Numerical simulation and comparison of aerodynamic characteristics between ducted and isolated propellers

The complicated flows around the ducted and isolated propellers were numerically simulated by solving the unsteady Euler equations based on unstructured dynamic overset grids,and the aerodynamic characteristics between them were compared.For the effective treatment of the complicated flow field involving relative motion between the propeller and duct,the computational domain was decomposed into two subzones,namely,rotational subzone and stationary subzone.The rotational subzone contained the propeller and the stationary subzone contained the duct.The good agreement between the present calculation result and experimental data demonstrates that the present method has good accuracy to simulate ducted-propeller problems.The lower-pressure area at the leading duct leads to the generation of additional thrust on the duct.Compared to the isolated propeller,the existence of duct changes the flow characteristic around the blade tip,and decreases the tip-loss.For the same rotational speed of the propeller,the ducted-propeller can generate greater thrust with less power,resulting in the conclusion that the ducted-propeller system has a better aerodynamic efficiency.