| With the national shipping enterprise growing, the study on high performance ship has received more and more attention. Along with the military, economic and shipping development, more and higher comprehensive performance of new type ship has been required. Comparing with the other ships with the same amount of drainage, people obviously are all favored about trimaran, which has large deck area, high maneuverability, high sea-keeping performance,high stability and high navigation features. Water jet propulsion is an important means of propulsion for the high speed trimaran. It has a different hydrodynamic action principle with a conventional propeller. There have little reports on the impact of water jet propulsion for the trimaran resistance, seakeeping and manipulation performance.Understanding the influence on ship performance by water jet propulsion has an important theoretical and practical significance for a deeper understanding of the hydrodynamic characteristics of the trimaran and excellent practical trimaran design etc.This study is based on the viscous flow theory, established the trimaran and jet propulsion for the integration of the flow field and resistance prediction method,discussed the dynamic mesh form, studied the connection settings and fusion of the fixed grid and sliding mesh around ship and the rotating domain boundary conditions, achieved effectively resistance prediction method of the water jet propulsion trimaran. This method can compute and analyze the total resistance, the resistance of the hull, propeller flow resistance,mechanical rotor and stator forces of water jet propulsion ship in detail. It took Wigley trimaran and utility trimaran for example,verified the theoretical methods in this study,achieved the force, resistance component between hull and water jet propulsion, and the flow field around ship hulls. This paper compared and analyzed the force for each part of different navigation state, discussed the relationship between the resistance of trimaran and the rotor thrust, researched on the effect of rotor speed for every part of the water jet propulsion trimaran, predicted the resistance of different navigation state. This paper discussed the impact of mesh form to resistance prediction, analyzed the resistance of different navigation state of water jet propulsion trimaran. Find a way to forecast the hull of a fast performance,for setting waterjets to identify the best method for determining the speed of ship.Research shows that, the method used in this paper is feasible. Water jet propulsions have a certain impact on the trimaran resistance. It mainly displays the total resistance of boat increases by the water jet propulsion duct resistance. The effect to the hull resistance by water jet propulsion is varies with the rotor speed. There has flow interference between the water jet and hull. The impact on the flow field in the rear of the hull will increase resistance to a certain extent. Through calculation and analysis, it was determined the theoretical methods of waterjet propulsion trimaran fast prediction. The propulsion efficiency at high speed is obviously higher than low speed, the highest can up to 60%. |
