Study On Mechanical And Acoustic Characteristics Of An Underwater Acoustic Source Bomb

Underwater explosive acoustic source is the most commonly used signal source in ocean acoustic experiment and underwater acoustic countermeasure because of its advantages of broadband,high power,directionless.However,the study of acoustic source characteristics of underwater explosion has always been a concern in the field of explosion mechanics and underwater acoustic.At present,scholars mainly focus on the explosion process,shock wave characteristics and damage effect of underwater explosion,and the measurement of sound pressure level and the separation and processing of acoustic signals.However,there is no effective means to obtain the energy evaluation of underwater explosion acoustic source by measuring acoustic parameters.In this paper,taking an underwater acoustic source bomb as the research object,according to the transformation relationship between the mechanical and acoustic characteristics of underwater explosion acoustic source,the pressure field of underwater explosion is calculated by numerical simulation,and its mechanical characteristics are analyzed.Then the acoustic characteristics and acoustic field characteristics of the acoustic source are obtained by acoustic conversion of the explosion pressure field,and the basic work of energy evaluation of underwater explosion acoustic source is completed by measuring the acoustic parameters.The main contents of this paper include the following aspects:The theoretical analysis method of underwater explosion sound source characteristics is studied to provide theoretical basis for the subsequent underwater explosion simulation.The transient phenomena of underwater explosion,such as physical characteristics of underwater explosion,energy distribution of charge explosion and dissipation process,are introduced and analyzed.The calculation methods of mechanical and acoustic parameters of underwater explosion are studied.A land-based static explosion test method is proposed to measure the explosion shock wave overpressure,and the shock wave overpressure is transformed in to the explosion sound source level,which solves the problem that the underwater explosion test is expensive and difficult to measure the sound source level.In this method,AUTODYN simulation software is used to simulate the static explosion process of large equivalent charge with shell under ideal condition,and the overpressure values of several calibration points are obtained.Then,the shock wave overpressure is transformed into sound source level by COMSOL simulation software.Finally,the effectiveness of the simulation calculation is verified by land-based static explosion experiment.The propagation characteristics of underwater explosion sound in aquatic media are studied.The formation,propagation and attenuation process of underwater explosion are obtained firstly.The influence of boundary conditions on the propagation process of underwater shock wave is analyzed,and the pressure time history curves of underwater shock wave at different distances are obtained.Then,the pressure signal of shock wave is used as input parameter to simulate the sound field of underwater explosion.The distribution of sound field and the propagation law of explosion sound in underwater medium are given,and the variation law of acoustic characteristic parameters is analyzed and summarized.