| Underwater explosion is able to release great energy in a short time.The shockwave load and bubble load can cause the destruction of structures in water.In the bubble pulsation stage of underwater explosion,the bubble produced by explosion may produce jet phenomenon due to gravity or boundary effect.At present,a large number of studies have shown that the jet load caused by underwater explosion bubble can greatly damage the ship structure and shipboard equipment.With the focus of the world’s military strategic competition gradually shifting to the struggle of sea control,the status of underwater explosion research in national defense construction is more and more obvious,and all naval powers pay more attention to the research of underwater explosion and further increase the research investment.The research on underwater explosion in China started late,and due to technical limitations,the research level of underwater explosion is far lower than that in other developed countries.The existing research mainly focuses on the damage characteristics of shock wave load and high-speed fragment load on the protective structure,but does not pay attention to the research on the formation of water jet when the underwater explosion bubble interacts with the free surface.In view of the lack of research on the characteristics of water jet formed by the interaction between underwater explosion bubble and free surface at home and abroad,this study uses the large-scale finite element software LS-DYNA,and adopts the arbitrary Lagrange Euler algorithm to study the influence of the explosive quantity and explosion depth on the jet velocity,jet height and jet width of the water jet formed by the interaction between underwater explosion bubble and free surface.To sum up,the main contents of this paper are as follows:(1)In this paper,the research and development status of underwater explosion and bubble jet were summarized from three aspects of theoretical research,experimental research and numerical simulation,and the necessity and feasibility of studying the characteristics of water jet were analyzed.(2)In this paper,the effectiveness of the ALE algorithm in simulating the bubble pulsation process is verified by experiment and theory,and the result proves that the numerical model based on the ALE algorithm can simulate the bubble pulsation process of underwater explosion well.(3)In this paper,based on ALE algorithm,the characteristics of water jet formed by the interaction between the underwater explosive bubble and the free surface during the pulsation are studied.Through the research,the following conclusions were found: 1)The characteristics of water jet formed by the interaction of underwater explosion bubble and free surface have a great relationship with the explosion depth and the explosive quantity.However,the obvious water jet can not be formed at any depth.When the depth of the surface exceeds a certain value,the water jet can not be formed,and the free surface can only be slightly raised;2)With the increase of the depth of the explosion depth,the velocity of the water jet decreases,the jet height decreases,and the jet width increases;3)With the increase of explosive quantity,the velocity,height and width of water jet increase gradually;4)When the explosion bubble pulsates,the velocity of the free surface water jet reaches the peak in a very short time,then decreases sharply,and then reaches the next peak;5)On the path of bubble pulsation,the pressure of shock wave decreases gradually and attenuates sharply.With the increase of explosive quantity,the peak value of shock wave pressure increases gradually,and the earlier the peak value of shock wave pressure appears.With the increase of explosion depth,the peak value of shock wave pressure decreases gradually,and the later the peak value of shock wave pressure appears. |
PDF Full Text Request