TURBOMACHINE ASSEMBLY INCLUDING A SECTION OF A CHANNEL PREVENTING THE FORMATION OF ICE

Abstract

TITLE: TURBOMACHINE ASSEMBLY COMPRISING A SECTION OF A CHANNEL PREVENTING THE FORMATION OF ICING One aspect of the invention relates to a turbomachine assembly (10) comprising: an air stream (200) having an annular duct (220) having an inner wall (222), and an oil circuit (400) having: at least one supply channel (410) in which the oil flows to a chamber to be lubricated (50), at least one discharge channel (420) in which the oil flows from the chamber to be lubricated (50), in operation of the turbomachine, the temperature of the oil contained in the discharge channel is higher than that of the supply channel. The drain channel includes an anti-icing section (426) connecting an inner section (422) to an outer section (424). The anti-icing section covers and is in contact with at least a portion of the inner wall of the annular conduit (220). Figure to be published with the abbreviation: Figure 4

Description

Title of the invention: TURBOMACHINE ASSEMBLY COMPRISING A SECTION OF A CHANNEL PREVENTING THE FORMATION OF ICING TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of aircraft turbomachines and more particularly to an air stream of a turbomachine.

[0002] The present invention relates more particularly to the anti-icing of air streams in turbomachines. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] As shown in [Fig. 1], a turbomachine 10 with a double flow of axis X comprises an outer casing 12, also called a nacelle or a fan casing, and a fan 14 which supplies air to a primary air stream 200 and to a secondary air stream 300 which are annular and separated from each other by an air separator nozzle 16.

[0004] The primary air stream 200 extends from upstream to downstream, in an axial direction A of air flow parallel to the axis X, in: - a low pressure compressor 210 in which outlet guide vanes 212 are arranged, - an annular conduit 220 having a swan-neck shaped section, and - a high pressure compressor 230.

[0005] The annular duct 220 comprises an inner wall 222 divided into an inner shell 224 and an outer shell 226. The secondary air stream 300 is delimited radially by the outer casing 12 and the air separator nozzle 16 and comprises from upstream to downstream the fan 14 and outlet guide vanes 310.

[0006] Generally, under certain flight conditions of an aircraft, the passage of a cloud of water droplets or ice crystals can form a layer of ice, called frost, in the turbomachine 10 and thus cause degradations such as a reduction in aerodynamic performance, mechanical damage or even a loss of thrust. Generally speaking, the formation of frost corresponds to the transformation of water in liquid form into ice when it comes into contact with an external wall of the turbomachine having a very low temperature. The formation of frost therefore implies the presence of water in the liquid state. Consequently, the formation of frost is caused by ice accretion phenomena within the turbomachine 10.

[0007] As shown in [Fig.2], the ice accretion process of the turbomachine 10 includes the following steps: - Ingestion el corresponding to the impact and fragmentation of crystals 70 against a wall of the fan 14 of the turbomachine, the crystals comprising only a solid part 71, - E2 of heating corresponding to the partial melting of the crystals 70 until the formation of a liquid part 72 covering the solid part 71 of the crystals 70 in the low pressure compressor 210, the partial melting of the crystals 70 being caused by the heating of the air flow in the primary air stream 220, and - E3 of accretion in the annular conduit 220 comprising the following sub-steps: • E30: formation of a liquid film 74 on an interior wall 222 of the annular conduit 220, more particularly on the internal 224 and external 226 ferrules, by the adhesion of the partially melted crystals 70 to the internal wall 222, • E31: evaporation 76 of the liquid film 74 by impact and frag mentation of new crystals 70 against the inner wall 222 of the annular conduit 220, and • E32: formation of a layer of ice 78 between the inner wall 222 of the annular conduit 220 and the liquid film 74 when the inner wall 222 reaches a temperature less than or equal to 0°C.

[0008] There are anti-icing devices for preventing the formation of a layer of ice on a wall. In the field of aircraft turbomachines, anti-icing devices are for example installed at the air inlet lips of an air stream, the nacelle or even an outer cone of a rotating part. Anti-icing can be carried out for example by circulating a flow of hot air inside the part to be anti-iced, or by an electric anti-icing device. However, existing solutions are not suitable for anti-icing the annular duct 220 of a turbomachine 10 or involve the addition of an additional device increasing the on-board mass of the turbomachine and complicating its architecture. Summary of the invention

[0009] The invention provides a solution to the problems mentioned above, by proposing a turbomachine assembly allowing the anti-icing of an inner wall of an annular duct of a turbomachine.

[0010] A first aspect of the invention relates to a turbomachine assembly comprising: - an air stream comprising an annular duct comprising an inner wall, and - an oil circuit comprising: • at least one supply channel in which the oil circulates towards an enclosure to be lubricated, and • at least one discharge channel in which the oil circulates from the enclosure to be lubricated, during operation of the turbomachine, the temperature of the oil contained in the discharge channel is higher than the temperature of the oil contained in the supply channel; characterized in that the discharge channel of the oil circuit comprises: - an internal section connected to the enclosure to be lubricated and passing through the annular conduit, - an external section, and - an anti-icing section connecting the inner section and the outer section, the anti-icing section covers and is in contact with at least a portion of a length of the inner wall of the annular duct.

[0011] The turbomachine assembly according to the invention makes it possible to combat the formation of ice inside the annular duct by means of the oil circuit initially present inside the turbomachine thanks to the use of an anti-icing section of the discharge channel of the oil circuit which covers the annular duct to carry out a heat transfer between the oil contained in the discharge channel and the annular duct so as to heat it during operation of the turbomachine. Consequently, thanks to a modification of the architecture of the oil circuit forming an anti-icing device, no addition of an external device is necessary and the on-board mass of the turbomachine therefore remains constant.

[0012] Advantageously, the annular duct comprises an accretion zone, and the anti-icing section of the oil circuit discharge channel is arranged along the accretion zone of the annular duct.

[0013] According to a first embodiment of the invention, the annular duct comprises an inner wall divided into an inner shell and an outer shell, and in that each anti-icing section of the oil circuit discharge channel is arranged along the outer shell of the inner wall of the annular duct.

[0014] According to a variant of the first embodiment of the invention, the oil circuit comprises several discharge channels, and the anti-icing sections of the discharge channels are distributed along the inner wall of the annular duct.

[0015] According to a second embodiment of the invention, the anti-icing section of the oil circuit discharge channel is wound around the inner wall of the annular conduit.

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[0023] Preferably, according to the first and second embodiments of the invention, the anti-icing section of the evacuation channel covers the inner wall of the annular conduit along its entire length. A second aspect of the invention relates to a turbomachine comprising a turbomachine assembly according to the first aspect of the invention. Advantageously, the turbomachine comprises an oil supply manifold connected to the supply channel of the oil circuit, and a receptacle connected to the discharge channel of the oil circuit. Preferably, the turbomachine comprises an outer casing secured to the annular duct. The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which: - [Fig.l], already described, is a schematic axial sectional view of a turbomachine; - [Fig.2], already described, is a partial axial sectional diagram of the turbomachine according to [Fig.l] and of an accretion process of the turbomachine; - [Fig.3] is a schematic view in partial axial section of the turbomachine according to the figure comprising an oil circuit according to the state of the art; - [Fig.4] is a schematic view in partial axial section of the turbomachine according to the figure comprising a corresponding oil circuit according to a first variant of a first embodiment of the invention; - [Fig.5] is a schematic view in partial cross-section of the turbomachine according to the figure comprising an oil circuit according to a second variant of the first embodiment of the invention; - [Fig.6] is a schematic view in partial axial section of the turbomachine according to the figure comprising an oil circuit according to a second embodiment of the invention. DETAILED DESCRIPTION An exemplary embodiment of a turbomachine assembly according to the invention is described in detail below, with reference to the attached drawings. This example illustrates the characteristics and advantages of the invention. Unless otherwise specified, the same element appearing on different figures presents a unique reference.

[0024] For the understanding of the invention, the radial, tangential and axial orientations will be adopted according to the RTA reference frame indicated in the figures, the tangent axes T and axial A of which extend in a horizontal plane according to the orientation in the figures. The axial axis A is parallel to an axis X of the turbomachine. A low-pressure compressor towards a high-pressure compressor of the turbomachine is oriented according to the axial axis A of the RTA reference frame.

[0025] In the description, the terms "upstream" and "downstream" are defined relative to the direction of air flow from the air inlet into the turbomachine to the air outlet from the turbomachine. The terms "internal" and "external" are defined relative to the X axis, the internal elements designate the elements closest to the X axis, in contrast the external elements designate the elements furthest axially from the X axis.

[0026] As illustrated in Figures 3 to 6, a turbomachine 10 with double flow of axis X conventionally comprises: - an outer envelope 12 also called a nacelle, - a primary air stream 200 and a secondary air stream 300 supplied with air by a blower 14 (visible in [Fig.l]), - an air separator nozzle 16 arranged between the primary air stream 200 and the secondary air stream 300, and - a 400 oil circuit.

[0027] The primary air stream 200 extends from upstream to downstream, in an axial direction A of air flow parallel to the axis X, in: - a low pressure compressor 210 in which outlet guide vanes 212 are arranged, - an annular conduit 220 having a swan-neck shaped section, - a high pressure compressor 230.

[0028] The annular duct 220 comprises an inner wall 222 divided into an inner shell 224 and an outer shell 226. The length of the annular duct extends between the low-pressure compressor 210 and the high-pressure compressor 230. The secondary air stream 300 is delimited radially by the outer casing 12 and the air separator nozzle 16 and comprises, from upstream to downstream, the fan 14 and outlet guide vanes 310.

[0029] During operation of the turbomachine 10, the fan 14 is rotating relative to the axis X, and the annular duct 220 which is integral with the outer casing 12 is fixed.

[0030] [Fig. 3] illustrates an oil circuit 400 according to the state of the art. Figures 4 and 5 illustrate an oil circuit 400 according to a first embodiment of the invention, and [Fig.6] illustrates an oil circuit according to a second embodiment of the invention.

[0031] As shown in [Fig.3], the oil circuit 400 according to the state of the art comprises: - at least one supply channel 410 in which the oil circulates towards an enclosure to be lubricated 50, the supply channel 410 comprising: • an internal section 412 connected to the enclosure to be lubricated 50 and passing through the annular conduit 220, and • an external section 414 connected to an oil supply manifold 430, and - at least one discharge channel 420 in which the oil circulates from the enclosure to be lubricated 50, the discharge channel 420 comprising: • an internal section 422 connected to the enclosure to be lubricated 50 and passing through the annular conduit 220, and • an external section 424 connected to a receptacle 430.

[0032] The enclosure to be lubricated 50 generally corresponds to a rotary bearing.

[0033] As shown in Figures 4 to 6, the oil circuit 400 according to the first, second and third embodiments of the invention comprises: - at least one supply channel 410 in which the oil circulates towards an enclosure to be lubricated 50, the supply channel 410 comprising: • an internal section 412 connected to the enclosure to be lubricated 50 and passing through the annular conduit 220, and • an external section 414 connected to an oil supply manifold 430, and - at least one discharge channel 420 in which the oil circulates from the enclosure to be lubricated 50, the discharge channel 420 comprising: • an internal section 422 connected to the enclosure to be lubricated 50 and passing through the annular conduit 220, • an external section 424 connected to an oil supply manifold 430, and • an anti-icing section 426 connecting the internal section 422 and the external section 424 and extending along the annular duct 220.

[0034] The operation of the oil circuit 400 comprises the following steps: - circulation of the oil in the supply channel 410 from the supply manifold 430 circulates towards the enclosure to be lubricated 50, - lubrication of the enclosure to be lubricated 50, a step during which the temperature of the oil increases, and - circulation of oil in the discharge channel 420 from the enclosure to lubricate 50 to the receptacle 440, the temperature of the oil contained in the discharge channel 420 being higher than the temperature of the oil contained in the supply channel 410 of the oil circuit 400.

[0035] The discharge channel 420 of the oil circuit 400 is arranged so that the anti-icing section 426 is positioned as close as possible to the primary air stream 200 of the annular duct so as to promote heat exchanges between the hot oil contained in the anti-icing section 426 and the inner wall 222 of the annular duct 220 of the cold primary air stream 200. Consequently, the oil circuit 400 of the turbomachine 10 according to the invention forms an anti-icing device for the annular duct 220.

[0036] According to the first embodiment of the turbomachine assembly 10 as shown in FIGS. 4 and 5, the oil circuit 400 comprises at least one discharge channel 420 according to which each anti-icing section 426 is arranged along the outer shell 226 of the inner wall 222 of the annular duct 220 and extends longitudinally between the inner section 422 and the outer section 424 of the discharge channel 420.

[0037] According to a first variant of the first embodiment of the turbomachine assembly 10 as shown in [Fig.4], the oil circuit 400 comprises a single discharge channel 420.

[0038] According to a second variant of the first embodiment of the turbomachine assembly 10 as shown in [Fig. 5], the oil circuit 400 comprises several discharge channels 420 along which the anti-icing sections 426 are distributed along the inner wall 222 of the annular duct 220 and arranged circumferentially next to each other so as to cover at least a portion of the outer shell 226 of the inner wall 222.

[0039] According to an example of arrangement not shown, the anti-icing sections 426 are in contact with each other so as to optimize the heating of the outer shell 226 of the inner wall 222 by the discharge duct 420. According to another example of arrangement, the anti-icing sections 426 are spaced apart from each other so as to circumferentially enlarge the heated zone of the outer shell 226 of the inner wall 222 by the discharge duct 420. As shown in [Fig. 5], the oil circuit 400 comprises four discharge channels separated from each other by an angle of 90 degrees.

[0040] According to the second variant of the second embodiment of the turbomachine assembly 10, the anti-icing sections 426 are distributed circumferentially: - On only a part of the external shell 226 of the internal wall 222, - on the entire outer shell 226 of the inner wall 222, or - on the entire outer shell 226 of the inner wall 222, or - on the entire inner wall 222 including the inner 224 and outer ferrules.

[0041] According to the second embodiment of the turbomachine assembly 10 as shown in FIG. 6, the oil circuit 400 comprises at least one discharge channel 420 along which the anti-icing section 426 is wound between the inner section 422 and the outer section 424 in a helically manner against the inner wall 222 of the annular duct 220 according to a winding pitch extending substantially along the axis X. Preferably, the oil circuit 400 comprises a single discharge channel 420.

[0042] Advantageously, the anti-icing section 426 is wound with a minimum winding pitch so as to completely cover the inner wall 222 of the annular duct 220 between the inner section 422 and the outer section 424 and thus optimize the heating of the inner wall 222 by the evacuation duct 420.

[0043] Advantageously, according to the first and second embodiments of the invention, the anti-icing section 426 of the evacuation channel 420 extends along the annular conduit 220 along its entire length.

[0044] One of the turbomachine assembly 10 according to the invention makes it possible, thanks to a heat transfer between the oil circulating in the discharge channel 420 (channel in which the oil temperature is the highest) of the oil circuit 400 and the primary air stream 200 circulating in the annular duct 220 of the turbomachine 10, to increase the temperature of the primary air stream 200 and thus avoid any phenomenon of ice accretion inside the annular duct 220.

Claims

Claims

1. Turbomachine assembly (10) comprising: - an air stream (200) comprising an annular duct (220) comprising an inner wall (222), and - an oil circuit (400) comprising: • at least one supply channel (410) in which the oil circulates towards an enclosure to be lubricated (50), and • at least one discharge channel (420) in which the oil circulates from the enclosure to be lubricated (50), in operation of the turbomachine (10), the temperature of the oil contained in the discharge channel (420) is higher than the temperature of the oil contained in the supply channel (410) of the oil circuit (400);characterized in that the discharge channel (420) of the oil circuit (400) comprises: - an internal section (422) connected to the enclosure to be lubricated (50) and passing through the annular conduit (220), - an external section (424), and - an anti-icing section (426) connecting the internal section (422) and the external section (424), the anti-icing section (426) covers and is in contact with at least part of a length of the internal wall (222) of the annular conduit (220).;

2. Turbomachine assembly according to claim 1, characterized in that the annular duct (220) comprises an accretion zone, and in that the anti-icing section (426) of the discharge channel (420) of the oil circuit (400) is arranged along the accretion zone of the annular duct (220).

3. Turbomachine assembly according to any one of the preceding claims, characterized in that the inner wall (222) of the annular duct (220) is divided into an inner shell (224) and an outer shell (226), and in that each anti-icing section (426) of the discharge channel (420) of the oil circuit (400) is arranged along the outer ferrule (226) of the inner wall (222) of the annular conduit (220).

4. Turbomachine assembly according to claim 3, characterized in that the oil circuit (400) comprises several discharge channels (420), and in that the anti-icing sections (426) of the discharge channels (420) are distributed along the inner wall (222) of the annular duct (220).

5. Turbomachine assembly according to claim 1 or 2, characterized in that the anti-icing section (426) of the discharge channel (420) of the oil circuit (400) is wound around the inner wall (222) of the annular duct (220).

6. Turbomachine assembly according to any one of the preceding claims, characterized in that the anti-icing section (426) of the discharge channel (420) covers the annular duct (220) along its entire length.

7. Turbomachine (10) characterized in that it comprises a turbomachine assembly according to any one of the preceding claims.

8. Turbomachine (10) according to claim 7, characterized in that it comprises an oil supply manifold (430) connected to the supply channel (410) of the oil circuit (400), and a receptacle (440) connected to the discharge channel (420) of the oil circuit (400).

9. Turbomachine (10) according to claim 7 or 8, characterized in that it comprises an outer casing (12), and in that the annular duct (220) is integral with the outer casing (12).

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