Study On The Influence Of Air Interlayer On Underwater Explosion Energy And Vibration

With the development of marine resources and underwater blasting technology,underwater blasting engineering is gradually increasing,and the problem of underwater blasting safety protection has been paid more and more attention.In the field of military industry,the requirements of the modern naval vessels to the impact resistance of underwater torpedoes are also increasing,and the research on the new type of lightning protection cabin structure has gradually become the focus of research.The study of underwater explosion parameters measurement and the control of the harmful effects of explosion have important research value and significance in both civil and military marine protection engineering.In this paper,the underwater explosion pressure tests of different sizes of air interlayer protection structures were carried out at the(05.5m,H3.62m)small pool in Anhui University of Science and Technology,and the influence of air interlayer structure on underwater explosion energy was studied.The vibration signals were monitored by the UBOX-6016 vibration testing instrument,and the influences of the air interlayer structure on the maximum vibration velocity and main vibration frequency were studied.Numerical simulation software was used to simulate the protection of large amount of explosive underwater explosion air interlayer.HHT software(Hilbert-Huang)was used to analyze the vibration monitoring signals by writing related procedures using Matlab software,the influences of air interlayer on the global frequency of vibration signal were studied.Based on the experiment and simulation analyses,the following conclusions were obtained under the existing experimental conditions:(1)The influence of air interlayer structure on underwater explosion parameters.Effect on the peak pressure:The air interlayer can effectively attenuate the peak pressure,the measured attenuation rate of the peak value at 0.3m reached 49.57%?5.93%,the attenuation rate excluding shell effects reached 54.14%?92.47%.And the measured attenuation rate of the peak value at 0.5m reached 59.36%?75.09%,the attenuation rate excluding shell effects reached 80.47%?100.87%.(2)The influence of air interlayer structure on underwater explosion energy.Effect on underwater explosion output structure:Under the action of air interlayer,the energy output structure of underwater explosion changed:The proportion of specific shock wave energy accounted for total energy at 0.3m dropped from 40.98%?37.85%to 13.89%?1.64%.The proportion of specific shock wave energy accounted for total energy at 0.5m reduced from 37.46%?26.37%to 13.33%?2.55%.The ratio of specific bubble energy to total energy increased accordingly.(3)The influence of shell sizes on underwater explosion parameters:With the increase of the radius of interlayer structure,the proportion of bubble pulsation peak pressure accounted for the peak pressure of shock wave was gradually increased.That is,under the constraint of the shell,the impact of the shock wave was weakened,and the pulsation of the bubble was strengthened.(4)The influence of air interlayer structure on the impulse value of underwater explosion:The effect of air interlayer can obviously reduce the impulse value of underwater explosion,the attenuation rate at 30cm reached 64.48%?82.99%,and the attenuation rate at 50cm reached 50.75%?73.68%.The attenuation rate of impulse value was biggest when the interlayer thickness reached between ?80mm??120mm.(5)The influence of air interlayer structure on the vibration of the adjacent foundation of the explosive pool.The influence on the maximum vibration velocity:With the increase of the thickness of the air interlayer,the vibration velocity decreased first and then increased,and the vibration velocity was smallest when the air interlayer thickness was 120mm.The equation of the air thickness to the attenuation of vibration velocity was fitted,which can provide guidance for the design of blasting vibration protection.Effect on global frequency:The amplitude of the global frequency can be obtained by the HHT method.Under the action of the air interlayer structure,the amplitude of the 5Hz-15Hz interval decreased obviously,and the acting time was shortened.The protective effect was better when air interlayer thickness was between ?80mm??120mm.The experimental results and analysis in this paper have certain theoretical reference value for the underwater explosion hazard protection in the field of engineering blasting and the structural design of the lightning protection of naval craft in the military field.