| In order to obtain the good ship-propeller-rudder matching and the appearance of the hull structure, in the process of ship design research, the interference problem between the hull, propeller and rudder have long been the concern of the research and design personnel. However, due to the complexity on the problem of the dynamic performance of the disturbance of the model of the ship-propeller-rudder combination, in the early computational fluid dynamics(CFD) method, the integrated model of the ship-propeller-rudder is seldom involved. Today, with the continuous improvement of the CFD method and the substantial increase in computer performance, the numerical solution of the hydrodynamic performance of the ship has been further developed, which makes the prediction of the whole hydrodynamic performance of the ship and its accompanying body become possible. By studying the characteristics of the coupling of the ship-propeller-rudder, the interaction among the ship, propeller and rudder is analyzed which is very important for the optimization of the ship hull and the design of the energy saving device.In order to study the matching and interaction among the hull, propeller, rudder and energy saving appendages, this paper takes the standard ship type KCS ship, KP505 propeller and NACA0018 rudder as the research object and the CFD commercial software FINE/Marine is used as the computational solution. With the sliding mesh technology, the hydrodynamic performance and fluid dynamic performance of the bare hull, ship-propeller combination system, ship-propeller-rudder combination system, open water propeller, propeller-rudder combination system, propeller-rudder-rudder ball combination system and ship-propeller-rudder-rudder ball complete combination system are studied. Specific work and main research results are as follows:(1) In this paper, the development status and significance of the research of the ship-propeller-rudder full coupling motion and stern additional energy saving appendages from home and abroad are comprehensively reviewed and summarized. Research methods of the ship-propeller-rudder hydrodynamic performance and the design optimization method of energy saving appendages are completely studied. And the research content and innovation points are further clarified.(2) Numerical calculation method for computational fluid dynamics, the basic principle of the ship-propeller-rudder characteristics and the energy saving mechanism of rudder ball are systematically introduced in this paper.(3) Based on software FINE/Marine, numerical simulation of the unsteady interference of the bare hull, hull-propeller and hull-propeller-rudder with free surface in viscous flow field are finished. The resistance of the bare hull, hull-propeller and hull-propeller-rudder are given by calculation at the 8 cases which propeller speed is set up from 9.1r/s to 9.9r/s. The results show that the calculation results of the resistance is in good agreement with the experimental results, and the relative error is within 5%, then the matching speed of propeller is obtained. Meanwhile, through the global solution of the hull-propeller-rudder, the influence of the propeller and rudder on the ship stern flow field is discussed, in order to obtain the velocity and pressure distribution in stern. This has great practical significance for the prediction of the actual flow field of the ship.(4) Based on software FINE/Marine, the hydrodynamic performance of the single propeller and propeller-rudder system are respectively calculated. The results show that the calculation results of the bare propeller is in good agreement with the experimental results, and the relative error is within 5% when the propeller speed coefficient is from 0.1 to 0.8. At the same time, the total efficiency of propeller-rudder system is higher than the compared with the efficiency of bare propeller at low speeds, and the highest increase of 1.27%. However, the efficiency of propeller-rudder system reduce a lot at high speeds, maximum reduction of 6.36%.(5) Based on propeller-rudder system, design of the energy saving device of the rudder ball is carried out. what’s more, propeller-rudder-rudder ball combination system is calculated and the influence of the rudder ball size to the energy savings of propeller-rudder systems is discussed by changing the geometric parameters of airfoil rudder ball. Calculation results show that, energy-saving effect is best, when the airfoil profile relative thickness ratio is 0.28, and the ratio of the maximum diameter and the propeller diameter is0.16. The best energy-saving effect reaches 1.62%. Meanwhile, comparing and analyzing the wake field of the propeller-rudder system and propeller-rudder-rudder ball system, this provides an important theoretical basis for the practical application of rudder ball.(6) The optimum airfoil is calculated in the propeller-rudder-rudder ball system, and is applied to the ship-propeller-rudder system, which composed ship-propeller-rudder-rudder ball system. The optimal size of the rudder ball is calculated. The energy saving effect of the ship-propeller-rudder system at the design speed is 2.06, about two times the average energy saving effect of the propeller-rudder-rudder ball system. This confirms the energy saving effect of this rudder ball, when the propeller speed is set up as 9.75r/s and the ship speed is 2.1968m/s. |
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