It is shown by this experiment that an appreciable first subharmonic component(one-half of driving frequency)can be observed when a traoelling wave of low-intensity sound goes through the disturbed water in a tank.
An acoustical inversion method to measure parameters, such as the distributions of thesizes, the volume concentration of bubbles and the thickness of the bubbly curtain, is pro-posed. A concept of equivalent incidence...An acoustical inversion method to measure parameters, such as the distributions of thesizes, the volume concentration of bubbles and the thickness of the bubbly curtain, is pro-posed. A concept of equivalent incidence is introduced to describe the sound interactionsamong bubbles. Thus, the problem of multiple bodies can be reduced into a single-body one.By taking the distributions in the sizes of bubbles into account, the covibration mass, thedamping constant and the stiffness as well as the complex wavenumber can be given. Thesound interactions result in a dependence of mass and stiffness of bubbles upon frequency.leading to a double-peak resonance, increasing the damping constant and decreasing thesound attenuation. Using the complex wavenumber to denote the wavenumber in bubbly cur-tain, the problem of reflection and transmission from it can be considered as a three-layer-medium one. Optimization methods are used to invert the parameters of the bubbly cur-tains. Comparisons of the the ory with our experiments are given.展开更多
文摘It is shown by this experiment that an appreciable first subharmonic component(one-half of driving frequency)can be observed when a traoelling wave of low-intensity sound goes through the disturbed water in a tank.
基金Project supported by the National Natural Science Foundation of China and China State Shipbuilding Coorperation.
文摘An acoustical inversion method to measure parameters, such as the distributions of thesizes, the volume concentration of bubbles and the thickness of the bubbly curtain, is pro-posed. A concept of equivalent incidence is introduced to describe the sound interactionsamong bubbles. Thus, the problem of multiple bodies can be reduced into a single-body one.By taking the distributions in the sizes of bubbles into account, the covibration mass, thedamping constant and the stiffness as well as the complex wavenumber can be given. Thesound interactions result in a dependence of mass and stiffness of bubbles upon frequency.leading to a double-peak resonance, increasing the damping constant and decreasing thesound attenuation. Using the complex wavenumber to denote the wavenumber in bubbly cur-tain, the problem of reflection and transmission from it can be considered as a three-layer-medium one. Optimization methods are used to invert the parameters of the bubbly cur-tains. Comparisons of the the ory with our experiments are given.
