validated analytical model for a cyclorotor wave energy device

Abstract

We present a new analytical model for a horizontal axis cyclorotor-based wave energy converter (WEC). A number of cyclorotor-based WEC concepts and models, with different numbers of hydrofoils, have previously been studied. Our model is derived for a horizontal cyclorotor with 2 hydrofoils. The governing equations are optimised and converted to the polar coordinate system. The mechanical model is based on Newton's second law for rotation. Rotation is considered in two-dimensional potential flow, for both monochromatic and panchromatic waves, including waves generated by the rotating rotor, and viscous losses. The developed model is very convenient for modelling, analysis and control design for a cyclorotor based WEC.
 The authors of this work have derived new, exact, analytic functions for the free surface perturbation and induced fluid velocity field caused by hydrofoil rotation. These new formulae significantly decrease the model calculation time, compared to previous models, and increase the accuracy of the results. We present the results of free rotation simulations for the rotor in monochromatic and panchromatic waves obtained with the use of the newly derived equations.

Energy-Maximising Control Philosophy for a Cyclorotor Wave Energy Device

“…However, we note that, in general, the model of Section 3 validates well against previously published experimental data[17] though, of course, no model is perfect.…”

“…In the 2D model, we consider the side profile of the cyclorotor, with the output power expressed in Watts per meter of foil width (W/m). The results of the free rotor rotation in waves, obtained with the use of a point source model, are presented in [17].…”

“…In the following, we briefly present some general equations of the point source model to highlight the nonlinear influence of the optimisation parameters on tangential force generation and the performance metrics of the rotor. For a fuller treatment, the reader is referred to [17][18][19].…”

Control Strategies for Power Enhancement and Fatigue Damage Mitigation of Wave Cycloidal Rotors

“…Each hydrofoil is modeled as a point vortex beneath the free surface. The model has been previously developed and applied to wave cycloidal rotors in the works of Ermakov and Ringwood [23,26] under regular waves and has been validated…”

Near Wake Hydrodynamics and Structural Design of a Single Foil Cycloidal Rotor in Regular Waves

“…The explicit terms of equation 3 are included in Emarkov and Ringwood [19] for a two foil rotor. Here, because we consider a single foil rotor, 𝑝 and 𝜁 are the same, i.e.…”