Antifouling coating with reliefs and structure comprising such a coating

Abstract

Antifouling coating with reliefs and structure comprising such a coating The present application aims to improve an antifouling coating intended to cover a structure (2) likely to move on which an insect (5) or any other type of contaminant (3) can come to crash. The antifouling coating comprises projections of which at least a part is located on at least one line and of which the shape, allowing the contaminant (3) moving towards the coating to be broken into several pieces (8), is determined and created by a surface texturing operation in the body of the antifouling coating itself. By having a determined shape and being distributed in a non-random manner, the projections allow the contaminant to be broken into several pieces. Abstract figure: Figure 1

Description

Title of the invention: Antifouling coating with reliefs and structure comprising such a coating

[0001] The present invention relates to an antifouling coating of an aerodynamic surface as well as a structure provided with such a coating. Such a coating can be applied for example to a vehicle and in particular an aircraft.

[0002] When an aircraft is moving, particularly during takeoff and landing, insects may crash onto its surfaces, agglomerate and form residues which disrupt the airflow near the surface in question. This results in an increase in aircraft drag and fuel consumption. In order to maintain an airflow along the aerodynamic surfaces of the aircraft as laminar as possible, the height of the residues formed must be limited and as low as possible.

[0003] Patent application FR3115286 filed by Airbus Operations SAS on October 19, 2020 proposes an external layer of a vehicle and in particular an aircraft, comprising a self-cleaning aerodynamic surface providing a lubricating effect allowing the evacuation of residues. The surface may have a certain roughness promoting the shredding of insects at the time of impact.

[0004] The present invention aims to provide a solution that can complement existing antifouling coating solutions such as that presented in the aforementioned application.

[0005] To this end, the present invention relates to an antifouling coating intended to cover a structure likely to move on which an insect or any other type of contaminant may come to crash, characterized in that it comprises projections of which at least a part are located on at least one line and of which the shape allowing the contaminant moving towards the coating to be broken into several pieces, is determined and created by a surface texturing operation in the body of the antifouling coating itself.

[0006] In this way, a suitable shape of protrusions makes it possible to break up a contaminant more reliably. The fact that the protrusions are aligned ensures a non-random distribution.

[0007] The invention provides at least one of the following optional features, taken alone or in combination.

[0008] The shape of the projections is produced using a press whose imprint corresponds to the desired texture.

[0009] The shape of the projections is produced by machining in the coating itself.

[0010] The projections are aligned along lines parallel to each other and staggered from one line to the other.

[0011] The projections are aligned in two directions perpendicular to each other.

[0012] The coating comprises projections of two types, the first type of projection being that allowing the contaminant to be broken into several pieces and the second type of projection being of lesser thickness to allow the pieces to take a direction away from hollows formed between the projections.

[0013] The second type of projection is contiguous to the first projections and has a surface of increasing thickness moving away from the first projection.

[0014] The surface of the relief-forming projections itself comprises reliefs forming the second type of projection.

[0015] The present application also relates to a structure capable of moving covered with an antifouling coating comprising at least one of the preceding characteristics taken in isolation or in combination along which an air flow circulates when the structure is in movement, characterized in that the coating is affixed to the structure so that the line is positioned transversely to the air flow.

[0016] The present application also relates to an aircraft comprising such a structure.

[0017] Other aims, characteristics and advantages will emerge from the description of the invention which follows, a description given by way of non-limiting example only, with reference to the attached drawings in which: [Fig.l] is a schematic view of a structure provided with a coating according to the present invention before, during and after contamination; [Fig.2] is a schematic view of the same structure provided with a coating according to the prior art before, during and after contamination; [Fig.3] is a simplified perspective view of an aircraft comprising a structure capable of being provided with a coating according to the present invention; [Fig.4] is a schematic side view of projections formed in a coating according to the present invention; [Fig.5] is a schematic perspective view of another possible embodiment of the projections according to the present invention; [Fig.6] is a perspective view of another possible embodiment of the projections according to the present invention; [Fig.7] is a schematic view of the different steps A, B, C of a method of manufacturing projections of the coating according to the present invention.

[0018] As shown in [Fig.l], the present invention provides a self-cleaning coating 1 also called an anti-fouling coating intended to cover a structure 2 likely to move. When the structure 2 is in motion, an air flow flows along it. Contaminants 3 such as insects can come crash against the structure when it is in motion. The antifouling coating according to the present invention has a specific texture 4 with reliefs comprising projections and shown diagrammatically by a simple rectangle in [Fig.l], allowing, when an insect 5 impacts the surface 6 of the surface-textured coating 7, to separate it into two or more pieces forming residues 8. The bursting of the insect into several pieces releases the liquid hemolymph 10. However, as shown in [Fig.2], when an insect 5 collides with a surface 12 of a coating without surface texture, it crashes against said surface. Certain small parts 14 of its body may be broken and a small quantity of hemolymph 10 may spill out.This hemolymph lObis, liquid at the moment of impact, participates when it hardens on contact with the air to reinforce the adhesion of the insect residue 16 on the surface and to make its removal more difficult.

[0019] According to an example of application shown in [Fig. 3], the present invention can be applied to a surface 18 of a structure 20 of an aircraft 22 and for example the aerodynamic surface 24 of a nacelle 26 of a propulsion unit 28.

[0020] The nacelle 26 extends around a longitudinal axis called axis L oriented in a longitudinal direction X. The direction Z corresponds to the vertical direction or height when the aircraft is on the ground. The direction Y is such that the three directions X, Y and Z are orthogonal to each other. The term transverse is used in the remainder of the description to indicate a direction which is not that of the direction X. In the remainder of the description, the terms "front" and "rear", "upstream" and "downstream" are understood according to the direction of the air flow in the propulsion unit in operation, i.e. in the direction and sense of the axis X in [Fig.3]. The air enters through the front of the propulsion unit, i.e. through the air inlet of the nacelle and exits through the rear thereof.

[0021] As shown in [Fig.l], the structure 18, in this case the nacelle 26, has an anti-fouling coating 1.

[0022] As illustrated in [Fig. 2], coatings of this type are known and the patent cited above describes an example. A coating is said to be antifouling if it comprises at least one component and / or if its properties make it possible to promote the sliding of insect residues. The coating may for example be of the hydrophobic type. Various lubricating additives may be incorporated therein. Due to its composition and its physical properties, the coating 1 allows the residues 14 of small insects to slide on the surface 12, the composition of the latter preventing the residue from attaching to it. However, it may be that certain residues 16 still remain stuck to the surface.

[0023] Also according to the present invention, with reference to figures 1 and 4, the antifouling coating 1 is applied to the structure 18. Before or after its application, it undergoes a manufacturing operation called texturing described later to form a texture 4 with projections 30. Projections of a determined shape and adapted to reinforce the shredding are created in the body itself of the coating in such a way that at least a part of these are arranged along at least one line. The projections can be distributed along these lines regularly at an equal distance from each other. In the illustrated form, each of the lines extends in a transverse direction. Unlike a natural roughness of a surface according to which the shapes of the projections are random, the creation of projections makes it possible to determine and adapt the shapes of these in order to reinforce the shredding of the insects. In particular, the projections are aligned along at least one transverse line. According to one embodiment, the line extends over the entire span, namely the transverse extent of the surface. This makes it possible to be certain that the insects encounter a projection.The projections 30 have a shape whose dimension narrows away from the structure, for example a tapered, pointed, tooth-shaped or any other shape allowing an insect 5 colliding with a projection to be broken into several pieces, one of which 31 is illustrated in [Fig. 4]. The projections in the illustrated examples are formed in the coating 1 and more precisely, as will be seen later, machined or formed by impression under pressure: they are an integral part thereof.

[0024] According to a particular form illustrated in [Fig. 4], two types of protrusions 30 are formed in the coating 1, thus forming a textured coating 7. A first series of protrusions 32 serves to break the insect 5 into several pieces (including the piece 31). A second series of protrusions 34, which is lower than the first, serves to dislodge the formed pieces 31 to prevent them from entering the recesses 35 between the protrusions. The displacement of the piece 31 is represented by arrows in [Fig. 4]. The protrusions 34 serve to modify the movement of the pieces moving towards the structure and to allow them to take a direction moving them away from it.In some configurations such as the one shown, the projections 34 are arranged contiguously with the first projections 32 and downstream with respect to the air flow but they can be arranged quite differently, the essential thing being that at a lower level than the projections 32, the projections 34 make it possible to retain the pieces 31 of insects in their fall towards the hollows 35 and to make them return to the air flow. According to the illustrated embodiment, the projections 34 have a surface inclined with respect to the axis L, the inclination being such that the surface moves away from the axis L as it moves away from the projection 30. According to a particular form, the projections 32 are all of identical shape. Other examples of texture are given in Figures 5 and 6.

[0025] In [Fig. 5], the texture 4 is of the shark skin type, namely with rough scales. Machined in the coating 1 are contiguous plates 38 extending along lines 36 circumferential in transverse planes YZ. The lines 36 are offset in a direction X and the plates 38 are arranged in a staggered manner from one line to the other. Each plate 38 has a tapered upstream edge 40 forming the projection 32 and roughnesses 42 over the entire external surface of the plate 38 forming the projections 34. The plate is fixed at its downstream edge and gradually peels off in a direction opposite to the X axis, the longitudinal end 41 of the edge 40 being furthest from the structure in a radial direction.

[0026] In [Fig. 6] another example of texture 4 with projections 30 is illustrated. The coating 7 comprises bumps 48 aligned in two directions perpendicular to each other and in the illustrated shape, transversely along the Y axis and longitudinally along the X axis. Each bump 48 forms a projection 30. Each bump 48 does not have a smooth surface but is itself bumpy, namely provided with protuberances 50 forming the projections 34.

[0027] As indicated above, the projections 30 can be machined by laser in the coating 1 but other manufacturing methods are possible as shown by a second example in [Fig.7] with a method based on a press 52. The principle consists of manufacturing a press 52 by machining by laser 54 (step A) by creating shapes such that when applied against the coating 1 (step B), by deformation, the press creates an imprint corresponding to the desired texture 4 (step C).

[0028] Thanks to these projections created on the coating, the insects no longer crush themselves, forming large residues, but are separated into numerous pieces of much smaller sizes, easier to evacuate thanks to the properties of the anti-fouling coating. In addition, if certain pieces remain attached, they are of a smaller size than in the presence of a coating without reliefs and therefore have a much lower impact on the air flow.

Claims

Claims

1. An antifouling coating for covering a structure (2) capable of moving onto which an insect (5) or any other type of contaminant (3) may crash, characterized in that it comprises projections (30) at least a portion of which is located on at least one line and the shape of which, enabling the contaminant (3) moving towards the coating to be broken into several pieces (31), is determined and created by a surface texturing operation in the body of the antifouling coating itself.

2. Coating according to claim 1, characterized in that the shape of the projections (30) is produced using a press (52) whose imprint corresponds to the desired texture.

3. Coating according to claim 1, characterized in that the shape of the projections (30) is produced by machining in the coating itself.

4. Covering according to one of claims 1 to 3, characterized in that the projections (30) are aligned along lines parallel to each other and staggered from one line to the other.

5. Covering according to one of claims 1 to 3, characterized in that the projections (30) are aligned in two directions perpendicular to each other.

6. Coating according to one of claims 1 to 5, characterized in that it comprises projections (30) of two types, the first type of projections (32) being that allowing the contaminant (3) to be broken into several pieces and the second type of projections (34) being of lesser thickness to allow the pieces to take a direction away from hollows formed between the projections.

7. Covering according to claim 6, characterized in that the second type of projections (34) is contiguous to the first projections (32) and has a surface of increasing thickness moving away from the first projection.

8. Covering according to claim 6, characterized in that the surface of the projections (30) forming relief itself comprises reliefs (42, 50) forming the second type of projection (34).

9. A movable structure covered with an antifouling coating according to one of claims 1 to 8 along which an air flow circulates when the structure is in motion, characterized in that the coating covers the structure so that the line is positioned transversely to the air flow.

10. Aircraft characterized in that it comprises a structure according to claim 9.

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