On the Simultaneous Design of Blade and Duct Geometry of Marine Ducted Propulsors

In ducted propulsor design for marine vessels, due to the strong interaction between the duct and the propeller blades, it is very important to design the duct and the blade geometry simultaneously. Here, a three-dimensional inverse design method is presented to take this into consideration. The method is based on three-dimensional potential flow; however, the effect of the inlet shear flow and the resulting rotational flow is also modeled via the Clebsch formulation. The duct profile is designed to achieve a target velocity distribution while the blade geometry is computed to attain a desired mass-flow rate and a certain circulation distribution. The method is applied to the design of three generic ducted propulsors with a 7-bladed contrarotating configuration.