Optimisation of a Multi-Body Three Floats Wave Energy Converter in Irregular Waves

Abstract

A multi-body wave energy converter, consisting of three floats and modeled as a two body problem, is optimised to enhance its mean absorbed power using the Response Surface Optimisation Method. The optimisation focuses on two input parameters namely; the floats’ diameters and the spacing, in various sea states and at different PTO dampings. A frequency domain analysis is performed for the WEC model scaled at 1:50 in regular and irregular waves. Obtained results are validated against numerical and experimental data available in the literature. Validations show good agreement against the unmoored model’s added mass, radiation damping, response amplitude operator, mean absorbed power and, capture width ratio. The sea states selected for optimisation are represented by a JONSWAP wave spectrum with, a range of significant wave heights (0.04 to 0.06 m) and a range of peak periods (0.8 to 1.3 s). This corresponds to (2 to 3 m) significant wave heights and (5.6 to 9.2 s) peak periods in full scale. Results show that the optimised WEC model demonstrates good and consistent enhancement of its mean absorbed power and capture width ratio.

Keywords

Multi-body wave energy converter / Capture width ratio / Irregular waves / Power absorption / Optimisation

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