Internal cooling circuit of a turbomachine blade

Abstract

A turbomachine blade (3) for mounting in a cavity of a turbomachine disk centered on an axis (X) and comprising a root (31) and a crest (32) opposite the root (31), the blade (3) extending in a radial direction (Y) from the root (31) to the crest (32) and having an aerodynamic surface with a leading edge (33), a trailing edge (34), an intrados (30) and an extrados, the leading edge (33) and the trailing edge (34) being connected by the intrados (30), the blade (3) further comprising an internal cooling circuit, including at least one air outlet (42) opening onto the trailing edge (34) for expelling from the blade (3) a flow of cooling air circulating in the internal cooling circuit, each air outlet (42) having a cross-section elliptical shape having a major axis of length a, a minor axis of length b, and a shape ratio m = (ab) / (a+b) between 0.2 and 0.5. Figure for the abbreviation: Fig. 2

Description

Title of the invention: Internal cooling circuit for a turbomachine blade technical field

[0001] This disclosure relates to the general field of turbomachinery, and more particularly to internal cooling circuits of turbomachine blades. STATE OF THE ART

[0002] A turbomachine generates thrust using a gas flow circulating in an airflow channel. After compression in several compressor stages, the gas flow is heated to high temperature in a combustion chamber and expelled at high speed and high temperature through turbine stages, between rotor blades movable about an axis of rotation, and fixed stator blades.

[0003] To improve the performance of the turbomachine, it is possible to increase the temperature of the gas flow circulating in the combustion chamber. The blades are thus subjected to severe thermo-mechanical stresses when the turbomachine is operating. In particular, it is advantageous to cool the thermally stressed parts, and especially to reduce the temperature at the blades, particularly the distributor blades of the high- and low-pressure turbines. This can be achieved by internal cooling circuits, using the cooler gas flow drawn from the compressor outlet.

[0004] For example, to improve cooling efficiency at the trailing edge of the blades, the blades may have circular orifices allowing the extracted gas flow to pass through the blade walls for cooling. However, the presence of such orifices can lead to stress concentrations at the blade's trailing edge and critically degrade the mechanical behavior of the component. This negatively impacts the blade's mechanical strength in an area already subjected to significant thermo-mechanical stress. GENERAL STATEMENT

[0005] One purpose of the present disclosure is to enable efficient cooling of the trailing edge of a turbomachine blade by limiting stress concentrations.

[0006] This objective is achieved by a turbomachine blade intended to be mounted in a cavity of a turbomachine disk centered on an axis, the blade comprising a root and a blade extending from the root to a vertex opposite the root, the blade having an aerodynamic surface, a leading edge, a trailing edge, an intrados and an extrados, the leading and trailing edges being connected by the intrados, the blade extending along a radial direction from the base to the top and further comprising an internal cooling circuit, the internal cooling circuit comprising:

[0007] at least one air outlet opening onto the trailing edge to vent a flow of cooling air circulating in the internal cooling circuit from the blade,

[0008] each air outlet orifice having an elliptical section having a major axis of length a, a minor axis of length b, and a shape ratio m = (ab) / (a+b) between 0.2 and 0.5.

[0009] The fact that the outlet of the internal cooling circuit has an elliptical cross-section advantageously reduces the stress concentration at the trailing edge compared to that at a circular orifice. It is therefore possible to avoid reaching the plastic deformation limit under identical operating conditions. Furthermore, this can also limit crack propagation, since crack initiation could not be prevented due to the high stress levels. The mechanical strength of the blade is thus improved.

[0010] The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations: • the aspect ratio is between 0.3 and 0.35; • the major axis of the elliptical section of each air outlet extends in the radial direction; • the internal cooling circuit includes a row of air outlet ports arranged on the trailing edge to evacuate the cooling airflow; • each air outlet has an elliptical cross-section with the same aspect ratio; • the blade comprises a plurality of air outlet orifices arranged in pairs according to the same radial spacing measured in the radial direction; • the radial gap between two successive air outlet orifices along the radial direction is between 0.1 mm and 0.6 mm; • the cooling circuit includes an internal cavity, each air outlet orifice extending in an axial direction between the internal cavity and the trailing edge, so as to allow the cooling airflow to flow out of the blade from the internal cavity; • The blade comprises a platform that radially separates the root from the blade, the root extending radially inwards from the platform, and the platform having a junction zone between the blade and the platform, and at less an air outlet opening onto said junction area between the blade and the platform. • the blade extends over a height in a radial direction from the platform to the top, and includes a plurality of air outlets arranged along at least 90% of the height of the blade, preferably along at least 95% of the height of the blade;

[0011] According to a second aspect, a turbomachine turbine is proposed comprising a stator and a rotor, the stator surrounding the rotor and the rotor comprising a rotor disk centered on the axis and a plurality of blades as described previously, each blade being mounted in a cavity of the disk.

[0012] According to a third aspect, a turbomachine is proposed comprising a turbine stage, with a plurality of blades according to the present invention.

[0013] According to a final aspect, an aircraft comprising a turbomachine according to the third aspect of the invention is proposed. DESCRIPTION OF THE FIGURES

[0014] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings.

[0015] Fig. 1 represents a simplified diagram of a turbomachine cross-section in a plane containing the axis of rotation.

[0016] Fig. 2 schematically illustrates a turbomachine blade according to one embodiment.

[0017] Fig. 3 represents dimensions characterizing air outlet orifices with an elliptical cross-section.

[0018] Fig. 4 schematically represents the impact of the shape ratio on the stress concentration factor (Kt) at the air outlet of the cooling circuit.

[0019] Fig. 5 schematically represents the evolution of the stress along the trailing edge of a blade, without a cooling circuit, with a cooling circuit according to the prior art, and with a cooling circuit in an embodiment.

[0020] Throughout all the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0021] In this application, upstream and downstream are defined with respect to the normal flow direction of the gas through the turbomachine. Furthermore, the X-axis of the turbomachine is the axis of rotation of its rotor parts. The axial direction corresponds to the direction of the X-axis, and a radial direction is a direction perpendicular to and passing through this axis. Unless otherwise specified, internal (respectively, interior) and exterior (respectively, exterior), respectively, are used with reference to a radial direction such that the inner part or face of an element is closer to the X axis than the outer part or face of the same element.

[0022] Fig. 1 schematically represents a section of a turbomachine 10 in a plane containing the X-axis. This disclosure extends more generally to different turbojet architectures, including unfaired turbojets, and is not limited to a faired turbojet with a turbofan engine, as described below.

[0023] The turbomachine 10 comprises, from upstream to downstream in the direction of the gas flow, a blower 11, a compressor section 16, a combustion chamber 14, a turbine section 15 and an exhaust casing.

[0024] The turbine section 15 comprises a succession of stages, each including a fixed stator part behind which a movable rotor part can be driven in rotation around the X axis.

[0025] The turbomachine 10 includes an engine casing 21. The engine casing 21 forms an enclosure surrounding the compressor section 16, the combustion chamber 14, the turbine section 15 and the exhaust casing, and delimiting a primary channel 13 allowing the flow of a primary gas stream A.

[0026] The stator and rotor sections are formed of blades extending radially from an inner ferrule 18 into the primary flow 13. The stator blades are fixed at their outer end to the engine casing 21. When the turbomachine 10 is operating, the gas flow circulating in the primary flow 13 is deflected by the rotating rotor sections and straightened by the stator sections. The stator sections of the turbine section 15 are called distributor blades.

[0027] With reference to [Fig.2], the turbomachine includes a blade 3 comprising an aerodynamic surface, i.e. a surface along which the flow of gas flowing in the primary duct 13 can circulate and having a trailing edge, and requiring cooling.

[0028] The turbomachine blade 3 may be intended to be mounted in a cavity of a turbomachine disk centered on the X axis. For example, the turbomachine blade 3 may include a platform 35 which radially and internally delimits the airflow in the turbomachine.

[0029] The turbomachine blade 3 can be a fixed blade relative to the housing 21, in particular a distributor blade for the stator parts of the turbine section 15. The turbomachine blade 3 can also be a rotating turbine blade. The present invention is advantageously applicable to a blade 3 located in the stages of the high-pressure turbine section 15, downstream of the combustion chamber 14. Indeed, these parts are subjected to high temperatures and are in particular need of cooling.

[0030] The blade 3 extends along a radial axis Y (carrying a radial direction Y) between a base 31 and a tip 32. The blade 3 comprises, in a manner known per se, a blade extending from the base 31 to the tip 32 opposite the base 31. The blade has an aerodynamic surface, a leading edge 33, a trailing edge 34, an underside 30, and an upper surface. The leading edge 33 and the trailing edge 34 are connected by the underside 30, on the one hand, and by the upper surface, on the other. The leading edge 33 is oriented to extend towards the flow of gases entering the turbomachine 10. It corresponds to the upstream part of an aerodynamic profile that faces the gas flow and divides the gas flow into an underside flow and an overside flow. The trailing edge 34, for its part, corresponds to the downstream part of the aerodynamic profile, where the intrados and extrados flows meet.

[0031] The platform 35 forms a junction zone with the foot 31 of the turbomachine blade 3. In other words, the foot 31 extends radially inwards from the platform 35 and the platform presents a junction zone between the blade and the platform 35.

[0032] The blade 3 also has a height h, which corresponds to the distance, measured at the level of the leading edge 33 along the radial axis Y, between the platform 35, and the apex 32 of the blade 3.

[0033] When the turbomachine 10 is in operation, the blade 3 is subjected to severe thermomechanical conditions. To enable its cooling, the blade includes an internal cooling circuit. A flow of cooling air is intended to circulate within the cooling circuit, so as to cool the walls of the blade 3 by conduction / convection.

[0034] The cooling airflow typically originates from the compressor section 16, particularly from the high-pressure stages, and is then diverted to cool the blades of the stator and rotor parts of the turbine section 15. The cooling airflow is colder than the gas flow exiting the combustion chamber 14.

[0035] The cooling circuit may include at least one internal cavity 4 extending from the base of the blade 31 to the top of the blade 32 along the radial axis Y, over all or part of the height of the blade 3.

[0036] The internal cavity 4 is in fluid communication with the cooling airflow, for example from the compressor stages 16. The turbomachine blade 3 may include ports allowing the passage of the cooling airflow from outside the blade 3 to the internal cavity 4. For example, the turbomachine blade 3 may include an air inlet port at the base of the blade 31. Alternatively or in addition, the turbomachine blade 3 may include at least one air inlet orifice 41 disposed at the leading edge 33. Alternatively or in addition, the turbomachine blade 3 may include at least one air inlet orifice 41 disposed on the lower surface 30 and / or the upper surface.

[0037] The air inlet orifice 41 is an orifice passing through the wall of the turbomachine blade 3 and opening into the internal cavity 4.

[0038] In order to improve the efficiency of the cooling at the trailing edge 34, the internal cooling circuit includes at least one air outlet 42 disposed on the trailing edge 34 to vent the cooling airflow circulating in the internal cooling circuit out of the blade 3.

[0039] The air outlet 42 allows the cooling airflow circulating in the internal cavity 34 to pass through the wall of the blade 3 at the trailing edge 34 and escape to the outside of the blade 3. The circulation of the cooling airflow through the air outlet 42 allows the trailing edge area 34 to be cooled by convection and conduction. Such air outlets 42 are conventionally called "blown-out ends".

[0040] Like the air inlet orifice 41, the air outlet orifice 42 is an orifice passing through the wall of the turbomachine blade 3 and opening into the internal cavity 4. Preferably, each air outlet orifice 42 extends along the axial direction, i.e. the X axis, between the internal cavity 4 and the trailing edge 34, so as to allow the cooling airflow to circulate out of the blade 3 from the internal cavity 4.

[0041] The air outlet orifice 42 has an elliptical cross-section.

[0042] More specifically, with reference to [Fig. 3], the elliptical section has two orthogonal axes of symmetry. The intersection of the two axes with the elliptical section delimits two segments.

[0043] The elliptical section has a major axis of length a, corresponding to the segment of greatest length. The elliptical section has a minor axis of length 6, corresponding to the segment of greatest length. Within the framework of an elliptical section, we have « > b.

[0044] The form ratio m is defined by the following formula:

[0045] m =

[0046] According to the preceding definition, we have directly, for an elliptical section 0 < m < 1. In the case of a circular section we would have a = b, and m = 0.

[0047] The parameters characterizing the elliptical section of each air outlet 42 can be chosen in order to limit the level of stress.

[0048] The elliptical cross-section of each air outlet 42 has an aspect ratio between 0.2 and 0.5. Indeed, as schematically illustrated in [Fig. 4], of the Stress measurements carried out for an internal cooling circuit of the blade 3 including air outlet ports 42 with elliptical sections of different geometries, shows that a reduction of the maximum stress greater than or equal to 30% can be obtained for a shape ratio m between 0.2 and 0.5.

[0049] The presence of the air outlet 42 with an elliptical cross-section makes it possible to reduce the stress concentration at the trailing edge 34, compared to an air outlet with a circular cross-section, and thus to improve the mechanical strength of the blade 3. Indeed, drilling the air outlet 42 induces a stress concentration which penalizes the mechanical strength at the trailing edge 34, which is already heavily thermo-mechanically loaded.

[0050] The stress concentration factor Kt is conventionally calculated as the ratio between the stress value due to a geometric anomaly, for example, the presence of an opening, and the stress value with the same parameters (force and cross-section) but without the geometric anomaly. The stress concentration factor Kt influences the maximum stress value. Criticality is defined, as is known per se, as the ratio between the stress exerted at a point, for example, due to pressure forces, and the elastic limit. The elastic limit (or yield strength), also expressed in N / mm², is the stress up to which a material can be elastically deformed.

[0051] The stress exerted at a point can be obtained by numerical simulation calculations.

[0052] Preferably, with the blade 3 extending in the radial direction Y, the elliptical section has a major axis parallel to the radial direction. Indeed, the tensile stress is exerted mainly in the radial direction, particularly when the blade 3 is rotating about the X axis of the turbomachine 10. In order to reduce the maximum stress, the major axis of the elliptical section can be in the direction of tension, while the minor axis is oriented in a direction orthogonal to the direction of tension.

[0053] Preferably, the elliptical cross-section of the air outlet 42 has an aspect ratio between 0.30 and 0.35. Stress measurements from the study schematically illustrated in [Fig. 4] indicate that the maximum stress reduction is obtained for an aspect ratio m = 0.33. This corresponds to a minimum stress value at the trailing edge 34. Indeed, this corresponds to the minimum value of the stress concentration factor Kt. This means that the impact in terms of stress of the presence of the air outlet 42 having such an aspect ratio m is minimal.

[0054] Preferably, the cooling circuit comprises a plurality of air outlet orifices 42 arranged on the trailing edge 34 to discharge the cooling airflow. The air outlet orifices 42 have elliptical cross-sections.

[0055] The respective elliptical cross-sections of the air outlet orifices 42 may have different shapes, i.e., have different major axis lengths a and / or minor axis lengths b. The orientation of the air outlet orifices 42 may vary depending on their location on the trailing edge 34. This may improve the efficiency of the internal cooling circuit.

[0056] The respective elliptical sections of the air outlet orifices 42 can have the same aspect ratio m. This simplifies the drilling of the air outlet orifices and the numerical fluid mechanics calculations.

[0057] The respective elliptical sections of the air outlet orifices 42 can have the same orientation, preferably all having a major axis oriented parallel to the radial direction Y. In other words, the elliptical section of each air outlet orifice 42 can extend along the radial direction Y.

[0058] The location and arrangement of the air outlets 42 can vary. For example, the turbomachine blade 3 can comprise a row of air outlets 42. In other words, the turbomachine blade 3 can comprise a plurality of air outlets 42 arranged on the trailing edge 34 along the same straight line, preferably a single straight line parallel to the radial direction Y. Alternatively, the air outlets 42 can form several rows, for example, be arranged along several straight lines parallel to the radial direction Y.

[0059] The air outlet ports 42 can be arranged over the entire height of the blade 3, or alternatively over only a part of the height of the blade 3.

[0060] Preferably, the turbomachine blade includes at least one air outlet 42 located on the junction area of ​​the platform 35. This advantageously allows the junction area near the blade's foot 31 to also be cooled. The cooling circuit can extend into an internal cavity of the foot 31, so as to also cool the foot 31 with the cooling airflow.

[0061] Preferably, the turbomachine blade 3 comprises a plurality of air outlet ports 42 arranged so as to cover at least 90% of the height of the blade 3, preferably at least 95% of the height of the blade 3.

[0062] The air outlet orifices 42 are preferably equidistributed over the height of the blade 3, so as to allow homogeneous cooling of the blade 3 at the trailing edge 34.

[0063] More generally, with reference to [Fig.3], a radial gap e (also called "air gap") is defined as the distance between two successive, i.e., neighboring, air outlet orifices 42, measured along the radial direction Y, knowing that the major axes of the two air outlet orifices 42 extend along the same straight line.

[0064] This additional parameter advantageously reduces the stress concentration factor Kt at the air outlet ports 42. Preferably, the radial gap e between two successive air outlet orifices 42 is between 0.1 mm and 0.6 mm, preferably still between 0.1 mm and 0.3 mm.

[0065] Indeed, numerical simulations have shown that the value of the stress concentration factor Kt decreases with the value of the radial gap e. Typically, the evolution of the stress concentration factor Kt can be modeled according to a cubic law of the form Kt = Ae3-Be2+Ce+D, with A, B, C, and D being positive coefficients whose value depends on the relative position within the trailing edge 34. Thus, the lowest value of stress concentration Kt at each air outlet is minimal for a radial gap e equal to 0.1 mm. However, reducing the radial gap to a value less than 0.1 mm might no longer be beneficial. If the radial gap e is too small, the model would fall outside its scope, and the stress concentrations of two successive air outlets would be cumulative.

[0066] For example, the coefficients A and B are lower when the corresponding air outlet 42 is not surrounded by two neighboring air outlet 42s, and therefore the reduction of the radial gap has less impact on the reduction of the stress concentration factor Kt for an air outlet 42 located at one end of a row of air outlet 42s. In other words, the gain in terms of stress reduction is more limited for an air outlet 42 not being framed by air outlet 42s on either side of its major axis.

[0067] For example, for an internal cooling circuit comprising three air outlet orifices 42 aligned on the trailing edge 34 in the radial direction Y to evacuate the cooling airflow, the air outlet orifices 42 being separated in pairs by the same radial gap measured in the radial direction Y, the stress reduction will be greater at the central air outlet orifice.

[0068] Typically, a decrease in the radial gap e from a value of 0.7 mm to a value of 0.1 mm results in a reduction of the order of 20% of the stress concentration factor Kt.

[0069] It is therefore advantageous to have a small radial gap e between two successive air outlet orifices 42 to reduce the concentration of stresses at trailing edge 34.

[0070] Figure 5 shows a comparison of the evolution of the maximum criticality value as a function of the height of the blade 3. Curve 1 corresponds to a blade 3 without an internal cooling circuit and with perforations at the trailing edge 32. Curve 2 corresponds to a blade 3 with an internal cooling circuit according to the prior art, having circular air outlet orifices distributed along the height of the blade 3. Curve 3 corresponds to a blade 3 with an internal cooling circuit according to the present invention, in an embodiment where the plurality of air outlet orifices 42 are distributed along the height of the dawn and present the same elliptical section, with a shape ratio m = 0.33.

[0071] It is noted that the presence of air outlet orifices corresponds to local maxima of the maximum criticality value.

[0072] By comparing the Cl and C2 curves, it can be observed that the presence of circular openings at the trailing edge results in an overall increase in the maximum criticality value along the entire height of the blade 3. The increase corresponds to a multiplication by a factor of approximately 2. This indicates a more severe stress state along the entire height of the blade 3 when drilling is performed.

[0073] In particular, curve C2 shows that the maximum criticality value is greater than 1 at the intersections between the internal cavity and the circular air outlet orifices. This indicates plastic deformations in these areas, which contribute to degrading the thermo-mechanical strength of the blade 3.

[0074] A complete stress map in the trailing edge zone 32 can be obtained through numerical simulations. The stress concentration induced by the presence of circular air outlets results in maximum stress values ​​at the holes, which can exceed 270 N / mm². These values ​​can exceed the yield strength of the materials used to manufacture the blade 3. Indeed, the yield strength of materials depends on their temperature. For temperatures in the trailing edge zone, the yield strength of the materials can drop to 200 MPa (i.e., 200 N / mm²). This confirms the presence of plastic deformation at the circular air outlets, which could lead to premature damage to the blade 3.

[0075] Comparing curves C2 and C3, it can be observed that the presence of elliptical air outlets limits the increase in stress to 60% of the value reached with circular air outlets. This equates to a relative gain of 40% compared to drilling traditionally used in internal cooling circuits. Furthermore, the criticality value remains below 1 at every point along the trailing edge. This means that there is no plastic deformation in this case. Thus, the use of elliptical air outlets contributes to improving the mechanical strength of the internal cooling circuit and the turbomachine blade 3.

[0076] The air outlet ports 42 can be drilled by a machining process after the manufacture of the turbomachine blade 3, for example by an electrical discharge machining (EDM) process.

[0077] The turbomachine blade 3 described above can advantageously be integrated into a turbine comprising a plurality of blades. In a manner known per se, the The turbomachine turbine comprises a stator portion and a rotor portion, the stator portion surrounding the rotor portion, and the rotor portion comprising a rotor disk centered on the X-axis. The plurality of blades are distributed radially around the X-axis and fixed to the inner shell 18, for example. Each blade 3 can be mounted in a recess formed in the disk and opening onto the outer periphery of the rotor disk. Advantageously, each blade 3 of the plurality of blades includes an internal cooling circuit as disclosed herein.

[0078] This disclosure also relates to a turbomachine 10 comprising the turbine as described above. The turbine section 15 generally comprises a low-pressure turbine and a high-pressure turbine. The high-pressure turbine and the low-pressure turbine may each have a rotor shaft that drives their rotor portion in rotation relative to their stator portion about the X-axis. The blade 3 comprising the cooling system described above typically belongs to the high-pressure turbine. This disclosure also relates to an aircraft 100, comprising at least one turbomachine 10 as described above. The turbomachine 10 is mounted on the aircraft 100 by means of a pylon.

Claims

Demands

1. Turbomachine blade (3) for mounting in a cavity of a turbomachine disk centered on an axis (X), the blade comprising a root (31) and a blade extending from the root to a crest (32) opposite the root (31), the blade having an aerodynamic surface, a leading edge (33), a trailing edge (34), an intrados (30) and an extrados, the leading edge (33) and the trailing edge (34) being connected by the intrados (30), the blade (3) extending in a radial direction (Y) from the root (31) to the crest (32) and further comprising an internal cooling circuit, the internal cooling circuit comprising: at least one air outlet (42) opening onto the trailing edge (34) to discharge from the blade (3) a flow of cooling air circulating in the circuit internal cooling, each air outlet orifice (42) having an elliptical cross-section having a major axis of length a, a minor axis of length b,and a ratio of the form m = (ab) / (a+b) between 0.2 and 0.

5.

2. Turbomachine blade (3) according to claim 1, wherein the aspect ratio is between 0.3 and 0.

35.

3. Turbomachine blade (3) according to any one of claims 1 and 2, wherein the major axis of the elliptical section of each air outlet orifice (42) extends along the radial direction (Y).

4. Turbomachine blade (3) according to any one of claims 1 to 3, wherein the internal cooling circuit comprises a row of air outlet ports (42) arranged on the trailing edge (34) to vent the cooling airflow.

5. Turbomachine blade (3) according to any one of claims 1 to 4, wherein each air outlet orifice (42) has an elliptical cross-section with the same aspect ratio.

6. Turbomachine blade (3) according to any one of claims 1 to 5, comprising a plurality of air outlet ports (42) arranged two by two with the same radial spacing measured in the radial direction (Y).

7. Turbomachine blade (3) according to claim 6, wherein the radial gap between two successive air outlet orifices (42) along the radial direction (Y) is between 0.1 mm and 0.6 mm.

8. Turbomachine blade (3) according to any one of claims 1 to 7, wherein the cooling circuit comprises an internal cavity (4), and wherein each air outlet orifice (42) extends in an axial direction between the internal cavity (4) and the trailing edge (34), so as to permit the cooling airflow to flow out of the blade from the internal cavity (4).

9. Turbomachine blade (3) according to any one of claims 1 to 8, comprising a platform (35) which radially separates the foot (31) of the blade, the foot (31) extending radially inwards from the platform (35) and the platform (35) having a junction zone between the blade and the platform (35), and at least one air outlet (42) opening onto said junction zone between the blade and the platform.

10. Turbomachine blade (3) according to claim 9, having a height along a radial direction (Y) from the platform (35) to the top (32), and comprising a plurality of air outlet ports (42) arranged along at least 90% of the height of the blade (3), preferably along at least 95% of the height of the blade (3).

11. Turbomachine turbine (10) comprising a stator and a rotor, the stator surrounding the rotor and the rotor comprising a rotor disk centered on the axis (X) and a plurality of blades (3) according to any one of claims 1 to 10, each blade (3) being mounted in a pit of the disk.

12. Turbomachine (10) comprising a turbine according to claim 11.

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