A novel twin-rotor radial-inflow air turbine for oscillating-water-column wave energy converters

António F.O. Falcão, Luís M.C. Gato, João C.C. Henriques, João E. Borges, Bruno Pereiras and Francisco Castro

Energy, 2015, vol. 93, issue P2, 2116-2125

Abstract: A novel air turbine for bidirectional flows in oscillating-water-column wave energy converters is presented and its performance is analyzed. The turbine is based on a pair of conventional radial-inflow rotors mounted on the same shaft, complemented by the corresponding guide vane rows, by a curved-duct manifold arranged circumferentially in a period manner and by a two-position cylindrical valve. Numerical values of the performance of the whole machine were obtained from published experimental data of the flow through a conventional radial-inflow gas turbine, together with CFD (computational fluid dynamics) results for aerodynamic losses in the curved duct manifold. Four different geometries, combined with five different sizes, of the curved-duct manifold were numerically simulated. Windage losses, that occur at the inactive rotor and are inherent to the machine conception, were found to be a major loss. A peak value of about 86% was obtained for the overall efficiency of the machine. Comparisons are presented between the new turbine and the biradial turbine (sliding guide-vanes version), the latter being possibly the most efficient self-rectifying turbine model-tested so far. The new turbine was found to be more efficient, both in peak instantaneous efficiency and in maximum average efficiency in random waves, by a margin of about 8%.

Keywords: Air turbine; Wave energy; Oscillating water column; Numerical simulation; Aerodynamics (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (15)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:93:y:2015:i:p2:p:2116-2125

DOI: 10.1016/j.energy.2015.10.046

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