DE-ICING DEVICE FOR AN AIR INLET OF AN AIRCRAFT TURBOCHARGE ENGINE NON-BOARD

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of aircraft turbojet engines and more particularly to a de-icing device for an air intake of an aircraft turbojet engine nacelle. STATE OF THE ART

[0002] As is known, an aircraft has one or more turbojet engines to enable its propulsion by accelerating an airflow that circulates from upstream to downstream in the turbojet.

[0003] With reference to the figure 1A turbojet engine 100 is shown extending along an axis X and comprising a fan 101 mounted for rotation about the axis X in a nacelle having an outer shell 102 in order to accelerate an airflow F from upstream to downstream. Hereafter, the terms upstream and downstream are defined with respect to the circulation of the airflow F. The turbojet engine 100 has at its upstream end an air inlet 200 having a cavity 204, extending annularly around the axis X, which has an inner wall 201 facing the axis X and an outer wall 202 which is opposite the inner wall 201; the walls 201, 202 are connected by a leading edge 203 also called the "air inlet lip". Thus, the air inlet 200 allows the incoming airflow F to be separated into an internal airflow FINT guided by the internal wall 201 and an external airflow FEXT guided by the external wall 202.Subsequently, the terms inside and outside are defined radially with respect to the X axis of the turbojet 100.

[0004] As is known, during the flight of an aircraft, due to temperature and pressure conditions, frost is likely to accumulate at the leading edge 203 and the inner wall 201 of the air inlet 200 and to form blocks of frost which are likely to be ingested by the turbojet 100. Such ingestions must be avoided in order to improve the life of the turbojet 100 and reduce malfunctions.

[0005] To eliminate frost buildup, again referring to the figure 1 It is known to circulate a flow of hot air FAC in the inner cavity 204 in order to heat the inner wall 201 by thermal convection and thus prevent the accumulation of frost which melts as it accumulates.

[0006] The introduction of the hot air flow FAC into the internal cavity 204 is achieved by an injector 300, traditionally in the form of a cylindrical tube oriented tangentially to the axis of the turbojet engine, as illustrated in the figure 2 The hot air flow FAC moves circumferentially in the inner cavity 204 in order to heat the inner wall 201.

[0007] In practice, the energy efficiency of such a heater is low since the hot air flow FAC also heats the exterior wall 202, resulting in a loss of heat. In fact, with reference to the figure 3During the injection of the hot air flow FAC, it comes into direct contact with the outer wall 202, which absorbs a significant portion of the heat from the hot air flow FAC as it is guided through the inner cavity 204. Therefore, to ensure optimal heating of the inner wall 201, it is necessary to inject a superheated air flow FAC into the inner cavity 204. An immediate solution to eliminate this drawback would be to change the orientation of the injector 300 within the inner cavity 204 to target the inner wall 201. However, such an immediate solution does not allow for uniform heating of a circumferential outer wall 202. At best, this solution results in a shift in the contact area of ​​the hot air flow FAC with the outer wall 202, which thus remains in place.

[0008] One of the objectives of the present invention is to enable heating of the inner wall 201 of the air inlet 200 of a nacelle of a turbojet with improved energy efficiency.

[0009] Incidentally, patent application CA2689195 discloses an injector for a twisted hot air stream. Patent application FR2813581 discloses an injector for a twisted hot air stream and an axial hot air stream arranged concentrically to form a hot air stream symmetrical about the injector's nozzle axis, thereby heating the walls of the internal cavity equally. PRESENTATION OF THE INVENTION

[0010] The invention relates to a de-icing device for an air inlet of an aircraft turbojet nacelle extending along an axis X in which an airflow flows from upstream to downstream, the air inlet having an internal cavity, extending annularly around the axis X, which has an inner wall facing the axis X and an outer wall which is opposite the inner wall, the walls being connected by a leading edge, the de-icing device having at least one injector of a hot air flow into the internal cavity, the injector having a mouth extending along a mouth axis.

[0011] The invention is remarkable in that the nozzle is configured to inject a hot air flow with an asymmetry about the nozzle axis, so as to generate turbulence near the outer wall while simultaneously heating the inner wall. In other words, the hot air flow does not exhibit rotational symmetry around the nozzle axis. This advantageously allows the inner and outer walls of the internal cavity to be heated differently, maximizing heat exchange with the inner wall and minimizing it with the outer wall. Thus, the heating of the inner wall is optimal.

[0012] Preferably, the inlet comprises at least one first channel configured to conduct a first elementary flow and at least one second channel configured to conduct a second elementary flow, thus forming the hot air flow. The channels are superimposed, i.e., non-concentric. Thanks to the invention, the inlet allows for the formation of a first elementary flow dedicated to the outer wall and a second elementary flow dedicated to the inner wall, thereby enabling differentiated heating. Advantageously, the pressure differential creates, in the mixing zone of the elementary flows FE1 and FE2, a deflection of the hot air flow FAC by the Coanda effect.

[0013] Preferably, the first channel includes at least one air deflection element. Preferably, the air deflection element is configured to twist the first elementary flow. In a preferred configuration, the air deflection element has a helical shape. Thus, the twisted first elementary flow generates turbulence which, on the one hand, limits heat exchange with the outer wall of the cavity and, on the other hand, twists the first elementary flow to promote circumferential circulation within the annular inner cavity.

[0014] Preferably, the second channel is devoid of an air deflection device so as to provide a second elementary flow that is substantially axial.

[0015] In a preferred design, the mouth includes a separating element to divide the mouth into the first and second channels. In other words, the mouth consists of two channels. Preferably, the separating element is a substantially flat wall, preferably parallel to the axis of the mouth. Thus, the elementary flows are guided independently within the mouth, allowing for two different flow paths. In a preferred design, the mouth has only two channels.

[0016] Preferably, the first channel converges from upstream to downstream to accelerate the first elementary flow. Preferably, the second channel converges from upstream to downstream to accelerate the second elementary flow.

[0017] The invention also relates to an air inlet for an aircraft turbojet nacelle extending along an X-axis through which an upstream to downstream airflow flows. The air inlet comprises an internal cavity extending annularly around the X-axis, having an inner wall facing the X-axis and an outer wall opposite the inner wall. The walls are connected by a leading edge. The air inlet includes a de-icing device, as described above, in which the first elementary flow is configured to be injected on the outer wall side of the internal cavity. Preferably, the second elementary flow is configured to be injected on the inner wall side of the internal cavity.

[0018] Preferably, the first elementary flux is radially external to the second elementary flux.

[0019] The invention also relates to a method of using a de-icing device as previously described for de-icing an air inlet of an aircraft turbojet nacelle extending along an axis X in which an airflow flows from upstream to downstream, the air inlet having an internal cavity, extending annularly around the axis X, which has an inner wall facing the axis X and an outer wall which is opposite the inner wall, the walls being connected by a leading edge, the method comprising a step of injecting a hot air flow having an asymmetry about the inlet axis so as to generate turbulence in the vicinity of the outer wall while heating the inner wall. PRESENTATION OF THE FIGURES

[0020] The invention will be better understood upon reading the following description, given solely by way of example, and referring to the accompanying drawings given by way of non-limiting examples, in which identical references are given to similar objects and on which: There figure 1 is a schematic representation of a gondola air intake according to the prior art, The figure 2 is a schematic cross-sectional representation of the theoretical circulation of a hot air flow in the air inlet, The figure 3 is a schematic cross-sectional representation of the actual circulation of a hot air flow in the air inlet. figure 4 is a schematic representation of an air inlet of a nacelle according to the invention, The figure 5 is a schematic representation of the circulation of a hot air flow in the air inlet according to one embodiment of the invention, The figure 6is a schematic representation of the nozzle of an injector of a de-icing device according to the invention; The figure 7 is a schematic transparent representation of the nozzle of an injector of a de-icing device according to the invention; The figure 8 is a schematic perspective representation of a partition wall and an air deflection device; and The figure 9 is a schematic side view representation of the separating wall and the air deflection device.

[0021] It should be noted that the figures explain the invention in detail for implementing the invention, and these figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0022] With reference to the figure 4A turbojet engine 1 extending along an axis X is shown, comprising a fan 10 mounted for rotation about the axis X within a nacelle having an outer shell 12 in order to accelerate an airflow F from upstream to downstream. Hereafter, the terms upstream and downstream are defined with respect to the circulation of the airflow F. The turbojet engine 1 has at its upstream end an air inlet 2 which has an inner cavity 20, extending annularly about the axis X, which has an inner wall 21 facing the axis X and an outer wall 22 which is opposite the inner wall 21. The walls 21, 22 are connected by a leading edge 23 also called the "air inlet lip". Thus, the air inlet 2 allows the incoming airflow F to be separated into an internal airflow FINT guided by the internal wall 21 and an external airflow FEXT guided by the external wall 22.Subsequently, the terms inside and outside are defined radially with respect to the X axis of the turbojet 1.

[0023] The turbojet engine 1 includes a de-icing device to eliminate the accumulation of frost. As is known, the de-icing device comprises an injector 3 of a hot air flow FAC into the internal cavity 20. Such circulation of a hot air flow FAC allows, by thermal convection, the heating of the internal wall 21 and thus prevents the accumulation of frost, which melts as it accumulates.

[0024] With reference to the figure 5The injector 3 has a nozzle 30 extending along a nozzle axis X2 so as to allow circumferential injection into the inner cavity 20 of the air inlet 2. Preferably, the nozzle axis X2 is tangential to the axis of the turbojet X. According to the invention, the nozzle 30 is configured to inject a hot air flow FAC having an asymmetry about the nozzle axis X2. In other words, the hot air flow FAC does not exhibit rotational symmetry about the nozzle axis X2.

[0025] In this example, with reference to figures 6 And 7The opening 30 comprises a first channel 31 configured to conduct a first elementary flow FE1 and a second channel 32 configured to conduct a second elementary flow FE2, thus forming the hot air flow FAC. In other words, the hot air flow FAC comprises the first elementary flow FE1 and the second elementary flow FE2. Preferably, the opening 30 comprises only two channels 31 and 32 to allow for optimal defrosting, but it is understood that the number of channels could be higher. The first elementary flow FE1 and the second elementary flow FE2 are different. In this example, the first elementary flow FE1 is twisted around the opening axis X2, while the second elementary flow FE2 flows parallel to the opening axis X2, together forming an overall flow with an asymmetry about the opening axis X2.

[0026] In this example, the cross-section of the first channel 31, along the mouth axis X2, is larger than the cross-section of the second channel 32. This advantageously allows the first elementary flow FE1 to be twisted optimally, as will be shown later.

[0027] The first channel 31 converges from upstream to downstream so as to accelerate the first elementary flow FE1. In other words, the cross-section of passage of the first channel 31 narrows from upstream to downstream, its inlet section being greater than its outlet section.

[0028] According to one aspect of the invention, the second channel 32 converges from upstream to downstream so as to accelerate the second elementary flow FE2. In other words, the cross-sectional passage of the second channel 32 narrows from upstream to downstream, its inlet section being greater than its outlet section.

[0029] The convergence rate of a channel 31, 32, that is to say the ratio of their input section and their output section, is equal or different between the two channels 31, 32.

[0030] As illustrated in figures 6 And 7 The mouthpiece 30 includes a separating element 4 and an air deflection element 5. Preferably, the separating element 4 is in the form of a substantially flat wall in order to separate the mouthpiece 30 into two channels 31, 32. It goes without saying that the separating element 4 could be in a different form, in particular, a concave or convex form.

[0031] Preferably, the separating element 4 extends parallel to the mouth axis X2 to allow for differentiated guidance in the channels 31 and 32. In this example, the first channel 31 has a single air deflector 5. However, it is understood that it could have several, in series or in parallel. Preferably, the length of the separating wall 4 is adapted to the length of the air deflector 5.

[0032] In this example, the air deflection device 5 is configured to twist the first elementary flow FE1. To this end, the air deflection device 5 has a helical shape forming three twists as illustrated in figures 8 And 9Preferably, the number of twists is between 2 and 5 in order to optimally twist the first elementary flow FE1. Preferably, the first channel 31 has a decreasing cross-section towards its outlet so as to allow the first elementary flow FE1 to twist and accelerate, thereby increasing turbulence in the inner cavity 20 and preventing frontal impact on the outer wall 22. Furthermore, such an air deflection device 5 promotes natural circumferential circulation in the air inlet 2 since the first elementary flow FE1 is ejected in a twisted manner.Also, unlike the prior art which allowed circumferential guidance of the hot air flow FAC solely by the outer wall 22 of the inner cavity 20, resulting in heat loss, the present invention also allows circumferential guidance due to the torsion of the hot air flow FAC, thus limiting heat loss. The second channel 32 is devoid of an air deflection device so that the elementary flows FE1, FE2 are injected at different angles (axial trajectory / helical trajectory) and at different velocities.

[0033] The two elementary flows FE1 and FE2 are ejected in a superimposed manner. The pressure differential creates, in the mixing zone of the elementary flows FE1 and FE2, a deflection of the hot air flow FAC by the Coanda effect. The position, angle, flow ratio, and relative velocities of the two elementary flows FE1 and FE2 are determined to allow for optimal deflection, i.e., one that follows the annular shape of the internal cavity 20. Preferably, to control the deflection, the injector 3 includes a static or dynamic pressure-loss control device.

[0034] With reference to the figure 5The first elementary flow FE1 is configured to be injected on the outer wall 22 side of the inner cavity 20, while the second elementary flow FE2 is configured to be injected on the inner wall 21 side of the inner cavity 20. In other words, the first channel 31 is radially internal to the second channel 32. As will be shown in the example of an embodiment of the invention, the use of such a defrosting device optimizes the heating of the inner wall 21 of the inner cavity 20 while limiting heat loss.

[0035] Alternatively, the second channel 32 is radially external and the first channel 31 is radially internal depending on the supply pressures of channels 31, 32.

[0036] The process includes an injection step into the inner cavity 20 by injector 3 of a total hot air flow FAC with an asymmetry about the inlet axis X2. In this example, the first radially external channel 31 injects a first elementary flow FE1, which is twisted and thus creates a twist in the total hot air flow FAC, limiting contact with the outer wall 22. Furthermore, the first elementary flow FE1 generates turbulence near the outer wall 22, limiting the circulation velocity in the vicinity of the outer wall 22, which therefore absorbs a limited amount of heat. In other words, the heat exchange between the outer wall 22 and the first elementary flow FE1 of the hot air flow FAC is significantly reduced.

[0037] Conversely, the second channel 32, radially internal, injects a second elementary flow FE2, which is axial. This allows a large amount of heat to be supplied to the inner wall 21 to keep it dry. Advantageously, the first elementary flow FE1 guides the circumferential circulation of the second elementary flow FE2 without drawing heat from it, which is beneficial. The asymmetry of the hot air flow FAC advantageously allows the inner wall 21 and the outer wall 22 to be heated differently. Thanks to the invention, the defrosting of an air inlet 2 is improved practically by modifying the nozzle 30 of the injector 3. In practice, an efficiency greater than 75% is obtained, which is higher than defrosting devices available on the market, which do not exceed 70%.

[0038] Following injection, after the hot air flow FAC circulates over a length approximately 15 times the overall diameter of the injector 3's nozzle 3 within the inner cavity 20, the entire volume of air in the inner cavity 20 is displaced to heat the air inlet lip by convection. Advantageously, due to the initial asymmetry, the transverse temperature of the air volume is homogeneous, thus allowing for optimal heat exchange.

Claims

1. A deicing device for an air intake (2) of a nacelle of an aircraft turbojet engine (1) extending along an axis X in which an air stream (F) circulates from upstream to downstream, the air intake (2) comprising an internal cavity (20) annularly extending about axis X, which comprises an internal wall (21) facing axis X and an external wall (22) which is opposite to the internal wall (21), the walls (21, 22) being connected by a leading edge (23), the deicing device comprising at least one injector (3) for a hot air stream (FAC) into the internal cavity (20), the injector (3) comprising a mouthpiece (30) extending along a mouthpiece axis (X2), which deicing device is characterized in that the mouthpiece (30) comprises a separating member (4) in order to separate the mouthpiece (30) between at least one first channel (31) configured to lead a first elementary stream (FE1) and at least one second channel (32) configured to lead a second elementary stream (FE2), the mouthpiece (30) being configured to eject the first elementary stream (FE1) and the second elementary stream (FE2) in a superposed manner so as to form a hot air stream (FAC) having an asymmetry along the mouthpiece axis (X2) so as to generate turbulence in the vicinity of the external wall (22) while heating the internal wall (21).

2. The deicing device according to claim 1, wherein the first channel (31) comprises at least one air deflection member (5).

3. The deicing device according to claim 2, wherein the air deflection member (5) is configured to twist the first elementary stream (FE1).

4. The deicing device according to any of claims 2 and 3, wherein the air deflection member (5) has a helical shape.

5. The deicing device according to any of claims 1 to 4, wherein the first channel (31) is convergent from upstream to downstream.

6. An air intake (2) of a nacelle of an aircraft turbojet engine (1) extending along an axis X in which an air stream (F) circulates from upstream to downstream, the air intake (2) comprising an internal cavity (20), annularly extending about axis X, which comprises an internal wall (21) facing axis X and an external wall (22) which is opposite to the internal wall (21), the walls (21, 22) being connected by a leading edge (23), the air intake (2) comprising a deicing device according to one of claims 1 to 5, wherein the first elementary stream (FE1) is configured to be injected on the side of the external wall (22) of the internal cavity (20).

7. The air intake (2) according to claim 6, wherein the second elementary stream (FE2) is configured to be injected on the side of the internal wall (21) of the internal cavity (20).

8. A method for using a deicing device according to one of claims 1 to 5 for deicing an air intake (2) of a nacelle of an aircraft turbojet engine (1) extending along an axis X in which an air stream (F) circulates from upstream to downstream, the air intake (2) comprising an internal cavity (20), annularly extending about axis X, which comprises an internal wall (21) facing axis X and an external wall (22) which is opposite to the internal wall (21), the walls (21, 22) being connected by a leading edge (23), the method comprising a step of injecting a hot air stream (FAC) having an asymmetry along the mouthpiece axis (X2) so as to generate turbulence in the vicinity of the external wall (22) while heating the internal wall (21).