T.A. Lokocz – Masters thesis, University of Maine, 2012
This research analyzes the performance of a ducted axial flow tidal turbine and compares the result to an unducted turbine. While the focus of this research is on experimental results obtained in tow tank tests, the turbine and duct were designed using the open source software code, OpenProp. OpenProp was used because of the suitability of the design approach for the optimization of a turbine design and its modeling capability for ducted propellers. While OpenProp has the capability to analyze ducted turbines, this capability has been added only recently and has not been validated. Thus, the duct used in the experimental work could not be optimized and was intended to provide data which could be used as a part of the validation of the ducted portion of the code. Literature reviews indicate that limited experimental data exists for the performance of comparable ducted and unducted turbines. The design used is a three-bladed, ducted turbine with blade shapes optimized in OpenProp. For the unducted case, an optimal Cp of 0.44 was measured at a tip speed ratio of 4.43. The duct was shown to have a detrimental effect on the performance of the turbine with a maximum Cp = 0.4 at a tip speed ratio of 4.4. This result demonstrates the challenges associated with the design of an efficient ducted turbine.