Wind tunnel with a closed section for aeroacoustic measurements with an anechoic coating

摘要

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.