Abstract: A wind tunnel with a closed section for aeroacoustic measurements with an anechoic coating including: a) a first cavity having a thickness D1 in a range of 20?D1?50 mm filled with a fibrous material with a flow resistance R in a range of 10?R?50 kRayl/m; b) a first microperforated panel having a thickness t1 in a range of 0.25?t1?0.75 mm and with a perforation percentage p1 in a range of 15%?p1?30%; c) a second air cavity having a thickness D2 in a range of 10?D2?30 mm; d) a second microperforated panel having a thickness t2 in a range of 0.25?t2?0.75 mm and with a perforation percentage p2 in a range of 15%?p2?30%. The perforations of the panels can be circular or longitudinal slot-shaped having a diameter d or width w in a range of 0.2?d, w?0.5 mm.

Abstract: A wind tunnel with a closed section for aeroacoustic measurements with an anechoic coating including: a) a first cavity having a thickness D1 in a range of 20?D1?50 mm filled with a fibrous material with a flow resistance R in a range of 10?R?50 kRayl/m; b) a first microperforated panel having a thickness t1 in a range of 0.25?t1?0.75 mm and with a perforation percentage p1 in a range of 15% ?p1?30%; c) a second air cavity having a thickness D2 in a range of 10?D2?30 mm; d) a second microperforated panel having a thickness t2 in a range of 0.25?t2?0.75 mm and with a perforation percentage p2 in a range of 15%?p2?30%. The perforations of the panels can be circular or longitudinal slot-shaped having a diameter d or width w in a range of 0.2?d, w?0.5 mm.

Abstract: It is applied in those processes in which it is required to modify the configuration of a first piece (1) for which, when joined to a second piece (2), for carrying out different tests, as is the case of measurements of aerodynamic properties of objects in a wind tunnel, it is required to modify the first piece, which implies modifying the coupling part of the second piece (2) on the first piece (1). The invention avoids manufacturing the complete second piece (2) with each new design of the first piece (1), for which the latter is designed and manufactured with a fixed configuration, valid for any possible configuration (1a, 1b) of the first piece (1) and which lacks the coupling part (3) with the first piece (1) in such a way that a third piece (3) is designed and manufactured corresponding to the coupling part between the configuration (1a, 1b) of the first piece (1) and the second piece (2) for carrying out the joint between both, with each design of the first piece.

Abstract: The dummy elements (1) are pieces which are backed on to the object to test for measurement of aerodynamic properties. Once the geometry is known that the dummy element has to have on account of flight conditions, atmospheric conditions and the original aerodynamic surface, the shape of the dummy element (1) is reproduced by stereolithography, at the same time forming certain extensions (4) which follow the aerodynamic geometry of the object (3) and which are located in strategically selected positions, the whole acting by way of a negative template which is restricted to and follows the shapes of the leading edge. An adhesive is then applied to the surface of the dummy element (1) without it affecting the extensions (4) since they then have to be removed.