Blades, associated cores, and manufacturing methods for aircraft turbine engines

Abstract

The present invention relates to a blade comprising: - a blade extending along an elongation axis (Y); - at least one internal flow cavity (20) for allowing a cooling airflow (F3) to pass through, the at least one internal flow cavity being defined by an inner wall (18) of the blade; - at least one first air outlet opening (22) disposed in at least one of a pressure side and a suction side; - at least one internal channel (30) connected to the first outlet opening (22) and extending along an axis transverse to the elongation axis (Y); characterized in that the at least one internal channel (30) is also connected to at least one second air outlet opening (32), the at least one second air outlet opening being disposed in the inner wall (18) and leading to the internal cavity (30), the second outlet opening (32) having a bottom wall (34) connected to the internal channel (30) and inclined relative to the axis of the internal channel (30).

Description

Technical Field

[0001] This invention relates to the field of turbine blades for aircraft turbine engines.

[0002] In particular, the present invention relates to the field of impellers including an internal cavity through which cooling air flows.

[0003] The present invention also relates to the field of cores for manufacturing these blades, and methods for manufacturing these blades. Background Technology

[0004] Aircraft turbine engines (such as turbojet engines) typically consist of a fan that can rotate about a longitudinal axis, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and a gas exhaust nozzle, arranged from upstream to downstream in the direction of airflow.

[0005] The fan allows airflow to be drawn in, which is then split into a main stream and a secondary stream. The main stream flows through the main duct of the turbine engine, while the secondary stream is directed into secondary ducts surrounding the main duct.

[0006] The main stream is compressed within the compressor. The compressed air is then mixed with fuel and burned in the combustion chamber. The gases produced by combustion pass through the turbine and then escape through nozzles whose cross-section allows these gases to be accelerated to generate thrust.

[0007] Turbines are typically equipped with blades evenly distributed around an impeller, which can rotate about a longitudinal axis. The blades extend radially between the root and the head. The blades also include blades connected to the root, for example, via a platform. The blades have an outer wall and an inner wall, the outer wall having an aerodynamic shape that typically includes a pressure side and a suction side connected by a leading edge and a trailing edge.

[0008] Because the high-pressure turbine blades are located downstream of the combustion chamber, they are subjected to extremely high temperatures. These blades are typically made of metals or composite materials, particularly ceramic matrix composites (CMCs). These materials offer the advantage of high-temperature resistance. However, such blades may not be able to withstand temperatures exceeding those that metal or ceramic matrix composites can withstand.

[0009] In this context, it has been proposed that the blades be equipped with a cooling system to increase the temperature range within which these blades can be implemented. The cooling system includes a cooling circuit arranged inside the blade and allowing air from the compressor to pass through the blade. The cooling circuit includes internal cavities formed during the manufacturing of the blade. Each internal cavity is defined by the inner wall of the blade. Furthermore, it has been proposed to drill holes in the blade, particularly on the pressure or suction side surface of the blade, leading to the internal cavities, to create an air film around the blade. To improve the efficiency of this cooling system, it has been proposed to form at least one row of holes in the blade.

[0010] To improve the cooling efficiency of the impeller blades, an optimized construction of these orifices is proposed. The orifices have air outlet openings disposed in the outer wall of the impeller blade and internal channels connecting the outlet openings to internal cavities. The outlet openings have a generally elongated shape in the direction of the trailing edge, allowing the air film to be as close as possible to the outer wall of the impeller blade, thereby improving impeller blade cooling.

[0011] However, while this solution improved the cooling of the impeller, it was not entirely satisfactory. The internal channel has an axis perpendicular to the flow direction of the airflow in the internal cavity. Therefore, this type of channel construction restricts the airflow entering the channel and thus restricts the airflow leaving through the outlet opening.

[0012] Therefore, despite the presence of the outlet opening, the amount of cooling airflow leaving the internal cavity is insufficient to ensure effective cooling of the blades. Consequently, the blades may come into contact with high temperatures, which could lead to oxidation.

[0013] In this case, it is necessary to provide impeller blades with improved cooling. Summary of the Invention

[0014] Therefore, the present invention proposes a blade for an aircraft turbine engine, the blade comprising: - A blade, extending along its elongation axis and having an outer wall comprising a pressure side and a suction side connected by a leading edge and a trailing edge. - At least one internal cavity for allowing cooling airflow, the at least one internal cavity being located within the blade and extending along its elongation axis, the internal cavity being defined by the inner wall of the blade. - At least one first air outlet opening, wherein the first air outlet opening is formed in at least one of the pressure side and the suction side. - At least one internal channel, the at least one internal channel being connected to the first outlet opening and extending along an axis transverse to the elongation axis.

[0015] The notable feature of the impeller is that the at least one internal channel is also connected to at least one second air outlet opening, which is formed in the inner wall and leads to the internal cavity. The second outlet opening has a bottom wall connected to the internal channel and inclined relative to the axis of the internal channel. The second outlet opening has a generally trapezoidal or triangular shape and a flared shape in a direction substantially parallel to the elongation axis. The second outlet opening also includes sidewalls located on both sides of the bottom wall and originating from the inner wall.

[0016] Therefore, the impeller of the present invention includes a second cooling air outlet opening, which is formed in the inner wall of the impeller and leads to the internal cavity.

[0017] Due to the second outlet openings, the cooling airflow flowing into the internal cavity is preferably directed towards the internal channels. The sloping bottom walls of these second outlet openings cause the cooling airflow to be deflected into the second outlet openings via the Coanda effect. This allows a larger volume of cooling airflow to pass through the internal channels, thereby improving the cooling of the outer wall of the impeller.

[0018] The present invention may include one or more of the following features, which may be employed individually or in combination with each other: - The sidewalls slope inward toward the interior of the cavity. - The sidewalls are inclined at an angle between 30° and 60° relative to the elongation axis. - The second exit opening has a curved wall that connects the side walls to each other and to the internal passage.

[0019] The present invention also relates to a core for manufacturing a blade according to any one of the foregoing features by lost-wax casting, the core comprising a body extending along a main axis and defining an reverse form of an internal cavity, the body having at least one protrusion defining a reverse form of a second air outlet opening, the protrusion having a main surface inclined relative to the main axis and an axis perpendicular to the main axis, the main surface having a generally trapezoidal or triangular shape, the protrusion further comprising two sidewalls connecting the body to the main surface, the sidewalls being inclined relative to the main axis of the core.

[0020] The present invention also relates to a method for manufacturing a blade according to any one of the above features, the method comprising the following steps: (a) Provide a core that defines the reverse form of an internal cavity, (b) Construct a model defining the outer wall of the blade. (c) Arrange the core in the model, (d) Create a shell-shaped mold around the model. (f) Pour the metal into a shell mold. The remarkable feature of this method is that, in step (a), the core is a core according to any of the aforementioned features. Attached Figure Description

[0021] Further features and advantages will become apparent from the following description of non-limiting embodiments of the invention with reference to the accompanying drawings, in which: Figure 1 This is a schematic longitudinal cross-sectional view of the semi-turbine engine of an aircraft according to the present invention. Figure 2 This is a schematic diagram of the blade according to the present invention. Figure 3 yes Figure 2 A schematic cross-sectional view of the impeller blades. Figure 4yes Figure 2 A schematic perspective view of the first outlet opening of the impeller. Figure 5 This is a schematic diagram of a longitudinal cross-section of the inner wall of the impeller according to the present invention, through which cooling air flows. Figure 6 This is another schematic diagram of the inner wall of the impeller according to the present invention, through which cooling air flows. Figure 7 This is a block diagram of the method of the present invention. Figure 8 This is a schematic perspective view of a core for manufacturing a blade according to the present invention. Detailed Implementation

[0022] Figure 1 An example of an aircraft turbine engine 1 according to the present invention is shown. The turbine engine 1 extends around and along the longitudinal axis X.

[0023] In this application, the terms "upstream" and "downstream" are defined relative to the gas flow direction along the longitudinal axis X in the turbine engine 1.

[0024] The terms “axial”, “axially”, “radial”, “longitudinal”, and “longitudinal” are defined with respect to the longitudinal axis X of the turbine engine 1.

[0025] The terms “internal”, “inner”, “external”, “outer”, and “externally” are defined relative to the distance from the longitudinal axis X of the turbine engine 1 along the radial axis.

[0026] The turbine engine 1 includes, from upstream to downstream, a fan 2, at least one compressor such as a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, at least one turbine such as a high-pressure turbine 6 and a low-pressure turbine 7, and a nozzle (not shown).

[0027] Fan 2 enables the intake of airflow F, which is divided into a main airflow F1 and a secondary airflow F2. The main airflow F1 passes through the main duct of turbine engine 1, while the secondary airflow F2 is directed to a secondary duct surrounding the main duct.

[0028] The main airflow F1 is compressed in the low-pressure compressor 3, and then in the high-pressure compressor 4. The compressed air is then mixed with fuel and burned in the combustion chamber 5. The gases produced by combustion pass through the high-pressure turbine 6 and the low-pressure turbine 7. The gases finally escape through nozzles whose cross-section allows them to be accelerated to generate thrust.

[0029] The fan 2 is, for example, a duct type. The fan 2 is surrounded by an annular housing 2b centered on the longitudinal axis X. The housing 2b is, for example, surrounded by the nacelle (not shown) of the turbine engine 1.

[0030] Reference Figure 2 The high-pressure turbine 6 includes blades 8 extending radially from a disk (not shown), which is rotatable or stationary relative to a longitudinal axis X. Each blade 8 extends along an elongation axis Y between a head 10 and a root 12 mounted in the disk to hold the blade 8 on the disk. When the blades 8 are mounted in the turbine engine 1, the elongation axis Y of the blades 8 extends radially relative to the longitudinal axis X of the turbine engine 1.

[0031] Each blade 8 includes a blade 14 extending along an elongation axis Y between a head 10 and a root 12. The blade 14 includes an outer wall 16 and an inner wall 18 located inside the outer wall 16. The outer wall 16 has an aerodynamic shape and includes a pressure side 16i and a suction side 16e connected by a leading edge 16a and a trailing edge 16b.

[0032] The outer wall 16 and the inner wall 18 are separated by the thickness e of the blade 14 (e.g.) Figure 3 (As shown) Separated, the thickness e is measured along the transverse axis Z, which is transverse to the elongation axis Y of the blade 8. The thickness e varies within the blade 8.

[0033] The blades 8 are made of a conductive material. This material can be, for example, a metallic material or a composite material. Advantageously, the composite material is a ceramic matrix composite (CMC). The advantage of this material is that it can withstand high temperatures and allows these blades to be implemented in high-temperature environments near the combustion chamber 5.

[0034] To further improve the temperature resistance of the blades 8, each blade 8 includes a cooling system. (See reference...) Figure 3 The cooling system includes a function to direct cooling airflow F3 (in) Figure 4 (As shown in the figure) At least one internal cavity 20 for circulation. Advantageously, a plurality of internal cavities 20 are formed in the impeller 8.

[0035] Each internal cavity 20 is located inside the blade 8 and advantageously extends along the elongation axis Y between the head 10 and the root 12 of the blade 8. Each internal cavity 20 is defined or defined by the inner wall 18 of the blade 8.

[0036] Cooling airflow F3 is drawn in, for example, from low-pressure compressor 4 and delivered to internal cavity 20.

[0037] To further improve the temperature resistance of the blade 8, the cooling system also includes at least one first air outlet opening 22 formed in the outer wall 16. Advantageously, the blade 8 includes a plurality of first air outlet openings 22 formed in the outer wall 16. Advantageously, the blade 8 includes at least one row of first outlet openings 22 aligned along the elongation axis Y of the blade 8. The first outlet openings 22 may also be staggered.

[0038] Each first outlet opening 22 includes an elongated shape. Each first outlet opening 22 is elongated and flares out toward the trailing edge 16b. The shape of each first outlet opening 22 is generally trapezoidal or triangular.

[0039] If possible Figure 4 As seen in the diagram, each first outlet opening 22 includes a bottom wall 26 extending from the outer wall 16 of the impeller 8 toward the inner wall 18. The bottom wall 26 is inclined toward the inside of the impeller 8. The bottom wall 26 is inclined from the outer wall 16 in a transverse plane P relative to the transverse axis Z, the transverse plane P including the suction side 16a or pressure side 16i of the outer wall 16. Advantageously, in this plane, the inclination angle α of the bottom wall 26, measured between the bottom wall 26 and the outer wall 16, is, for example, between 10° and 40°. Each first outlet opening 22 also includes a connecting wall 28 extending from the outer wall 16 of the impeller 8 toward the inner wall 18. The connecting wall 28 is connected to the end of the first outlet opening 22 opposite to the end connected to the bottom wall 26. The connecting wall 28 is inclined toward the inside of the impeller 8. The connecting wall 28 is inclined in the transverse plane P. Advantageously, the connecting wall 28 is inclined from the outer wall 16 in the transverse plane P at an angle β between 80° and 90°.

[0040] The first outlet opening 22 allows air to flow from the internal cavity 20 to the outer wall 16 of the blade 8, thereby creating an air film around the blade 8 to cool it. This configuration of the first outlet opening 22 creates an air film as close as possible to the outer wall 16 to optimize cooling of the outer wall.

[0041] The impeller 8 also includes at least one internal channel 30 connected to the first outlet opening 22. Advantageously, the impeller 8 includes a plurality of internal channels 30, each internal channel 30 being connected to the first outlet opening 22. Thus, there are as many internal channels 30 as there are first outlet openings 22.

[0042] Each internal channel 30 is advantageously tubular or cylindrical. In this example, each internal channel 30 has a circular cross-section. The cross-section of each first outlet opening 22 is larger than the cross-section of each internal channel 30.

[0043] Each internal channel 30 has an air inlet end 30a and an air outlet end 30b connected to a first outlet opening 22. A bottom wall 26 and a connecting wall 28 are connected to the outlet end 30b of the internal channel 30.

[0044] Each internal channel 30 has an axis Z' that is parallel or inclined relative to the transverse axis Z. Advantageously, the axis Z' of each internal channel 30 is inclined at an angle π between 5° and 30° relative to the transverse axis Z. The axis Z' of each internal channel 30 is inclined relative to the surfaces of the outer wall 16 and the inner wall 18.

[0045] According to the invention, each internal channel 30 is advantageously manufactured by EDM (Electrical Discharge Machining). This method is compatible with the aerodynamic shape of the blade 8 and allows for the preservation of material integrity when drilling the internal channels 30. Each internal channel 30 can be manufactured by laser drilling or casting.

[0046] Reference Figure 5 At least one internal channel 30 leads to the internal cavity 20 through at least one second air outlet opening 32. Advantageously, each internal channel 30 leads to the internal cavity 20 through a second outlet opening 32. Thus, the impeller 8 includes as many second outlet openings 32 as it has internal channels 30.

[0047] Each second outlet opening 32 forms a recess in the thickness e of the blade 14. Each second outlet opening 32 is formed in the inner wall 18 of the blade 8 and leads to a corresponding internal channel 30. The internal channel 30 connects the first outlet opening 22 and the second outlet opening 32 to each other.

[0048] Advantageously, each second outlet opening 32 has an elongated shape. Each second outlet opening 32 has a flared shape facing inward toward the inner side of the internal cavity 20. The shape of each second outlet opening 32 is generally trapezoidal or triangular. Thus, each second outlet opening 32 has a large base 32a upstream and a small base 32b downstream, the terms "upstream" and "downstream" being understood herein as the flow direction of the cooling airflow F3 in the internal cavity 20.

[0049] According to the invention, each second outlet opening 32 has a bottom wall 34 connected to the internal channel 30. The bottom wall 34 is inclined relative to the axis Z' of the internal channel 30. The bottom wall 34 is also inclined relative to the elongation axis Y of the impeller 8 and the internal cavity 20. The bottom wall 34 is inclined at an angle Δ of less than 90°, which, when measured relative to the elongation axis Y, is preferably between 5° and 80°, and even more preferably between 5° and 45°. The bottom wall 34 causes the large base 32a to extend outward from the internal cavity 20.

[0050] Advantageously, each second outlet opening 32 has a curved wall 36 that causes the small base 32b to extend outward from the inner cavity 20. The curved wall 36 is concave from the inside of the inner cavity 20 outward. The curved wall 36 connects to the inner channel 30.

[0051] Advantageously, each second outlet opening 32 also includes two sidewalls 38 located on either side of the bottom wall 34 and extending from the inner wall 18. The sidewalls 38 flare towards the inner cavity 20. In other words, the sidewalls 38 diffuse from downstream to upstream relative to the cooling airflow F3 in the inner cavity 20. The sidewalls are inclined at an angle relative to the elongation axis Y, which is advantageously between 30° and 60°.

[0052] The presence of this second outlet opening 32, and in particular this bottom wall 34, generates the Coanda effect. This allows the cooling airflow F3 to be preferentially guided toward the internal channel 30 by promoting the deflection of the cooling airflow F3. Due to these second outlet openings 32, a larger amount of cooling airflow F3 flows into the internal channel 30, thereby improving the cooling of the outer wall 16 of the impeller 8.

[0053] Preferably, the blade 8 includes at least one row of second outlet openings 32 aligned, particularly along the elongation axis Y of the blade 8. Even more preferably, the second outlet openings 32 are located at the upper part of the blade 8, which is located between the head 10 of the blade 8 and the midpoint between the head 10 and the root 12 of the blade 8.

[0054] The blade 8 is more sensitive to thermal stress in this upper part. Distributing the second outlet opening 32 in this way optimizes the cooling of the blade 8 in this upper part and limits thermal damage to the blade 8.

[0055] The impeller 8 is manufactured using the lost-wax casting method. (See reference...) Figure 7 The method includes the following steps: (a) A core 100 is provided, the core 100 defining an internal cavity 20 in a reverse configuration. (b) Optionally, a model of the outer wall 16 defining the blade 16 is made. (c) Arrange the core 100 in the model. (d) Create a shell-shaped mold around the model. (e) Remove the model. (f) Pour the metal into a shell mold. (g) Destroy the shell mold, and (h) Remove core 100.

[0056] The method may optionally include step (i) to drill a hole in the impeller 8 to form an internal channel 30.

[0057] In step (b), the model advantageously contains wax. To maximize manufacturing efficiency, multiple models are produced and these models are combined into a cluster to manufacture multiple blades 8 simultaneously.

[0058] The shell-shaped mold is made of ceramic material.

[0059] Step (d) may include the following steps: (d0) Immerse the model in the slurry. (d1) If necessary, spray powder such as gravel onto the model. (d2) Dry the model.

[0060] Steps (d0), (d1), and (d2) can be repeated until a shell mold with sufficient mechanical properties is obtained.

[0061] Step (e) of removing the mold corresponds to the dewaxing step. For example, the shell mold is subjected to temperatures higher than the degradation temperature of the wax.

[0062] Then, in step (f), the metal is poured into a shell-shaped mold. After the pouring step, the metal is cured. This forms the rough casting of the blade 8.

[0063] After curing, in step (g), for example by impact breaking the shell mold, the core 100 is removed to form the internal cavity 20 of the blade 8.

[0064] Then, in step (i), a hole can be drilled in the outer wall 16 of the impeller 8 to form an internal channel 30 connecting the first outlet opening 22 and the second outlet opening 32. The hole in the outer wall 16 is drilled by electro-erosion or laser drilling.

[0065] Alternatively, the internal channel 30 is formed by casting. Then, the core 100 takes on the reverse form of the internal channel 30.

[0066] The core 100 according to the invention used in step (a) of the method will now be described.

[0067] like Figure 8 As shown, the core 100 includes a body 102 and at least one protrusion 104.

[0068] The body 102 has an elongated shape that extends along the main axis W, which corresponds to the manufactured elongation axis of the blade 8. The body 102 is the reverse form of the internal cavity 20 of the blade 8.

[0069] The protrusions 104 are located on the body 102. Advantageously, the core 100 includes a plurality of protrusions 104 located on the body 102. The protrusions 104 are distributed along the main axis W of the core 100.

[0070] Each protrusion 104 defines a reverse form of the second outlet opening 32. Each protrusion 104 protrudes from the body 102. Each protrusion 104 is generally trapezoidal or triangular in shape. Thus, each protrusion 104 includes a main face 106 that is generally triangular or trapezoidal in shape. The main face 106 has an end 106a connected to the body 102 of the core 100 and an opposing end 106b forming the top of the main face 106. The opposing end 106b is configured to connect to the internal channel 30. The main face 106 lies in a plane inclined relative to the main axis W of the core 100. Preferably, the main face 106 is inclined at an angle between 5° and 45°.

[0071] Each protrusion 104 also includes two side surfaces 108 projecting from the body 102 and on either side of the main surface 106. The side surfaces 108 connect the body to the main surface 106. Each side surface 108 extends between the ends 106a, 106b of the side surfaces 106.

[0072] Each protrusion 104 also includes a curved surface 110 that connects the top 106b of the main surface 106 to the body 102 of the core 100.

[0073] Because of the implementation of this core 100, the second outlet openings 32 can be manufactured in a precise manner, thereby limiting the risk of incorrect positioning of these second outlet openings 32.

[0074] The core 100 may include a reverse form of the internal channel 30. This reverse form is connected to the protrusion 104 via the opposite end 106b of the main surface 106.

[0075] The first outlet opening 22 can also be cast. The shell mold can include a reverse form of the first outlet opening 22.

Claims

1. A blade (8) for an aircraft turbine engine (1), said blade (8) comprising: - Blade (14), the blade extends along the elongation axis (Y) and has an outer wall (16) including a pressure side (16i) and a suction side (16e) connected by a leading edge (16a) and a trailing edge (16b). - At least one internal cavity (20) for allowing cooling airflow (F3) to pass through, said at least one internal cavity being located in the blade (14) and extending along the elongation axis (Y), said internal cavity (20) being defined by the inner wall (18) of the blade (14), - At least one first air outlet opening (22), said at least one first air outlet opening being formed in at least one of the pressure side and the suction side (16i, 16e), - At least one internal channel (30), said at least one internal channel being connected to the first outlet opening (22) and extending along an axis (Z') transverse to the elongation axis (Y), The feature is that the at least one internal channel (30) is also connected to at least one second air outlet opening (32), the at least one second air outlet opening being formed in the inner wall (18) and leading to the internal cavity (30), the second outlet opening (32) having a bottom wall (34) connected to the internal channel (30) and inclined relative to the axis (Z') of the internal channel (30), the second outlet opening (32) having a generally trapezoidal or triangular shape and having a flared shape in a direction substantially parallel to the elongation axis (Y), the second outlet opening (32) also including side walls (38) located on both sides of the bottom wall (34) and starting from the inner wall (18).

2. The blade according to the preceding claim, characterized in that, The sidewall (38) is inclined toward the interior of the internal cavity (20).

3. The blade according to the preceding claim, characterized in that, The sidewall (38) is inclined at an angle between 30° and 60° relative to the elongation axis (Y).

4. The blade according to any one of the preceding claims, characterized in that, The second outlet opening (32) has a curved wall (36) that connects the side walls (38) to each other and to the internal channel (30).

5. A core (100) for manufacturing a blade (8) according to any one of the preceding claims by lost-wax casting, the core (100) comprising a body (102) extending along a main axis (W) and defining an reverse form of the internal cavity (20), the body (102) having at least one protrusion (104) defining an reverse form of a second air outlet opening (32), the protrusion (104) having a main surface (106) inclined relative to the main axis (W) and an axis perpendicular to the main axis (W), the main surface (106) having a generally trapezoidal or triangular shape, and the protrusion (104) further comprising two sidewalls (108) connecting the body (102) to the main surface (106), the sidewalls (106) being inclined relative to the main axis (W) of the core (100).

6. A method for manufacturing a blade (8) according to any one of claims 1 to 4, the method comprising the following steps: (a) Providing a core (100) defining an internal cavity (20) in a reverse form, (b) Construct a model defining the outer wall (16) of the blade (14), (c) Arrange the core (100) in the model, (d) Construct a shell-shaped mold around the model. (f) Pouring the metal into the shell-shaped mold, The feature is that, in step (a), the core (100) is the core as described in claim 5.

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