The Research Of Underwater Sound Produced By Water-drops Impact

When rain falls on the water surface, the power spectrum density of underwater soundpossesses unique characteristics. Several elementary attempts to predict underwater soundpower spectrum density produced by precipitation parameters and to inverse someprecipitation parameters by unique sound power spectrum density are discussed.Firstly, an experimental study of the underwater sound produced by single drop impacts,influenced by different wind speeds, free fall heights and drop-sizes at different depths, isdescribed. Three kinds of acoustic radiation are distinguished by a typical pressure-time trace.Some statistics laws of initial impact sound and irregular bubble sound, affected by differentcondition, are concluded. The process of delay bubble entrainment is photographed byunderwater camera and the measurement of bubble entrainment probability is listed. Secondly,the simulation model of multiple water-drops impact noise is constructed by the noise dateproduced by single drop impacts. The simulation model is testified not bad, throughcomparisons with laboratory experiment. The radiation pattern and the attenuation law ofmultiple water-drops impact noise are measured. Finally, the linear artificial neural networkmodel to inverse single drop impact noise energy spectrum density is constructed by Medwintheory formula. The uniqueness of the inversion solution is discussed by matrix analysis. Theapplicability and stability of the inversion system are researched by three different trainingprocesses. In addition, the theory method and simulation of water-drops granularitydistribution inversion are discussed. Only when water-drops are partitioned suitably, that thenoise energy spectrum density impacted by different water-drops are dissimilar remarkably,the inversion of water-drops granularity distribution is correct.