Numerical Research Of Free-flooding Anti-roll Tanks' Application On The Floating Platforms Around Islands And Reefs

China has a vast ocean and numerous islands,especially islands and reefs in the south China sea,providing rich resources of Marine fish and the reef coral around also playing an important role in weaking the waves and protecting the island.From the military strategy,to gain the initiative in the south China sea islands and reefs,means to control the mostly sea lanes from the strait of malacca to the continents of Asia,Africa,Europe to some extent.However,the basic living facilities on islands and reefs at present is deficient,so that how to effectively develop islands and reefs economy,fisheries and tourism resources,is to be solved at present.Considering environmental protection,convenience of construction and economic cost and so on,use the concrete material floating platform as the comprehensive life safeguard base of developing reefs,fishery production and tourism.This paper focus on a concrete floating life ensures platform,considering the influence of the reefs on the platform in the six degrees of freedom movement,to explore the anti-rolling applications of the free-flooding anti-roll tanks on the platform.In this paper CFD method of the potential flow theory is used to numerically calculate the box type platform,with or without free-flooding anti-roll tanks,and platform and reefs coupling hydrodynamic,with the ANSYS AQWA software as the research platform,and the free-flooding tanks' anti-rolling effect.In this paper,the first step is to establish 3-D models of the box-shaped platform using software CATIA,then to numerically simulate the platform' six degree of freedom of motion.According to the calculation results of box-shaped platform,design five kinds of free-flooding anti-roll tanks,and select the best performer in the five options by comparing.Finally,respectively taking the effect of two kinds of relative position of the island and box-shaped platform into account to study the existence of the reefs and island,when it comes to the calculation water depth,takes 12 meters and 1000 meters.From this paper we can get the following three conclusions:(1)When the platform is in shallow water,such as less than 20 meters,it has a great influence on the hydrodynamic performance of the platform,especially to the roll and yaw performance of the platform,and the smaller the water depth is,the clearer the influences are.(2)among the five kinds of free-flooding anti-roll tanks,the E type has the best effect,the order of good damping effect of other free-flooding tanks are D,B,C,A type,the A type has no anti-roll effect almost,but increases to some degrees when the platform is under a sea with a certain range of wave time period.(3)When it comes to determining the relative position between islands and reefs and the box-shaped platform,first of all,analyze the condition of ocean near the islands and reefs,statistically analyze the main wave direction distribution,to define roll and pitch covered areas of the reefs only to make sure that the platform serious movement(roll or pitch)are in the well covered area.