Elliptical side resonators for broadband noise reduction: theory and experiments

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Previous research of the authors pointed out that side-resonators can be applied to reduce fan noise. However, the noise reduction capabilities of most resonator geometries, e.g. tube resonators, cylindrical resonators (cylindrical air layers) and circular resonators (disc shaped air layers), are relatively narrow banded. This is disadvantageous in case resonators are used in combination with a noise source that emits broadband noise or tonal noise at varying frequencies (for instance a speed controlled fan). It was found that the choice of the resonator geometry influences the broadband reduction capabilities (circular resonators offering the best broadband reduction capabilities). In the present study, it is investigated to what extent elliptical resonators, consisting of an elliptically shaped air layer, can be used to achieve broadband noise reduction. A semi-analytical model is proposed that describes the wave propagation in the elliptically shaped air layer. This model is connected to the analytical solution for wave propagation in a tube. The dimensions of the elliptical resonator can be optimized for broadband noise reduction using this model. In addition, an experimental setup was built to verify the semi-analytical model of the elliptical resonator.
Original languageUndefined
Number of pages8
Publication statusPublished - 2006
Event13th International Congress on Sound and Vibration, ICSV 2006 - Vienna, Austria
Duration: 2 Jul 20066 Jul 2006
Conference number: 13


Conference13th International Congress on Sound and Vibration, ICSV 2006
Abbreviated titleICSV


  • IR-58882

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