Sequential optimization and performance prediction of an oscillating water column wave energy converter

This paper presents a sequential optimization procedure and a performance prediction of an Oscillating Water Column (OWC). The effects of the Power Take-off (PTO) model, the geometry, and the wave conditions on the device performance are investigated. Numerical simulation tests are carried out within a Numerical Wave Tank (NWT), where nonlinear higher-order Stokes regular wave's velocity profile is continuously applied at the tank inlet. The wave propagation is predicted according to Reynolds Averaged Navier-Stokes and two-phase homogeneous Volume of Fluid model. By considering an OWC with a specific configuration, the developed optimization procedure consists in determining the optimal parameters set in a sequential manner (i.e. determine the 1st optimal parameter, keep it fix, optimize the 2nd, and so on...). A recurrent procedure is used to check the non-interactivity between the various tuned parameters and consequently the design optimality. The obtained results show that for an OWC there is a single optimal operating point that depends on the PTO damping, the thickness of the OWC front wall and its immersion depth, and the wave conditions. It is also shown that the use of a performance prediction based on rational- polynomial functions yields an accurate approximation of the optimal operating point.