Estimation on the Underwater Explosion Equivalent Based on the Threshold Monitoring Technique

Yan Wang,De Nan,Jian Li,Zhehan Liu,Wei Tang,Shiya Zou,Xiaoming Wang,Chao Tao

doi:10.1155/2021/1933744

Abstract

Underwater nuclear explosions can be monitored in near real-time by the hydroacoustic network of the International Monitoring System (IMS) established by the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which could also be used to monitor underground and atmospheric nuclear explosions. The equivalent is an important parameter for the nuclear explosions’ monitoring. The traditional equivalent estimation method is to calculate the bubble pulsation period, which is difficult to obtain satisfactory results under the current conditions. In this paper, based on the passive sonar equation and the conversion process of acoustic energy parameters in the hydroacoustic station, the threshold monitoring technique used for underwater explosion equivalent estimation was studied, which was not limited to the measurement conditions and calculation results of the bubble pulsation period. Through the analysis of practical monitoring data, estimation on the underwater explosion equivalent based on the threshold monitoring technique was verified to be able to reach the accuracy upper boundary of current methods and expand the measurement range to further ocean space, along with the real-time monitoring capability of IMS hydroacoustic stations which could be estimated by this method.

Highlights

Introduction e Comprehensive Nuclear-Test-Ban Treaty was adopted by the United Nations General Assembly on 10 September 1996 [1]. e purpose of the CTBT is to prohibit all States Parties from carrying out any form of nuclear weapon test explosion or any other nuclear explosions, which is of great significance to promote the comprehensive prevention of the proliferation of nuclear weapons in all its aspects, to the process of nuclear disarmament, and to the enhancement of international peace and security
International Monitoring System (IMS) hydroacoustic monitoring network is composed of 11 hydroacoustic stations, including 6 hydrophone (H-phase) stations and 5 T-phase stations. ese stations are designed to monitor the oceans all over the world and detect signals that might originate from any underwater nuclear test [2]. ese deep sound channel hydrophones could be used to detect and locate underwater explosions with long distance [3]. erefore, the location and equivalent estimation are the study emphases within the underwater explosion monitoring field
Underwater explosions could produce gas bubbles. e expansion and contraction of gas bubbles could induce a series of bubble pulses: the first one comes from the explosion, the second one comes from bubble collapse, the third one comes from the expansion again, and so on. ere are many studies on the measurement of bubble pulsation

Summary

Methods

Different from the active sonar, passive sonar has no transmitting system and detects underwater targets and their state by receiving the radiated noise of the target. Ere are three basic links in the information flow of the passive sonar, including sound source, seawater channel, and hydrophone array. Sonar parameters include source level SL, transmission loss TL, target strength TS, ocean environment noise level NL, receiving directivity index DI, and detection threshold DT. If the difference between the received signal level and the background noise level is less than the detection threshold, the target cannot be detected by the sonar system. E acoustic model can be obtained by the simulation test, including the maximum pressure and acoustic energy spectrum of the underwater explosion. Considering equations (3) and (4) and assuming R 1 m and the peak pressure Pm P, the relationship between the peak pressure of the underwater explosion water Radiated nosie

Reception array

Underwater explosion

Conclusions