FR2648876A1 - Wing surface (canopy) with a flexible surface with vortex generators - Google Patents

Abstract

The invention relates to a wing surface with a flexible surface enhanced by the presence of special vortex generators which force the streams of air to attach to the upper wing surface, they thus delay detachment and reduce drag at high curvatures or high incidences, according to the principle of the turbulent boundary layer. The wing surface 1 according to the invention includes, on at least one of its widths 2, vortex generators 3 adapted to the flexible nature of the material of which the upper wing surface consists. The wing surface according to the invention is intended for microlight aircraft for which it enhances the performance at low speed and safety, as well as for vehicles propelled by a wing.

Description

 The present invention relates to a wing with a flexible surface which is improved for light aircraft or for a machine powered by a sail.

 For all types of canopy b known flexible surface, if the curvature of the profile becomes too large, the air streams come off the upper surface; from e-e, if the incidence relative to the apparent wind becomes too strong, there is also a stall of the air streams.

 This can cause loss of wing control as well as a sudden increase in drag.

 These drawbacks are present on all types of sails.

ais more particularly on airfoils with flexible surface, because of their deformability, their care good surface condition and especially their very large curvature and variable parlois.

 The airfoil with flexible surface according to the invention persets to delay the appearance of the stall and therefore to keep an airfoil airfoil at low speed as well as to decrease the treatment induced by the partial stalling of the airfoil, especially when the curvature is very strong.

 The known flexible surface canopies only use the twist to delay the stalling of the ends, and no known device reduces the treated to strong bends.

 The flexible surface canopy according to the invention uses the principle of the turbulent boundary layer, discovered at the beginning of the century by the German aerodynamicist C. Weisselberger: if turbulence is generated in the licit layer, these lower the surface pressure, which delays the detachment of the air tilets. This is the principle used on planes by vortex generators, small metallic fins which generate vortices in the licit layer, which makes It turbulent.

 The device according to the invention is a wing with a flexible surface on which are fixed special vortex generators adapted to the flexible nature of the material constituting the upper surface, and where appropriate to the variable curvature.

 FIG. 1 represents a winged paraglider of a wing (1> according to the invention. On at least one width (2), special vortex generators (3) are fixed.

 The entire airfoil generally peddles several whirlpool generators (3).

 The vortex generating elements (3) can be distributed over the entire span or over a part thereof. Thus, for a paraglider, or may for example place them on or just in front of the corner surfaces to improve the efficiency thereof; if we place the vortex generators close enough to the trailing edge, we will have a lift effect with little drag below a critical curvature and a classic function beyond, from where the generators are located in the turbulent area. With a classic paraglider, you cannot increase the lift without strongly braking, which penalizes the performance.

 The vortex generators can be placed closer to the leading edge towards the ends to delay the stall at this location.

 Figures 2,3,4 and 5 show preferred embodiments of the vortex generating part; for clarity, these figures represent magnifications of the zane marked (4) in Figure 1, seen slightly in perspective.

 The vortex generators (3), monobloc or not, consist of an active vortex generating part and a part intended for fixing, which can be combined.

The active part can be constituted by any non-smooth or prominent structure, since such a structure generates vortices.

 FIG. 2 represents an embodiment where the vortex-generating part is confined by a small obstacle (5) or fin, the surface of which, normal to the width (2), is placed at an angle with respect to the flow of the air. The geometry of the tourbillon generator (3) is adapted to the flexibility and the tension of the width (2): the less the structure is closed, the flatter the profile of the generator (3).

 Figure 3 shows a mode of realization similar to that of Figure 2, know whose part (5) is a simple piece of fabric; it is then raised by the air pressure and held in position by a curved geometry and / or by shackles.

 FIG. 4 represents an embodiment iodine where the vortex-generating part (3) is made up of one or more rougher surfaces than the rest of the airfoil. It is a piece (6), of fabric or a file in synthetic material, attached to the width (2), or which simply replaces a piece.

 Figure 5 shows an iodine of realization or the part generating vortices (3) consists of several fins (7) grouped on the same fixing parts (8).

The part intended for fixing is typically constituted by a hollowed out plate or not or a set of pieces of very light calla material, welded or sewn to the width (2);
FIG. 6 represents an embodiment iodine where the active part (9) is removable from the part intended for fixing (10) and is removed therefrom.

 The airfoil according to the invention can peddle a mixture of generators of vortices of different types.

FIG. 7 represents an ultra-light glider with a wing according to the invention
FIG. 8 represents a sail or windsurfing sail according to the invention.

 The vortex generators can be attached to a conventional flexible surface wing by gluing, welding, sewing, or by a removable Velcro fastener.

 The airfoil according to the invention is intended for paragliders, parachutes and ultra-light gliders, iotorized or not whose performance and safety of use it improves, as well as for vehicles powered by the wind, note the sailboats and the windsurfing boards, of which it improves the perfor.ances with bearing gaits.

Claims (6)

1) Blade with flexible surface (1) characterized in that it peddles, on care one of its widths (2) one or more generators of vortices or turbulence (3) 2) Blade according to claim 1 characterized in that the vortex generators (3), monoblock or not, consist of an active part and a part intended for attachment to the wing. 3) Blade according to claim 1 characterized in that the vortex generators consist of pieces of fabric or rows in synthetic fiber which have a rough surface state, attached to the width or replacing part of it. . 4) blade according to claim 1 or 2 characterized in that the active parts of the vortex generators (3) consist of small obstacles (5) or fins whose surface is sensitive noreale to that of the upper surface, and has an angle non-zero attack relative to the direction of the air streams. 5) blade according to claim 4 characterized in that the active part (5) of the vortex generators <a> (3) is flexible material.  ) Wing according to any one of the preceding claims, characterized in that the vortex generators are fixed to the wing by gluing, welding, sewing or by hook and loop fastening known under the brand "Velcro". 7) Parachute, paraglider, ultralight glider, boat, windsurfing or sand yachting according to any one of the preceding claims.  8) Parachute or paraglider wing according to any one of claims 1, 2, 3, 4, 5 or 6, characterized in that vortex generators are placed on the light surfaces or slightly ahead of them. 9) Wing according to any one of the preceding claims, characterized in that the active part (9) of the generators