Experiment of Underwater Acoustic Produced by Single Drop Impacts

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 is described in this article. Three kinds of acoustic radiation named impact sound, irregular bubble sound and delay bubble sound are distinguished by the pressure time trace. The images of bubbles taken near the point where the drop falls into water are shown. Some statistics laws of initial impact sound and irregular bubble sound affected by different condition included wind levels, heights of free fall and drop sizes are concluded. The directionality of initial impact sound is measured with wind and no wind. The process of delay bubble entrainment is analyzed and the measurements of bubble excitation probability in different condition are listed.