EP1367221B1 - Double injector arrangement for cooling of the sideplate of a high pressure turbine - Google Patents

Description

The invention relates to the field of ventilation of high-pressure turbine rotors of turbojets.

It relates more specifically to a device for ventilating a high-pressure turbine rotor of a turbomachine, this turbine being disposed downstream of the combustion chamber and comprising, on the one hand, a turbine disk having an internal bore and an upstream flange for fixing it to the downstream cone of a compressor, at high pressure, and, secondly, a flange disposed upstream of said disk and separated from the latter by a cavity, said flange comprising a massive radially inner part. also having an internal bore, through which the upstream flange of said disk extends, and an upstream flange for attachment to said downstream cone, said device comprising a first circuit for cooling the blades fed by a first flow of air sampled at the bottom of the chamber and delivering this first air flow into said cavity via main injectors arranged upstream of said flange and ventilation holes formed in said flange, and a second circuit for cooling the flange, fed by a second air flow through a labyrinth of discharge located downstream of the high-pressure compressor, at least a portion of said second air flow serving to ventilate the upstream upper face of said flange through a second labyrinth located under the injectors.

FIG. 1 shows such a high-pressure turbine rotor 1, disposed downstream of a combustion chamber 2, and which comprises a turbine disc 3 equipped with vanes 4, and a flange 5 disposed upstream of the disc 3. The disc 3 and the flange 5 each comprise an upstream flange referenced 3a for the disc 3 and 5a for the flange 5, for their attachment to the downstream end 6 of the downstream cone 7 of the high-pressure compressor driven by the rotor 1.

The disc 3 has an internal bore 8 through which the shaft 9 of a low-pressure turbine passes, and the flange 5 has an internal bore 10 surrounding the flange 3a of the disc 3, and ventilation holes 11 through which a first flow C1 cooling air taken from the bottom of the chamber is delivered into the cavity 12 separating the downstream face of the flange 5 of the upstream face of the disk 3. This cooling air flow C1 circulates radially outwards and enters the 4a cells containing the feet of the blades 4 to cool them. This air flow is taken from the chamber bottom, circulates in a conduit 13 disposed in the chamber 14 separating the flange 5 from the chamber bottom and is rotated by injectors 15 in order to lower the temperature of the chamber. air delivered into the cavity 12.

A second cooling air flow C2 taken from the chamber bottom flows downstream into the chamber 16 separating the downstream cone 7 of the high-pressure compressor from the inner casing 17 of the combustion chamber 12. This air flow rate C2 flows through a discharge labyrinth 18 and enters the chamber 14 from which a portion C2a flows through orifices 19 formed in the upstream flange 5a of the flange 5, passes through the bore 10 of the flange 5 in order to cool the radially inner portion of the latter and rejoins the cooling air flow C1 of the blades 4. Another part C2b of the second air flow C2 cools the upstream face of the flange 5, bypasses the injectors 15 and is discharged into the upstream bleed cavity 20 of the turbine rotor 1.

Finally, a third part C2c of the third air flow C2 serves to ventilate the upstream upper face 21 of the flange 5 through a second labyrinth 22 located under the injectors 15. This third part C2c enters the chamber 23 located in downstream of the second labyrinth 22, between the flange 5 and the injectors 15, and is discharged into the upstream bleed cavity 20 of the turbine rotor 1 through a third labyrinth 24 located above the injectors 15, or is mixed with the first one. C1 air flow.

The second air flow C2 serves to cool the downstream cone 7, the connecting rod of the high pressure compressor to the high pressure turbine, and the flange 5. This second flow of air flowing axially in an annular space defined by fixed walls integral with the chamber and rotating movable walls integral with the rotor, undergoes heating related to the power dissipated between the rotor and the stator.

To lower the temperature of the upstream flange according to the specifications of its mechanical strength, it is therefore necessary to increase the air flow C2 passing through the discharge labyrinth 18 located downstream of the high-pressure compressor, and to reject it either in the blade cooling circuit, either in the vein upstream of the high pressure turbine wheel. This increase in flow generates an increase in the temperature of the cooling air of the blades of the the rejection of heated air in the blade cooling circuit, and a drop in turbine performance due to rejection in the vein.

Furthermore C2c air flow for cooling the flange downstream of the second labyrinth 22 located under the injectors 15, is not controllable because it undergoes changes in the games labyrinth discharge 18, the second labyrinth 22 and the third labyrinth 24 located above the injectors 15, during operation and during the life of the engine.

The temperature of the upstream face of the flange downstream of the second labyrinth is therefore quite high and poorly controlled. This requires the use of special materials for the production of the flange and appropriate sizing.

U.S. Patent Nos. 5,816,776 A and 4,822,244 A disclose turbine rotor ventilation devices typical of the prior art.

The object of the invention is to lower the temperature of the upstream face of the flange to facilitate its dimensioning in overspeed, to increase its life and to use an economical material.

This object is achieved according to the invention with the features of claim 1 in that said device further comprises a bypass between the first circuit and the inner enclosure located downstream of the second labyrinth, said bypass delivering a third flow of air for cooling the upper upstream face of the radially inner portion of said flange, this third air flow being pre-rotated by means of additional injectors.

This third flow of air pre-driven and injected downstream of the labyrinth under main injectors thus reduces the total relative temperature of the air from cooling the upstream face of the flange downstream of the second labyrinth. This third air flow mixes with the leakage flow of the labyrinth under injectors and is discharged downstream of the main turbine injectors, in the supply circuit of the high pressure turbine wheels.

The air injected into the supply circuit of the turbine wheel is thus colder than that of the air injected according to the state of the art.

Advantageously, the additional injectors are made in the form of bores tilted tangentially in the direction of rotation of the rotor.

Preferably, said bores remove air from the main injectors and deliver it immediately downstream of the second labyrinth.

• la figure 1 est une demi-coupe axiale d'un rotor de turbine à haute pression d'un turboréacteur, qui montre les circuits d'air de refroidissement selon l'art antérieur ;
• la figure 2 est une demi-coupe axiale d'un rotor de turbine de turboréacteur qui comporte le dispositif de refroidissement selon l'invention ; et
• les figures 3 à 5 montrent les évolutions de température de l'alésage du flasque amont respectivement en fonction du jeu du labyrinthe de décharge du compresseur, du labyrinthe sous injecteurs et du labyrinthe sur-injecteurs, avec un dispositif de ventilation classique et avec un dispositif de ventilation selon l'invention.

Other advantages and characteristics of the invention will become apparent on reading the following description given by way of example and with reference to the appended drawings in which:

• FIG. 1 is an axial half-section of a high-pressure turbine rotor of a turbojet, which shows the cooling air circuits according to the prior art;
• FIG. 2 is an axial half-section of a turbojet turbine rotor which comprises the cooling device according to the invention; and
• FIGS. 3 to 5 show the temperature changes of the bore of the upstream flange respectively as a function of the clearance of the compressor discharge labyrinth, the labyrinth under injectors and the labyrinth over-injectors, with a conventional ventilation device and with a device ventilation according to the invention.

The state of the art shown in Figure 1 has been discussed in the introduction and does not require further explanation.

FIG. 2 shows a turbine rotor 1 which differs from that shown in FIG. 1 in that the enclosure 23 situated downstream of the second labyrinth 22 is supplied with air, on the one hand, by an air leak C2c coming from the enclosure 14 via the second labyrinth 22 and, secondly, by an air flow C1a delivered by a bypass arranged between the duct 13 delivering the first air flow C1 and the enclosure 23. The derivation consists of a plurality of holes 30 opening, on the one hand, to the inlet of the main injectors 15 and, on the other hand, in the chamber 23 immediately downstream of the second labyrinth 22. The holes 30 are cylindrical and inclined tangentially in the direction of rotation of the turbine rotor 1.

As can be seen in FIG. 2, the radially inner portion 31 of the flange 5 has a massive shape, and extends axially towards the front of the motor until it reaches the radial flange 5a which serves to fix it at the end. downstream 6 of the downstream cone 7 of the compressor. The labyrinth 22, located under the injectors 15 is disposed at the periphery of the radial flange 5a. The bores 30 are substantially radial and directed towards the upper face 32 of the radially inner part of the flange 5.

Since the bores 30 are inclined in the direction of rotation of the turbine rotor 1, the air flow C1a delivered by the bores 30 is at a reduced relative total temperature with respect to the cooling air of the same regions in the region. state of the art.

The temperature gain can be estimated at 30 ° C. The air flow C1a mixes with the C2c leakage rate of the labyrinth under injectors 22 and is discharged downstream of the main injectors 15 in the turbine wheel supply circuit.

As can be seen in FIG. 2, the radial flange 5a does not have orifices for supplying the annular chamber 33 located between the radially inner portion 31 of the flange 5 and the downstream flange 3a of the turbine disk 3, since the third air flow C1a is sufficient to ensure by itself the cooling of the entire flange 5.

The air injected into the pre-entrained turbine wheel feed circuit for cooling the blades is colder than the cooling air of the vanes in conventional ventilation. The temperature gain can be estimated at 15 °, which equates to a specific consumption gain of about 0.06%.

In addition, the cold air flow C1a delivered by the holes 30 is not influenced by the variations of the games of the surrounding labyrinths, because this flow is calibrated by the holes 30.

FIG. 3 shows in dotted line the evolution of the temperature of the bore 31 of the flange 5 in a conventional turbine rotor ventilation, and in full lines, the evolution of the temperature in the same place with the ventilation device according to FIG. according to the clearance of the labyrinth discharge 18 expressed in mm.

It is noted that the evolution of this temperature with the device according to the invention is substantially constant and always lower than the temperature obtained at this point with conventional ventilation.

FIG. 4 shows the evolution of the temperature of the bore 31 of the flange 5 as a function of the clearance of the second labyrinth 22 located beneath the main injectors 15, with a conventional ventilation (dashed curve) and with a ventilation device according to FIG. 'invention.

It is also noted that, all things being equal, the temperature in this zone with the device according to the invention is substantially constant and lower than that obtained with conventional ventilation.

FIG. 5 shows the evolution of the temperature at the same place of the flange, as a function of the play of the third labyrinth 24, for a conventional ventilation (dashed curve) and for ventilation with the device according to the invention. The temperature in this region is substantially constant with a ventilation device according to the invention.

Because the temperature of the flange 5 in the vicinity of the third labyrinth 24 is substantially constant with the ventilation device according to the invention, and lower than that obtained with conventional ventilation, the flange 5 is less stressed by thermal stresses, and it can be made in a less expensive material and easier to work.

Claims (6)

1. A ventilation device for a high pressure turbine rotor of a turbomachine, said turbine being disposed downstream from the combustion chamber and comprising firstly a turbine disk (3) presenting an internal aperture and an upstream flange (3a) for fixing to the downstream cone (7) of a high pressure compressor, and secondly an end plate (5) disposed upstream from said disk and separated therefrom by a cavity (12), said end plate comprising a solid radially inner portion (31) likewise having an internal aperture, through which the upstream flange (3a) of said disk extends, and an upstream flange (5a) for being fixed to said downstream cone, said device comprising a first circuit for cooling blades fed with a first flow of air (C1) taken from the end of the combustion chamber and delivering said first flow of air into said cavity (12) via main injectors (15) disposed upstream from said end plate, and ventilation holes (11) formed through said end plate, and a second circuit for cooling the end plate fed with a second flow of air (C2) through a discharge baffle (18) situated downstream from the high pressure compressor, at least a fraction of said second air flow serving to ventilate the upstream top face of said end plate through a second baffle (22) situated beneath the injectors (15),
   the device being characterised by the fact that it further comprises a branch connection between the first circuit (13) and the enclosure (23) situated downstream from the second baffle (22), said branch connection delivering a third flow of air (C1a) for cooling the upstream top face (32) of the radially inner portion (31) of said end plate (5), said third flow of air (C1a) being entrained into pre-rotation by means of additional injectors (30).
2. A device according to claim 1, characterised by the fact that the additional injectors are implemented in the form of bores (30) that are inclined tangentially in the of rotation of the rotor.
3. A device according to claim 2, characterised by the fact that said bores (30) take air at the of the main injectors (15).
4. A device according to claim 3, characterised by the fact that said bores (30) deliver air immediately downstream from the second baffle.
5. A device according to any one of claims 2 to 4, characterised by the fact that the second baffle (22) is disposed between the main injectors (15) and the upstream flange (5a) of the end plate (5).
6. A device according to claim 5, characterised by the fact that the upstream flange (5a) of the end plate (5) is radial.

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