FIELD OF INVENTION
[0001] The present invention relates to the field of aeronautics high pressure gas turbine blades, More particularly, the cooling circuit of the vanes, and a gas turbine having such blades.
STATE OF THE ART
[0002] The moving blades of a gas of an aircraft turbine engine, and in particular of the high-pressure turbine, are subjected to very high temperatures of the combustion gases during engine operation. These temperatures reach values ​​well above those that can withstand without damage the various parts that are in contact with the gas, which has the effect of limiting their lifespan.

[0003] Furthermore, an elevation of the gas temperature of the high-pressure turbine improves the efficiency of an engine, therefore the ratio between the engine thrust and weight of an aircraft powered by the engine. Therefore, efforts are undertaken to make turbine blades that can withstand increasingly higher temperatures, and to optimize the cooling of these vanes.

[0004] It is well known to provide such cooling circuits blades to reduce the temperature of the latter. With such circuits, the cooling air (air or "cold"), which is generally introduced into the blade by its foot passes therethrough along a path formed by cavities formed in the thickness of the blade before being ejected through orifices opening on the surface of the blade.

[0005] Such cooling systems are called "advanced" when they are composed of several independent cavities in the thickness of the blade, or when some of these cavities are dedicated to localized cooling. These cavities are used to set consistent with the dawn engine performance requirements and service life of parts.

[0006] However, the cooling circuits draw air 'cold' in the primary flow path of the engine, so that the temperature of this cold air, acting as a heat transfer fluid is less than the air temperature s' flowing the surface of the blade, said "hot air".

The air drawn into the engine of the primary vein therefore a loss and degrades the performance and overall engine performance.

[0007] In addition, advanced circuits have the disadvantage of generating a large temperature difference between the outer walls of the vane into contact with the vein and the heart walls of the vane. These significant differences in temperature induced stress could jeopardize the mechanical strength of the dawn in operation and minimize its life.

[0008] There is therefore a need for a cooling circuit blade aeronautical gas turbine to minimize the thermal gradients in order to reduce internal stresses and optimize the cooling of the blade by reducing the flow air used for cooling, thus improving the overall efficiency of the turbine.

PRESENTATION DE L'INVENTION

[0009] The present disclosure relates to an aeronautical turbine vane extending in the radial direction and having an intrados and an extrados, having a plurality of cavities pressure face extending radially beside the concave face of the blade, a plurality of suction cavities extending radially beside the convex face of the blade, and at least one central cavity situated in the central part of the blade and surrounded by recesses intrados and extrados cavities, the vane having also a plurality of cooling circuits, wherein at least a first cooling circuit comprises:

a first cavity and a second cavity, the first and second cavity communicating between them at an inner radial end and an outer radial end of the blade,

a third cavity communicating with the second cavity at the outer radial end,

a fourth cavity communicating with the third cavity at the inner radial end,

the first cavity and the second cavity being configured to be supplied together with cold air through a common air intake opening at the inner radial end, and so that air flows there in the same direction as the radial direction,

the first cavity being a cavity pressure face, the second cavity being a central cavity, the third recess and the fourth recess being of suction cavities.

[0010] In the present specification, by radial direction, it is understood the direction extending blade foot, that is to say the base of the blade, the blade head, that is i.e. the radially opposite end to the root of the blade. Thus, in the present specification, the internal radial end means the blade root, and the outer radial end refers to the blade head.

[0011] Furthermore, in the present specification, the term "uplink", the direction of air flow in a blade root of the cavity towards the blade head, and "downward direction", the direction of air flow in a cavity of the blade head to the blade root.

[0012] Each cavity is bounded by a wall. Cavities pressure side extend radially, that is to say the blade root to the blade head, the side of the blade pressure face. In other words, a face of at least a portion of the wall defining each cavity pressure face is in contact with the outside air to the blade on the pressure side. No face of the wall defining each cavity pressure face is in contact with the outside air to the blade on the suction side.

[0013] Similarly, the convex side cavities extend radially, that is to say the blade root to the blade head, the side of the suction surface of the blade. In other words, a face of at least a portion of the wall defining each convex side cavity is in contact with the outside air to the blade on the suction side. No face of the wall defining each convex side cavity is in contact with the outside air to the blade on the pressure side.

[0014] The central cavity also extends radially, that is to say the blade root to the blade head, in the central part of the blade. By central portion of the blade, it is understood that no face of the wall defining the central cavity is in contact with the outside air at dawn. In other words, the wall defining the central cavity is in contact either with one or more cavity (s) and pressure face with a cavity or (s) suction, with the exception of the walls delimiting said cavities 'pressure and suction.

[0015] A cooling system refers to a plurality of cavities communicating with each other. In the present disclosure, at least one cooling circuit comprises a first, a second, a third and a fourth cavity.

[0016] The first and second cavity communicate with it at the root of the blade so as to form a first common chamber, and are supplied simultaneously with cold air at this first common chamber. The first and second cavities are then isolated from each other by a wall extending in the radial direction, and again communicate with each other at the blade head so as to form a second common chamber.

[0017] Thus, when cold air is supplied to the first common chamber, the latter is divided between the first cavity and the second cavity by flowing in each of these cavities, in the uplink direction.

[0018] The first cavity is a cavity of intrados. Therefore, when the cold air flows into the first cavity, it exchanges heat by forced convection with the wall separating the first cavity of the hot air pressure side. Thus, the air flowing in the upward direction into the first cavity absorbs heat from the wall as it warms as it nears the blade head.

[0019] The second cavity is a central cavity. Therefore, the cold air flowing into this cavity does not exchange heat with the hot air outside of the blade. Thus, the air flowing in the upward direction into the second cavity, parallel to the air flowing into the first cavity, is heated very little as it approaches the blade head. Cold air can thus reach the second common chamber, mixing with the air from the first cavity.

[0020] The third cavity communicates with the second cavity at the blade head, and the fourth cavity at the blade head. The air from the first and second cavities flows then in the third cavity in the downlink direction and then in the fourth cavity in the uplink direction.

[0021] Accordingly, the third and fourth cavities, being the convex side cavities, can be fed by cold air from the second cavity, thereby improving the suction side cooling.

[0022] This configuration also has the advantage of targeting the cooling to the desired areas. Indeed, the air moving within the cavities undergoes Coriolis force linked to the rapid rotation of the blade. This allows plating to the maximum cold air against the outer walls, that is to say the walls defining the intrados and extrados of the blade, constituting the hottest zones. The heat exchanges are optimized at the outer walls, it further to improve the temperature uniformity in the heart of the blade, to minimize thermal gradients in the heart of the vane, thus limiting the stresses internal in the walls forming the cavities, thereby enhancing the mechanical strength thereof. In addition, the second cavity, acting as a mechanically flexible heart, absorbs the mechanical stresses generated by thermal expansion of the outer walls in contact with hot air.

[0023] In some embodiments, the blade comprises a plurality of concave holes, each communicating with the first cavity and through the pressure face of the blade.

[0024] These pressure-side orifices may be holes made in the wall separating the first cavity and the lower surface of the blade and distributed in the radial direction over at least a portion of the first cavity, allowing a certain volume of cold air flowing in the upward direction into the first cavity to be discharged on the pressure side of the blade.

[0025] This exhaust air makes it possible to further cool the outer face of the pressure side wall, generating a cooling film on the lower surface of the blade. In addition, air flowing into the first cavity warms up gradually in the uplink, as described above. These concave openings are provided to evacuate outside the first cavity much of the heated air. Therefore, the air supplied to the third cavity, from the first and second cavities, is mainly constituted by the cold air from the second cavity. This improves the cooling of the convex side cavities, that is to say, the third and the fourth cavity.

[0026] In some embodiments, the blade comprises a plurality of suction ports each communicating with the fourth cavity and through the upper surface of the blade.

[0027] The suction orifices may be holes made in the wall separating the fourth cavity and the upper surface of the blade and distributed in the radial direction over at least a portion of the fourth cavity,

allowing a certain volume of air flowing in the uplink direction in the fourth cavity being evacuated on the extrados of the blade.

[0028] This exhaust air makes it possible to further cool the outer surface of the suction side wall, generating a cooling film on the upper surface of the blade. Additionally, these suction openings are provided to draw air along the cooling circuit. Indeed, the suction side pressure being much lower than the supply pressure of the cooling circuits, the presence of these holes allows to naturally create an air flow in the cooling circuit.

[0029] In some embodiments, the blade comprises at least one second cooling circuit comprising two cavities communicating intrados together by a plurality of passages distributed in the radial direction along the blade between these two cavities, one of these cavities being fed with cold air via an air inlet opening at the inner radial end of the blade.

[0030] The cavity which is supplied with cold air may also communicate with the pressure face of the blade through openings distributed in the radial direction over at least a portion of said cavity. Thus, when the cold air flows into the cavity, it exchanges heat by forced convection with the wall separating the cavity of the hot air pressure side, and is also evacuated through the openings, generating a film cooling of the intrados of the blade, while also extending into the other cavity through the plurality of passages.

[0031] In some embodiments, the blade comprises at least one third cooling circuit comprising a suction cavity and a trailing edge cavity extending radially to both the suction side and the pressure side of the blade at the trailing edge, the two cavities being supplied with cold air via an air inlet opening at the inner radial end of the blade, the convex side cavity forming an angle at the external radial end of the blade, so as to extend to the trailing edge of the blade.

[0032] In some embodiments, the third coolant cavities communicate with a plurality of trailing edge orifices opening on the side face of the blade.

[0033] In some embodiments, the plurality of cooling circuits are independent of each other.

[0034] For independent of each other, it is understood that none of the recesses a given component cooling system communicates with a cavity of a further cooling circuit. This allows for each cooling circuit to produce a targeted cooling in specific areas of dawn, without these circuits interfere with each other.

[0035] In some embodiments, the blade comprises less than two fine recesses, the fine recesses having a first length greater than or equal to at least seven times a second length in a section perpendicular to the radial direction.

[0036] In some embodiments, the thickness of each thin cavity is less than or equal to 1.2 mm, the thickness being the distance between two sides of the thin cavity according to the first length in a section perpendicular to the radial direction.

[0037] In some embodiments, each thin cavity extends over at least half of the blade in the radial direction.

[0038] In some embodiments, the blade comprises at most a thin cavity.

[0039] The presence of a limited number of fine recesses facilitates the process of manufacture of the blades. Indeed, the ceramic cores necessary for the development of the cooling circuits are very fragile due to their geometry related to the small thickness of the fine recesses. Minimizing the number of fine cavities overcomes these drawbacks.

[0040] The present disclosure also relates to a gas turbine having blades of the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

[0041] The invention and its advantages will be better understood from reading the detailed description given below of various embodiments of the invention given as non-limiting examples. The description refers to the accompanying figures of pages, where:

- Figure 1 shows a perspective view of a turbine blade according to the present invention;

- Figure 2 is a symbolic perspective view showing the cavities of the various cooling circuits of the blade;

- Figure 3 is a symbolic perspective view showing the cavities of the first cooling circuit of the blade

- Figures 4A to 4E show cross-sections as shown in Figure 3 for different position in the radial direction from the blade root to the blade head;

- Figure 5 shows a cross section of the blade, illustrating the areas where heat transfer is most important.

DETAILED DESCRIPTION OF EXAMPLES OF REALIZATION

[0042] The following describes the invention with reference to Figures 1 to 5. It is noted that Figures 2 and 3 do not represent parts of the blade as such but represent the cavities of the blade. In other words, the lines illustrated in Figures 2 and 3 symbolize the inner walls of the vane defining these cavities.

[0043] Figure 1 illustrates a rotor blade 10, for example metal, of a turbine engine high pressure turbine. Of course, the present invention is also applicable to other mobile or fixed blades of the turbomachine.

[0044] The blade 10 includes an airfoil 12 (or blade) extending radially between a blade root 14 and a blade head 16.

[0045] The blade root 14 is adapted to be mounted on a rotor disc of the high-pressure turbine, the blade head 16 being radially opposite to the blade root 14.

[0046] The airfoil 12 has four distinct areas: a board 18 disposed attack next to the flow of hot gases from the combustion chamber of the turbomachine, a trailing edge 20 opposite the edge 18 , a side face intrados 22 and a suction side face 24, these side faces 22, 24 connecting the leading edge 18 to trailing edge 20.

[0047] At the level of the blade head 16, the aerodynamic surface 12 of the blade is closed by a transverse wall 26. Furthermore, the aerodynamic surface 12 extends radially slightly beyond the transverse wall 26 of to form a bowl 28, referred to hereinafter bath of the blade. This bath 28 therefore has a bottom formed by the transverse wall 26, an edge formed by the aerodynamic surface 12 and is open towards the blade head 16.

[0048] In the example described, the blade 10 comprises three cooling circuits, independent of each other, for the cooling of the blade: a first cooling circuit 1, a second cooling circuit 2, and a third cooling circuit 3.

[0049] The first cooling circuit 1 comprises a first cavity A, a second cavity B, a third cavity C and a fourth cavity D. The first cavity A is a cavity pressure face, the second cavity B is a central cavity, the third and fourth cavities C and D are suction cavities.

[0050] The first cooling circuit is supplied with cold air by the cavities A and B at the blade root level 14. The cold air is an air drawn in other circuits of the engine, colder than the air flowing over the side faces intrados 22 and extrados 24 and acting as a transfer medium. The first and second chambers A and B communicate with each other at the blade root 14, in the bottom 40% of the blade, preferably 25%, more preferably 10% in the radial direction so as to form a first common chamber 31 (figures 3 and 4E) extending radially from the blade root 14 of a length Ll. The Ll length may be at most 40% of the total length of the blade. The first and second chambers A and B communicate with each other also at the blade head 16, the top 20% of the blade, preferably 15%, more preferably 10% in the radial direction, so as to forming a second common chamber 32 (figures 3 and 4A) extending radially over a length L2. The length L2 may represent more than 20% of the total length of the blade. Between the common chambers 31 and 32, the cavities A and B are isolated from each other by a P wall extending radially along the blade 10. Accordingly, air from the first common chamber 31 then flows separately and in parallel in the uplink direction in the cavities A and B (arrows in Figure 3) to the second common chamber 32.

[0051] Furthermore, the first cavity A communicates with the pressure side surface 22 of the blade 10 via a plurality of pressure-side orifices 40, distributed radially along the blade 10. Thus, a portion of air flowing in the first cavity a is discharged through the orifices 40, so as to create a

cooling film on the side face 22, and a blade head 42 port located on the blade head, so as to create a cooling film on the wall 26 of the tub 28. The air flowing in the first cavity A is not discharged through the orifices 40 or 42 is mixed with air from the second cavity B, in the second common chamber 32.

[0052] In addition, the cavity A may be delimited in its upper part by a curved wall A 'extending over 20%, preferably 15%, more preferably 10% of the length of the vane in the radial direction, the curvature of the wall a 'being directed towards the leading edge 18. the curved shape of the wall helps to guide the air flowing into the cavity a to the following cavities, and ensure distribution homogeneous air into the cavities while minimizing losses. In addition, the wall P separating the cavities A and B may comprise, in its upper part, a bent portion P 'forming an angle with respect to the rest of the wall P, so that the curved portion P' is directed towards the leading edge 18. the curved portion P 'is used to guide the air flowing in the cavity B toward the cavity C. the curved wall A and the curved portion P' thus make it possible to facilitate the reversal of the air from the cavities a and B to the cavity C, that is to say, to facilitate the change of direction of flow of air, from one upstream in the cavities a and B in a downward direction in cavity C. this will also limit the losses during this downturn.

[0053] The second and third chambers B and C communicate with each other at the blade head 16, the top 20% of the blade, preferably 15%, more preferably 10% in the radial direction so as to form a third common chamber 33 (Figure 3 and 4B) extending radially over a length L3. The second and third chambers 32 and 33 thus communicate with each other at the blade head 16 (Figures 3 and 4A), so that the first cavity A may also communicate with the third chamber C. The air flowing in the third cavity C so from the cavities A and B, and flows in the downlink direction.

[0054] The length L3 may preferably be greater than the length L2. Thus, air flowing into the third cavity C comes mainly from the second cavity B. In addition, the air from the

A first cavity was evacuated largely by the pressure-side openings 40 and the blade head opening 42. More specifically, at least 75%, preferably at least 80%, more preferably at least 85% of air flowing into the third cavity C from the second chamber B. this has the advantage of maintaining a cold air within the third cavity C so as to cool effectively the upper surface 24 of the 'dawn. Indeed, the second cavity B is a central cavity, air from thereof is colder than the air from the first cavity A, the latter being heated by heat transfer, in particular by forced convection with the side intrados 22.

[0055] The third and fourth cavities C and D communicate with each other at the blade root 14 in the bottom 10% of the blade, preferably 8%, more preferably 6% in the radial direction, so as to forming a fourth common chamber 34 (Figure 3 and 4E). The air flowing in the fourth cavity D therefore comes from the third cavity C, and flows in the uplink direction, that is to say, since the blade root 14 to the blade head 16. The fourth D cavity communicates with the upper surface via a plurality of suction holes 44 distributed radially along the blade 10. Thus, a portion of the air flowing in the fourth cavity D is discharged through the orifices 44 so creating a cooling film on the upper surface 24, and a blade head 46 port located on the blade head 16, so as to create a cooling film on the wall 26 of the tub 28 .

[0056] The first cooling circuit 1 thus extends from the pressure side surface 22, the side of the trailing edge 20, until the upper surface 24 of the leading edge of the side 18. This configuration allows to exploit the different effects related to the rapid rotation of the blade 10, including the Coriolis force, to press the air to areas requiring optimization of heat transfer, including the walls defining the sides of soffit or suction of the interior of the blade. The hatched area in Figure 5 indicate areas where the work of the air is minimized, that is to say where the heat transfers are the least important. The arrows in Figure 5 indicate the contrary orientation of the Coriolis force, in other words the zones where air is pressed and where the heat transfer are optimized. This configuration thus reduces the cold air flow required for cooling the blade 10, targeting the heat transfer to the desired areas.

[0057] The central cavity B thus acts as a mechanically flexible heart of the blade. Indeed, it allows to compensate for mechanical distortions in the walls constituting the blade 10 adjacent to the faces intrados 22 and extrados 24, caused by thermal expansion due to elevated temperatures on these faces. This allows to limit external overstress on the blade 10.

[0058] The second cooling circuit 2, independent of the first cooling circuit 1 comprises two cavities intrados E and F. The recess E adjacent to the cavities A, B, C and D of the first cooling circuit, is supplied cold air at the blade root 14 (FIG 4E). The cavity F is located on the side of the leading edge 18 of the blade 10. The cavities E and F connected to one another by a plurality of passages 52 distributed in the radial direction along the blade 10 between the two cavities ( figures 4B and 4D).

[0059] The cavity E communicates with the pressure side surface 22 of the blade 10 via orifices 50 distributed in the radial direction over at least a portion of the cavity E. Thus, when the cold air flows into this cavity, it exchanges heat by forced convection with the wall separating the cavity of the hot air pressure side, and is also discharged through the holes 50, creating a cooling film on the pressure side of the blade, while also penetrating into the other cavity through the plurality of passages 52. the air flowing into the cavity is discharged through F of 54 orifices distributed in the radial direction over at least a portion of this cavity F.

[0060] The third cooling circuit 3, independent of the first and second cooling circuits 1 and 2, comprises a suction cavity G adjacent to the cavities A, B and C, H and trailing edge cavity extending radially both the suction side 24 and the concave 22 side of the blade on the side of the trailing edge 20. the cavities G and H are mutually supplied with cold air via an air inlet opening at the root of blade 14.

[0061] The suction cavity G extending firstly radially into a first cavity portion G ', since the blade root 14 to the blade head 16 along the upper surface 24, and extends on the other hand in

a direction substantially perpendicular to the radial direction in a second cavity portion G "along the tub 28, forming an angle toward the trailing edge 20 (Figure 2), the second cavity portion G" for cooling the transverse wall 26 at the trailing edge 2. in other words, the cavity G extends from blade root 14 to the trailing edge 20.

[0062] Furthermore, the first cavity portion G 'has a high aspect ratio so that, in cross section (Figures 4C and 4D, for example), a dimension (length) is at least three greater than another dimension (width), giving it a form of "slender", or elongated. This allows to maximize the exchange surface between air flowing in the cavity G and the upper surface 24. Apart from the trailing edge cavity H, whose shape is determined by the shape of the blade 10 at the trailing edge 20, the suction cavity G of the third cooling circuit 3 is the only one on the set of cavities that comprises the blade 10, to present such a report. Limiting the number of cavities having such aspect ratios facilitates the manufacturing process of the blade.

[0063] The H trailing edge cavity does not extend radially over the entire length of the blade 10, and is limited in length by the second part of G "cavity. In addition, the cavities of the third cooling circuit 3 communicate with trailing edge holes 56 opening on the pressure side surface 22 at the trailing edge 20, the trailing edge apertures 56 are distributed radially along the vane 10. These holes 56 make it possible to discharging cold air flowing through these two cavities.

[0064] While the invention has been described with reference to specific embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the revendications. In particular, cooling circuits and numbers of cavities each component of these circuits are not limited to those presented in this example. Therefore, the description and drawings should be considered illustrative rather than restrictive sense.

[0065] It is also clear that all the features described with reference to a method are transposed, alone or in combination, to a device, and vice versa, all the features described with reference to a device can be transposed, alone or in combination, to a method.

CLAIMS
1. blade (10) of aviation turbine extending in the radial direction and having a pressure face (22) and a suction side (24) having a plurality of cavities pressure face extending radially beside the concave face (22) of the vane (10), a plurality of suction cavities extending radially beside the convex face (24) of the blade (10), and at least one central cavity situated in the central part of the blade (10) and surrounded by cavities intrados and extrados cavities, the vane (10) also having a plurality of cooling circuits, wherein

at least a first cooling circuit (1) comprises:

a first cavity (A) and a second cavity (B), the first and second cavity communicating between them at an inner radial end (14) and an outer radial end (16) of the blade (10 )

a third cavity (C) communicating with the second cavity (B) at the outer radial end (16),

a fourth cavity (D) communicating with the third cavity

(C) at the inner radial end (14),

the first cavity (A) and the second cavity (B) being configured to be supplied together with cold air through a common air intake opening at the inner radial end

(14), and so that air flows there in the same direction in the radial direction,

the first cavity (A) being a cavity pressure face, the second cavity (B) being a central cavity, the third cavity (C) and the fourth cavity (D) being suction cavities.

Blade (10) according to claim 1, comprising a plurality of concave holes (40) each communicating with the first cavity (A) and opening on the lower surface (22) of the blade (10).

3. blade (10) according to claim 1 or 2, having a plurality of suction orifices (44), each communicating with the fourth cavity (D) and opening on the upper surface (24) of the blade (10 ).

4. blade (10) according to any one of claims 1 to 3, comprising at least a second cooling circuit (2) comprising two cavities intrados (E, F) communicating together through a plurality of passages (52) distributed in the radial direction along the blade (10) between the two cavities, one of these cavities being fed with cold air via an air inlet opening at the inner radial end (14) the blade (10).

5. blade (10) according to any one of claims 1 to 4, comprising at least one third cooling circuit (3) including a suction cavity (G) and a trailing edge cavity (H) extending radially from both the suction side (24) and the concave side (22) of the blade (10) at the trailing edge (20), the two cavities being supplied with cold air by an intake opening air at the inner radial end (14) of the blade (10), the convex side cavity (G) forming an angle at the outer radial end (16) of the blade (10), so as to extend to the trailing edge (20) of the blade (10).

6. blade (10) according to any one of claims 1 to 5, wherein the plurality of cooling circuits are independent of each other.

7. blade (10) according to any one of claims 1 to 6 comprising less than two fine recesses, the fine recesses having a first length greater than or equal to at least seven times a second length in a section perpendicular to the radial direction .

8. A gas turbine comprising blades as claimed in any preceding claim.