SHOCK DETECTION DEVICE ON A DRAW

Abstract

The invention relates to a sensor (28) for detecting stress that could damage a component (16, 20) of an aircraft turbomachine (10), characterized in that it comprises a support plate (32) fixed to said component (16, 20) and capable of breaking when the amplitude of a stress on the component (16, 20) exceeds a predefined value, and an electrical circuit (36) that is closed as long as the support plate (32) is intact and is opened after the support plate (32) breaks. The invention also relates to a turbomachine in which at least some of the blades carry such a sensor. See Figure 4 for the abstract.

Description

Title of the invention: SHOCK DETECTION DEVICE ON A BLADE technical field

[0001] The invention proposes a device for determining whether a turbomachine blade has been subjected to stress which could have caused damage to the blade. PREVIOUS STATE OF THE ART

[0002] In a shrouded or unshrouded turbomachine fan, certain blades are intended to straighten the aerodynamic flow at the outlet of the turbomachine propeller.

[0003] These bladed parts are fixed and have a role similar to that of a conventional compressor stator. They are associated with the moving blower blades and allow the airflow, which has been accelerated and deflected (gyration phenomenon) by the latter, to be straightened.

[0004] In recent turbomachinery, fixed blades can be made of organic matrix composite materials, as these materials allow a significant mass saving with equivalent mechanical properties compared to metallic blades.

[0005] The design of these fixed blades takes into account, in particular, the blade's resistance to ingestion, that is, when they are struck by elements drawn into the turbomachine. These elements are, for example, birds or objects located on the runway.

[0006] The shock resulting from the contact of such an element with a blade can produce damage to the blade.

[0007] In certain cases, it is possible to accept a level of damage that allows the aircraft either to continue its mission without incident or to land on the tarmac and be repaired. In all cases, the safety of passengers, flight crew, and populations living under flight paths must be guaranteed.

[0008] In the case of permissible damage, it must be clearly identifiable during the ground inspection. The damage may be located either in the aerodynamic part, i.e. in the area of ​​the flow in contact with the external flow or at the attachment point under the flow, in which case the damage is more easily identifiable, or it may be located under the aerodynamic flow, i.e. in the part of the blade that is hidden by the platform used to recreate the flow; this part of the blade is therefore not visible without disassembly.

[0009] Solutions exist for identifying damage at the blade root using deformation markers / tracers. The application published under number FR3036796 in the name of the applicant discloses such a solution.

[0010] However, such solutions require taking into account the properties of the tracers, which may be different from the rest of the part and which may also be subject to damage.

[0011] Furthermore, these solutions require the use of other components to control the level of damage to the blade.

[0012] Damage to the blade can be difficult to detect, especially when it is a blade made of composite materials, because specific inspection methods must be used.

[0013] The invention aims to provide a device and a method for determining whether a blade has suffered an impact that could have damaged it. Description of the invention

[0014] The invention proposes a sensor for detecting a stress that could damage a component of an aircraft turbomachine, characterized in that it comprises a support plate which is fixed on said component and which is capable of breaking when the amplitude of a stress on the component is greater than a predefined value and an electrical circuit which is closed as long as the support plate is not broken and which is open after the support plate breaks.

[0015] When the turbomachine component, in particular the blade, is subjected to a sufficiently large shock, the rupture of the support plate allows the electrical circuit to be opened and thus to produce information relating to damage to the blade at the level of the sensor.

[0016] Preferably, the support plate includes a portion with controlled breaking strength, which is intended to break when the component has been subjected to a stress whose amplitude exceeds the predefined value.

[0017] Preferably, the electrical circuit is fixed on the portion with controlled breaking strength.

[0018] Preferably, the sensor is associated with a display device which changes state when the support plate breaks.

[0019] The invention also relates to an aircraft turbomachine comprising such a sensor, a plurality of movable or fixed blades distributed around a main axis A of the turbomachine, characterized in that at least a part of the blades carries at least one sensor.

[0020] Preferably, each sensor is associated with a compressive stress on the blade along an axis B of the blade or is associated with a tensile stress on the blade along the axis B.

[0021] Preferably, the blade comprises an aerodynamic part located at one end along the axis B of the blade and a foot part located at the other end of the blade along its axis B, and each sensor is mounted on a so-called foot end of the blade.

[0022] Preferably, the turbomachine comprises an electrical assembly consisting of a single power source and several assemblies each comprising at least one sensor and a display device which is associated with said at least one sensor and is mounted in series with said at least one sensor and the power source.

[0023] Preferably, said assemblies, each comprising at least one sensor and one display device, are mounted in parallel with each other.

[0024] Preferably, each sensor is fixed by gluing the support plate with an epoxy resin to an area of ​​the blade likely to be damaged by said stress. Brief description of the drawings

[0025] Other features and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference should be made to the accompanying figures, among which: - Fig. 1 is a schematic perspective representation of a turbomachine with an unfaired fan; - [Fig.2] is a schematic representation of a blower blade shown in [Fig.1]; - [Fig.3] is a larger scale detail of one end of the blade shown in [Fig.2], showing the sensor mounting area; - [Fig.4] is a schematic representation of the sensor according to the invention; - [Fig. 5] is a diagram representing an electrical circuit composed of a plurality of sensor assemblies and display devices.

[0026] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0027] Figure [1] shows a turbomachine 10 of a twin-flow aircraft, which is here a turbomachine of the unfaired fan type.

[0028] The turbomachine includes a blower 12 composed of a plurality of movable blades 16 which are mounted on a rotor 14 and which are movable in rotation around a main axis A of the turbomachine 10.

[0029] The turbomachine 10 also includes a flow rectifier 18 composed of a plurality of fixed blades 20 with variable orientation which are mounted on a stator part 22 of the turbomachine 10.

[0030] In the following description, reference will be made to a fixed blade 20 forming part of the flux straightener 18. It will be understood that the invention is not limited to a fixed blade 20 and that it can also be applied to a movable blade 16. Also, it will be understood that the invention can also relate to a fixed blade 20 or a movable blade 16 of a turbomachine 10 with a shrouded fan 12.

[0031] As can be seen in more detail in figures 2 and 3, the blade 20 has a main axis B, which is globally radial with respect to the main axis A of the turbomachine when the blade 20 is mounted in the turbomachine 10.

[0032] The blade 20 comprises an aerodynamic portion 24 located at a first end along axis B, which is commonly called the blade. The blade 24 constitutes the portion of the blade 20 that interacts with the airflow. It exhibits naturally high resistance, particularly due to its aerodynamic volume, the minimum manufacturing thicknesses, and the properties of the materials used.

[0033] The blade 20 includes a second part 26 located at the other end of the blade 20 along its axis (B) which has the function of carrying the means of connecting the blade 20 with the stator part 22. This second part 26 is commonly called the foot of the blade 20 and is isolated from the airflow by a fairing element of the stator part 22 which reconstitutes the airflow duct.

[0034] The foot 26 has a naturally low resistance due in particular to the shape imposed by requirements related to the connection of the blade 20 with the stator part 22, in particular assembly and disassembly constraints, external interface constraints, etc.), constraints related to the available space, the thicknesses and properties of the materials used.

[0035] Thus, the critical area of ​​the blade 20, which is most likely to be damaged, is located at the foot 26 of the blade 20.

[0036] Since foot 26 is covered by the fairing element, it is not visible for inspection without dismantling this fairing element.

[0037] The blade 20 carries a sensor 28 coupled to a display device 30 (represented in [Fig.5]) which are configured to inform a technician performing maintenance operations on the turbomachine 10 whether the blade 20 has been subjected to stresses whose amplitude has exceeded a reference amplitude or critical stress.

[0038] According to a preferred embodiment, the sensor 28 is intended for a stress oriented along the axis B of the blade 20, in compression or in tension.

[0039] According to one embodiment, the blade 20 carries two sensors 28, a first sensor 28 being associated with a compressive stress, the second sensor 28 being associated with a tensile stress.

[0040] The sensor 28, or the sensors 28 carried by the same blade 20 are associated with a display device 30 such as, for example, a light-emitting diode (or LED).

[0041] The sensor(s) assembly 28 and display device 30 is configured so that the display device 30 is on as long as the blade 20 has not been subjected to a stress whose amplitude exceeds the critical stress associated with the sensor 28.

[0042] In the case where two sensors 28 are carried by the blade 20, the display device 30 switches off when the blade 20 has undergone a stress associated with at least one of the two sensors 28 whose amplitude exceeds the critical stress.

[0043] Alternatively, the sensor(s) assembly 28 and display device 30 is configured so that the display device 30 is off until the blade 20 has been subjected to a stress whose amplitude exceeds the critical stress associated with the sensor 28.

[0044] According to a preferred embodiment shown in [Fig. 4], a sensor 28 comprises a support plate 32 preferably made of ceramic because it is a material exhibiting, in particular, high compressive strength and good electrical insulation. The support plate 32 comprises a portion 34 with controlled fracture resistance. This portion 34 is designed to break when the blade 20 has been subjected to a stress whose magnitude exceeds the critical stress associated with the sensor 28.

[0045] The support plate 32 carries an electrical circuit 36 ​​which is fixed on a portion 34 with controlled breaking strength and which is capable of opening in the event of breakage of the portion 34 of the support plate 32.

[0046] The electrical circuit 36 ​​is connected to the display device 30 by electrical cables 38. The electrical circuit 36 ​​and the display device 30 are connected in series with a power source 42.

[0047] The support plate 32 is further covered by a protective coating 40.

[0048] The sensor 28 is fixed to the base of the blade 20 by any known means, preferably by gluing the support plate 28 with an epoxy resin to the critical area of ​​the blade 20, which is most likely to be damaged.

[0049] By way of non-limiting example, the size of the support plate 32 is less than 10% of the rope length of the blade 20. Its thickness is less than 20mm and preferably less than 10mm.

[0050] For a sensor 28 associated with a tensile constraint, the section A0 of the portion 34 is less than a predefined value, for example the section A0 is less than 800 mm2.

[0051] For a sensor 28 associated with a compressive stress, the cross-section A0 of the portion 34 is less than a predefined value, for example the cross-section A0 is less than 100 mm2 and the length LO of portion 34 is within a predefined range of values, for example the length LO is between 40 mm and 100 mm.

[0052] The sensor 28 is preferably positioned on the foot 26 on the side of an intrados face of the blade 24. It is positioned along a chord direction of the blade 20 at a distance of about 30% of the chord length from the trailing edge of the blade 20.

[0053] The electrical circuit 36 ​​present on the support plate 32 has the function of a switch, which remains closed as long as the support plate 32 is intact, in which case the display device 30 is on, and which is open if the portion 34 of the support plate 32 is broken, in which case the display device 30 is off.

[0054] The display device 30 is placed in an area allowing easy visual control of its condition so that a technician can assess the condition of the blade 20 associated with the display device 30.

[0055] The description just given refers to a blade 20 carrying one or two sensors 28. In a turbomachine 10, several blades 20 carry one or two sensors 28. According to a first embodiment, all the blades 20 of the same stage of the rectifier 18 (or all the blades 16 of the blower 12) carry one or two sensors 28.

[0056] According to a second embodiment, only part of the blades 20 of the same stage of the rectifier 18 (or part of the blades 16 of the blower 12) carry one or two sensors 28. This is particularly the case where, depending on their positioning, some blades 20 are more critical than others.

[0057] According to an alternative embodiment, part of the blades 20 of the same stage of the rectifier 18 carry a sensor 28 associated with a given constraint, for example a compressive constraint, and another part of the blades 20 of this same stage of the rectifier 18 carry a sensor associated with another constraint, that is to say in this example, a tensile constraint.

[0058] Figure 5 shows an example of an electrical assembly 44 of a plurality of sensors 28 and their associated display devices 30.

[0059] According to this embodiment, each sensor 28 is arranged in series with the display device 30 associated with it and with a power source 42.

[0060] Also, the electrical assembly 44 includes several sets of sensors 28 and display devices 30 as defined previously, which are associated with the same power source 42.

[0061] Preferably, the sensor assemblies 28 and display devices 30 are mounted in parallel with each other.

Claims

Demands

1. Sensor (28) for detecting a stress that may damage a component (16, 20) of an aircraft turbomachine (10), characterized in that it comprises a support plate (32) which is fixed on said component (16, 20) and which is capable of breaking when the amplitude of a stress on the component (16, 20) is greater than a predefined value and an electrical circuit (36) which is closed as long as the support plate (32) is not broken and which is open after the support plate (32) breaks.

2. Sensor (28) according to the preceding claim, characterized in that the support plate (32) has a portion (34) with controlled breaking strength, which is intended to break when the component (16, 20) has been subjected to a stress whose amplitude exceeds the predefined value.

3. Sensor (28) according to claim 2, characterized in that the electrical circuit (36) is fixed on the portion (34) with controlled breaking strength.

4. Sensor (28) according to any one of the preceding claims, characterized in that it is associated with a display device (30) which changes state when the support plate (32) is broken.

5. Aircraft turbomachine (10) comprising a sensor (28) according to any one of the preceding claims, a plurality of movable or fixed blades (16, 20) distributed around a main axis (A) of the turbomachine (10), characterized in that at least a portion of the blades (16, 20) carries at least one sensor (28).

6. Turbomachine (10) according to the preceding claim, characterized in that each sensor (28) is associated with a compressive stress on the blade (16, 20) along an axis (B) of the blade (16, 20) or is associated with a tensile stress on the blade (16, 20) along the axis (B).

7. Turbomachine (10) according to claim 5 or 6, in which the blade comprises an aerodynamic part (24) located at a first end along the axis (B) of the blade (16, 20) and a foot part (26) located at the other end of the blade (20) along its axis (B), characterized in that each sensor (28) is mounted on a so-called foot end (26) of the blade (16, 20).

8. Turbomachine (10) according to any one of claims 5 to 7, in combination with claim 4, characterized in that it comprises an electrical assembly (44) consisting of a single power source (42) and several assemblies each comprising at least one sensor (28) and a display device (30) which is associated with said at least one sensor (28) and is mounted in series with said at least one sensor (28) and the power source (42).

9. Turbomachine (10) according to the preceding claim, characterized in that said assemblies each comprising at least one sensor (28) and a display device (30) are mounted in parallel with respect to each other.

10. Turbomachine (10) according to any one of claims 5 to 9, characterized in that each sensor (28) is fixed by bonding the support plate (32) with an epoxy resin to an area of ​​the blade (16, 20) which is liable to be damaged by said stress.