Simulation and Statistical Modeling of Acoustic Scattering of Bubble Wakes

Zhu Ling-Guo,Wang Jin,Cao Qing-Gang,Zhao An-Bang,Yang Bao-Shan,Ma Zhong-Cheng

doi:10.1155/2018/3242703

Zhu Ling-Guo, Wang Jin + Show 4 more

Open Access

https://doi.org/10.1155/2018/3242703

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Abstract

Ship wakes are large, exist for a long time, and are difficult to disguise or conceal. These characteristics can be used as an important basis for ship tracking and recognition. However, distinguishing between wakes, underwater targets, and sea surface is a difficult problem that currently limits acoustic wake homing technology. To solve this problem, in this study, from the viewpoint of feature recognition, the effects of bubble radius, air volume fraction, frequency, depth, and other parameters on the group bubble were first investigated. The volume scattering intensity of acoustic wakes at different frequencies and depths was also calculated and analyzed, and the results of our theoretical calculations were verified through an experiment using a multifrequency single wave sonar dock. Subsequently, through the single frequency and multibeam sonar sea trial test, a statistical model of target characteristics with a clear physical mechanism was developed. The developed model can be utilized for the guidance and recognition of acoustic wake targets. Thus, this study lays the foundation for the practical application of acoustic wake guidance.

Highlights

As a type of underwater acoustic target, a bubble wake is the main source of information for detecting and identifying underwater targets by torpedoes and sonars
In this study, starting from bubble dynamics, we investigated the motion of bubbles in the sea water under good hydrology and deduced the volume scattering intensity of the wake of the target with changes in frequency
According to the second law of thermodynamics, when a bubble is forced to vibrate, part of the sound energy is used to counteract the work done owing to the friction force of the bubble’s vibration, which is released in the form of heat

Summary

Introduction

As a type of underwater acoustic target, a bubble wake is the main source of information for detecting and identifying underwater targets by torpedoes and sonars. During the middle and late stages of World War II, the United States measured and analyzed the acoustic characteristics of wakes of more than ten types of ships, from yachts to destroyers, conducting many measurements and compiling the results into monographs [6, 7]. Donghua et al used the improved Reynolds average Navier-Stokes flow model and bubble transport theory to calculate and analyze the number density (BND) distribution of the wake bubble [12]. No detailed sea test and analysis of the characteristics of ship acoustic wakes have been conducted. In this study, starting from bubble dynamics, we investigated the motion of bubbles in the sea water under good hydrology and deduced the volume scattering intensity of the wake of the target with changes in frequency. Using high-performance test equipment, we conducted several sea tests on the target wake of a surface ship at typical frequencies, extracted the clear and stable acoustic characteristics of the acoustic wake, and subsequently developed a statistical model of target wake characteristics for target guidance and recognition of acoustic wake targets

Acoustic Scattering Modeling of Bubble Wakes

Experimental Details and Results

Conclusions