DE-ICING DEVICE FOR AN AIRCRAFT ENGINE COMPONENT

Abstract

This de-icing device for an aircraft engine element (6, 9) comprises at least one hot air duct (10) and hot air distribution means (11) in heat exchange relationship with the engine element (6, 9). It further comprises a set of electric heaters in heat exchange relationship with said hot air duct (10) or hot air distribution means. Figure for the abbreviation: Fig 1

Description

Title of the invention: DE-ICING DEVICE FOR AN AIRCRAFT ENGINE ELEMENT Technical field

[0001] The present invention relates to the field of surface de-icing and particularly the de-icing of an element of an aircraft engine.

[0002] On the ground or in flight, aircraft may be required to operate in icing conditions. Indeed, under certain conditions, the atmosphere contains supercooled water droplets which may be deposited on different surfaces of the aircraft, and particularly on different surfaces of the aircraft's engine. These droplets, transported by the air flow, will in particular be ingested by the engine and be deposited on the different surfaces exposed to the flow, for example the blades of the fan or the compressor, or the separation nozzle between the primary flow and the secondary flow for a twin-flow turbojet.

[0003] Depending on the local thermodynamic conditions or the shape of the aerodynamic vein, these droplets can then turn into frost and have serious consequences for the operation of the engine. Indeed, there are risks of obstruction of the air intakes, risks of detachment of the accumulated ice damaging the surrounding parts, a risk of extinction of the combustion chamber of the engine...

[0004] In a dual-flow aircraft turbojet, an ice protection system may be provided to protect the separation nozzle. This system is located upstream of a compartment located between a primary vein receiving a primary air flow, and a secondary vein receiving a secondary air flow.

[0005] This system is typically supplied by a hot air sampling on a stage of the high-pressure compressor of the primary stream. The air flow, once heated by its compression up to the sampling stage, circulates in a set of pipes, and allows the separation nozzle to be heated by convective exchanges. This set of pipes includes in particular a main pipe, equipped with a valve, which allows the hot air to be transported to a distribution ramp on which several distribution vents are arranged, dispersing the hot air over the entire separation nozzle.

[0006] The portions of the separation nozzle located directly opposite the distribution vents naturally receive more heat than the portions furthest from them. In addition, along the hot air distribution ramp, the pressure and temperature of the air decrease (heat losses and friction losses), amplifying temperature heterogeneity across the entire separation nozzle.

[0007] This heterogeneity is a significant problem. Indeed, a frost protection system must guarantee a sufficiently high internal hot air flow to prevent frost from forming on the coldest points of the separation nozzle. To achieve this, the system must in particular be sized to guarantee a sufficiently high internal heat flow to prevent frost from forming on the coldest points.

[0008] Furthermore, an ice protection system must be sized over a fairly wide range of engine operating speeds. At idle speeds, external convective exchanges are moderate, but the flow rates and temperatures of the bleed air are lower. Conversely, at higher speeds, external convective exchanges are significant, but the flow rates and temperatures of the bleed air are higher.

[0009] As a replacement for frost protection systems based on hot air circulation, it has been considered to use electric heaters to efficiently and uniformly heat the entire engine element to be defrosted. However, such heaters have major integration constraints. They must be as close as possible to said element. However, this is complex to achieve, for high-power heaters, when the element to be defrosted is a thin surface or an area with a small radius of curvature. Statement of the invention

[0010] The present invention aims to overcome the aforementioned drawbacks and, in particular, to propose an anti-icing protection system making it possible to homogenize the temperature on the engine element to be protected against ice.

[0011] The invention therefore relates to a de-icing device for an aircraft engine element comprising at least one hot air duct and hot air distribution means in heat exchange relationship with the engine element. It comprises a set of electric heaters in heat exchange relationship with said hot air duct or the hot air distribution means.

[0012] Advantageously, the distribution means comprise a distribution ramp and a set of pipes opening into a cavity of the engine element.

[0013] According to one embodiment, the engine element is a separation nozzle between a primary air flow and a secondary air flow, the ramp being an annular ramp extending in the periphery of the separation nozzle.

[0014] According to another embodiment, the engine element is a blade.

[0015] Optionally, the ramp is a hot air distribution ramp which communicates with the different blades of the blower or the compressor.

[0016] According to one embodiment, the electric heaters each comprise an enveloping heating surface positioned on the pipe or on the hot air distribution means.

[0017] According to another embodiment, the electric heaters each comprise at least one resistive wire, wound around the pipe or around the hot air distribution means, or integrated into the pipe or into the hot air distribution means using grooves.

[0018] The electric heaters are electrically powered by an electrical power supply element, said power supply element comprising a permanent magnet alternator integrated in the aircraft, or a generator dedicated to powering the electric heaters.

[0019] Advantageously, the electric heaters are configured to be able to be switched on or off.

[0020] The invention also relates to an aircraft comprising a de-icing device as defined above. Brief description of the drawings

[0021] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0022] - [Fig.l] is a partial sectional view of an aircraft engine equipped with a defrosting device for engine element;

[0023] - [Fig.2] is a schematic view of a first embodiment of a device deicing for an aircraft engine component;

[0024] - [Fig.3] is a schematic view of a second embodiment of a de-icing device for an aircraft engine component;

[0025] - [Fig.4] is a schematic view of a third embodiment of a deicing device for an aircraft engine component; and

[0026] - [Fig.5] is a schematic view of a fourth embodiment of a de-icing device for an aircraft engine component. Detailed description

[0027] In [Fig.l], there is shown a part of an aircraft engine, designated by the general numerical reference 1, constituted here by a double-flow turbojet.

[0028] As illustrated, the engine conventionally comprises at least one air inlet 2 equipped with a blower 3, a low-pressure compressor 4, a high-pressure compressor 5, and a separation nozzle 6, placed upstream of an inter-vein compartment 7, ensuring the separation of the air flow admitted at the inlet 2 of the engine between a primary flow F1 and a secondary flow F2.

[0029] The engine is also equipped with a defrosting device 8 ensuring protection against frost of an element to be defrosted.

[0030] According to the embodiment illustrated in [Fig. 1], the element to be defrosted is constituted by the separation nozzle 6 between the primary air flow F1 and the secondary air flow F2.

[0031] Of course, it does not go beyond the scope of the invention when the element of the engine to be defrosted is another element of the engine, for example a blade 9 of a fan 3 or a compressor 4, 5.

[0032] The defrosting device 8 comprises at least one pipe 10 which extends between an internal compartment of the turbine engine in which the primary flow circulates and the element to be defrosted, and hot air distribution means 11, illustrated in [Fig.2],

[0033] The hot air distribution means 11 comprise a distribution ramp 12 and a set of pipes 13 opening into a cavity 14 of the element to be defrosted. The pipe 10 opens on one side directly onto the distribution ramp 12 and on the other side onto the high-pressure compressor 5.

[0034] According to the embodiment illustrated in [Fig. 1], the distribution ramp 12 is an annular ramp which extends into the periphery of the separation nozzle 6 of the engine.

[0035] In operation, the high-pressure compressor 5 ensures the compression of the primary air flow F1 by increasing the pressure and the temperature of this air flow. This heated air is conveyed to the cavity 14 of the element to be defrosted via the pipe 10 and the hot air distribution means 11. A valve 15 shown in [Fig.l] makes it possible to regulate the entry of hot air into the pipe 10. The air thus heats and partially defrosts the element by convective exchanges. The portions of the element located opposite the pipes 13 are hot. On the other hand, the portions of the element which are not located opposite the pipes 13 are relatively cold. In addition, the pressure and the temperature of the air transported along the distribution ramp 12 decrease when the air moves away from the pipe 10. The temperature of the element to be defrosted is therefore not uniform.It is important that this is sufficiently homogeneous to prevent certain portions of the element from being cold and causing the appearance of frost.

[0036] Thus, so that the temperature of the element is uniform, the defrosting device 8 also comprises an electric heating system which notably comprises electric heaters 16, comprising, for example, heating mats or resistive wires, positioned at the level of the distribution means 11 or on the pipe 10. The electric heaters 16 also make it possible to heat the element to be defrosted by convective exchanges.

[0037] The electric heaters 16 are electrically powered by a power supply element. According to the embodiments, the power supply element electric includes a permanent magnet alternator integrated into the aircraft or a generator dedicated to powering the electric heaters 16.

[0038] Of course, it does not depart from the scope of the invention when the power supply element has a different structure.

[0039] For example, the electric heaters 16 each comprise a heating mat, consisting of an enveloping heating surface comprising an electrically resistive layer and intended to envelop, that is to say to surround with contact, an element to be heated. Such a heating surface is positioned on the pipe 10 or on the hot air distribution means 11.

[0040] According to another embodiment, the electric heaters 16 each comprise at least one resistive wire wound around the pipe 10 or around the hot air distribution means 11. It can also be integrated into the pipe 10 or into the hot air distribution means 11 using grooves.

[0041] If necessary, the pipe 10, the distribution means 11 and other pipes of the defrosting device 8 include thermal protection to prevent heating of the surrounding equipment.

[0042] For optimal efficiency, the electric heaters 16 should be placed as close as possible to the element to be defrosted and in particular at the level of its coldest portions. However, depending on the geometric complexity of the element to be defrosted, the electric heaters 16 can be placed at different strategic locations.

[0043] [Fig. 2] illustrates a first embodiment of the defrosting device 8, in which the defrosting device 8 comprises four electric heaters 16, two of which are positioned at the ends of the distribution ramp 12, and two of which are positioned on the pipes 13 furthest from the duct 10. This effectively makes it possible to heat the cold portions of the element, which are furthest from the hot air duct 10.

[0044] According to a second embodiment of the defrosting device 8 illustrated in [Fig. 3], the pipe 10 opens onto one end of the distribution ramp 12. Thus, the first pipes 13 opening into the cavity 14 of the element to be defrosted are hotter than those which are at the other end of the distribution ramp 12. Two electric heaters 16 are therefore positioned on the end of the distribution ramp 12 furthest from the pipe 10 and two other electric heaters 16 are positioned on the two pipes 13 furthest from the hot air pipe 10. Consequently, the cold portions of the element are heated by the electric heaters 16, and defrosted.

[0045] [Fig. 4] proposes a third embodiment of the defrosting device 8, in which the defrosting device 8 comprises three electric heaters 16 positioned in series on the pipe 10 which opens onto one end of the defrosting ramp. distribution 12. The portions of the element furthest from the pipe 10 are heated less than the portions closest to the pipe 10. The electric heaters 16 make it possible to heat more the relatively cold portions of the element to be defrosted.

[0046] According to a fourth embodiment of the de-icing device 8 illustrated in [Fig. 5], the elements to be de-iced are the blades 9 of the fan 3 or of a compressor 4, 5 of an aircraft engine. A duct 10 opens onto a distribution ramp 12 which, itself, distributes the hot air in each duct 13. The ducts 13 furthest from the duct 10 distribute hot air to the blades 9 furthest from the duct 10 thanks to four electric heaters 16 which are positioned on the distribution ramp 12, at the level of the ducts 13 furthest from the duct 10.

[0047] In the various embodiments described above, the de-icing device 8 is associated with a regulation system and the electric heaters 16 are configured to be able to be started or paused by the regulation system depending on different operating conditions of the engine and in particular depending on the engine speeds of the aircraft. The electric heaters 16 can, for example, be started at critical speeds, specifically at idle speeds, and be paused when only the heat produced by the hot air system is sufficient to de-ice the element to be de-iced.

[0048] The increase in the temperature of the air at the outlet of the pipes 13 is calculated according to the following equation:

[0049] dTair = Pelec / Qair / CPair (1)

[0050] with Peiec the power provided by the electric heater(s) 16,

[0051] Qair the mass flow rate of the pipes 11, and

[0052] Cpair the specific heat capacity of the air circulating in the pipes.

[0053] The electric heating system is more advantageous for compensating for a lack of efficiency at low speeds which imply lower air pressure and temperature at the sampling level, and therefore reduced available defrosting power.

[0054] Figures 2, 3 and 4 show the evolution of the temperature in the cavity 14, as a function of the angular position 0 in the cavity 14, when the electric heaters 16 are in operation (curve 16a) or on hold (curve 16b).

[0055] In [Fig. 2], the temperature of the entire cavity 14 of the element to be defrosted is approximately uniform when the electric heaters 16 are switched on (curve 16a). When the electric heaters 16 are switched on 16b, a drop in temperature appears at the ends of the cavity 14 of the element to be defrosted. In this example, it is considered that the electric heaters 16 have a power of the order of a few W / cm2. They thus allow an increase in the internal heat flow of 10% to 25% at the level of the element to be defrosted, and make it possible to compensate for temperature heterogeneities from one pipe 13 to another of 1°C to 5°C.

[0056] According to the second embodiment illustrated in [Fig. 3], the temperature of the entire cavity 14 is substantially constant when the electric heaters 16 are in operation (curve 16a), whereas when the heaters 16 are paused (curve 16b), the temperature of the cavity 14 drops at the end of the cavity 14 opposite the pipe 10.

[0057] Finally, with reference to [Fig. 4] which represents a third embodiment, the temperature of the entire cavity 14 is substantially constant both when the electric heaters 16 are switched on (curve 16a) and when they are paused (curve 16b). However, when the electric heaters 16 are switched on, the temperature of the cavity 14 increases since the electric heaters 16 provide more heat, thus allowing the entire element to be defrosted better.

[0058] These graphs show the advantage of implementing the electric heaters 16 in a deicing device 8 to improve a conventional aircraft deicing system.

[0059] Furthermore, the de-icing device 8 comprising an electric heating system can be used to correct a design problem of the hot air system identified late in the design phase of the aircraft engine.

Claims

Claims

1. De-icing device (8) for an aircraft engine element (6, 9), comprising at least one hot air duct (10) and hot air distribution means (11) in heat exchange relationship with the engine element (6, 9), characterized in that it comprises a set of electric heaters (16) in heat exchange relationship with said hot air duct (10) or the hot air distribution means (11).

2. Defrosting device (8) according to claim 1, in which the distribution means (11) comprise a distribution ramp (12) and a set of pipes (13) opening into a cavity (14) of the engine element (6, 9).

3. Defrosting device (8) according to one of claims 1 and 2, in which the element of the engine (6, 9) is a separation nozzle (6) between a primary air flow (F1) and a secondary air flow (F2), the distribution ramp (12) being an annular ramp extending in the periphery of the separation nozzle (6).

4. Defrosting device (8) according to one of claims 1 and 2 in which the motor element (6, 9) is a blade (9).

5. Defrosting device (8) according to claim 4, in which the ramp (12) is a hot air distribution ramp which communicates with the different blades (9) of the blower (3) or of the compressor (4, s \

6. jj. Defrosting device (8) according to any one of claims 1 to 5, in which the electric heaters (16) each comprise an enveloping heating surface positioned on the duct (10) or on the hot air distribution means (11).

7. Defrosting device (8) according to any one of claims 1 to 5, in which the electric heaters (16) each comprise at least one resistive wire, wound around the pipe (10) or around the hot air distribution means (11), or integrated into the pipe (10) or into the hot air distribution means (11) using grooves.

8. A defrosting device (8) according to any one of claims 1 to 7, wherein the electric heaters (16) are electrically powered by an electrical power supply element, said power supply element comprising an integrated permanent magnet alternator in the aircraft, or a generator dedicated to powering the electric heaters (16).

9. A defrosting device (8) according to any one of claims 1 to 8, wherein the electric heaters (16) are configured to be able to be switched on (16a) or paused (16b).

10. Aircraft comprising a de-icing device (8) according to any one of claims 1 to 9.

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