| 1. |
- Barbarelli, S., et al.
(författare)
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CFD Investigation of the Open Center on the Performance of a Tidal Current Turbine
- 2019
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Ingår i: Renewable Energy Integration with Mini/Microgrid. - : Elsevier. ; , s. 28-33
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Konferensbidrag (refereegranskat)abstract
- In the present paper, a revision of the layout of an innovative open center self-balancing tidal turbine is presented. Initially, the design was characterized by a central deflector, responsible for the machine equilibrium, hosted in the central part of the machine; the presence of this device, however, affected the size of the opening. Moreover, the turbine was conceived as connected to a steel rope subject to tensile stress. These peculiarities brought some critical issues due to the excessive length of the rope and to the size of the deflector, which constrained the diameters ratio. The new design involves the possibility of reducing the anchoring line length by substituting the rope with a series of tubular elements connected by alternate heavy and light nodes. The heavy nodes can gather the anchoring line when the tides stops acting. Moreover, the light nodes are floating deflectors, which develop the same action of the central deflector, whose size, in this configuration, does not affect the equilibrium. In the new machine configuration, the main deflector is located out of the center so that it can counterbalance the torque exerted by the rotor during its rotation. Finally, by means of CFD simulations, some criteria for assessing the best diameter ratio are defined.
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| 2. |
- Lo Zupone, G., et al.
(författare)
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Open center tidal turbine : How a new mooring system concept affects the performances
- 2021
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Ingår i: International Journal of Energy Research. - : Wiley. - 0363-907X .- 1099-114X. ; 45:5, s. 6727-6744
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Tidskriftsartikel (refereegranskat)abstract
- The huge manufacturing and installations costs, together with the adverse impact of the mooring systems and structures on the environment, flora and fauna have become one of the major constraints for the application of many marine technologies. An innovative mooring system coupled to an open centre turbine has been developed, adopting a full floating concept, which allows a kite like connection between the turbine and the coast. Replacing the huge underwater mooring structures with such kite flying system dramatically reduces the environmental impact and effects, meanwhile the lightweight open centre turbine coupled to this mooring system, assures a self-adaptive optimal orientation, achieving a new equilibrium arrangement at given depth and distance to the coast, following only the fluid dynamics rules. In addition, the synergy between the two machine components makes also suitable the adoption of low aspect ratio blades, characterized by lower specific loads, and leads to a reduction of the manufacturing cost. To optimize the kite concept, the connecting rope has been replaced with heavy and light nodes connected by tubular elements, where the light ones accommodate the deflectors to increase the lateral force responsible of the machine positioning, facilitating the machine transients, and manoeuvring and leading to improve the output reliability, reducing also the mooring line length. A case study shows that a 12 m diameter open centre turbine with the new mooring line produces, at Messina Strait site (Italy), an output of 362 MWh/year, 17.5% higher than, at same operating conditions, a classic 3 blades turbine moored on the seabed. It confirms the high suitability of this solution for marine purposes.
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