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Impedance eduction from energy dissipation measurements with flow |
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| Authors: | Christoph Richter Frank Thiele Stefan Busse Claus Heuwinkel Ingo Röhle Lars Enghardt Ulf Michel |
| Affiliation: | 1. Technische Universität Berlin, Sekr. MB1, Müller–Breslau–Str. 8, 10623 Berlin;2. Deutsches Zentrum für Luft– und Raumfahrt e. V., Institut für Antriebstechnik;3. Technische Universität Berlin, Sekr. MB1, Müller–Breslau–Str. 8, 10623 Berlin Deutsches Zentrum für Luft– und Raumfahrt e. V., Institut für Antriebstechnik |
| Abstract: | An optimization method for the calculation of the wall impedance of a perforate from measurements under grazing flow conditions is presented. It is in particular characterized by the simultaneous eduction of the parameter set defining the impedance as function of frequency, which allows interpolation and extrapolation. The Extended Helmholtz Resonator is applied as impedance model and the simultaneous eduction is performed using a time–domain CAA method. Furthermore, the method uses processed energy data from experiments to define the objective function. The results give an insight in the effect of bias flow on the wall impedance under grazing flow conditions. It proves to be an important acoustic design parameter. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
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