Numerical simulation and analysis of the aerodynamic characteristics of a marine three-blade ducted propeller
In order to study the aerodynamic characteristics of a marine three-blade ducted propeller carried on a hover-craft,established a numerical prediction model of the flow field of the ducted propeller based on the slip grid method.Three sets of unstructured and structural hybrid grid schemes with different grid density are designed for uncertainty analysis,and the numerical calculation results of NASA's ducted propeller are compared with the experimental data to verify that the mod-el has good reliability and accuracy.Based on the established model,the complex flows of open propeller and ducted pro-peller at different rotating speeds are calculated respectively.The results show that at the same rotating speed,the total thrust coefficient of ducted propeller is 10％higher than open propeller,the working efficiency is 25％higher.The duct broadens the distribution range of low pressure areas before the propeller.The duct wall changes the streamline characteristics of the propeller tip,inhibits the formation of the tip vortex,and reduces the energy loss.The static thrust of this type of propeller in isolated state is 470 N,which cannot meet the design requirements of this type of air cushion vehicle.After adding the duct,static thrust is 516 N and the thrust is 327 N under sailing conditions,which can meet the design requirements.
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