Numberical Sutdy Of Ship’s Self-propulsion Performance With An Iterative Body-force Propeller Model

Propeller, which is the main propulsion device used by ships, plays an important role on the ship’s performance. The research of self-propulsion performance plays a vital role in the ship-design and the development of the novel ship. Therefore, the study of the interaction between propeller and hull will play an important role in the optimization designing of the traditional vessels, developing of new type vessels and improving of the ship’s performance.In the study of fluid mechanics, there are three commonly used methods, as theoretical research methods, numerical methods and experimental research methods. The theoretical research method has the advantages in being able to reveal the inherent law of fluid clearly and generally, but limited to a few simple theoretical model, it cannot solve the practical engineering problems effectively. The remarkable characteristics of the experimental research method are to obtain reliable results. But often because of the similarity criterion of the limitations, it cannot satisfy all size limits, boundary effect. And also it needs much money and time. The numerical calculation method requires less money and time, it also has high accuracy. Nowadays, computer consumables costs decreased gradually but its computing power continues to improve. So it has obvious advantages in the expenditure and time cost when the calculation need large calculating capacity. So the Computational Fluid Dynamics(CFD) gradually cut a striking figure in fluid mechanics research field, and become an important research mean following the theory of fluid mechanics and experimental fluid mechanics.When predicting of the ship’s performance, we should also consider the interaction between the propeller and the hull. To achieve the prompt prediction of propulsive performance, the paper uses a convenient prescribed body-force method to simulate hull/propeller interaction with CFD. The free surface viscous flow around MOERI container ship(KCS) is simulated at the self-propulsion point. An iterative body-force method which couples the Vortex Lattice Method(VLM) of the propeller lifting surface with the RANS solver is presented in the paper. Both force and moment computed by VLM are inputted to RANS as the source term while the inflow to the propeller computation is from the viscous velocity subtracted the induced velocity at the propeller plane. The iterations between VLM and RANS are prosecuted until the propeller thrust and torque coefficients are converged within a specific tolerance. All the progress is done automatically by an integrated program which couples RANS/VLM solvers. The computed results agree well with the measured data. The method adopted in the paper predicts the performance of self-propulsion accurately and efficiently.