抄録
This paper presents development research of a silencer called “multi degree of freedom type Helmholtz resonator”. It was newly developed and its attenuation characteristics (transmission loss and insertion loss) were investigated theoretically and experimentally. Unlike a conventional Helmholtz resonator, this device has a feature that it is possible to adjust freely the resonance modes to desired resonance modes, i.e., the desired resonance frequencies and mode shapes, with a single closed-end cylindrical tube configuration. The present resonator was devised in order to attenuate the successive several harmonics of fixed discrete-frequency pressure pulsation such as those generated by a fixed speed hydraulic pump. A successful mathematical means (optimum design method) of sizing the desired variables so that the plural resonance frequencies coincide with the desired ones is outlined. Calculated (designed) attenuation characteristics of the present resonators, which are designed under three kinds of constraint conditions, i.e., constraint condition of transmission loss, amplitude of pressure pulsation after silencer insertion and insertion loss at the desired objective resonance frequencies, all agree well with experimental results.
