The initial results of a test series are reported to evaluate a method for extracting the normal-incidence impedance of a locally reacting, acoustically absorbing linear located on the lower wall of a duct in a grazing-incidence, multimodal, nonprogressive acoustic wave environment without flow. This initial evaluation tests the method's ability to converge to the known normal-incidence impedance of a solid steel plate, and to the normal-incidence impedance of an absorbing test specimen whose impedance has been measured in a conventional normal-incidence tube. The method converges to the normal-incident impedance values and thus is an adequate tool for extracting the impedance of specimens in a grazing-incidence, multimodal, nonprogressive acoustic wave environment for a broad range of source frequencies.
Validation of a numerical method for extracting liner impedance
Überprüfung eines numerischen Verfahrens zur Ermittlung der Auskleidungsimpedanz
AIAA Journal ; 34 , 3 ; 548-554
1996
7 Seiten, 12 Bilder, 2 Tabellen, 9 Quellen
Article (Journal)
English
Flugzeugtriebwerk , technische Akustik , Lärmminderung , Schallwelle , Schallfortpflanzung , Wellenausbreitung , Mach-Zahl , partielle Differenzialgleichung , Versuchsanlage , numerisches Verfahren , Finite-Elemente-Methode , Randbedingung , Rohrströmung , Luftströmung , Schallpegel , akustische Eigenschaft , Schalldruck , akustisches Messverfahren , Impedanz (akustisch) , Rohrauskleidung , praktische Untersuchung , Helmholtz-Gleichung
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