Hydrodynamic Performance Research On Moonpool Under Uniform Flow Condition

A moonpool structure, in which the water is continuous from inside to outside, may be fixed on some special function ships. The moonpool likes a kind of cave-in cavity with free surface and is always set in the middle of the ship which has the biggest gross longitudinal bend moment. Therefore, the un-continuous of the structure always brings on some negative effect to the general strength and vibration. Furthermore, because the moonpool is a cavin cavity relative to the bottom of the ship, when the ship is sailing, the fluctuating force of the fluid always induces the vibration response of local structure of the moonpool, which may influence the sailing and working. Consequently, it is necessary to research on the structure and hydrodynamic performance of the moonpool.In this dissertation, the computational fluid dynamics software CFX is applied to calculate the experimental model at first in order to determine the most reasonable model scale and the fixed position of the equipment. Afterwards, the model experiment is developed in the towing tank using circle and square shaped moonpool under different uniform flow conditions. The motion rule of the liquid inside the moonpool of two different cross-sections and the liquid's action on the structure of moonpool are gained. It is discovered that under low speed flow conditions, the surge phenomena inside the moonpool may result in the distinctive change of the pressure distribution of the side wall of the moonpool. In addition, through the comparison between circle and square moonpool among the pressure distribution trend, the change of the pressure versus Froude Number and the change of the height of the liquid inside in moonpool, it is considered that the circle moonpool possesses a better structural and hydrodynamic performance than the square moompool.