ABSTRACT
The prediction of ship speed and sailing trim/sinkage is an important issue in quick forecast of ship energy efficiency operation reality. The paper presents a method to calculate forward speed and floating condition in calm water with computational efficiency and accuracy to meet the smart ship sailing requirements. It considers the interaction between hull and propeller. The first-order Taylor expansion boundary element method (TEBEM) is used to calculate the ship wave-making resistance and the zero-order TEBEM is applied to predict the performance of the propeller. Since the ship is in equilibrium in the still water and the force is symmetrical, three independent equilibrium equations are derived and then solved by Newton-Raphson method. The numerical results are compared to self-propulsion experiments results to validate the reliability and accuracy of the method in this paper.
Smart ship sailing speed and trim/sinkage are the main parameters for energy efficiency operation consideration. It mainly includes ship resistance and ship propulsion simulation, which should be as quickly as possible.
Nowadays the extensive application of computational viscous fluid dynamics(CFD) in ship hydrodynamics makes people have a deeper understanding of the flow around the hull model. CFD computations of ships are typically performed in model scale due to the lack of experimental results in full scale, and the added complexity of running codes at very high Reynolds numbers. The ship model and the ship at full-scale only meet the Froud number and the advancing coefficient, but the Reynolds number is not the same, which causes a large error in the conversion of model data to the real ship due to the existence of scale effects.
Compared with the viscous CFD simulation for model scale. Direct full scale ship potential flow simulation with necessary experience based modification is more efficient to satisfy the requirement of smart ship sailing optimization.
The boundary element method (BEM) has played an important role in hydrodynamic problems for its virtue of transforming threedimensional problem into two dimensional one. As for BEM, most of computational amount lies in computation of Green’s function and solving the resulting boundary integral equations.
