Influence of jet flow on hydrodynamic performance of a ducted propeller

This study introduces a concept that jet technology in the aeronautical field is used for active flow control to improve the hydrodynamic performance of a ducted propeller. Jet flow is added in front of the ducted propeller, and it produces a circumferential velocity that is opposite to the rotation direction of the rotor. An international standard ducted propeller was adopted to demonstrate this concept. The unsteady Reynolds-averaged Navier-Stokes method and the shear stress transport K - omega turbulence model were employed for the simulations. The open-source platform OpenFOAM was utilized. The overall efficiency eta(0) of the ducted propeller first increases and then decreases with increasing the jet flow velocity R-jf from 1 to 3 and the distance L to the rotation center from 0.2D to 0.4D. When the jet flow is at the optimal condition of R-jf =2 and L=0.3, the maximum efficiency improvement of 3.1% is achieved for the ducted propeller. The reason is that the jet flow contributes to a pressure increase in the flow through the rotor. This effect is related to tip and hub vortices, which are disrupted by the jet flow and have relatively low vorticity magnitudes compared to the reference case without jet. The findings in this study have the potential to advance the development of active flow control technology for ships.