Advances in design and analysis of ducted propellers for dredging vessels

This paper addresses the challenges and advances made in the hydro-dynamic design and design evaluation of ducted propellers. The application of new ducted propeller analysis tools is shown for the practical case of the design of controllable pitch propellers for hopper dredgers. Results of model tests and sea trials are compared with results of a state-of-the-art boundary element method (BEM) code that is used for the simulation of the unsteady cavitating flow around ducted propellers. The results of the BEM simulations are com-pared to more time consuming and comprehensive URANS sliding interface calculation results in which the flow including the unsteady flow around the ro-tating propeller is modelled in the RANS domain. Comparisons are made of pressure distributions and pressure side cavitation margins that are important in the propeller blade design. The details of the flow into the duct are discussed as well as its implications on the propeller blade design. The employed BEM method is proposed as the best practical next step in ducted propeller design given its reasonable calculation times. Based on the obtained results a new re-search initiative has been started to obtain better sea trial data from ducted pro-pellers to improve and validate the ducted BEM method as well as the SI URANS method.