Thèse de doctorat en Acoustique
Sous la direction de Jean-Louis Guyader.
Soutenue en 2009
à Lyon, INSA .
The present work deals with the thermoviscous characteristics of the fluids in reducing the radiated noise levels. Various configurations with varying cases have been considered to demonstrate the effectiveness of thermoviscous properties of the medium in noise elimination. The configurations studied are essentially kept simple and emphasis is rather put on finding the trends than solving complicated industrial problems. By and large, the investigation is limited to only regular structures, however, the fluids are studied in a comprehensive manner. A general fluid model is introduced which permits to examine any medium, provided the characteristics of the fluid are known. The proposed model relies on the simultaneous solution of the full set of Navier Stoke’s equations and hence is essentially different from the contemporary solution methods. A 3D solution is obtained using modified differential operators. This model is applied on the simple plates initially and later on the double wall panel. The theoretical results are encouraging in showing considerable gain in sound isolation with the use of thermoviscous media. Results for both air and water are shown. Experimental validation has been performed also. Differences are indicated in the text and appropriate reasons given
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