FAILURE DETECTION SYSTEM FOR AN AIR COOLING CIRCUIT IN AN AIRCRAFT TURBOMACHINE COMPONENTS

Abstract

The invention relates to a failure detection system (50) for a cooling air circuit (31) of components (32, 32') of an aircraft turbomachine. The circuit is designed to communicate with a channel (11A) so that pressurized cooling air can escape from the circuit (31) through this channel (11A). The detection system comprises: - a fluid circulation duct (52); - a temperature-sensitive element (54) for closing the duct (52); - a failure detection device (56). The system is configured such that the temperature-sensitive element (54) closes the duct (52) as long as its temperature remains below a reference temperature, and degrades when it reaches or exceeds this reference temperature, allowing the circulation of a by-flow of gas (60) through the duct (52). Figure for the abstract: Fig. 3

Description

Title of the invention: SYSTEM FOR DETECTING FAULTS IN A COOLING AIR CIRCUIT FOR PARTS FROM AN AIRCRAFT TURBOMACHINE technical field

[0001] The present invention relates to the field of air cooling circuits for parts of an aircraft turbomachine, in particular rotating parts.

[0002] It applies to any type of aircraft turbomachine, preferably of the turbojet or turboprop type. Prior art

[0003] Aircraft turbomachinery includes cooling air circuits whose primary function is to cool certain turbomachine components. Typically, cooling air, also known as fresh air, is drawn from a turbomachine compressor or from an external source and then injected towards the sensitive components requiring cooling. In some cases, the cooling air circuit connects to a duct within the turbomachine, allowing pressurized cooling air to escape from the circuit through this duct. This helps to limit or prevent the intake of a portion of the gas flow circulating in the duct towards the cooling air circuit.

[0004] In the event of a failure in the cooling air circuit, leading to degraded operation, the cooling air flow rate may be altered. This results in a decrease in the cooling performance of sensitive parts, as well as a risk of gas ingestion from the cooling stream into the cooling circuit due to the pressure loss in the cooling air flow rate. This ingestion of hot gas from the cooling stream, also known as gas reinjection, further impairs the cooling of sensitive parts.

[0005] It is noted that such a failure of the cooling air circuit can have several causes, such as the rupture of a pipe or its clogging, or any other case of failure of cooling air supply.

[0006] Reduced cooling performance has a thermal impact on the parts being cooled, potentially shortening their lifespan. However, this type of failure in a cooling air circuit is generally undetectable during turbomachine operation. It is therefore a case of a failure or degraded operation known as "dormant," the detection of which generally occurs during operation. only during dismantling of the turbomachine, during maintenance operations on it. However, in this situation, the turbomachine parts must be sized so that they can function without impacting flight safety, and this throughout the entire lifespan of these parts, taking into account that a failure may occur.

[0007] This safety principle has significant impacts on the sizing of the cooling air circuit and / or on the sizing of the parts to be cooled. This results in suboptimal air intake and / or overall mass, negatively impacting the overall performance of the turbomachine. Description of the invention

[0008] To address at least partially the drawbacks mentioned above relating to prior art inventions, the invention first relates to a system for detecting failures in a cooling air circuit for parts of an aircraft turbomachine, the circuit being intended to communicate with a duct of the turbomachine so that pressurized cooling air can escape from the circuit through this duct, in order to limit / prevent the ingestion of part of a gas flow circulating within the duct into the cooling air circuit, the detection system comprising:

[0009] - a fluid circulation duct, connected to the cooling air circuit;

[0010] - a thermosensitive device for closing the fluid circulation conduit;

[0011] - a fault detection device;

[0012] the system being configured so that the thermosensitive element closes the conduit as long as its temperature remains below a reference temperature, and that it degrades when it reaches or exceeds this reference temperature, thus allowing the circulation of a derived gas flow through the circulation conduit, from the cooling circuit to the detection device, the latter being configured so as to be able to emit a fault signal in the presence of the derived gas flow.

[0013] The invention is advantageous in that it provides a system for detecting a fault in the cooling air circuit during the operation of the turbomachine. Indeed, the basic principle of the invention lies in the use of a heat-sensitive shut-off device. It acts as a thermal fuse, which opens the circulation duct to the detection device only in the presence of hot gases, characteristic of a failure or degraded operation of the cooling air circuit.

[0014] The invention therefore represents a technological breakthrough, since this type of failure no longer needs to be categorized as a "dormant" failure, as was the case in the prior art. Performance gains The benefits are significant, as it allows for precise sizing of the cooling airflow and the parts to be cooled. This contributes to improving the overall efficiency of the turbomachine, implying that the invention represents a result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of these aircraft (decarbonization).

[0015] Preferably, the invention also provides for at least one of the following additional optional features, taken individually or in combination.

[0016] Preferably, the detection device is passive in nature, and configured to emit a fault signal when the derived gas flow passes through.

[0017] Preferably, the detection device is configured to emit a visual failure signal, for example a change of color and / or a change of state of a thermosensitive warning element of this detection device, the thermosensitive warning element being preferably intended to be arranged externally with respect to an external housing of the turbomachine.

[0018] According to another possibility, the detection device is active in nature, and configured so as to emit an electrical fault signal when it detects the presence of the derived gas flow, or when it detects a physical characteristic of this derived gas flow, of a value lower or higher than a reference value.

[0019] Preferably, the detection device comprises at least one of the following elements:

[0020] - a flow sensor;

[0021] - a temperature sensor, for example of the thermocouple type;

[0022] - a pressure sensor.

[0023] Preferably, the detection system is configured so as to deliver the electrical fault signal to a piece of equipment of the turbomachine, and / or to equipment of an aircraft equipped with this turbomachine.

[0024] Preferably, the fluid circulation conduit includes a threaded portion, and the thermosensitive element includes a threaded body screwed onto the threaded portion of the circulation conduit, the threaded body including a through passage filled with a thermosensitive material.

[0025] The invention also relates to an aircraft turbomachine comprising an air cooling circuit for parts of the turbomachine, as well as a system for detecting failure of this circuit, as described above.

[0026] Preferably, the cooling air circuit includes at least one cooling air cavity delimited in part by a turbine wheel disc, corresponding to one of the parts to be cooled.

[0027] Preferably, at least part of the fluid circulation conduit passes through a fixed arm of an inter-turbine housing.

[0028] Finally, the invention relates to a method for detecting failure of a cooling air circuit of parts of an aircraft turbomachine, using a system as described above, the method comprising monitoring the detection device.

[0029] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Brief description of the drawings

[0030] The detailed description that follows refers to the attached drawings on which:

[0031] [Fig.1] is a schematic axial cross-sectional view of a turbojet engine according to the invention;

[0032] [Fig.2] is a half-axial cross-sectional view of a part of the turbomachine shown in the preceding figure, comprising a system for detecting failure of a cooling air circuit, according to a first preferred embodiment of the invention and in a configuration of absence of failure of this circuit;

[0033] [Fig.3] is a view similar to that of the previous figure, in a configuration of failure of the cooling air circuit;

[0034] [Fig.4] is a schematic view representing an example of an embodiment of an organ heat-sensitive shut-off valve, belonging to the cooling air circuit shown in the preceding figures; and

[0035] [Fig.5] is a schematic view representing part of the detection system failure, according to a second preferred embodiment of the invention. Detailed description of implementation methods

[0036] The figures include a reference frame L, R and C defining respectively longitudinal, radial and circumferential directions orthogonal to each other, these directions corresponding to those of an aircraft turbojet 1 according to the invention.

[0037] [Fig. 1] represents the aircraft turbojet 1, preferably having a twin-spool, twin-flow design. However, other types of turbojets are possible, as are turbomachines other than turbojets.

[0038] Hereafter, the terms "upstream" and "downstream" are defined with respect to a principal direction DI of gas flow through the turbojet 1 when it is operating in direct thrust mode. The direction DI is parallel to the longitudinal direction L, and also parallel to a longitudinal axis Al of the turbojet, around which its various components extend. In this case, from upstream to downstream of the turbojet 1, these components are a fan 4 and a low-pressure compressor. 5, a high-pressure compressor 6, a combustion chamber 7, a high-pressure turbine 8 and a low-pressure turbine 9.

[0039] During the operation of the turbojet 1, an airflow 10 enters the turbojet 1 through an air inlet 3, passes through the fan 4, and then splits into a central primary flow 10A and a secondary flow 10B. The primary flow 10A flows in a main gas circulation channel 11A passing through the compressors 5 and 6, the combustion chamber 7, and the turbines 8 and 9. The secondary flow 10B, on the other hand, flows in a secondary channel 11B surrounding the main channel 11A, also called the primary channel, or aerodynamic flow channel.

[0040] Fig. 2 represents a part of the turbojet 1, shown in the previous figure. In particular, it represents the high-pressure turbine 8, as well as part of the low-pressure turbine 9. In this first preferred embodiment, the high-pressure turbine preferably comprises a single stage 12. In a manner known per se, this stage 12 comprises a stator assembly 12A including a distributor 30, also called a bladed stator ring, and a moving wheel 12B, arranged directly downstream of the assembly 12A.

[0041] The impeller 12B is mounted on a high-pressure shaft 15 of the turbomachine, centered on the axis AL. The impeller 12B comprises movable blades 14, forming a bladed rotor ring configured to be traversed by the primary flow 10A, in order to drive this impeller in rotation about the axis AL.

[0042] Similarly, the low-pressure turbine 9 comprises one or more stages 12', only the first stage being visible in [Fig. 2]. This stage 12' also includes a stator assembly 12A' comprising a distributor 30', and a runner 12B', arranged directly downstream of the assembly 12A'.

[0043] The impeller 12B' is mounted on a low-pressure shaft 17 of the turbomachine, centered on the axis Al and surrounded by the high-pressure shaft 15. The impeller 12B' comprises movable blades 14', forming a bladed rotor ring configured to be traversed by the primary flow 10A, in order to drive this impeller in rotation about the axis AL

[0044] In a manner known and represented very schematically on [Fig.2], the shafts 15 and 17 cooperate with bearing supports 19, supported by support members 21 connected to stator parts of the turbojet.

[0045] Between the rotating wheel 12B of the high-pressure turbine 8 and the stator assembly 12A' of the first stage 12' of the low-pressure turbine 9, an inter-turbine housing 20 is provided. This housing may be multi-component and includes, in particular, fixed arms 22 extending radially through the flow 1IA. This inter-turbine housing 20 extends radially outwards beyond the primary flow 1IA, being connected to an external housing 24 of the turbomachine, enveloping, in particular, the turbines 8 and 9.

[0046] The turbojet 1 here includes a cooling air circuit 31, intended to cool several parts of this turbomachine, in particular the discs 32, 32' of the turbine wheels 12B, 12B'. In this respect, the cooling air circuit 31 includes one or more air supply lines, schematically represented by arrow 34 in [Fig. 2]. This line 34 is, for example, connected upstream to one of the compressors, so that air drawn from this compressor can serve as cooling air, also called ventilation air or fresh air, in comparison to the much higher temperature of the gas flow circulating in the primary duct 11A, through the turbines 8, 9. It should be noted that the line 34 can be connected to other conventional fresh air sources without departing from the scope of the invention.

[0047] This conduit 34, passing for example through the shafts 15, 17, can open directly downstream of the disc 32 of the rotating wheel 12B, so that the cooling air propagates radially outwards, into an upstream cooling air cavity 40, belonging to the circuit 31. This cavity 40 is thus delimited upstream by the disc 32, and downstream by one or more of the support members 21.

[0048] Due to the high pressure of the cooling airflow circulating in cavity 40, this air escapes from circuit 31 through an axially defined gap 42 between a radially internal platform 43 of the bladed ring of the rotating wheel 12B and a radially internal stator wall 44 delimiting the primary flow 11A. Thus, the pressurized cooling air enters the flow 1IA through the annular gap 42 establishing the fluidic communication between circuit 31 and flow 1IA. This prevents / limits the ingestion of a portion of the primary flow 10A into the cooling air circuit 31 and allows the latter's performance to be maintained.

[0049] Part of the cooling air located in the cavity 40 can also flow downstream, towards one or more other cooling cavities of the circuit 31, and in particular towards a downstream cooling air cavity 40' delimited downstream by the disc 32' of the movable wheel 12B', and upstream by one or more of the support members 21.

[0050] Due to the high pressure of the cooling airflow circulating in cavity 40', this air escapes from circuit 31 through an axially defined gap 42' between a radially internal platform 43' of the bladed ring of the rotating wheel 12B' and the radially internal stator wall 44 delimiting the primary flow 1IA. Thus, the pressurized cooling air enters the flow 11A through the annular gap 42', establishing another fluidic communication between circuit 31 and flow 1IA. This also prevents / limits the ingestion of a portion of the primary flow 10A into the cooling air circuit 31.

[0051] These cooling air flows in the circuit 31, schematically represented by the arrows 46 of [Fig.2], allow the cooling of the disks 32, 32', as well as the cooling of other parts such as the platforms 43, 43' of the movable bladed rings.

[0052] One of the features of the invention lies in the implementation of a system 50 for detecting failures in the circuit 31, leading to a loss of cooling performance of the thermally sensitive parts 32, 32', etc. Such a failure could, for example, take the form of a rupture or blockage in a pipe of the circuit 31, or any other case of failure in the supply of cooling air. In other words, the aim is to detect any failure in the circuit 31, up to its connection with the compressor from which the cooling air is drawn, which would result in an excessively restricted flow of fresh air within one or more of the cavities 40, 40' of this circuit, or other parts (not shown) thereof.

[0053] To this end, the detection system 50 includes a fluid circulation conduit 52, connected to the circuit 31 such that one end of this conduit 52 opens into one of the cavities 40, 40'. In the first preferred embodiment of [Fig. 2], the end of the conduit 52 opens into the upstream cooling cavity 40, for example near the gap 42. This conduit then extends downstream and then passes radially outwards through the inter-turbine casing 20. More precisely, the conduit 52 can travel radially through one of the fixed arms 22 of the inter-turbine casing internally, and thus through the primary channel 11 A.

[0054] The fluid circulation conduit 52 then extends to the outer casing 24, preferably by passing through this casing 24 in order to open outwards to it, in the radial direction R.

[0055] The detection system 50 further includes a thermosensitive element 54 for closing the conduit 52, this element 54 being preferably arranged in the conduit, on the end opening into the cooling cavity 40, or near this end as shown schematically in [Fig.2].

[0056] Finally, the system 50 includes a fault detection device 56, here preferably arranged on the opposite end of the conduit 52, being arranged at least partly radially outwards relative to the outer casing 24.

[0057] The principle implemented is such that the thermosensitive element 54 closes the conduit 52 as long as its temperature remains below a reference temperature, corresponding for example to an acceptable temperature limit in terms of impact on the lifespan of the parts to be cooled. In this configuration due to the sealing, no gas flow circulates through the conduit 52, towards the detection device 56.

[0058] However, when the temperature of the thermosensitive element 54 reaches or exceeds the reference temperature, it degrades, thereby allowing the circulation of a derived gas flow through the conduit 52, from the cavity 40 to the detection device 56. Moreover, as will be explained below, this detection device 56 is configured so as to be able to emit a fault signal, in the presence of the derived gas flow.

[0059] This failure configuration is schematically represented in [Fig. 3], in which the thermally sensitive element 54, shaped like a thermal fuse, is shown schematically in a degraded state. When the circuit 31 is no longer able to provide the required cooling air flow rates, as shown schematically by the crossed-out arrow 34 in [Fig. 3], a gas reinjection phenomenon occurs in cavity 40, and / or in cavity 40'. In other words, part of the primary flow 10A enters these cavities 40, 40', through the gaps 42, 42', due to the pressure drop of the cooling air in the circuit 31. The introduction of this hot flow, shown schematically by the arrows 146 on the [Fig.3], increases the temperature of the parts to be cooled, and therefore also increases the temperature of the thermal fuse element 54 which degrades, like a fuse.After the melting of organ 54, a derivative flow 60, originating from the heated gases located in cavity 40, can indeed penetrate and circulate through conduit 52, up to the detection device 56.

[0060] According to an embodiment shown in [Fig. 4], the fluid circulation conduit 52 comprises a threaded portion 62, preferably corresponding to its end opening into the cooling air cavity 40 of the circuit 32. The heat-sensitive element 54 comprises a threaded body 64, screwed onto the threaded portion 62 of the conduit 52. The threaded body 64 includes a through passage 66, filled with a heat-sensitive material 68, forming the fusible element. Furthermore, it is noted that the body 64 can be screwed onto the end of the conduit 52 in a self-locking manner.

[0061] The heat-sensitive material 68, also called a hot-melt material, is preferably shrink-fitted inside the through-hole 66. It may be a low-melting-point alloy, for example, a bismuth-based non-ferrous alloy. The choice of material depends on the desired reference temperature, corresponding to the melting temperature. Ideally, as mentioned above, the melting temperature of the material 68 can be determined in such a way as to detect a temperature threshold above which the impact on the service life of the parts to be cooled becomes significant. This reference temperature is therefore preferably between 230°C and 900°C.

[0062] In this first preferred embodiment of the invention, the detection device 56 is passive in nature, and configured so as to emit a failure signal following the simple passage of the derived gas flow 60, over or through this device 56, depending on the design of the latter.

[0063] Indeed, the passive detection device 56 is preferably configured to emit a visual fault signal, for example a change of color and / or a change of state, from a heat-sensitive warning element 70 that is an integral part of this detection device 50. The warning element 70 can, for example, take the form of an element coated with heat-sensitive paint, which, upon contact with the derived hot gas flow 60, can change its state and / or color. This heat-sensitive warning element 70 is preferably arranged externally with respect to the outer casing 24, so that its change of state / color is easily visible to an operator during a simple visual inspection of the exterior of the turbojet engine 1. Advantageously, this is therefore no longer a case of a "dormant" fault, the detection of which generally occurs late, namely only during dismantling of the turbojet engine during its maintenance.

[0064] According to a second preferred embodiment of the invention, shown schematically in [Fig. 5], the detection device 56 is active. More specifically, it is configured to emit an electrical fault signal 72 when it detects the presence of the by-flow of gas 60 circulating through the conduit 52. Indeed, the mere presence of a flow circulating through this conduit 52 indicates degradation upstream of the fusible sealing element 54, and therefore the occurrence of a failure. Alternatively, the detection device 56 can be configured to emit an electrical fault signal 72 when it detects a physical characteristic of this by-flow of gas 60 with a value lower or higher than a reference value.In this case, this reference value can be set to correspond to a threshold indicating a gas temperature deemed sufficiently problematic within circuit 31 to trigger an alarm signal. This reference value, for the probed physical characteristic, can coincide with the reference temperature that leads to the melting of the sealing element 54. However, according to another possibility, the detection device can be stipulated to emit a signal only following a further temperature increase after the melting of the sealing element.

[0065] For the detection of the mere presence or of a given characteristic value of the derived gas flow 60, the detection device 56 may include a sensor 74 inserted inside the conduit 52. This sensor may be of the type flow sensor, temperature sensor such as a thermocouple, or pressure sensor.

[0066] The detection device 56 also includes means 76 for processing the information delivered by the sensor 74, and for generating the electrical fault signal 72. This can be delivered to equipment 78 of the turbojet, and / or to equipment of an aircraft equipped with this turbojet, for example equipment located in the cockpit of this aircraft.

[0067] Thus, whether the design of the detection device 56 is passive or active, the invention allows the implementation of a method for detecting failure of the cooling air circuit 31, using the system 50 described above, simply by operating a monitoring of the device 56 configured to emit a failure signal.

[0068] Of course, various modifications can be made by a person skilled in the art to the invention just described by way of non-limiting examples, and within the scope of the appended claims. For example, the technical characteristics of the different preferred embodiments are combinable and / or interchangeable.

Claims

Demands

1. A failure detection system (50) for a cooling air circuit (31) of parts (32, 32') of an aircraft turbomachine, the circuit being intended to communicate with a channel (1 IA) of the turbomachine so that pressurized cooling air can escape from the circuit (31) through this channel (1 IA), in order to limit / avoid the ingestion of a portion of a gas flow (10A) circulating within the channel into the cooling air circuit (31), the detection system being characterized in that it comprises: - a fluid circulation duct (52), connected to the cooling air circuit (31); - a temperature-sensitive element (54) for closing the fluid circulation duct (52); - a failure detection device (56);the system being configured so that the thermosensitive element (54) closes the conduit (52) as long as its temperature remains below a reference temperature, and degrades when it reaches or exceeds this reference temperature, thus allowing the circulation of a derived gas flow (60) through the circulation conduit (52), from the cooling circuit (31) to the detection device (56), the latter being configured so as to be able to emit a fault signal in the presence of the derived gas flow (60).

2. Detection system according to claim 1, characterized in that the detection device (56) is passive in nature, and configured to emit a failure signal on the passage of the derived gas flow (60).

3. A detection system according to claim 2, characterized in that the detection device (56) is configured to emit a visual failure signal, for example a change of color and / or a change of state of a thermosensitive warning element (70) of this detection device, the thermosensitive warning element (70) being preferably intended to be arranged externally with respect to an external housing (24) of the turbomachine.

4. A detection system according to claim 1, characterized in that the detection device (56) is active in nature, and configured to in order to emit an electrical fault signal (72) when it detects the presence of the derived gas flow (60), or when it detects a physical characteristic of this derived gas flow (60), of a value lower or higher than a reference value.

5. A detection system according to claim 4, characterized in that the detection device comprises at least one of the following elements (74): - a flow sensor; - a temperature sensor, for example of the thermocouple type; - a pressure sensor.

6. A detection system according to claim 4 or 5, characterized in that it is configured to deliver the electrical fault signal (72) to equipment (78) of the turbomachine, and / or to equipment of an aircraft equipped with this turbomachine.

7. A detection system according to any one of the preceding claims, characterized in that the fluidic circulation conduit (52) comprises a threaded portion (62), and in that the thermosensitive element (54) comprises a threaded body (64) screwed onto the threaded portion of the circulation conduit (52), the threaded body comprising a through passage (66) filled with a thermosensitive material (68).

8. Aircraft turbomachine (1) comprising a cooling air circuit (31) for parts (32, 32') of the turbomachine, and a system for detecting failure of this circuit (31), according to any one of the preceding claims.

9. Turbomachine according to claim 8, characterized in that the cooling air circuit (31) comprises at least one cooling air cavity (40, 40') delimited in part by a disc (32, 32') of turbine wheel (12B, 12B'), corresponding to one of the parts to be cooled.

10. Turbomachine according to claim 8 or 9, characterized in that at least a part of the fluidic circulation conduit (52) passes through a fixed arm (22) of an inter-turbine casing (20).

11. Method for detecting failure of a cooling air circuit (31) of parts (32, 32') of an aircraft turbomachine, using a system (50) according to any one of claims 1 to 7, comprising monitoring the detection device (56).