Numerical Simulation Of ABS Retrievement

To relieve conflict between exploration of deep water and cost of operating, ADTH raises a new conception—ABS. The principle of ABS is using buoy to elevate the seabed,which makes equipments in the shallow water used in the deep water possible. In June 2004,ADTH and COSL worked together to research and develop this project,and in June 2008,the trial of the deep water drilling was put into practice in South China Sea. In the process of retrieving the buoy, it showed that the speed of the buoy was too fast, and the drift in horizontal direction was inevitable. It leaded the connection between the buoy and the equipment on surface of the water to be a problem.This paper is aimed at the two problems above. The motion trail and velocity variation law of the buoy while retrieving is discussed. The panel method is used to calculate the added mass of the buoy by FORTRAN. And then, different conditions were simulated by the CFD software FLUENT using dynamic mesh technology when retrieving the buoy from deep water. The motion laws of the buoy in different working conditions were obtained. The added mass of the buoy which is solved by panel method is combined with the force and velocity of the buoy calculated by FLUENT. Then, the relationship between coefficient of viscous force and Reynolds number is investigated. The motion equations of the buoy is established and solved by fourth order Runge-Kutta method. At last, the motion equations of the buoy while out of water are established ignoring waves. The hydrodynamic force of the buoy in motion equations mentioned above is calculated by Semi-empirical Formula from Russia which is used to solve the missile getting out of water. The velocity and horizontal displacement of the buoy is calculated when getting out of water.According to this paper, the motion law and horizontal displacement of the buoy is obtained, which is valuable for controlling the motion of the buoy.