FILTERING CHARACTERISTIC OF RESONANCE CHANGER USED FOR LONGITUDINAL VIBRATION CONTROL OF MARINE SHAFTING

A resonance changer is an effective device expected to be used for the longitudinal vibration control of marine propulsion shafting. The work focuses on the filtering characteristic of a resonance changer. With the modular modeling conception, the transfer matrix equations describing the dynamic behavior of components of a resonance changer are deduced. In conjunction with boundary conditions, the fluctuating pressure transfer function of internal hydraulic oil is derived. By analyzing the amplitude spectrum, it shows that the resonance changer emerges anti-resonance phenomenon at the natural frequency of a branch, which can be used for amplitude attenuation of fluctuating pressure. This amounts to filter the fluctuating pressure of a certain frequency. The anti-resonance amplitude is closed with the minimum impedance of a branch, and the measure of decreasing the minimum impedance of a branch can improve the filtering effect of a resonance changer. Since the filtering frequency band of a resonance changer with a single pipe and a single chamber is too narrow, three modified resonance changers are presented.