Archives of Acoustics, 29, 1, pp. , 2004

The response of Helmholtz resonator to external excitation. Part I: Acoustically induced resonance

M. Meissner
Institute of Fundamental Technological Research Polish Academy of Sciences

The first of two companion papers theoretical and
experimental results are presented for a Helmholtz resonator subject to external
excitation by an acoustic plane wave. The response of the resonator was analysed
in terms of the relation between the pressure induced in the interior of the
resonator and the driving pressure. Equations for the resonance frequency and
the quality factor were developed for the cavity that was a rectangular
parallelepiped with a centered circular orifice. The flow from the cavity had a
constant velocity profile. The resonator was modelled by an equivalent impedance
circuit, predicted from the classic theory of sound radiation, with an
additional resistive term connected with the viscous action inside the orifice.
The theoretical results were compared with experimental data for a frequency
chosen so as to tune the system to the lowest resonance mode. The experiment has
shown that the acoustic response of resonator was changed considerably when
mechanical vibrations of the resonator elements were excited. A phenomenon of
flow-induced resonance in the considered system geometry will be presented in
the companion paper.
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