Metal attack shield for turbomachine blade, turbomachine blade, manufacturing and use method

Abstract

Leading edge shield (40) of a metal turbine blade (34), the shield (40) extending longitudinally between a shield base and a shield head, the shield (40) comprising an upper fin (40A), an upper fin (40B), and a thicker central section (40D) designed to overlap a leading edge (36C) of a blade body (36) and connecting the upper fin (40A) and the upper fin (40B), the central section (40D) comprising a plurality of channels (44) extending longitudinally from the shield base to the shield head. Blade comprising the shield, method for manufacturing the shield, and method for de-icing it. Figure for the abstract: Fig. 2

Description

Title of the invention: METALLIC LEADING SIDE SHIELD FOR TURBOMACHINE BLADE, TURBOMACHINE BLADE, METHOD OF MANUFACTURING AND USING technical field

[0001] The present exposition relates to the de-icing of an aircraft engine and in particular, a metallic leading edge shield for a turbomachine blade, for example fixed blades or rotating blades. Previous technique

[0002] Defrosting means both preventing the formation of ice (anti-icing) in parts of the engine and removing ice (defrosting) that may have formed there.

[0003] FR3034145 is known to be an aircraft engine comprising a compression stage with hollow guide vanes that allow hot air to circulate within the vane body. Thanks to the circulation of hot air within the vane body, i.e., within the part to be de-iced, it is possible to prevent ice formation in the compressor and / or to remove any ice that may have formed there.

[0004] Rotating blades include both fan blades and propeller blades or moving compressor blades. Fixed blades include both fan guide blades and compressor guide blades.

[0005] In order to limit their weight, these blades are typically made of composite with a polymer matrix reinforced by carbon fibers.

[0006] The de-icing system by circulating hot air in the hollow blade body is not suitable for blades whose blade body is made of composite with a polymer matrix reinforced by carbon fibers.

[0007] For blades whose blade body is made of a carbon fiber reinforced polymer matrix composite without a leading edge shield, de-icing systems are known that include a heating layer on the surface of the part, commonly called a "heating mat." This heating layer is actually composed of multiple layers, some of which are conductive and others insulating. This heating mat allows the blade to be heated by the Joule effect by passing an electric current through multiple layers of conductive wires separated by insulating layers. However, this solution has drawbacks, such as high energy consumption in de-icing mode (in com (comparison of the anti-freeze mode), the heating mat also has an extra thickness on the part which is less regularly shaped than the structural part.

[0008] Although the materials used for blades whose blade body is made of composite with a polymer matrix reinforced by carbon fibers generally have very favorable mechanical qualities, in particular in relation to their mass, they are subject to erosion and impacts with foreign bodies (gravel from the runway, hailstones, birds, etc.), which can generate in particular delamination phenomena within the material.

[0009] Shields, typically made of highly resistant metallic material such as titanium alloys, are therefore normally installed on the leading edges of such blades to protect them against these impacts. These shields normally take the form of a thin lower surface fin and a thin upper surface fin joined by a thicker section overlapping the leading edge, the assembly conforming to the shape of the blade on the leading edge and adjacent sections of the lower and upper surfaces. The lower and upper surfaces fins extend over these sections of the lower and upper surfaces of the blade, respectively, and serve primarily to ensure the positioning and attachment of the shield to the leading edge.

[0010] Such leading edge shields are typically intended to protect the leading edges of rotating or fixed blades against impacts.

[0011] These shields increase the amount of metallic material present and therefore increase the electrical consumption required during heating by Joule effect.

[0012] Furthermore, adding a heating mat between the blade and the shield can create additional difficulties, particularly during blade production. This addition can also lead to a less secure mechanical fit between the shield and the blade, which is undesirable.

[0013] It therefore remains desirable to find a solution for de-icing a blade comprising a metal shield which would consume less energy than the heating mats of the prior art. Description of the invention

[0014] The present exposition aims to remedy at least some of these drawbacks.

[0015] For this purpose, the present description relates to a metallic leading edge shield for a turbomachine blade, the shield extending in a longitudinal direction between a shield foot and a shield head, the shield comprising an intrados fin, an extrados fin and a thicker central section, intended to overlap a leading edge of a blade body and connecting the intrados fin and the extrados fin, the central section comprising a plurality of channels extending in the longitudinal direction from the shield foot to the shield head.

[0016] Thanks to the presence of channels in the central section of the shield, it is possible to circulate a heating fluid along the shield and thus defrost and / or prevent the formation of frost on the blade (anti-icing). By way of non-limiting example, the heating fluid can be a hot gas, originating from a part of the turbomachine, for example from a turbomachine compressor. By way of non-limiting example, the heating fluid can be water, kerosene, or a heat transfer fluid.

[0017] It is understood that when the leading edge shield is assembled on a blade body, and the blade thus formed is mounted in a turbomachine, the longitudinal direction of the shield corresponds to the radial direction of the turbomachine.

[0018] In some embodiments, the central section includes a sacrificial zone, the sacrificial zone being free of channels.

[0019] The sacrificial zone corresponds to the area of ​​the shield that can be eroded during the operation of the turbomachine when the shield is assembled onto a blade body and the resulting blade is mounted in a turbomachine. This reduces the risk of channels being exposed during shield wear.

[0020] In some embodiments, a minimum distance between two channels is greater than or equal to 1.5 times a diameter of a circle circumscribing a maximum cross-section of the larger of the two channels.

[0021] This helps to reduce the risk of shield failure at the channel level.

[0022] In some embodiments, a minimum distance between a channel and an outer surface of the shield is greater than or equal to 1.5 times a diameter of a circle circumscribing a maximum cross-section of the channel.

[0023] This helps to reduce the risk of shield failure at the channel level.

[0024] It is understood that when the shield includes a sacrificial zone, the surface ex The outer surface of the shield is the surface after wear.

[0025] In certain embodiments, when three channels are aligned, the minimum distance between the three channels, taken two by two, is greater than or equal to 3 times a diameter of a circle circumscribing a maximum cross-section of the widest of the channels.

[0026] It is understood that it is preferable to avoid aligning three channels. However, when three channels are aligned, it is preferable to space them out in this way to reduce the risk of shield breakage at the channel level.

[0027] In some embodiments, the plurality of channels includes at least one junction or bifurcation between the shield foot and the shield head.

[0028] It is thus possible to split certain channels from the base of the shield to the top of the shield or vice versa. For example, a channel at the base of the shield can split into two channels that will open at the top of the shield, or two channels at the base of the shield can join into a single channel opening at the top of the shield.

[0029] In some embodiments, a cross-section of at least one of the channels decreases at a channel end opening at the base of the shield or at the head of the shield.

[0030] The flow of the heating fluid can thus be accelerated at this end to facilitate its incorporation into the surrounding airflow when it exits the channel.

[0031] The present disclosure also relates to a turbomachine blade comprising a blade body made of fiber-reinforced organic matrix composite material and a shield as defined above, the shield being assembled on the blade body.

[0032] It is understood that the blade body comprises an upper surface and an lower surface connected by a leading edge of the blade body. When the shield is assembled on the blade body, the lower surface fin of the shield is fixed to the lower surface of the blade body, the upper surface fin of the shield is fixed to the upper surface of the blade body, and the central section overlaps the leading edge of the blade body.

[0033] The blade can be a fixed blade or a rotating blade.

[0034] The present exposition also relates to a method of manufacturing a shield as defined above, comprising a step of forming cores in fugitive material, a step of forming the shield, and a step of removing the cores to form the channels.

[0035] The core removal step can be carried out, for example, by solubilization or fusion, and can be followed by a shield completion and finishing step.

[0036] The shield formation stage may include several stages.

[0037] By way of non-limiting example, when the shield is manufactured by an electrodeposition process, the shield formation step may include a sub-step of positioning the fugitive material cores in a specific electrodeposition tool, a sub-step of electrodeposition of the metallic material around the fugitive material cores and a mandrel defining the internal shape of the shield, intended to receive the leading edge of the blade, a sub-step of demolding and deburring the raw shield including the fugitive material cores.

[0038] By way of non-limiting example, when the shield is manufactured by shell mold casting, the shield formation step may include a substep of positioning the fugitive material cores in a wax matrix, a substep of forming the shell mold around the wax matrix, a substep of melting the wax, a substep of pouring the molten metal, a substep of cooling and a substep of demolding the rough shield including the fugitive material cores.

[0039] By way of non-limiting example, when the shield is manufactured by welding metal sheets, the shield formation step may include a sub-step stacking of metal sheets alternating with fugitive material cores, a sub-step of compacting the sheets and welding by diffusion welding or by electron beam welding to obtain a rough shield including fugitive material cores.

[0040] The present exposition also relates to a method of manufacturing a shield as defined above, the shield being obtained by an additive manufacturing process, for example by selective powder bed fusion.

[0041] The present exposition also relates to a method for de-icing or anti-icing a turbomachine comprising a blade as defined above, the method comprising a step of circulating a heating fluid in the channels of the shield.

[0042] In some embodiments, the heating fluid may be a hot gas taken from a turbomachine compressor. Alternatively, however, the process may include a step of heating the heating fluid in a heat exchanger before circulating it through the shield channels. The heating fluid could then be a heat transfer fluid such as, for example, a lubricant or fuel from the turbomachine, or even circulate in a closed loop between the heat exchanger and the shield channels. Brief description of the drawings

[0043] Other features and advantages of the subject matter of this presentation will become apparent from the following description of embodiments, given by way of non-limiting examples, with reference to the attached figures.

[0044] [Fig-1] Fig. 1 is a schematic longitudinal cross-sectional view of a tower bomachine.

[0045] [Fig.2] The [Fig.2] is a schematic cross-sectional view of a blade comprising a leading edge shield according to a first embodiment.

[0046] [Fig.3] The [Fig.3] a schematic perspective view of a leading edge shield according to a second embodiment.

[0047] [Fig.4] The [Fig.4] is a schematic cross-sectional view of a leading edge shield according to a third embodiment.

[0048] [Fig.5] The [Fig.5] is a schematic view of a leading edge shield and a de-icing circuit according to a fourth embodiment.

[0049] [Fig.6] The [Fig.6] is a flowchart representing the steps of a manufacturing process for the leading edge shield.

[0050] [Fig.7] The [Fig.7] is a detail view of one end of a channel of the leading edge shield according to any one of the first to third embodiments.

[0051] Throughout all the figures, the common elements are identified by identical numerical references. Detailed description

[0052] Figure 1 shows a cross-section along a vertical plane passing through its principal axis A, A turbofan engine 10 is an example of a turbomachine. The turbofan engine 10 comprises, from upstream to downstream according to the airflow circulation F, a fan 12, a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20, and a low-pressure turbine 22.

[0053] The terms "upstream" and "downstream" are defined with respect to the direction of air flow in the turbomachine, in this case, according to the airflow F in the turbojet 10.

[0054] The turbojet 10 comprises a fan casing 24 extended rearward, i.e. downstream, by an intermediate casing 26, comprising an outer shell 28 and an inner shell 30 parallel and arranged, along a radial direction R, internally with respect to the outer shell 28. The radial direction R is perpendicular to the main axis A.

[0055] The terms "external" and "internal" are defined with respect to the radial direction R such that the internal part of an element is, along the radial direction, closer to the principal axis A than the external part of the same element.

[0056] The intermediate casing 26 further comprises structural arms 32 distributed circumferentially and extending radially from the inner shell 30 to the outer shell 28. For example, the structural arms 32 are bolted to the outer shell 28 and to the inner shell 30. The structural arms 32 provide rigidity to the structure of the intermediate casing 26, although they can also form fixed blades with an aerodynamic function of straightening the flow exiting the fan 12. Alternatively, however, the turbojet could comprise a set of fixed blades, separate from the structural arms 32, forming a flow straightener downstream of the fan 12.

[0057] Each of the low and high pressure compressors 14, 16 and the high and low pressure turbines 20, 22 comprises a plurality of impellers which form their respective rotors.

[0058] The main axis A is the axis of rotation of the blower 12 and of the rotors of the low and high pressure compressors 14, 16 and of the high and low pressure turbines 20, 22. This main axis A is therefore parallel to the axial direction.

[0059] Fig. 2 is a partial schematic cross-sectional view of a blade 34 comprising a leading edge shield 40 according to a first embodiment. The blade 34 can in particular be a fan blade 12, a fixed flow straightening blade of the fan 12 formed by a structural arm 32 or separate from these- here, or a fixed or rotating blade of the low pressure compressor 14.

[0060] The blade 34 comprises a blade body 36 made of fiber-reinforced organic matrix composite material, in particular carbon fibers, although other reinforcing materials such as, for example, PPD-T (also known under the brands Kevlar® and Twaron®), or UHMPE (also known under the brands Spectra® and Dyneema®) are also conceivable.

[0061] On the partial schematic view of [Fig.2], the blade body 36 comprises an intrados 36A and an extrados 36B connected by a leading edge 36C of the blade body 36.

[0062] The metallic leading edge shield 40 comprises an intrados fin 40A and an extrados fin 40B and a thicker central section 40D connecting the intrados fin 40A and the extrados fin 40B. The central section 40D comprises a leading edge 40C of the shield 40.

[0063] By way of non-limiting example, the shield 40 may be made of titanium-based alloy.

[0064] When the shield 40 is assembled onto the blade body 36, the lower winglet 40A of the shield 40 is fixed on the intrados 36A of the blade body 36, the extrados fin 40B of shield 40 is fixed on the extrados 36B of the blade body 36 and the central section 40D overlaps the leading edge 36C of the blade body 36.

[0065] In [Fig.2], the shield 40 is assembled by gluing with a film of glue 38 onto the blade body 36.

[0066] As can be seen in the embodiment of [Fig.2], the central section 40D comprises a plurality of channels 44. In the embodiment of [Fig.2], the channels 44 have diameters which are all equal to each other and the channels 44 are distributed in the central section 40D of the shield 40 such that three channels 44 are not aligned, i.e. that three channels 44 do not form a straight line or a straight line does not pass through the center of three channels 44.

[0067] In the embodiment of [Fig. 2], the maximum erosion limit of the shield in service, i.e., when the shield is assembled on a blade body, the blade being mounted in a turbomachine and the turbomachine operating, is represented by the dashed line 42. This dashed line 42, together with the leading edge 40C of the shield 40, delimits a sacrificial zone 50.

[0068] In the embodiment of [Fig.2], the sacrificial zone 50 is free of channels. It is understood that the channels 40 are arranged in the central section 40D, outside the sacrificial zone 50, at a distance greater than or equal to 1.5 times the diameter of the channels 44 from the dashed line 42, that is to say at a distance greater than or equal to 1.5 times the diameter of the channels 44 from the sacrificial zone 50.

[0069] As can be seen in [Fig. 3], the shield 40 comprises a shield foot 46 and a shield head 48, and the channels 44 extend from the shield foot 46 to the shield head 48, that is to say, the channels 44 pass through the entire shield 40 from the foot 46 to the shield at the head 48 of shield along the longitudinal direction of the shield 40 which corresponds to the radial direction R of the turbomachine when the shield 40 is assembled on a blade body 36 and the blade 34 thus formed is mounted in the turbomachine 10.

[0070] Fig. 4 represents another embodiment of the shield 40. The difference with the shields 40 of figures 2 and 3 is the geometric distribution and the diameter of the channels 44.

[0071] Figure 5 shows yet another embodiment of the shield 40, in which the channels 44 are not straight, as in the embodiments of Figures 2 to 4, but are bent to form serpentine shapes. In the illustrated embodiment, the channels 44 are bent at the side of the shield head 48, so as to enter the shield 40 and exit through the shield foot 46. However, it is also possible for the channels 44 to be bent in the opposite direction at the side of the shield foot 46, so as to enter the shield 40 and exit through the shield head 48.

[0072] The leading edge shield 40 can be manufactured by an additive manufacturing process, for example by additive manufacturing by selective powder bed fusion.

[0073] As illustrated in [Fig.6], the leading edge shield 40 can be manufactured by a process 100 which includes a core formation step 102 in fugitive material, a shield formation step 104, and a core removal step 106 to form the channels.

[0074] It is understood that the cores 102 are intended to form the channels 44 in the shield 40. Also, the shape and dimensions of the cores 102 are a function of the shape and size of the channels 44. The fugitive material of the cores can in particular be ceramic.

[0075] The shield formation step 104 may include several steps.

[0076] By way of non-limiting example, when the shield 40 is manufactured by an electrodeposition process, the shield formation step 104 may include a substep of positioning the ceramic material cores in a specific electrodeposition tool, a substep of electrodeposition of the metallic material around the ceramic material cores and a mandrel defining the shape of the shield, a substep of demolding and deburring the raw shield including the ceramic material cores.

[0077] The removal of the nuclei 106 can notably be carried out by solubilization. After the nuclei removal step 106, the process 100 can include a finishing step of the shield 108.

[0078] The de-icing or anti-icing method for the turbomachine 10 comprising a blade 34 including the shield 40 assembled on the blade body 36 includes a stage of circulation of a heating fluid in the channels 44 of the shield 40.

[0079] By way of non-limiting example, the heating fluid may be a hot gas from the compressor of the turbomachine 10, which is fed to the base of the shield 46. This hot gas can then flow towards the shield head 48 through the channels 44, and exit outwards at the shield head 48, through the ends 45 of the channels 44. As illustrated in [Fig. 7], each channel 44 can be tapered towards its respective end 45, so as to accelerate the flow of the hot gas before its exit through the end 45, and thus facilitate its incorporation into the surrounding airflow. For this purpose, the channel 44 may comprise a main segment 44a of diameter D, an outlet segment 44c, adjacent to the end 45, of length Hs and diameter d smaller than diameter D, and a tapered segment 44b, interposed between the main segment 44a and the outlet segment 44c, of length Ht.The diameter d can notably be greater than 0.2 times the diameter D, and in particular be about half the diameter D. The length Hs can for example be about twice the diameter d and the length Ht can for example be about twice the diameter D.

[0080] However, it is also conceivable that the heating fluid is another heat transfer fluid, such as for example a lubricant or a fuel from the turbomachine 10, circulating through the channels 44 after having been heated in a heat exchanger 49. As illustrated in [Fig. 5], the heating fluid can circulate in a closed circuit, returning to the heat exchanger 49 after passing through the channels 44, in a circulation which can be driven by a pump 51.

[0081] Although the present description has been made with reference to a specific embodiment, it is evident that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. For example, although the illustrated turbomachine is a ducted turbofan engine, the invention would also be applicable to other types of turbomachines, such as unducted turbofan engines, turboprops, or turboshaft engines. Furthermore, although the illustrated channels have a circular cross-section, other cross-sectional shapes, such as oval or polygonal, are also conceivable. In addition, individual features of the various embodiments mentioned can be combined in further embodiments.Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Demands

1. A metallic leading-edge shield (40) for a turbine blade (34) of a turbine (10), the shield (40) extending longitudinally between a shield foot (46) and a shield head (48), the shield (40) comprising an intrados fin (40A), an extrados fin (40B), and a thicker central section (40D) designed to overlap a leading edge (36C) of a blade body (36) and connecting the intrados fin (40A) and the extrados fin (40B), characterized in that the central section (40D) comprises a plurality of channels (44) extending longitudinally from the shield foot (46) to the shield head (48), with a minimum distance between any two channels (44) greater than or equal to 1.5 times the diameter of a circle circumscribing a maximum cross-section of the largest wide of both channels.

2. Shield (40) according to claim 1, wherein the central section (40D) comprises a sacrificial zone (50), the sacrificial zone (50) being free of channels.

3. Shield (40) according to any one of claims 1 or 2, wherein a minimum distance between a channel (44) and an outer surface of the shield is greater than or equal to 1.5 times a diameter of a circle circumscribing a maximum cross-section of the channel.

4. Shield (40) according to any one of claims 1 to 3, wherein, when three channels are aligned, the minimum distance between the three channels, taken two by two, is greater than or equal to 3 times a diameter of a circle circumscribing a maximum cross-section of the widest of the channels.

5. Shield (40) according to any one of claims 1 to 4, wherein the plurality of channels comprises at least one junction or bifurcation between the shield foot (46) and the shield head (48).

6. Shield (40) according to any one of claims 1 to 5, wherein at least one of the channels (44) is tapered towards an end (45) opening into the base of the shield (46) or the head of the shield (48).

7. Turbomachine blade (34) (10) comprising a blade body (36) of fiber-reinforced organic matrix composite material and a shield (40) according to any one of claims 1 to 6, the shield (40) being assembled on the blade body (36).

8. A method (100) for manufacturing the shield (40) according to any one of claims 1 to 6, comprising a core formation step (102) in fugitive material, a shield formation step (104), and a core removal step (106) to form the channels (44).

9. A method for manufacturing the shield (40) according to any one of claims 1 to 6, the shield (40) being obtained by an additive manufacturing process.

10. Method for de-icing or anti-icing a turbomachine (10) comprising the blade (34) according to claim 7, the method comprising a step of circulating a heating fluid in the channels (44) of the shield (40).

11. Defrosting or anti-icing method according to claim 10, wherein the heating fluid is a hot gas taken from a compressor of the turbomachine (10).

12. Defrosting or anti-icing method according to claim 10, comprising a step of heating the heating fluid in a heat exchanger (49) before its circulation in the channels (44) of the shield (40).

Images