Improved device for detecting cooling anomalies of aircraft turbine engines

Abstract

The present invention relates to a rotor for an aircraft turbine engine, comprising at least one moving wheel disc (63) supporting moving blades (64), the moving wheel disc (64) comprising a plurality of units (632), the roots (642) of the moving blades (64) being inserted into these units, a passage (P) being formed between the bottom of the unit and the roots (642) of the moving blades (63) inserted into the units (632), the rotor further comprising: a circulation channel configured to allow fluid circulation, the circulation channel comprising the passage (P); and a calibration device, the calibration device being configured to allow flow in the circulation channel at a first fluid flow rate when the temperature in the channel is below a predetermined temperature threshold, and to change state to allow flow in the channel at a second fluid flow rate greater than the first fluid flow rate when the temperature in the channel is higher than or equal to the predetermined threshold.

Description

Technical Field

[0001] The present invention relates to the field of turbine engines. More precisely, the present invention relates to detecting cooling anomalies of a turbine in an aircraft turbine engine. Background Art

[0002] In a turbine engine, air is usually discharged from a compressor located upstream, such as a high-pressure compressor, to cool the parts in the downstream stage with a warmer environment. The upstream and downstream extend according to the flow direction of the air in the turbine engine. The cooling air discharged from the high-pressure compressor is, for example, delivered to the low-pressure turbine or the high-pressure turbine of the turbine engine. The delivered air ensures a purge flow rate, allowing the hot air to be purged and certain parts of these turbines (such as wheels, moving blades) to be ventilated. The purge flow rate of this hot air limits the introduction of hot air flowing in the main vein and driving the rotation of the rotor blades in the area below the main vein. In this way, the risk of overheating of the movable parts of the turbine is limited, which risk may lead to degradation of the turbine and, in the worst case, to the rupture of these parts.

[0003] Additionally, it is common for cooling units to be oversized to ensure they meet aviation standards.

[0004] For example, a device can be made that includes several channels for exhausting air on the high-pressure compressor, which also ensure that the sampled air circulates towards the low-pressure turbine or towards the high-pressure turbine to cool it. These channels thus form a cooling device for these turbines. Oversizing of the cooling device can include creating channels whose diameter is larger than the required diameter, which channels convey more air than is required to cool the low-pressure turbine or the high-pressure turbine, or even increasing the number of channels. Advantageously, in the event of a malfunction, such as in the event of a partial obstruction, partial drilling or rupture of a channel, this oversizing ensures that the device continues to deliver sufficient cooling air to the low-pressure turbine or the high-pressure turbine. Another example of a malfunction that can be caused by a decrease in turbine tightness is, for example, due to wear of the labyrinth joints of the low-pressure turbine or the high-pressure turbine, which causes the cooling air to escape, thereby causing a reduction in the purge flow rate of the hot air.

[0005] Although reliable, the oversizing of the above cooling devices leads to the discharge of more air than is actually needed on the high-pressure compressor in nominal operating conditions of the turbine engine, for example in the absence of air circulation channel failures, i.e., in the absence of such failures. This over-sampling of air has a significant impact on the specific fuel consumption (SFC) of the aircraft and leads to a reduction in engine performance. Devices for detecting failures do exist, but they usually require external intervention, increasing the risk of degradation of parts and the engine.

[0006] It is therefore desirable to improve the performance of turbine engines and in particular to limit the impact of the cooling system on the aircraft's fuel consumption and to limit the risks of overheating of the movable parts of the turbine and of turbine degradation. Summary of the invention

[0007] In order to at least partially solve the above-mentioned drawbacks, the present disclosure relates to a turbine rotor for an aircraft turbine engine, comprising:

[0008] at least one moving wheel disc supporting the moving blades, the moving wheel disc comprising a plurality of grooves into which the roots of the moving blades are inserted, forming passages between the bottoms of the grooves and the roots of the moving blades inserted into said grooves,

[0009] - a circulation channel configured to allow the circulation of a fluid, the circulation channel comprising said passage,

[0010] - a calibration device configured to allow flow at a first fluid flow rate in the circulation channel when the temperature in the circulation channel is below a predetermined temperature threshold, and to change state to allow flow at a second fluid flow rate in the circulation channel that is greater than the first flow rate when the temperature in the circulation channel is greater than or equal to the predetermined temperature threshold.

[0011] Throughout the disclosure, nominal operation of an engine or turbine rotor means that there are no faults in the cooling circuit of the turbine in operation. It should be understood that this nominal operation may include wear of the turbine engine, but does not include fault conditions such as rupture of the air supply passage.

[0012] In nominal operation, part of the purge flow rate moves to the circulation channel, in particular to the passage existing between the bottom of the slot and the root of the moving blade inserted into said slot. The passage may be the gap existing between the bottom of the slot and the root inserted into said slot. Thus, the first fluid flow rate corresponds to a cooling air flow circulating in the circulation channel, in particular in said passage, in nominal operating conditions. These conditions are characterized in that the temperature in the circulation channel remains below a threshold value.

[0013] Exceeding this temperature threshold is characteristic of insufficient cooling air flow, i.e. a drop in the purge flow rate caused by an anomaly occurring in the cooling circuit of the turbine engine. The cooling circuit of a turbine engine means the circuit followed by the cooling air sampled from the compressor area to the circulation channel passing through the rotor. Thus, defective elements of the cooling circuit of a turbine engine may be elements of the air sampling area on the compressor, one of the channels that deliver air from the compressor to the turbine, the air distribution box, the purge passage between the moving blades and the stationary parts and the dynamic joints between the moving and stationary parts of the turbine.

[0014] The occurrence of an abnormal condition leads to a decrease in the purge flow rate and thus an increase in the introduction of hot air from the main pulse duct. By entering the circulation channel, this hot air increases the temperature in the circulation channel. Exceeding the temperature threshold leads to a change in the state of the calibration device, resulting in an increase in the fluid flow, in this case actually an increase in the flow of hot air from the main pulse duct and flowing in the circulation channel, in particular in the channel between the bottom of the slot and the root of the blade. The change in the state of the calibration device may include degradation, fusion, creep or detachment of the calibration device.

[0015] The increase in flow rate between the first flow rate and the second flow rate causes an increase in temperature in the passage below the blade root, resulting in degradation of the blade root. Since the root is no longer able to fulfil its function of holding the moving blade, the moving blade is detached from its mounting and released in the main duct. As is known, when a blade is released or detached, a safety device called IFSD (“InFlight Shut Down”) immediately creates a dynamic imbalance, triggering an alarm in the cockpit, prompting the user to shut down the engine immediately. The calibrated device ensures the release of at least one blade, so that the engine stops at the initial impact of the failure and before the moving disc deteriorates due to the reintroduction of hot gases from the main duct.

[0016] It is thus possible to stop the engine by means of the blade detachment, thereby detecting the presence of a malfunction or failure, without requiring permanent overdimensioning of the cooling device. It is also possible to provide a device allowing automatic stopping of the engine in the event of blade detachment. This detection can be achieved without requiring external intervention by an operator.

[0017] Therefore, the influence of the cooling system on fuel consumption is limited, thereby effectively improving engine performance. In addition, the configuration detects the presence of abnormality without adding additional sensors, such as temperature sensors.

[0018] In some embodiments, the calibration device comprises at least a portion of a root of at least one moving blade of the moving disk.

[0019] The calibration device is therefore closest to the air flowing in the passage under the blade root. In this way, when an anomaly occurs that leads to an increased introduction of hot air from the main duct, the detachment of the blade occurs more quickly, allowing the anomaly to be detected more effectively. This in particular limits the risk of degradation of the disc due to this anomaly and the resulting temperature increase.

[0020] In some embodiments, the portion of the blade root is configured to convert from a first state, in which, when the temperature in the circulation channel is lower than a predetermined threshold, it has a first geometric structure to a second state, in which, when the temperature in the circulation channel is higher than or equal to the predetermined threshold, it has a second geometric structure different from the first geometric structure, and increases the cross-section of the passage between the bottom of the groove and the root of the moving blade so that it has the first state.

[0021] The first state corresponds to the so-called usual shape of the blade root, for example, i.e. the shape that the blade root would have when mounted on a rotor that does not include calibration devices. The second state corresponds to a deformation caused by creep of the component, or to a partial or complete detachment of the component again. In other words, the second geometry is in the form of a bypass cross section that is greater than the initial bypass cross section when the portion of the blade root assumes the first geometry. This change in geometry is therefore equivalent to an increase in the gap present between the root of the blade and the bottom of the slot. This transition from the first state to the second state, caused by exceeding a threshold temperature value, allows an increase in the hot air flow rate in the passage below the blade root. The resulting temperature increase leads to a degradation of the blade root, which the change in state of the portion of the blade root has also made brittle, and thus to detachment of the blade.

[0022] In some embodiments, the portion of the blade root includes a fusible material configured to at least partially melt when a temperature within the circulation passage reaches a predetermined threshold.

[0023] In other words, the predetermined threshold value corresponds to the melting temperature of the portion of the blade root comprising the fusible material. Therefore, the material of this portion of the blade root must preferably be selected so that its melting temperature is below the critical temperature at which a turbine element such as a disk deteriorates. Thus, in the case of partial melting, resulting in creep or complete melting of this portion of the blade root, said portion of the blade root is converted from a first state having a first geometry to a second state having a second geometry, resulting in an increase in the hot air flow rate, which in turn leads to the detachment of the blade.

[0024] In some embodiments, the rotor includes an annular wall extending axially between two movable wheel discs of the rotor, the annular wall including a plurality of circulation holes, the circulation channel including the plurality of holes, and the calibration device including at least one fusible washer fixed on at least one circulation hole among the plurality of holes.

[0025] Preferably, each circulation hole of the annular wall is positioned opposite the root of the moving blade so that the air flowing in the passage below the root of the blade then passes through the hole, the circulation channel comprising the passage and the hole in this way. The air moving through each of these holes provides cooling air in particular to the area located above the annular wall and below the stator blade.

[0026] Furthermore, the calibration device may include a fusible washer, either instead of the fusible part of the blade root or in addition thereto. According to the same mechanism as the above, the temperature of the air flowing in the circulation channel, in particular in the passage under the blade root, increases, and then passes through the hole to which the fusible washer is fixed, resulting in a change in the state of this washer, in particular an increase in the diameter of the hole to which the washer is fixed. The increase in diameter leads, in abnormal cases, to an increase in the velocity of the hot air flow, which leads to the detachment of the blade.

[0027] In some embodiments, the fusible gasket is configured to transition from a first state to a second state, in which, when the temperature in the circulation channel is below a predetermined threshold, it has a first geometric structure that limits the diameter of the circulation hole to which it is fixed, and in the second state, when the temperature in the circulation channel is higher than or equal to the predetermined threshold, it has a second geometric structure different from the first geometric structure and causes the diameter of the hole to increase.

[0028] In a first state, the fusible gasket may have a shape that allows the diameter of the hole to which it is fixed to be the same as the diameter of the other holes of the annular wall including the one without the fusible gasket. The second state corresponds to a form in which the diameter of the hole is enlarged.

[0029] In some embodiments, the fusible gasket includes a fusible material configured to at least partially melt when a temperature within the circulation channel reaches a predetermined threshold.

[0030] The fusible material of the fusible washer may be different from the material of the fusible portion of the blade root and exhibit a different melting temperature range.

[0031] In some embodiments, the rotor comprises a plurality of moving disks, and the calibration device is positioned on an upstream moving disk among the plurality of moving disks, the upstream moving disk being positioned upstream of the plurality of moving disks according to a flow direction of hot air along a rotation axis of the rotor.

[0032] Since the upstream disk is the first stage of the disk exposed to hot air in the event of a hot air purge failure, positioning the calibration device on this upstream disk allows the device to change state more quickly in the event of a temperature increase caused by an anomaly, and then improves the efficiency of detecting such anomaly by releasing at least one blade.

[0033] In some embodiments, the threshold temperature value is between 700 and 850°C.

[0034] In some embodiments, a first threshold temperature value corresponding to a melting temperature of the fusible portion of the blade root is between 700 and 780°C, and a second threshold temperature value corresponding to a melting temperature of the fusible washer is between 800 and 850°C.

[0035] This temperature threshold is preferably lower than the critical temperature from which elements of the turbine, such as the blade roots, deteriorate. Thus, when the threshold temperature value in the circulation channel is reached, the change of state of the calibration device and the release of the associated blades allow the engine to stop before the disk carrying the blades deteriorates.

[0036] The present disclosure also relates to a turbine for an aircraft turbine engine, comprising an annular pulse duct for a hot air flow and a rotor according to any of the preceding embodiments.

[0037] The hot air flowing in the annular pulse duct is air coming from engine combustion of the turbine engine and driving the turbine rotor blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention and its advantages will be more clearly understood from the following detailed description of different embodiments of the invention given by way of non-limiting examples, said description referring to the accompanying drawings on the pages in which:

[0039] [ Figure 1 ] Figure 1 is a longitudinal section of a turbine engine equipped with an injection device;

[0040] [ Figure 2 ] Figure 2 A longitudinal partial cross-sectional view of a low-pressure turbine in a turbine engine according to the present disclosure is shown;

[0041] [ FIG. 3A to FIG. 3B ] Figure 3A shows a view of a moving blade root of a turbine without a calibration device according to the present disclosure in a cross-sectional plane perpendicular to the longitudinal direction, while Figure 3B shows a view of a moving blade root of a turbine with a calibration device according to the disclosure in a cross-sectional plane perpendicular to the longitudinal direction;

[0042] [ Figure 4 ] Figure 4 Shows Figure 2 Detailed view of the upstream stage of the low-pressure turbine;

[0043] [ Figure 5 ] Figure 5 Shows Figure 4 Plan view of the annular wall of the upstream stage according to direction V. DETAILED DESCRIPTION

[0044] In the following, relative to the direction of airflow through the turbine engine (eg Figure 1 The terms "upstream" and "downstream" are defined as shown by arrow F in FIG.

[0045] Figure 1 A dual-flow turbine engine 100 is shown which, as is known, comprises, from upstream to downstream, in sequence at least one fan 10 and engine components which in sequence include at least one low-pressure compressor stage 20 , a high-pressure compressor stage 30 , a combustion chamber 40 , at least one high-pressure turbine stage 50 and a low-pressure turbine stage 60 .

[0046] A rotor rotating about the main axis X of the turbine engine 100 and capable of being coupled together by means of different transmissions and gear systems corresponds to these different elements.

[0047] As is known, a portion of the air is sampled at the high pressure compressor 30 and routed via one or more cooling ducts 32 to cool warmer areas of the turbine engine 100 , particularly the high pressure turbine 50 and the low pressure turbine 60 .

[0048] Figure 2 1 is an enlargement of a region of turbine engine 100, showing in simplified manner the upstream components of low-pressure turbine 60. Although the remainder of this description refers to low-pressure turbine 60, for simplicity purposes, this example is not limited thereto, and the invention is also applicable to high-pressure turbine 50.

[0049] The low-pressure turbine 60 shown here comprises a plurality of turbine stages 61, 62. The first stage 61 and the stage 62 located downstream of the first stage respectively comprise sets of fixed distributors 70 and 65. Each stage 61, 62 also comprises a mobile disk 63 on which a set of blades 64 are mounted, the set of blades 64 being fixed in a number of slots located at the edge of the disk 63, the blades 64 being driven in rotation by the mobile disk 63. The mobile disks 63 are axially fixed to each other along the main axis X to form different stages 61, 62 of the turbine 60.

[0050] The first stage 61 of the low-pressure turbine 60 comprises at least one upstream mobile disk 63a and at least one hollow distributor 70 in which the cooling air circulates. Figure 2 In the example shown, the distributor 70 is hollow to allow the cooling air to pass through and to leave by means of injection means 80 associated with the distributor 70, which comprises a plurality of ejectors 81. The subsequent stages 62 situated downstream of the first stage 61 of the low-pressure turbine 60 each comprise at least one mobile blade 64 and a distributor 65 or stator in the form of stationary blades. The mobile disk 63 rotates firmly with the low-pressure shaft extending according to the axis X, while each stator 65 is connected to the casing 66 of the turbine.

[0051] The turbine engine includes a cooling device for delivering the portion of air sampled on the high-pressure compressor 30 to at least one stage of the low-pressure turbine 60 via a cooling duct 32. In the embodiment described below, the portion of cooling air sampled is distributed in the region of a downstream stage (not shown) of the high-pressure turbine 50 and an upstream stage of the low-pressure turbine 60. In this way, the high-pressure turbine 50 and the low-pressure turbine 60 are cooled. However, the present invention is not limited to this embodiment, and the portion of sampled air can also be distributed to other turbine stages.

[0052] exist Figure 2 In the embodiment shown, the part of the air exhausted from the high-pressure compressor 30 flows into the cooling duct 32 and then flows into the hollow distributor 70. The direction in which the part of the air circulates through the hollow distributor 70 is shown by the arrow 71. Then, the part of the air is injected into the cavity below the pulse tube 68 via the ejector 81. As shown by the arrow 75, the distributed air particularly cools the wheel disk 63 of the turbine.

[0053] The injection device 80 includes a plurality of injectors 81 distributed on the wall of the distributor 70 around the axis X. In order to simplify the description of this embodiment, Figure 2 A single ejector 81 is shown in FIG. The ejector 81 is a hole formed in the wall of the distributor 70 for continuously, i.e. continuously, ejecting a flow of cooling air into the cavity below the pulse tube 68 when the turbine engine is running. This flow rate ensures that the temperature of the low-pressure turbine 60 remains in its nominal operating conditions, i.e. in the absence of one of the above-mentioned faults. The size of the hole is determined so that the flow rate is, for example, between 270 g / s and 310 g / s.

[0054] More precisely, the cooling air injected via the ejector 81 allows to purge the hot air present in the low-pressure turbine 60, thus ensuring its cooling. The cooling air discharged in the high-pressure compressor 30 and conveyed far into the cavity below the pulse duct 68 constitutes a pressure barrier or purge, thus preventing the hot air coming from the combustion chamber and flowing in the main air circulation pulse duct of the turbine engine 100 from entering the cavity below the pulse duct 68 in the space between the turbine rotor and the turbine stator. The main pulse duct refers to the main air circulation pulse of the turbine, which is formed by Figure 2 The purging of hot air from the low-pressure turbine 60 is indicated here in particular by arrow 76. Thus, the risk of overheating the turbine rotor is limited. Specifically, by preventing the air of the main pulse duct from returning to the cavity below the pulse duct 68, which has a lower temperature than the pulse duct, the turbine rotor can resist higher centrifugal forces and be sized under lower constraints.

[0055] Figure 3AA detailed view of a section perpendicular to the axis X is schematically shown, i.e. a front view of the radially outer end of the disk 63, in particular of the slot 632 formed between two teeth 631 of the disk 63. The blades 64 each comprise a root 642 separated from the rest of the blade by a platform 641 and having a shape complementary to the slot 632, into which the root can be inserted. The air also circulates in a passage P formed between the root 642 of the blade 64 and the bottom of the slot 632 into which the root 642 is inserted. The passage P is on the cooling air channel. This circulation passage comprises the passage P, in which the airflow indicated by the arrow 77 circulates, cooling these severely restricted areas of the blade root.

[0056] Figure 4 A detailed side view of two mobile disks 63 of a low-pressure turbine 60 is schematically shown, i.e. perpendicularly to the axis X. The disks 63 of the rotor are fixed to each other by bolting of annular flanges 633 extending axially from each disk 63 in the direction of each other. A substantially cylindrical and annular wall 101 also extends between two adjacent disks 63. The wall 101 is formed at the radially outer ends of a radial wall 100 which is interposed between two annular flanges 633 and fixed by means of fastening bolts 640 of the annular flanges 633. This annular wall 101 carries in particular tabs (not shown) which come into contact with the wear-resistant layer carried by the stator 65.

[0057] The wall 101 comprises a plurality of holes 102. The circulation channel also comprises these holes 102, through which the cooling air flow 77 can flow in the case of nominal operation, and through which hot air can flow in abnormal conditions. These holes 102 are particularly calibrated for the cooling air flow through the passage P, in particular by having a bypass section smaller than the passage P. In particular, the holes 102 can be positioned opposite each root 642 of the blade 64. During nominal operation, the cooling air circulation channel comprising the passage P and the holes 102 also limits the reintroduction of hot gases from the main duct of the hot air flow in the region R between the wall 101 and the platform (not shown) supporting the fixed blades of the stator 65.

[0058] There may be several reasons for a turbine cooling failure. One reason for a cooling failure may be a failure of the ducts 32, such as a rupture or an unexpected blockage of one of the ducts 32 for air circulation. Another reason for this failure may be due to excessive wear or rupture of one or more sealing joints or dynamic joints of the low-pressure turbine 60. A cooling failure of the turbine 60 is caused, for example, by a rupture of the labyrinth joint 69 between the stator part and the rotor part, thereby ensuring that the cavity under the pulse tube 68 of the low-pressure turbine 60 is isolated under pressure.

[0059] The rotor of the low-pressure turbine 60 comprises calibration means for calibrating the air flow rate of the air flow 77 flowing in the circulation channel, as described below.

[0060] In a first embodiment, the calibration device comprises a portion referred to as "fusible portion 90". Figure 3B is similar to Figure 3A . According to this view, a portion 90 of at least one root 642 of a blade 64 comprises a material different from the material of the root 642 and the rest of the blade 64. The portion 90 comprising the different material is referred to as a "fusible portion 90", which may be the portion defining the passage P with the bottom of the groove 632. Specifically, portion 90 may be the lower portion of the root 642, i.e., the portion closest to the bottom of the groove 632, representing at least 1 / 4, preferably at least 1 / 3, and preferably even at least half of the total volume of the root 642. This portion 90 of the root 642 may be fixed to the rest of the root 642 by brazing. In addition, Figure 3A and Figure 3B An example is shown in which the root 642 has a fir trunk shape. However, this example is not limiting, and thus the present invention may be applied to other forms of blade roots, such as a dovetail shape.

[0061] The fusible portion 90 may comprise, for example, a eutectic material comprising 72% silver and 28% copper, and may have a melting temperature or creep temperature of 780° C. The melting temperature and therefore the material for the fusible portion 90 are determined so that, under nominal operating conditions, the temperature within the circulation channel remains below the melting temperature of the fusible portion 90. Thus, under nominal operating conditions, the fusible portion 90 has a constant form to maintain a constant cross-section of the passage P and, therefore, a constant flow rate in the circulation channel.

[0062] Whenever one of the above mentioned faults occurs, the purge flow rate drops, resulting in the introduction of hot gases from the main pulse duct which can be introduced into the circulation channels, in particular into the passage P. The temperature inside the circulation channels then increases and reaches values ​​higher than those representing nominal operation.

[0063] When the temperature in the circulation channel reaches the melting temperature of the fusible portion 90, the fusible portion at least partially melts and / or deforms under the effect of creep, causing the cross-section of the passage P to change, in particular to increase. The increase in the cross-section of the passage P causes the flow rate of the hot air flow 77 from the main pulse in the circulation channel to rise. The effect of this increase in the hot air flow rate is to significantly and quasi-instantaneously raise the temperature in this area of ​​the blade root, causing rapid degradation of the root 642 of the blade 64. The root 642 no longer performs its function of holding the blades 64, causing these blades 64 to release in the main pulse.

[0064] It is known that in the event that a blade is released or detached, a safety device called IFSD (“In Flight Shut Down”) will immediately generate a dynamic imbalance, triggering an alarm in the cockpit, prompting the user to immediately shut down the engine. In this case, the casing of the low-pressure turbine 60 is configured to retain the detached blades 64 inside the engine, avoiding degradation of other components of the turbine engine. The number of blades 64 called “fusible blades”, that is, the number of blades whose roots 642 include a fusible portion 90 is not limited, and one, two or more of them can be equipped with the root. In addition, according to the present embodiment, the fusible portion or portion 90 is located on the blade 64 of the upstream wheel 63a. Therefore, the fusible portion 90 is fixed in the turbine closest to the airflow 76 of the hot air that blows the low-pressure turbine 60.

[0065] According to a second embodiment, the fusible portion 90 is a first fusible portion and the rotor of the low-pressure turbine 60 comprises a second fusible portion 92. According to this second embodiment, the calibration device comprises a second fusible portion 92. More precisely, at least one of the holes 102 of the wall 101 is used as a fusible hole 102'. In the nominal operation of the turbine, the diameter of this fusible hole 102' is the same as the diameter of the other holes 102. However, the contour of this fusible hole 102' is defined by the second fusible portion 92, having the form of an annular ring or a gasket, whose inner diameter is equal to the diameter of the other holes 102 and whose outer diameter is equal to at least 1.5 times the inner diameter, preferably at least 1.8 times the inner diameter. The second fusible portion 92 can be fixed to the wall 101 by brazing.

[0066] It is also apparent that the second fusible portion 92 preferably comprises a different material than the first fusible portion 90 and has a higher melting temperature.

[0067] Thus, under nominal operating conditions, the fusible portion 92 has a constant form for maintaining the diameter of the hole 102' constant and equal to the diameter of the hole 102 not provided with the second fusible portion 92. In this way, a substantially constant flow rate can be maintained in the circulation channel.

[0068] Whenever one of the above mentioned faults occurs, the purge flow rate drops, resulting in the introduction of hot gases from the main pulse tube, which can be introduced into the circulation channel, in particular into the passage P, and then pass through the holes 102 and 102'. The temperature in the circulation channel increases and reaches a value higher than that representing nominal operation.

[0069] When the temperature in the circulation channel reaches the melting temperature of the second fusible portion 92, the second fusible portion at least partially melts and / or deforms under the effect of creep, causing the cross section of the hole 102' to change, especially increase. The increase in the cross section of the hole 102' causes the flow rate of the airflow 77 of the hot air from the main pulse in the circulation channel to increase.

[0070] The effect of this increase in the flow rate of the hot air is to significantly and quasi-instantaneously increase the temperature in this region of the blade root, leading to rapid degradation of the root 642 of said blade 64. In the case of the first fusible portion 90, the consequences described above also occur.

[0071] The number of holes 102' called "fusible holes", ie, those holes 102' comprising the second fusible portion 92 is also not limited, and one, two or more of them may be provided with these holes.

[0072] Furthermore, one or the other of the first fusible portion 90 or the second fusible portion 92 may be utilized. Alternatively, the first embodiment and the second embodiment may be combined, and the first fusible portion 90 and the second fusible portion 92 may be used simultaneously.

[0073] Although the present invention has been described with reference to specific exemplary embodiments, it is apparent that these examples can be modified and altered without departing from the overall scope of the present invention as defined by the claims. Specifically, the various features of the various embodiments illustrated / mentioned can be combined into other embodiments. Therefore, this specification and the drawings should be considered in an illustrative rather than a restrictive sense.

Claims

1. A turbine rotor (60) for an aircraft turbine engine, comprising: - at least one moving wheel (63) supporting a moving blade (64), the moving wheel (63) comprising a plurality of grooves (632), the roots (642) of the moving blades (64) being inserted into the grooves, and a passage (P) being formed between the bottom of the groove and the roots (642) of the moving blades (64) inserted into the grooves (632), - a circulation channel configured to allow the circulation of a fluid, said circulation channel comprising said passage (P), - A calibration device configured to allow flow at a first fluid flow rate in the circulation channel when the temperature in the circulation channel is below a predetermined temperature threshold, and to change state to allow flow at a second fluid flow rate in the circulation channel that is greater than the first flow rate when the temperature in the circulation channel is greater than or equal to the predetermined temperature threshold, the calibration device comprising a fusible material configured to at least partially melt when the temperature in the circulation channel reaches the predetermined threshold.

2. The rotor according to claim 1, characterized in that The calibration device comprises at least a portion (90) of a root (642) of at least one moving blade (64) of the moving disc (63).

3. The rotor according to claim 2, characterized in that The portion (90) of the root (642) of the moving blade (64) is configured to convert from a first state to a second state, in which, when the temperature in the circulation channel is lower than the predetermined threshold, it has a first geometric structure, and in the second state, when the temperature in the circulation channel is higher than or equal to the predetermined threshold, it has a second geometric structure different from the first geometric structure, and increases the cross-section of the passage (P) between the bottom of the groove (632) and the root (642) of the moving blade (64).

4. The rotor according to claim 2, characterized in that The portion (90) of the root (642) of the moving blade (64) comprises a fusible material.

5. The rotor according to claim 1, characterized in that The invention comprises an annular wall (101) extending axially between two movable wheels (63) of the rotor, the annular wall comprising a plurality of circulation holes (102), the circulation channel comprising the plurality of circulation holes (102), and the calibration device comprising at least one fusible gasket (92) fixed on at least one circulation hole (102') among the plurality of circulation holes (102).

6. The rotor according to claim 5, characterized in that The fusible gasket (92) is configured to transform from a first state to a second state, in which, when the temperature in the circulation channel is lower than the predetermined threshold, it has a first geometric structure that defines the diameter of the circulation hole (102') to which it is fixed, and in which, when the temperature in the circulation channel is higher than or equal to the predetermined threshold, it has a second geometric structure different from the first geometric structure and causes the diameter of the hole (102') to increase.

7. The rotor according to claim 5, characterized in that The fusible gasket (92) comprises a fusible material.

8. The rotor according to claim 1, characterized in that The rotor includes a plurality of moving wheel discs (63), and the calibration device is positioned on an upstream moving wheel disc (63a) among the plurality of moving wheel discs (63), wherein the upstream moving wheel disc (63a) is positioned upstream of the plurality of moving wheel discs (63) according to a direction in which hot air flows along a rotation axis of the rotor.

9. The rotor according to claim 1, characterized in that The temperature threshold is between 700 and 850°C.

10. A turbine for an aircraft turbine engine comprising an annular pulse duct for a hot air flow and a rotor according to any one of claims 1 to 9.

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