An Analysis Method for a Ducted Propeller with Pre-Swirl Stator Blades

A method is developed to analyze the flow around a ducted propeller operating in combination with a set of pre-swirl stator vanes. The method uses a boundary element method to solve for the flow around the duct and the hub and a lifting surface vortex lattice method to solve for the flow around the propeller and stators. The three-dimensional flow around the duct/hub, propeller, and stators is computed separately with the interactions between them being accounted for in an iterative manner. The interactions between the duct and the stators and between the duct and the propeller are treated in a non-axisymmetric manner. However, only the circumferentially averaged interactions between the propeller and the stators are considered. Using this method, a duct and set of stators are designed to operate efficiently with an existing propeller. This model was then built and tested in the MIT water tunnel at a variety of stator pitch angles. Comparisons are made between the theoretical and experimental values for the forces on the duct, propeller, and stators. A very good agreement is achieved in the region of the attached flow.