Apparatus for attaching aerodynamically functional films and use thereof

Description

[0001] The invention relates to a device for applying aerodynamically functional films to surfaces of bodies exposed to a flow, and to the use of such a device.

[0002] Aerodynamically functional films are known in various forms and applications from the prior art and regularly serve to reduce wall shear stress on the surfaces of bodies exposed to a flow. These aerodynamically functional films typically have a microstructured surface.

[0003] A common microstructure is the so-called riblet structure, with very small ribs that essentially run along the main flow direction. Riblet structures can be found, for example, on the outer surfaces of aircraft, but also on the rotor blades of wind turbines, on the outer hull of ships, or on the outer surfaces of high-speed trains. Such structures are also used, for example, on the inner surfaces of pipelines.

[0004] To achieve the greatest possible reduction in wall shear stress through aerodynamically functional films, and especially riblet structures, it is necessary that the film is aligned as precisely as possible with the local main flow direction – that is, the direction in which the flow over the surface in the area of ​​the film is primarily expected. In the case of an aircraft, the main flow direction over the outer wing – which can vary locally across the entire outer wing – results, for example, from the airflow around the aircraft during cruise flight.

[0005] In current technology, aerodynamically functional films, usually in the form of rectangular or square patches in standard sizes, are applied directly to a body exposed to airflow. This requires manual positioning and, if necessary, trimming to fit. Achieving the most precise positioning possible necessitates a complex and, in particular, time-consuming calibration process. For vehicles such as aircraft or high-speed trains, this results in an undesirably long downtime for the application of aerodynamically functional films.

[0006] Document DE 10 2013 102 164 A1 discloses a method for coating the outer skin of an aircraft with shrinkable foil material, the adhesive layer of which begins to flow at the temperature required for shrinkage to the ultimately desired size.

[0007] The object of the present invention is to improve the application of aerodynamically functional films to surfaces of bodies exposed to a flow of air in such a way that the disadvantages known in the prior art no longer occur or only occur to a reduced extent.

[0008] This problem is solved by a device according to claim 1, as well as by a use of the device according to independent claim 4. Advantageous embodiments are the subject of the dependent claims. The invention is defined by the claims. Aspects of this description that are not covered by the claims serve only for clarification and are not part of the invention.

[0009] Accordingly, the invention relates to a device for applying aerodynamically functional films to surfaces of bodies around which a fluid flows, comprising a self-adhesive, removable positioning film with positioning aids for the precise positioning of the positioning film on the surface of the body around which a fluid flows, and at least one application surface for the aerodynamically functional film to be applied, wherein at least one self-adhesive aerodynamically functional film is provided on the adhesive side of the positioning film in the area of ​​the at least one application surface, which adheres to the same surface of the body around which a fluid flows when the positioning film is applied, so that an adhesive connection exists both between the positioning film and the surface away from the at least one application surface and between the at least one aerodynamically functional film and the surface in the area of ​​the at least one application surface.and remains on the surface of the body being encased in fluid after the subsequent removal of the positioning film.

[0010] The invention further relates to the use of a positioning aid according to the invention for applying aerodynamically functional films to surfaces of bodies exposed to a flow, comprising the following steps: a) Applying the positioning film of the device to the surface of the body around which the fluid flows in the position specified by the positioning aids, wherein at least one self-adhesive aerodynamically functional film is provided on the adhesive side of the positioning film in the area of ​​the at least one application surface, such that it is applied simultaneously with the positioning film to the same surface of the body around which the fluid flows in the application surfaces of the positioning film, so that an adhesive bond exists both between the positioning film and the surface away from the at least one application surface and between the at least one aerodynamically functional film and the surface in the area of ​​the at least one application surface; and b) removing the positioning film.

[0011] A film is "self-adhesive" within the meaning of the present invention if, after being applied to a surface, its position and location are essentially fixed. It is not precluded that a self-adhesive film can also be removed from the surface again if necessary, preferably without damage. A self-adhesive film can, for example, be self-adhesive, designed to create a statically adhesive bond with the surface, or magnetic. The self-adhesive bond between the film and the surface can be full-surface or spot-based.

[0012] The invention recognizes that the application of aerodynamically functional films to surfaces in the correct position and orientation can be significantly simplified and accelerated by using a device in the form of a positioning film, without reducing the accuracy of the positioning of the aerodynamically functional film(s). The positioning film is designed as a removable, self-adhesive film, e.g., adhesive film, which is temporarily applied to the surface of a body for positioning the aerodynamically functional film(s) and then removed again after the aerodynamically functional film(s) have been applied.

[0013] The positioning film features positioning aids that allow for precise placement of the film on the surface of the body exposed to the flow. These positioning aids can be edges of the film that are aligned with, or at least in contact with, protrusions or similar features on the surface of the body. Alternatively or additionally, markings can be provided on the positioning film that must be aligned with specific predefined features, such as screws, holes, or joints, on the surface of the body. If the positioning film is applied to the surface of the body according to these positioning aids, correct positioning of the film is ensured.

[0014] Correct positioning of the positioning film ensures that at least one application surface of the film is correctly positioned on the surface of the body exposed to the airflow. The application surface is the area on which the aerodynamically functional film is to be, or is, applied to the surface of the body exposed to the airflow.

[0015] In the embodiment according to the invention, at least one self-adhesive aerodynamically functional film is provided in the area of ​​at least one application surface on the self-adhesive side of the positioning film. This film adheres to the surface of the body around which the positioning film is applied when the positioning film is applied and remains on the surface of the body when the positioning film is subsequently removed. In other words, the aerodynamically functional film and the positioning film initially form a multilayer unit such that when the positioning film is applied in the correct position ensured by the positioning aids, the aerodynamically functional film is also directly adhered to the surface. The position of the aerodynamically functional film on the surface can be directly determined by its position on the positioning film.It is of course also possible to provide more than one application surface and / or aerodynamically functional film on the positioning film in order to provide several areas of the surface of the body around which the flow is directed with an aerodynamically functional film.

[0016] If the positioning film is applied together with the aerodynamically functional film(s) in the application area(s) on the surface of the body around which the airflow is directed, an adhesive bond exists both between the positioning film and the surface – i.e., away from the application areas – and between the aerodynamically functional film(s) and the surface – in the area of ​​the application areas. In particular, the bond between the positioning film and the surface is designed to be removable. The bond between the aerodynamically functional film(s) and the surface, however, is generally not designed for easy removal.If the material bond between the aerodynamically functional film(s) and the surface of the body around which the airflow is directed cannot be removed or at least exhibits a significantly higher adhesion, the positioning film can be peeled off the surface, leaving the aerodynamically functional film(s) in the desired position on the surface of the body around which the airflow is directed.

[0017] It is preferred if, in the case of a required alignment of the aerodynamically functional film on the surface of the body around which the flow is directed – e.g., because it is a riblet film to be aligned along the main flow direction – the aerodynamically functional film is arranged on the positioning film in such a way that the desired alignment of the aerodynamically functional film is achieved after the positioning film has been applied and subsequently removed.

[0018] In the aerodynamically functional film, or at least one of the films, recesses and / or slots can be provided as cutouts for areas on the surface of the body around which the airflow must remain unobstructed. For example, if the aerodynamically functional film is positioned in the area of ​​a flap on the surface of the body around which the airflow is directed, suitable slots in the film can ensure the flap's functionality. Similarly, other openings or sensors on the surface of the body around which the airflow is directed can be kept clear by suitable recesses in the aerodynamically functional film.

[0019] In an embodiment not covered by the claims, an application window is provided in the area of ​​at least one application surface, within which, after application of the removable adhesive film, at least one aerodynamically functional film can be applied to the surface of the body around which the fluid flows. An application window is a recess in the positioning film which, after the positioning film has been applied to the surface of a body around which the fluid flows, indicates the position of the aerodynamically functional film to be applied in a further step and into which the aerodynamically functional film can be applied directly. Once the aerodynamically functional film has been completely applied within the application window(s), the positioning film can be removed.

[0020] It is preferred that the positioning film has alignment aids in the area of ​​the application surface for aligning the aerodynamically functional film to be applied. These alignment aids can be, for example, markings on the positioning film indicating how the aerodynamically functional film to be applied must be oriented, e.g., because it is a riblet film that must be aligned along the local main flow direction.

[0021] Alternatively or additionally, the outline of the at least one application window can be adapted to the shape of the aerodynamically functional film to be applied within at least one application window, wherein the outline of the at least one application window is preferably asymmetrical. In other words, the outline of the application window preferably corresponds to the outline of the film to be applied, so that the film can only be applied to the surface of the body in a flow through the application window in a few possible orientations, thereby reducing the risk of misalignment of the aerodynamically functional film.This can also apply in principle if several film sections are applied through the application window to form the desired aerodynamically effective area on the surface of the body around which the airflow is directed, provided that the film sections forming the outline or surface can each only be positioned in a few positions within an application window.

[0022] The risk of misalignment of the aerodynamically functional film can be almost completely eliminated if the outline of the application window, and thus preferably also the outline of the film to be applied through this application window, is asymmetrical. In this case, the film can generally only be applied through the application window in a single orientation. This also applies in principle even if several film sections are applied through the application window to together form the desired aerodynamically effective area on the surface of the body exposed to the airflow.

[0023] It is also possible to use a second positioning film, designed according to the invention, instead of an aerodynamically functional film whose outline is directly adapted to the edge of the application window. The positioning aids of the second positioning film, on which the final aerodynamically functional film is arranged, can then be adapted to the edge of the application window of the (first) positioning film.

[0024] The positioning film according to the invention can also be used additionally or alternatively for positioning so-called cutting tapes - also called knifeless tapes.

[0025] Appropriate cutting strips are regularly applied to the surface of the body exposed to the airflow before the aerodynamically functional film is applied. After the aerodynamically functional film is applied, the cutting strip is removed, so that the film is trimmed along the cutting strip. These cutting strips allow for the easy application of aerodynamically functional films even to interrupted surfaces, such as access openings in an aircraft fuselage.

[0026] For the precise positioning of cutting bands, these can be applied to the surface of the body around which the flow is directed using a positioning film according to the invention.

[0027] Preferably, at least one cutting strip is applied to the surface of the body around which the fluid flows at the edge of the application area. After the positioning film has been removed, the cutting strip remains on the surface of the body. The aerodynamically functional film can then be applied. Subsequently, the aerodynamically functional film is cut where it extends beyond the cutting strip by removing the cutting strip.

[0028] For an explanation of the use according to the invention, reference is made to the preceding statements.

[0029] The invention will now be described by way of example with reference to advantageous embodiments and the accompanying drawings. These show: Figure 1: Schematic top view of an aircraft wing to be fitted with aerodynamically functional film in specified areas; Figure 2: Kit comprising a device for applying aerodynamically functional film to the aircraft wing according to Figure 1 Figure 3a-c: schematic representation of the use of the kit according to Figure 2 for applying aerodynamically functional film to the aircraft wing according to Figure 1 ; and Figure 4a-b: schematic detailed representation of a variant of applying aerodynamically functional foil with the device made of Figure 2 .

[0030] In Figure 1The wing 1 of a commercial aircraft 2 is schematically depicted in plan view as a body exposed to airflow. A marking 3 is provided on the wing 2, indicating the area 4 of the wing 2 that may be walked on. Within this walking surface 4, areas 5.1-5.5 are provided, which are to be covered with an aerodynamically functional film, namely a riblet film. A flap 6 extends into area 5.3, which, when open, allows access to the engine mount 7. The function of the flap 6 must not be impaired by the aerodynamically functional film to be applied to the area 5.3 in question.

[0031] In Figure 2 A kit 10 is shown, with which the aerodynamically functional film can be quickly and accurately applied to the wing 2 in the desired areas 5.1-5.5.

[0032] Kit 10 comprises a positioning film 11, the upper side of which is shown and which is self-adhesive on the underside in such a way that the positioning film 11 can be removed from the surface to which it is applied without leaving any residue. In the illustrated embodiment, the positioning film 11 is self-adhesive, but it can also be designed to be statically or magnetically self-adhesive. The following descriptions, which refer to the self-adhesive property of the positioning film 11, then apply analogously.

[0033] The positioning foil 11 has three edges as positioning aids 12, which in the state of use correspond to the marking 3 of the tread surface 4 of the wing type for which the positioning foil 11 is intended and as it is shown in Figure 1 as shown, can be brought into alignment, thereby ensuring the correct alignment of the positioning foil 11.

[0034] Furthermore, the positioning film 11 has a number of application surfaces 13.1-13.5 corresponding to the aerodynamically functional areas 5.1-5.5 of the wing 1 to be provided with the film. The application surfaces 13.1-13.5 are each adapted in shape to the areas 5.1-5.5 with which they coincide when the positioning film 11 is properly applied to the wing 1.

[0035] The application area 13.1 is designed as an application window, i.e., as a recess in the positioning film 11, which has an asymmetrical outline. An aerodynamically functional film 14.1 is provided for the application area 13.1, which can only be applied to the wing 1 in a predetermined position within the application window. Thus, the orientation of the aerodynamically functional film 14.1 on the wing 1 is directly determined by the application window, which is why the film 14.1 has a riblet structure corresponding to the expected main flow direction in the area 5.1.

[0036] The application area 13.2 is also designed as an application window, i.e., as a recess in the positioning film 11. However, due to the size of the application area 13.2, the main flow direction can no longer be considered constant across the area. To account for this, two aerodynamically functional films 14.2', 14.2'' are provided, which together completely cover area 5.2 but have different orientations of their riblet structure. To nevertheless enable the simultaneous application of both films 14.2', 14.2'', a second positioning film 15 is provided, on whose self-adhesive underside the two films 14.2', 14.2'' are arranged in the correct orientation relative to each other. The adhesive layer of the films 14.2', 14.2'' is located on the side facing away from the positioning film 15. The application of the two aerodynamically functional films 14.2', 14.2'' is then carried out using the positioning film 15.The process of using the second positioning sheet 15 (2'') will be explained in more detail later.

[0037] In the application area 13.3, the positioning film 11 is continuous and has no recess. Instead, the aerodynamically functional film 14.3 is arranged directly on the underside of the positioning film 11, with its adhesive layer located on the side facing away from the positioning film 11. The aerodynamically functional film 14.3 has slots 16 that correspond to the perimeter of the flap 6 on the wing 4, so that the flap 6 can still be opened even after the aerodynamically functional film 14.3 has been applied in area 5.3. The application of the film 14.3 to the wing 1 will be described in more detail later.

[0038] Application areas 13.4 and 13.5 are rectangular application windows in the positioning film 11, corresponding to the respective areas 5.4 and 5.5. A large number of smaller sections of aerodynamically functional film 14.4 / 5 in a standard size are provided for application areas 13.4 and 13.5, which are to be used to cover areas 5.4 and 5.5 in a tile-like manner. To ensure that the sections of aerodynamically functional film 14.4 / 5 are applied to the wing 1 in the correct orientation in areas 5.4 and 5.5, alignment aids 17 are provided on the positioning film 11, which can be used to align the aerodynamically functional film 14.4 / 5 to be applied.

[0039] Based on the Figures 3a-c The use of device 10 will now be carried out in accordance with Figure 2 for the application of aerodynamically functional foil 14.1-5 in the designated areas 5.1-5 on the wing 1 of the aircraft 2 according to Figure 1 explained.

[0040] In a first, in Figure 3a In the step shown, the positioning film 11 is applied to the wing 1, ensuring that the designated edges 12 of the positioning film 11 coincide precisely with the marking 3 of the surface 4 on the wing 1. Once the positioning film 11 is applied precisely to the wing 1, the application surfaces 13.1-5 coincide with the respective areas 5.1-5 intended for the application of aerodynamically functional films 14.1-5. In area 5.3, the designated film 14.3 is even applied directly to the wing 1 in the correct position and orientation when the positioning film 11 is applied. The slot 16 in the film 14.3 coincides with the edges of the flap 6.

[0041] In the remaining areas 5.1, 5.2, 5.4 and 5.5, the following step (see below) will be carried out. Figure 3b) the respective slides 14.1, 14.2, 14.4 / 5 were applied.

[0042] In area 5.1, the foil 14.1 is applied in the only possible orientation within the application surfaces 13.1 due to the asymmetrical cut. The same applies to the foils 14.2' and 14.2'', which are attached to the second positioning foil 15. By applying the second positioning foil 15 to the wing 1 in a position and orientation relative to the application surface 13.2, as indicated by any positioning aids, the correct positioning of the foils 14.2' and 14.2'' is achieved directly.

[0043] In areas 5.4 and 5.5, the individual foil sections 14.4 / 5 are applied one after the other, resulting in a continuous surface of aerodynamically functional foil 14 that covers the entire areas 5.4 and 5.5. When applying the foil sections 14.4 / 5, care must be taken to align them according to the alignment aid 17.

[0044] Finally, the positioning foils 11, 15 are removed, leaving the aerodynamically functional foils 14.1-5 on wing 1.

[0045] It is of course possible that the aerodynamically functional films 14.1-5 may be further processed after the final application to the wing 1 and before or after removal of the positioning films 11, 15, e.g. to ensure the functionality of further flaps or sensors (not shown).

[0046] In Figure 4a, bThe application and removal of positioning film 11, 15 with an aerodynamically functional film 14.2 / 3 arranged directly on it is shown.

[0047] As in Figure 4a As shown, the positioning film 11 / 15 is adhered to a surface 4 of the wing 1 by means of its removable adhesive layer 11' / 15', wherein in sections that ultimately form application surfaces 13.3, an aerodynamically functional film 14.2 / 3 is provided directly adjacent to the positioning film 11 / 15. The aerodynamically functional film 14.2 / 3 is detachably connected to the positioning film 11 / 15 via the adhesive layer 11' / 15' which is otherwise intended for attachment to the wing 1 and in turn has an adhesive layer 18 with which the film 14.2 / 3 can be permanently bonded to the wing 1.

[0048] The multi-layered arrangement consisting of positioning film 11 / 15 and aerodynamically functional film 14.2 / 3 is applied in a known manner, e.g. by – as in Figure 4a shown - the non-adhesive carrier 19 is gradually removed and the arrangement is pressed onto the wing 1.

[0049] Once the positioning film 11 / 15 has been completely applied, it can then be removed. Due to the removable adhesive layer 11' / 15', the positioning film 11 / 15 can be removed without leaving any residue, while the aerodynamically functional films 14.2 / 3 remain on the wing 1 due to the non-removable adhesive layer 18.

Claims

1. Apparatus for attaching aerodynamically functional films (14.1-5) to surfaces (4) of bodies (1) around which flow passes, comprising a self-adhesive, redetachable positioning film (11) having positioning aids (12) for the exact positioning of the positioning film (11) on the surface (4) of the body (1) around which flow passes and having at least one application area (13.1-5) for the aerodynamically functional film (14.1-5) that is to be applied, wherein provided in the region of the at least one application area (13.3) on that side of the positioning film (11) that is provided with adhesive (11') is at least one self-adhesive, aerodynamically functional film (14.3) which, when the positioning film (11) is being attached, adheres to the same surface (4) of the body (1) around which flow passes, such that there is a respective adhesive connection both between the positioning film (11) and the surface (4) except for the at least one application area (13.3) and between the at least one aerodynamically functional film (14.3) and the surface (4) in the region of the at least one application area (13.3), and, when the positioning film (11) is subsequently removed, remains on the surface (4) of the body (1) around which flow passes.

2. Apparatus according to Claim 1, wherein, when it is necessary to align the aerodynamically functional film (14.3) on the surface (4) of the body (1) around which flow passes, the aerodynamically functional film (14.3) is arranged on the positioning film (11) in such a way that the aerodynamically functional film (14.3) the desired alignment of the aerodynamically functional film (14.3) is achieved after attachment and subsequent removal of the positioning film (11).

3. Apparatus according to one of the preceding claims, wherein the aerodynamically functional film (14.3) has openings and / or slots (13) in the form of cutouts for locations to be kept free on the surfaces (4) of the body (1) around which flow passes.

4. Use of an apparatus according to one of the preceding claims for attaching aerodynamically functional films (14.1-5) to surfaces (4) of bodies (1) around which flow passes, having the following steps: a) applying the positioning film (11) of the apparatus, in the position predefined by the positioning aids (12), to the surface (4) of the body (1) around which flow passes, wherein, in the region of the at least one application area (13.3) on that side of the positioning film (11) that is provided with adhesive (11'), at least one self-adhesive, aerodynamically functional film (14.3) is provided in such a way that it is applied to the same surface (4) of the body (1) around which flow passes, in the application areas (13.1-5) of the positioning film (11), at the same time as the positioning film (11) such that there is a respective adhesive connection both between the positioning film (11) and the surface (4) except for the at least one application area (13.3) and between the at least one aerodynamically functional film (14.3) and the surface (4) in the region of the at least one application area (13.3); and b) removing the positioning film (11).

5. Use according to Claim 4, wherein the aerodynamically functional film (14.1-5) is a riblet film and / or the body around which flow passes is an aircraft (2) or an aircraft wing (1).

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