The dynamics of a spark-generated bubble (a discharge short circuit) generated in proximity to a stationary air bubble attached to a plate is experimentally investigated by high-speed photography. Numerous interesting and complex interactions occur during the two bubble coupling pulsation owing to the deformation properties or “free surface” characteristics supplied to the plate by the attached air bubble. Complex bubble jetting behaviors, such as bubble splitting, jets away from the plate, variable directional jets, and multidirectional jets are observed. Passive pulsation of the air bubble is observed in response to the spark bubble. Moreover, five types of bubble behaviors are summarized: bubble coalescence, the air bubble skirt phenomenon, the “mountain”-shaped bubble, and the “cup cover”-shaped air bubble with or without splitting. To develop a better understanding of the coupling interactions between the two bubbles during their oscillations, four types of bubble volume–time curves are summarized using the image outline identification code established to obtain information regarding the bubble shape. The complex phenomena during the two-bubble interactions, such as the bubble jetting direction, air bubble shapes, and volume–time curves, are summarized as graphs and are highly dependent on the bubble size ratio, dimensionless cavitation bubble oscillation time, and initial displacement parameter.
The sound insulation of a sandwich plate system (SPS) was measured by the sound pressure method in fixed support boundary conditions and reverberation sound field. The results were compared with those obtained using the finite element method. The sound insulation curves obtained via experiments and numerical simulation were observed to be in agreement. This indicates that the numerical simulation method can effectively reflect the sound insulation performance of the structure. In addition, the influence of different parameters on the sound insulation performance of the structure was evaluated using the finite element method, and the weight of each parameter in the influence of sound insulation was ranked by applying the function of “fsrftest” in the software MATLAB. It was found that in the low-frequency domain, the length-to-width ratio of the SPS had the most significant effect on the sound insulation performance of the structure, and the mass ratio of the panel to core exerted the least influence on it. Furthermore, in the medium- and high-frequency domain, the main factors affecting the sound insulation were different in the different frequency ranges, and the frequency range should be considered during the design of the structure. The results can provide technical support for the analysis of the sound insulation performance of SPSs.
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