Design and initial testing of a contra-rotating tidal current turbine

Clarke, J.A. and Connor, G. and Grant, A.D. and Johnstone, C.M.; (2006) Design and initial testing of a contra-rotating tidal current turbine. In: Proceedings of the World Renewable Energy Congress IX. Pergamon Press. ISBN 00844671 (http://www.see.ed.ac.uk/~shs/Tidal%20Stream/April%...)

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Abstract

A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. High frequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials.