金属导爆索网栅结构水下爆炸声学特性研究

为了获得连续水下爆炸声源,文章设计了金属导爆索网栅结构,并开展了水下爆炸压力测试和气泡脉动实验,研究了金属导爆索网栅结构水下爆炸的声压级特性,水下爆炸的声持续时间,对应的混响效应,利用Hilbert-Huang变换对水下爆炸信号的频谱特性进行了分析.研究结果表明:金属导爆索网栅结构水下爆炸可根据设计连续产生多个脉冲冲击波信号,形成近似平稳的连续波,随后产生的气泡脉动和混响效应能够明显提高水下爆炸声的持续时间;金属导爆索网栅结构具有很强的声功率,水下爆炸声压级最高能够达到249 dB,爆炸60 ms后金属导爆索的爆炸声压级仍在200 dB以上;金属导爆索网栅结构水下爆炸声频率范围广,在100 kHz以下低频段能量最高.金属导爆索网栅结构水下爆炸脉冲信号频率成分丰富,具有低频和瞬时的特点,且大部分集中在100 kHz以下,尤以50 kHz以下的最为明显;脉冲信号具有多个能量峰值,能量值较集中,波动能量基本上都集中在频率为100 kHz范围以内,尤以50 kHz以下的低频能量最大,高于100 kHz以上频段的能量的分量很小.脉冲冲击波的个数和声持续时间可由金属导爆索网栅的排列方式和长度控制,脉冲冲击波间的时间间隔可调,发生装置稳定易控.

Acoustic Characteristics of Underwater Explosion about Metal Grid of Detonating Cords

To obtain a continuous sound source of underwater explosion, metal grid of detonating cords was designed. The pressure tests and the bubble pulsation experiments were conducted to investigate sound pressure level properties, sound duration and reverberation effect of underwater explosion about metal grid of detonating cords. The spectrum characteristics of underwater explosion signal were an-alyzed with Hilbert-Huang transform. The results showed that underwater explosion about metal grid of detonating cords could produce more than one pulse wave signal continuously, and form stable continuous wave. Subsequently, the produced bubble pulsation and reverberation effect could signifi-cantly improve the duration of underwater explosion. Detonating grid structure, had a strong sound power, and the highest sound pressure level of underwater explosion could reach 249 dB. Even after blasting 60 ms, the sound pressure level of the detonating cords was still above the 200 dB. Frequen-cy range of the underwater explosion sound about metal grid of detonating cords was wide and be-came the highest when the energy of the low frequency band was below 100 kHz. The frequency com-ponents of the pulse signal were rich, and had the characteristics of low frequency and instant, and most of them were below 100 kHz, especially 50 kHz. The pulse shock signal had multiple energy peaks, and the energy value was more concentrated. The fluctuation energy was basically concentrat-ed on the frequency range of 100 kHz, especially, the energy of the low frequency of below 50 kHz was the largest. Moreover, for the frequency above 100 kHz, their energy components were very small. The number and duration of the pulse shock wave could be controlled by the arrangement and the length of metal grid of detonating cords. The time interval between the pulse shock wave was ad-justable, and the device was stable and easy to control.