Ermakov, Andrei and Ringwood, John (2021) A control-orientated analytical model for a cyclorotor wave energy device with N hydrofoils. Journal of Ocean Engineering and Marine Energy, 7. pp. 201-210. ISSN 2198-6444

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Abstract

We present a new analytical model from which a model-based controller can be derived for a cyclorotor-based wave energy converter (WEC). Few cyclorotor-based WEC concepts and models have previously been studied and only one control strategy for the entire wave cancellation has been tested. Our model is derived for a horizontal cyclorotor with N hydrofoils and is suitable for the application of various control algorithms and the calculation of various performance metrics. The mechanical model is based on Newton’s second law for rotation. The cyclorotor operates in two dimensional potential flow. This paper modeled the velocity field in detail around the turbine with N hydrofoils by explaining each velocity term and estimated the generated torque using two methods (point source method and thin-chord method). The developed model is very convenient for control design, using the power take off torque and hydrofoil pitch angles as control inputs. 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 and increase the accuracy of the results. The new equations also provide useful insight into the nature of the associated variables, and are successfully validated against the results of physical experiments and numerical calculations previously published by two independent research groups. Representation of hydrofoils as both a point source and a thin chord were analysed, with both models cross-validated for the case of free rotation in monochromatic waves.

Item Type:	Article
Keywords:	Control design; Cyclorotor; Lift-based wave energy converter; LiftWEC; Rotor; Wave energy; Wave energy converter;
Academic Unit:	Faculty of Science and Engineering > Research Institutes > Centre for Ocean Energy Research
Item ID:	15170
Identification Number:	https://doi.org/10.1007/s40722-021-00198-8
Depositing User:	Professor John Ringwood
Date Deposited:	04 Jan 2022 11:42
Journal or Publication Title:	Journal of Ocean Engineering and Marine Energy
Publisher:	Springer
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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