engleski

Improving the hydrodynamic performance of hydrokinetic turbines by using additional stator elements

Hydrokinetic turbines are an emerging technology for the exploitation of mostly untapped energy contained in river streams, waves and tidal currents. In spite of numerous economic and environmental benefits over conventional hydropower technology, wide commercialization of the technology has not been achieved so far. This is primarily due to relatively low efficiency, bounded by a theoretical limit, known as the Betz limit. The objective of this paper is to investigate the potential of overcoming the efficiency limitation by using additional stator elements while keeping simplicity in design, which is one of the main advantages of hydrokinetic turbines. To validate the proposed design improvements, computational fluid dynamics is used. Different shapes and geometries of stator parts are taken into consideration to find the shape that best meets the specified design requirements. The results show improved hydraulic efficiency, relative to the efficiency of the bare rotor design, as a consequence of increased flow velocity at the rotor plane. However, significant increase in efficiency is not achieved with all the considered geometries which indicates the necessity of selecting an optimal stator geometry, to justify the additional cost by increased efficiency.

Hydrokinetic turbines ; shrouded turbines ; design improvements ; geometry modification

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