Tidal stream energy conversion: power augmentation using vortices generated by a delta wing

The use of delta wing vortices as power augmentors, originally proposed for wind energy conversion, has been explored for tidal streams and currents. Its effectiveness has been verified in wind tunnel tests, and design parameters for a vortex turbine rotor have been developed. The stability of a submerged delta wing suspended from a float was investigated in a towing tank, and a system which maintained a stable configuration over a wide range of stream velocities was devised. For a given rotor size, power outputs of 2 to 3 times that available in the free stream are anticipated. Tests at higher Reynolds numbers are needed to establish performance more precisely. The concept seems very promising for small and medium-scale applications. 1