Load And Structural Strength Analysis Of Bilge Keel

The ship motions in wind waves generated intense sway movement, which will significantly influence the navigation performance. Bilge keel is a kind of stabilizer whose anti-rolling effect is generated from the increase of rolling damping. Nowadays, due to its simple structure and highly cost effective, bilge keel is widely used in all kinds of ships.In recent years, the failure of the ship caused by fracture of the bilge keel has increasingly attracted the attention of researchers. It was found that some of the current single plate bilge keels fail to meet the specification requirements and consequently ruptured.However, for those who successfully meet the standard requirements, fracture also tend to occur at the connection of the bilge keel and the front end of the hull. Therefore, it is necessary for the analytical investigation of the functional law and influence factors of bilge keel load. At the same time, the local structural strength assessment of bilge keel should be conducted according to the relevant rules.As the bilge keel failxure occurs mainly at the connecting place of the bilge keel and the front end of the hull, in order to simplify the calculation, bilge keel end sections of the target ship are cut out and research of the end sections is implemented in this paper. The main works are as follows:1) Based on the hydrodynamic load simplification calculation model of the bilge keel,FLUENT software is adopted to calculate the bilge keel hydrodynamic load under different conditions. The calculated values are then compared with the empirical formula in specification value.2) The bilge keel hydrodynamic load under forced heaving and forced rolling is simulated based on CFD method. The hydrodynamic load characteristics of bilge keel under water are also studied.3) The bilge keel constant speed slamming load is calculated with FLUENT software.The bilge keel slamming load characteristics under extreme cases are compared with the experimental value to verify the numerical correctness.4) Based on the relevant specifications, the local strength of bilge keel is checked according to the direct calculation of all kinds of loads mentioned above. Rationalization proposals of bilge keel design are then proposed on the basis of the researches in this paper.