Numerical Study Of Underwater Explosion Bubble Dynamics And Respones Of An Adjacent Structure

Underwater explosion is a complex physical and chemical process with energy transforming. Its destructive force is the most threat to naval ship lives. Usually underwater explosion physical process is divided into two sequences: (1) Shock wave, (2) Bubble oscillation. In the past, People payed more attention to shock wave, but the experiment and analyse in lastest decades show that bubble oscillation can also cause serious damage to ships or other structures. Underwater explosion bubble movement and interplay between bubble and structure are becoming a focus in international researches.This thesis analyzes explosion bubble dynamics discipline and characteristic of structure loading under the bubble impact, dynamic response of structure under bubble loading by numerical methods. The boundary integral method is used to solve Laplace equation based on potential-flow theory. Coupled with time integral, we establish three-dimensional model of an underwater explosion bubble near a structure. Main job is as follows:(1) Research developments in domestic and oversea about bubble dynamic behavior are generally reviewed in aspects such as academic analysis, experimental techniques and numerical methods, etc. The developing process and key techniques of bubble numerical simulation are also reviewed and discussed. On the basis mentioned above, some problems demanding further study are presented, which establish foundation for instructing subsequent work of this paper.(2) Formulating the equations that control bubble dynamic motion; realizing dispersing all surfaces into a serial of cells through boundary integral method and finally simulating bubble dynamic motion; Solving the numerical problems such as bubble large deformation and toroidal bubble modeling.(3) Comprising numerical results with experiment data shows computational model we have found is accurate and stable. Analyzing and concluding the influence of charge weight and charge depth on bubble pulsation period, jet occurring time and jet speed.(4) Founding refined ellipsoid and ship model as structural boundaries of explosion bubble; Calculating structural loading under bubble impact in 48 cases which typical cases is chosen in to analyze characteristic of loading with different charge weights, charge depths or different bubble-structure distances. (5)Finally, dynamic response and preliminary analysis of ellipsoid structure have been solved by ANSYS solver as added mass of entrained water and damper are taken into account based on accurate calculating results of bubble load.All work in this thesis is to be important references to the engineering field of underwater explosion bubble dynamics and destruction mechanism of structures in water.