defining their relative positions accurately. As a result, air leakage between two consecutive sectors can be accurately calibrated. Such leakage can thus be identical through all of the inter-sector spaces. Overall, it is estimated that the leakage rate can be reduced by 10% to 20% compared with the above-described prior art configuration.
Another advantage of the invention lies in the fact that arranging the tongues in a chevron configuration on the hot face side makes it possible both to move the stress concentration zones further away from said hot face (since the slots go away therefrom), and also to provide sufficient space between the tongues and the hot face to allow cooling air ejection channels to open out therein, which channels are fed from a cavity formed within the sector itself.
More precisely, the invention also provides a turbine ring as defined above in which each sector includes a cooling air flow cavity, the ring further including air ejection channels extending between said cavity and at least one radial face of the sector, these channels opening out in said radial face between an inner edge thereof and said first and second tongues.
The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description given purely by way of example and made with reference to the accompanying drawings, in which:
In the drawings, and more particularly in
The tips of the rotor blades travel past the inner surface of the ring as constituted in this way. The direction of rotation is represented by arrow F in
Apart from the sealing systems between the sectors, the arrangement described above is already known. The invention relates in particular to an advantageous improvement in said sealing systems between the sectors.
More particularly (
In addition, each sealing system includes a third tongue 29 extending substantially from one end to the other of the adjacent sectors, parallel to the axis of the ring and on the outer side of said radial faces. The tongue 29 is engaged in rectilinear slots 33 in the adjacent sectors. As can be seen in
The pressures which become established in the spaces between the sectors on the inside and on the outside, and also between the third tongue and said first and second tongues taken together are such that said first and third tongues 27, 29 are pressed against the inside faces of the slots 31, 33 in which they are received, while said second tongue 28 is pressed against the outside faces of the slots 32 in which it is received, as can be seen in
The length of the first tongue 27 depends on the angle it makes with the first tongue 29. Once this angle has been determined (several possibilities are shown in
The angle defined between the first and third tongues may lie in the range 15° to 70°, approximately.
The slots can be machined accurately and they are well located. The tongues can be inserted in these slots and their relative positions can be well controlled. As a result the leakage section between said first and second tongues (at S1) and the leakage section between the first and third tongues (at S2) are well controlled.
With reference more particularly to
In the example, the channels 50 open out it the radial face 20 that is the first face to be reached by the blades, given the direction of rotation represented by arrow F. This is favorable for avoiding or limiting any reintroduction of hot gas into the inter-sector spaces. It would also be possible to make similar channels through the opposite wall, opening out in the radial face 21. The air escaping from the channels 50 cools the wall through which they are formed by convection (thermopumping), while the opposite wall (face 21) is cooled by the impact of the jets of air. In addition, the jets of air escaping from the channels 50 set up a kind of fluidic system preventing hot gas being ingested.
It should also be observed that the slots 31, 32, and 33 are preferably independent, i.e. they do not communicate with one another. This avoids any need to make any tool clearance at the junction between two slots. Leakage sections between the sectors are also reduced.
The invention also provides any ring sector or any assembly of ring sectors presenting the characteristics described above.
Number | Date | Country | Kind |
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04 03925 | Apr 2004 | FR | national |
Number | Name | Date | Kind |
---|---|---|---|
5088888 | Bobo | Feb 1992 | A |
5127793 | Walker et al. | Jul 1992 | A |
5997247 | Arraitz et al. | Dec 1999 | A |
6575697 | Arilla et al. | Jun 2003 | B1 |
6814538 | Thompson | Nov 2004 | B2 |
Number | Date | Country |
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1 162 346 | Dec 2001 | EP |