METHOD AND DEVICE FOR CONTROLLING THE ROPE OF A TURBOMACHINE BLADE

Abstract

A control element for the chord C of a turbomachine blade, said element being intended to be mounted on at least a portion of the blade faces and corresponding to the aerodynamic profile of the blade, characterized in that the control element comprises a reference gauge configured to measure a difference between at least a portion of the reduced blade and the control element, the control element being configured to indicate the chord reduction as a function of the measured difference. Figure for the abstract: Fig 1

Description

Title of the invention: METHOD AND DEVICE FOR CONTROLLING THE ROPE OF A TURBOMACHINE BLADE technical field

[0001] The invention relates to the control of the chord of a turbomachine blade and, in particular, the control of the reduction of the chord of a turbomachine blade resulting from erosion or from a repair by material removal, such as webbing, of a blade. Previous techniques

[0002] An aircraft turbomachine engine can conventionally be equipped with guide vanes called outlet guide vanes (OGV). An outlet guide vane (OGV) is a fixed vane whose function is to direct the flow at the outlet of a fan blade into the secondary flow of the turbomachine.

[0003] The OGV blades form rows of fixed blades which allow the flow through the turbomachine to be guided at an appropriate speed and angle.

[0004] The main function of the fan blades is to bring the incoming air to a certain level of compression, with a certain flow rate, in order to satisfy the aerodynamic objectives: thrust, specific consumption and operability (float, pumping).

[0005] Each blade comprises an upper surface and an lower surface connected by a leading edge and a trailing edge, which together define a chord. In practice, all the blades of an engine have the same chord length. The chord length contributes to the mechanical strength of the blade, as well as to the operability and performance of the engine.

[0006] When in service, fan blades are subjected to recurring impacts that cause erosion or the appearance of geometric defects at the leading edge. These impacts are due, for example, to the presence of macroscopic sand particles in the air drawn in by the engine, which over time cause erosion of the blade and are likely to damage the blades.

[0007] It is therefore necessary to control the reduction in the chord of the blades to determine whether the damaged blade complies with aerodynamic acceptability and mechanical strength criteria.

[0008] Controlling the reduction of the chord of a large number of blades makes it possible to construct and monitor the kinematics of chord reduction under erosion.

[0009] Damaged fan blades can be repaired by one or more resurfacing operations performed on the leading and trailing edges of the blade. Resurfacing helps to mitigate the blade defect when it is shallow. A grinding operation, commonly called "blending," removes the deteriorated material from the blade and modifies the blade geometry to reduce the stress concentration associated with the geometric defect.

[0010] It is therefore also necessary to validate that the repair of the blade and the length of the chord thus obtained remain in accordance with the requirements of aerodynamic acceptability and mechanical strength of an OGV blade.

[0011] Currently, only metrological checks performed using coordinate measuring machines (CMMs) allow for the measurement of the chord length of an OGV blade. For this type of check, each engine component, such as a blade, is disassembled. Then, a measurement of the damaged section of the blade is taken, and the blade ends are identified by a specific program on the measuring machine to determine the chord length.

[0012] Inspecting a blade using a coordinate measuring machine (CMM) has the disadvantages of a very high operating cost, the impossibility of inspecting the blade outside of a measurement laboratory, and the requirement to remove the part from the engine for inspection. Furthermore, the number of such CMMs is limited worldwide, and their accessibility is very difficult depending on location. Therefore, it is not possible to immediately determine the conformity of a damaged or repaired blade.

[0013] In the absence of CMM-type control methods, the characterization of the reduction in the chord of a blade due to erosion is left to the judgment of a mechanical engineer and can only be done approximately. Since the blade has a complex aerodynamic profile, estimating the chord reduction without specific tools becomes very imprecise. Description of the invention

[0014] In view of the foregoing, the invention aims to eliminate at least some of the aforementioned disadvantages by proposing an element and a method for controlling the chord of a turbomachine which is simple to use and inexpensive and which allows for an immediate conclusion as to whether a blade conforms or does not conform.

[0015] The invention therefore relates to a method for controlling the chord of a turbomachine blade, comprising the following steps:

[0016] - locate at least a portion of the reduced dawn,

[0017] - place a control element on at least a portion of the blade faces, the control element corresponding to an aerodynamic profile of the blade and including a reference gauge,

[0018] - measure a difference between at least a part of the reduced dawn element of control,

[0019] - determine the reduction in rope length as a function of the difference measured.

[0020] In one embodiment, the control element is mounted on a notch located on a lateral side of one of the faces of the blade.

[0021] Preferably, the method includes a step of comparing the reduction in rope length with a reference for the acceptability of the rope reduction.

[0022] The invention also relates to a control element for the chord of a turbomachine blade, said element being intended to be mounted on at least a portion of the blade faces and corresponding to the aerodynamic profile of the blade, characterized in that the control element comprises a reference gauge configured to measure a difference between at least a portion of the reduced blade and the control element, the control element being configured to determine the chord reduction as a function of the measured difference.

[0023] In one embodiment, the reference gauge includes at least one element selected from a graduation, a marking, a caliber, a measuring template.

[0024] Preferably, the control element forms a single piece obtained by three-dimensional printing of a polyurethane material.

[0025] In one embodiment, the blade comprises an upper surface, an lower surface and leading and trailing edges connecting the upper and lower surfaces, at least one of the faces of the blade comprising on its lateral side a notch intended to receive the control element.

[0026] Advantageously, the control element has a curved lateral profile having the shape of one of the faces of the blade before the reduction of the chord length.

[0027] Preferably, the control element comprises at least two parts, each of the two parts of the control element covering a desired length of the blade so that by connecting the two parts of the control element, the entire leading edge or trailing edge is covered by the control element.

[0028] Thus the control of the blade can be carried out over a desired length of the blade by using at least a part of the control element adapted to the aerodynamic shape of the blade. Brief description of the drawings

[0029] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0030] - Figure [Fig. 1] schematically illustrates a control element mounted on one of faces of a turbomachine blade whose leading edge is damaged by erosion;

[0031] - Figure [Fig.2] illustrates an extrados of a turbomachine blade;

[0032] - Figure [Fig.3] illustrates a control element mounted on one face of a blade damaged according to another embodiment of the invention;

[0033] - Figure [Fig.4] illustrates a rope of the dawn;

[0034] - Figure [Fig.5] illustrates a portion of a repaired blade;

[0035] - Figure [Fig. 6] is a flowchart illustrating a method for controlling the rope of a turbomachine blade. Detailed description

[0036] Fig. 1 and Fig. 2 illustrate the presence of erosion or a repair operation of the blade by grinding commonly called "blending" on a leading edge 2 of a blade 1. The length of the chord C of the blade is reduced, which decreases the aerodynamic performance of the blade 1.

[0037] Fig. 3 shows a schematic representation of a blade 1 comprising a leading edge 2 and a trailing edge 3 extending between a radially internal end, called the blade foot 4, and a radially external end, called the blade head 5. The leading edge 2 and the trailing edge 3 delimit an extrados 6 and an intrados 7. The faces of the intrados 6 and the extrados 7 are curved, respectively concave and convex.

[0038] In the following description, the terms "internal" and "external", "axial" and "radial", and their derivatives, are defined with respect to the longitudinal axis of the blade 1.

[0039] With reference to [Fig. 3] and [Fig. 4], the blade 1 has an elongated profile from the leading edge 2 to the trailing edge 3. The profile is defined according to a plurality of geometric characteristics such as, for example, a length and a thickness. In this example, the profile of the blade 1 is characterized by the chord C, which corresponds to the distance between the leading edge 2 and the trailing edge 3.

[0040] In order to control the reduction of the chord C following erosion or scouring applied to one of the edges 2, 3 of the blade 1, a control element 8 (illustrated in [Fig.1]) is used which is applied against the edge of the damaged blade.

[0041] The control element 8 includes a slat intended to be mounted in a removable manner on the leading edge 2 or the trailing edge 3 of the blade 1.

[0042] In one embodiment, the control element 8 forms a single part obtained by three-dimensional printing. The control element 8 can be made from a polymer material, such as polyurethane (commonly called PU).

[0043] The control element 8 is mounted on a lateral side of the blade 1 or on one of the ends of the blade 1, such as the foot of the blade 4 or the head of the blade 5. The foot and / or head 4, 5 of the blade may include a notch 9 for receiving the control element 8 (illustrated in [Fig. 1]). [Fig. 1] illustrates the reception of the control element 8 in the notch 9 of the blade 1.

[0044] The control element 8 can cover the entire leading edge 2 or trailing edge 3 (as illustrated in [Fig. 3]) or at least a portion of the reduced blade 11, for example, on the lateral side of the blade where erosion is present or where resurfacing has been carried out 12. The portion of the reduced blade 11 is also illustrated in [Fig. 2]. This damaged portion 11 of the blade can be located on one of the blade's ends (for example, the blade tip 5) or in the middle of the leading edge 2.

[0045] In a particular embodiment, the control element 8 can be fixed to the undamaged portions 12 of the blade, referred to as "healthy" portions, thus ensuring a stable attachment. In [Fig. 5], the portion 11 of the blade has been repaired by a web, and the portions of the blade not affected by erosion or webbing are illustrated by the element 12. The control element 8 is mounted, in this example, on the portions 12 of the blade that have not undergone erosion or repair.

[0046] Blades damaged by erosion or repaired by resurfacing are checked to meet the aerodynamic acceptability criteria for "Outlet Guide Vane" (OGV) type blades. The control element 8 mounted on the blade 1 allows for the determination of a clearance between the tip of the blade and the control element 8. To quantify the length of the chord C reduced due to erosion, the control element 8 is equipped with a reference gauge 10.

[0047] The reference gauge 10, visible in [Fig. 1], may include a graduation, a marking, a caliper, a measuring template, or a Go-No-Go gauge. The graduation allows the difference between at least one damaged portion 11 of the leading edge 2 or the trailing edge 3 and the control element 8 to be measured.

[0048] The control element 8, for example, has a curved lateral profile corresponding to the shape of one of the faces of the blade before the reduction of the length of the chord C. Thus, the difference between the damaged part of the blade and the control element 8 is better distinguished.

[0049] For example, a chord reduction tolerance of 8 mm is acceptable to meet the aerodynamic performance criteria of the blades, as specified in the aircraft maintenance manual (AMM) or the engine workshop manual (ESM).

[0050] The reference gauge 10, comprising a graduation or a plurality of colored ([Fig. 1]) or numbered bands, allows for an immediate determination of the accessibility or unacceptability of the damaged or repaired blade. The reference gauge 10 allows, for example, the measurement of a reduction in the rope length between 1 mm and 40 mm.

[0051] If the length of the chord C does not correspond to the previously defined dimensioning tolerances, the damaged blade generally needs to be repaired or replaced. The portable control element 8 makes it possible to determine the accessibility or unacceptability of each blade in the impeller assembly without the need for disassembly and without very expensive tools.

[0052] With reference to [Fig. 6], the method for checking the chord of a blade begins with a first step 100, during which at least a portion of the reduced blade 11 is located. This damaged or repaired portion may be located on the leading or trailing edge at one end or in the middle of the blade. The location of the reduced portion 11 may be visual or determined by a specific program.

[0053] In the next step 105, the control element 8 is placed on at least one portion 9, 12 of the faces of the blade 6, 7. The portion which is intended to receive the control element 8 can be either a notch 9 on a lateral side or on one of the ends of the blade (foot or head of the blade 4, 5) or an undamaged part of the blade 12.

[0054] During the next step 110, a difference between at least a part of the reduced blade 11 and the control element 8 is measured by the reference gauge 10.

[0055] In the following step 115, the reduction in the length of the rope C is determined as a function of the difference measured in the previous step 110.

[0056] In an optional step 120, the reduction in the length of the rope C is compared with a reference for the acceptability of the rope reduction in order to then conclude whether the damaged blade should be repaired or replaced.

[0057] Finally, the controlled dawn is accepted or rejected.

Claims

Demands

1. A method for controlling the chord C of a turbomachine blade (1), characterized in that it comprises the following steps: - locating at least a portion of the reduced blade (11); - placing a control element (8) on at least a portion (9, 12) of the faces of the blade (6, 7), the control element (8) corresponding to an aerodynamic profile of the blade and comprising a reference gauge (10); - measuring a difference between at least a portion of the reduced blade (11) and the control element (8) by the reference gauge (10); - determining the reduction in the length of the chord C as a function of the measured difference.

2. Control method according to claim 1, characterized in that the control element (8) is mounted on a notch (9) located on a lateral side of one of the faces of the blade (6, 7).

3. A control method according to claim 1 or 2, further comprising a step of comparing the reduction in the length of rope C with a reference for the acceptability of the rope reduction.

4. Control element (8) of the chord C of a turbomachine blade (1), said element (8) being intended to be mounted on at least a portion (9, 12) of the faces of the blade (6, 7) and corresponding to the aerodynamic profile of the blade, characterized in that the control element (8) comprises a reference gauge (10) configured to measure a difference between at least a reduced portion of the blade (11) and the control element (8), the control element (8) being configured to indicate the chord reduction as a function of the measured difference.

5. Control element according to claim 4, characterized in that the reference gauge (10) comprises at least one element selected from a graduation, a marking, a caliber, a measuring template.

6. Control element according to claim 4 or 5, characterized in that the control element (8) forms a single piece obtained by three-dimensional printing.

7. Control element according to any one of claims 4 to 6, characterized in that the blade (1) comprises an extrados (6), an intrados (7) and leading (2) and trailing (3) edges connecting the extrados and intrados (6, 7), at least one of the faces of the blade (6, 7) comprising on its lateral side a notch (9) intended to receive the control element (8).

8. Control element according to any one of claims 4 to 7, characterized in that the control element (8) has a curved lateral profile having the shape of one of the faces of the blade (6, 7) before the reduction of the length of the chord C.

9. Control element according to any one of claims 4 to 8, characterized in that the control element (8) comprises at least two parts, each of the two parts of the control element covering a desired length of the blade (6, 7) so that by connecting the two parts of the control element, the entire leading edge (3) or trailing edge (3) is covered by the control element (8).

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