Analysis of the equilibrium conditions of a double rotor turbine prototype designed for the exploitation of the tidal currents

• A design a new self-balancing turbine collecting energy from tidal currents has been presented.
• The equilibrium in the sea is guaranteed by a central deflector inserted in the blades disc.
• The sizing procedure of the turbine needs the knowledge of lift and drag coefficients of the deflector.
• A CDF analysis has been carried out for estimating these parameters.
• The feasibility of a first pilot plant in the Calabrian site of Punta Pezzo (Italy) has been evaluated.

For several years the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl, has been performing researches for the exploitation of tidal currents. An innovative turbine has been developed, anchored to the coast, which does not require the supporting structures on the seabed and should reduces installation costs and environmental impact. This machine, in its latest version, proposes the use of two concentric and contra-rotating rotors, in order to require a small, or non-existent, stabilizing torque.In the present work the machine equilibrium conditions have been defined and, by a CFD analysis, the lift and drag coefficients of the central deflector have been calculated, together with a final machine design procedure.As a case study, applying the above procedure for a machine installed on the Messina strait, the energy output and the payback period have been estimated.