Study Of The Maneuverability For Water-jet-propeled Ship

Maneuverability is one of the most important sailing performances of ships. With the improved demands of ship speed, ship intelligence as well as the greater importance of shipping industry, ship maneuverability is receiving increased attentions. Hydroplanes play a crucial role among high-speed small crafts thanks to its specific hydrodynamic performance. Water jet propulsion is widely applied to the high-speed crafts because of its outstanding maneuverability.The aim of this subject is to study the maneuverability of a planning ship, which is propelled by a single water jet propeller at stern.As is well known, mathematical modeling together with computer simulation is a routine and practical way to conduct simulation of ship maneuverability to predict the performance of maneuverability. Due to its complicated hydrodynamic performance, it is difficult to analyze the hydrodynamic coefficients. In order to establish an effective mathematical model for hydroplane maneuverability, this paper is aiming to find out the 6 Degrees of Freedom (DOF) motion equations by analyzing the different force acting on corresponded Degree of Freedom (DOF).Flow theory was used to analyze the flow field in this paper. The 6 DOF motion equations of the hydroplane were established after detailed analyzing of forces action on the vessel according to theory mechanics. Based on the characteristics of hydroplane, the resulting force placed on the vessel finally can be categorized in terms of gravity, buoyancy, hydrodynamic forces and other external forces. additional mass of the hull was numerically calculated by programming on the three-dimensional Hess-Smith. And trim angle and the wetting ratio of length and breadth of navigation were also obtained by employing SIT method. On the condition that needed thrust is equal to ship resistance, the components of thrust in six directions were achieved by use of the diffluence coefficient method.According to the results of this paper the mathematical model of hydroplane can be acquired. Based on the model, the motion acceleration of the vessel at each moment was calculated using the four-rank fixed pace Rung-Kutta method. By integration of the acceleration, the position and speed are acquired and the maneuverability performance of the vehicle can be predicted. Simulation experiments of ship maneuverability were conducted and specified targets of the appraisement of the maneuverability were acquired.