| Aiming at oil leakage from submerged damaged tanker, several key problems on hydrodynamic mechanics in the process of oil leakage had been explored. Theoretical analysis, physical model test and numerical simulation method were adopted, based on the theory of viscous fluid dynamics. Hydrodynamic mechanism of oil leakage was analyzed and the effects of characteristics of damaged hole specifications, oil physical properties on oil leakage behavior were revealed.First of all, the feasibility analysis was to explore the scientific problem on according to the particularity of underwater oil leakage from the damaged tankers. N-S equation and energy equation of viscous fluid were established, on based of viscous fluid dynamics theory. And the analysis using the viscous flow was carried on. The theoretical basis was established for theoretical analysis, numerical simulation, and model test.Secondly, the oil sample was selected and the model test device was designed. Several oil leakage scenarios in the scale model tests of single hull and double hull oil tanker was completed. The effects of damaged hole specifications, oil physical properties on the oil leakage were considered in model test. And theoretical analysis was to verify the effectiveness of the experimental data.Thirdly, the three-dimensional numerical model was established by viscous multiphase flow theory. And the oil-water-air multiphase flow was numerical simulation using the VOF method on based of the stability analysis of numerical model. Oil-water flow field characteristics were analyzed. And model test data from different leakage cases were used to verify the reliability of the calculation results of numerical simulation. The numerical results show the real feasibility and advantage of this method.Fourth, the main influence factors of oil leakage and oil leakage classification were determined. The whole process was divided into several stages, according to the periodic changes of oil leakage of the leakage rate, leakage of oil tank with time and the distribution of flow field vector. Kinetics and mechanism of oil leakage had been explored. Effect of different stages of various factors on leakage were revealed using Bernoulli equation of viscous fluid, phase analysis method was adopted, the role of various factors to reveal the effects of different stages of the process of leakage Analysis of a variety of effects on the leakage of the next process was to establish the theoretical and methodological basis.Fifth, the effects of the features of hole on oil leakage process were analyzed. The features of hole include the height from the bottom to the center of the hole and the hole diameter.The height and the diameter of hole as single variables were carried out the control group test. Influence of the volume of oil leakage and the leakage duration from features of hole were analyzed in several phases during oil leakage.Sixth, viscous effect on oil leakage process was analyzed deeply, such as effect of oil viscosity on leakage.The oil viscosity was selected as the single variable and carried out comparative test for oil leakage. The leakage characteristic parameters such as duration and volume of oil leakage were obtained, and the mechanism of viscous effects of fluid on leakage process was revealed through phase analysis.Seventh, the initial water lay in double bottom is on behalf of different damage time interval to inside and outside shell of double hull oil tanker. Effect of initial thickness of water layer on the leakage process was carried out. Several experiments under different thickness of the initial water lay were designed. Several Effects of initial layer was obtained, according to different water layer thickness affect volumes of oil leakage from tank and into the sea.In all, viscous fluid dynamics theory of submerged oil leakage from damaged tank was systematically established, and the law of oil leakage processes from submerged damaged tank of oil tanker is understood comprehensively. |
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