Prediction Of The Steady Hydrodynamic Performance Of Ducted Propeller

In recent years, enhanced propulsion efficiency and the reduced ships vibrates has become the significant duty which the ship designers face. Ducted propeller is one of the special propellers, which take great care in domestic and foreign. Compared with normal propeller, ducted propeller has many advantages like higher propulsive efficiency, better energy conservation effect and lower vibration in heave load. So, how studies can accurately prediction to the ducted propeller hydrodynamic performance is more important.In this thesis, the stead hydrodynamic performance of ducted propeller in uniform flow is predicted by lifting-surface method and surface panel method. Lifting-surface method is used on propeller while surface panel method is used on duct.Vortex lattice method is presented for calculating the loading distributions on all blades of propeller and hub which a number of small hyperboloidal quadrilateral panels are discreted. Constant source and vortex are distributed on each panel.The duct and the wake of duct is also discreted by a number of small hyperboloidal quadrilateral panels. Constant source and doublet are distributed on duct while there are only doublet on wake of duct.In order to cause the result to be more reasonable, the interference velocity by propeller is added to the inflow velocity of duct. We get the interference velocity induced by duct, add it to propeller, then we can get the loading distributions on propeller. The continuously iterative computation is executed for convergence. The propeller and duct is calculated together.The pressure distribution can be calculated by the Boluly equation, then the thrust and the torque of the propeller and the thrust of the duct can be calculated .In this paper, the steady performance Ka-series of propeller with No.l9A duct is computed, and its result is satisfying on the comparison with the test and the analysis with the actual value.