Study on single raindrop noise and energy conversion

Abstract

The measurement of rainfall in the ocean is more difficult than in land, but the noise signals produced by rainfall can be used for measuring the rainfall in the ocean. In this paper, a single raindrop measurement system was set up to measure the noise of the raindrop, the bubble sound are classified by the radius of the raindrop which was measured by the splash method. The mechanism of the initial impact and the bubble sound are analyzed, and the kinetic energy threshold and acoustic energy conversion efficiency of the single raindrops are also investigated. The results show that the bubble noise is the main noise compared with initial impact noise, the initial impact noise will become larger with the radius of raindrop, the acoustic energy of great and large raindrop is much larger than that of small one, but the tiny and medium raindrop have no acoustic energy. The kinetic energy threshold is not a constant, but it is proportional to the raindrop size.The acoustic energy conversion rate is about 1.04×10-3% for small raindrops, 10-5% for heavy rains and great raindrops, there are almost no acoustic energy for tiny raindrops and medium-sized raindrops.