Description

Title of the invention: Moving blade of a turbomachine with a cooling circuit having a double row of evacuation slots

Technical area

The present invention relates to the general field of turbomachine blades, and more particularly to the evacuation at the trailing edge of the air for cooling the blades of a turbomachine high-pressure turbine.

Prior technique

The blades of a turbomachine high-pressure turbine are subjected to the high temperatures of the gases issuing from the combustion chamber and which pass through the high-pressure turbine. These temperatures reach values ​​that are much higher than those that the blades which are in contact with these gases can withstand, which has the consequence of limiting their service life.

In order to limit the damage caused by these hot gases on the blades, it is known to provide them with internal cooling circuits aimed at reducing the temperature of the latter. Thanks to such circuits, cooling air, which is generally introduced into the blade by its root, crosses the latter following a path formed by cavities made in the blade before being ejected through slots opening on the surface of the blade, between the foot and the top thereof.

Growing needs in terms of performance, efficiency, service life and reliability are driving the design of increasingly efficient cooling circuits. Indeed, increasing the efficiency of these cooling circuits has many advantages. In particular, the admissible thermal level in the stream will be higher and the motor more efficient at iso-flow cooling. In addition, the cooling flow necessary to guarantee the integrity of the parts cooled by these cooling circuits will be less important for a point of cooling.

given operation. Finally, the service life of these parts will be longer for the same ventilation rate and for the same thermodynamic conditions.

With this in mind to increase the efficiency of the cooling circuits, it can be seen that the trailing edge of the moving blade is a critical zone from a thermal and mechanical point of view because of the difficulty in cooling it effectively. This is mainly due to the lack of space, in particular because of the minimum thicknesses of material required for the manufacture of the blade, and in particular at the junction of the intrados and extrados walls at the trailing edge.

To effectively cool the trailing edge, it is known practice to cast cooling circuit evacuation slots on the underside of the blade. These slots allow cooling of the material at the trailing edge by pumping, and by film (“film cooling” in English) with an ejection almost tangent to the profile of the blade, which greatly increases its efficiency.

On the other hand, the blade area upstream of the evacuation slots is a difficult area to cool which regularly displays a high thermal level. This is due in particular to the lack of space to put turbulence promoters for cooling and to have two cooling cavities in the thickness of the blade.

Disclosure of Invention

The object of the present invention is therefore to propose a moving blade of

turbomachine which does not have the aforementioned drawbacks.

According to the invention, this object is achieved by means of a turbine engine moving blade, comprising a blade extending radially between a blade root and a blade tip and axially between a leading edge and a trailing edge , and at least one cooling circuit comprising at least one cavity extending radially between the foot and the crown, at least one air intake opening at a radial end of the cavity, a plurality of first evacuation slots arranged along the trailing edge between the foot and the top, and a plurality of second evacuation slots distinct from the first slots and arranged along the trailing edge between the foot and the top, the second evacuation slots being offset axially upstream relative to the first vent slots and each of the first vent slots being radially offset relative to each of the second vent slots, with no overlap between the first and second vent slots cause.

The invention is remarkable in that it provides an additional row of evacuation slots upstream and radially offset without overlapping vis-à-vis

from the usual row of exhaust slots. Thus, this additional row makes it possible to benefit from cooling upstream of the usual slots. The lower surface of the blade is then cooled on a larger curvilinear abscissa at the level of the trailing edge of the blade. Moreover, upstream of this row

additional evacuation slots, the thickness of the blade profile is greater, which makes it possible to have a cavity provided with promot cooling owers or to have two separate cavities. Finally, this radially offset arrangement of the slots of the two rows without overlap between them makes it possible to increase the efficiency of the cooling, in particular for the

cooling of the slot ribs located downstream.

The first evacuation slots and the second evacuation slots may open into the same cavity of the cooling circuit.

Alternatively, the first evacuation slots and the second slots

evacuation can open into two separate cavities of the cooling circuit.

In this case, the cavity into which the second evacuation slots open is preferably offset axially upstream with respect to the cavity into which the first evacuation slots open.

The first evacuation slots emerge at the level of the trailing edge and the second evacuation slots can emerge at the level of a lower face of the blade.

Alternatively, the first evacuation slots and the second slots

evacuation can open at the level of a lower face of the blade.

The first evacuation slots and the second evacuation slots can be arranged in columns. Likewise, the second evacuation slots can occupy exactly each of the radial spaces left between the first evacuation slots

The invention also relates to a process for the manufacture by foundry of a blade as defined above, comprising the production of a ceramic core by additive manufacturing, the core making it possible to produce the first slots

exhaust and the second exhaust slots. This manufacturing solution makes it possible to produce the foundry cores necessary to reserve the locations for the cavities of the cooling circuit. Another subject of the invention is a turbomachine high-pressure turbine, comprising a disk which has a plurality of cells which open out at the periphery of the disk and a plurality of blades as defined previously.

Brief description of the drawings

[Fig. 1] Figure 1 is a perspective view of an example of a blade to which the invention applies.

[Fig. 2] Figure 2 is a cross-sectional view of a blade according to one embodiment of the invention showing the cooling circuit of the trailing edge of the blade.

[Fig. 3] Figure 3 is a partial view in perspective on the lower surface of a blade according to another embodiment of the invention showing the evacuation slots of the cooling circuit of the trailing edge of the blade.

[Fig. 4] Figure 4 is a partial view in perspective on the lower surface of a blade according to yet another embodiment of the invention.

Description of embodiments

FIG. 1 represents in perspective a blade 2 of a turbine, for example a moving blade of a high-pressure turbine of a turbomachine. The blade 2 is fixed on a turbine rotor (not shown) by means of a fitting 4 generally in the shape of a fir tree.

In known manner, the blade 2 comprises a blade 6 which extends radially between a root 8 of the blade and a tip 10 of the blade, and axially between a leading edge 12 and a trailing edge 14. The blade 6 of the dawn thus defines the intrados 6a and the extrados 6b of the dawn.

Blade 2, which is subjected to the high temperatures of the combustion gases passing through the turbine, needs to be cooled. For this purpose, and still in a known manner, the blade 2 comprises one or more internal cooling circuits, and in particular an internal circuit for cooling the trailing edge.

As shown in Figure 2, the internal circuit for cooling the trailing edge of the blade comprises at least one cavity 16 extending radially between the

root 8 and crown 10. Cavity 16 is supplied with cooling air at one of its radial ends through an air intake opening (not shown) which is generally provided at root 4 of the blade .

In the exemplary embodiment represented in FIG. 2, the internal circuit for cooling the trailing edge of the blade comprises two distinct cavities 16a, 16b which are offset axially with respect to each other.

According to the invention, the trailing edge cooling circuit also comprises a plurality of first evacuation slots 18 which are arranged along the trailing edge 14 of the blade between the root 8 and the tip 10, and a plurality second evacuation slots 20 which are separate from the first slots

evacuation 18 and which are also arranged along the trailing edge between the root and the tip of the blade.

In the embodiment shown in Figure 2, the first evacuation slots 18 open into the cavity 16b of the cooling circuit and open onto the intrados face 6a of the blade near its trailing edge 14. As for the second evacuation slots 20, they open into the cavity 16a of the cooling circuit and also open onto the lower surface 6a of the blade near its trailing edge 14.

Furthermore, as shown more specifically in Figure 3, the second evacuation slots 20 are axially offset upstream relative to the first evacuation slots 18 and arranged to be radially offset relative to the first evacuation slots without overlap between them, i.e. the lower wall of a given slot does not overlap the upper wall of the radially offset adjacent slot and vice versa.

Thus, the first and second evacuation slots 18, 20 are arranged so as to form two separate rows of slots which are offset axially and radially with respect to each other.

FIG. 3 represents a second embodiment of the invention in which the first evacuation slots 18 and the second evacuation slots 20 open into the same cavity 16 of the cooling circuit of the trailing edge of the blade. More precisely, in this example which cannot be limited to this supply by a single cavity, the lower walls of the first slots 18 coincide with the upper walls of the adjacent second slots 20 and the upper walls of the first slots 18 coincide with the lower walls of the adjacent second slots 20, so that the second slots exactly occupy each of the radial spaces left between the first slots.

FIG. 4 represents a third embodiment of the invention in which the first evacuation slots 18 of the trailing edge cooling circuit open at the level of the trailing edge 14 of the blade, while the second evacuation 20 emerge at the level of the intrados face 6a of the blade 2.

The blade 2 according to the invention is obtained directly by molding. To this end, the blade is made by casting a metal in a mold containing a ceramic core which has the particular function of reserving a location for the circuit of

cooling of the blade, and in particular for the cavity 16 and the first and second evacuation slots 18, 20 of the cooling circuit of the trailing edge of the blade.

In order to obtain the double row of evacuation slots directly from the foundry, the ceramic core is advantageously produced by additive manufacturing.

Claims

[Claim 1] Moving blade (2) of a turbomachine, comprising:

a blade (6) extending radially between a blade root (8) and a blade tip (10) and axially between a leading edge (12) and a trailing edge (14); and

at least one cooling circuit comprising at least one cavity (16; 16a, 16b) extending radially between the foot (8) and the crown (10), at least one air intake opening at a radial end of the cavity (16; 16a, 16b), a plurality of first evacuation slots (18) arranged to open out along the trailing edge between the foot (8) and the top (10), and a plurality of second slots evacuation slots (20) distinct from the first evacuation slots and arranged along the trailing edge (14) between the foot (8) and the crown (10), the second evacuation slots (20) being offset axially towards the upstream with respect to the first evacuation slots (18) and each of the first evacuation slots (18) being radially offset with respect to each of the second slots

vent (20), with no overlap between the first and second vent slots.

[Claim 2] Blade (2) according to claim 1, in which the

first evacuation slots (18) and the second evacuation slots (20) open into the same cavity (16) of the cooling circuit.

[Claim 3] Blade (2) according to claim 1, in which the

first evacuation slots (18) and the second evacuation slots (20) open into two cavities (16a, 16b) distinct from the circuit of

cooling.

[Claim 4] Vane (2) according to claim 3, in which the cavity (16a) into which the second discharge slots (20) open is offset axially upstream with respect to the cavity (16b) into which the second evacuation slots (20) open the first evacuation slots (18).

[Claim 5] Vane (2) according to any one of Claims 1 to 4, in which the first evacuation slots (18) open out at the level of the trailing edge (14) and the second evacuation slots (20) emerge at an intrados face (6a) of the blade.

[Claim 6] Vane (2) according to any one of Claims 1 to 4, in which the first evacuation slots (18) and the second evacuation slots (20) open out at an intrados face (6a ) of dawn.

[Claim 7] A vane (2) according to any one of claims 1 to 6, wherein the first vent slots (18) and the second vent slots (20) are arranged in columns.

[Claim 8] Vane (2) according to any one of claims 1 to 6, in which the second evacuation slots (20) exactly occupy each of the radial spaces left between the first evacuation slots (18).

[Claim 9] Method of manufacturing by casting a blade according to

any one of claims 1 to 6, comprising making a ceramic core by additive manufacturing, the core making it possible to make the first evacuation slots (18) and the second evacuation slots (20).

[Claim 10] High-pressure turbine of a turbomachine, comprising a disk which has a plurality of cells which open out at the periphery of the disk and a plurality of vanes (2) according to any one of claims 1 to 7, the root of each blade (2) being mounted in a respective cell of the disc.