ORCID Profile
0000-0002-8426-1798
Current Organisation
National University of Ireland Maynooth
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Publisher: Springer Science and Business Media LLC
Date: 06-08-2021
Publisher: Springer Science and Business Media LLC
Date: 05-2021
DOI: 10.1007/S40722-021-00198-8
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.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2022
Publisher: American Physical Society (APS)
Date: 13-09-2017
Publisher: American Physical Society (APS)
Date: 22-09-2017
Publisher: No publisher found
Date: 2019
DOI: 10.26192/EZ1N-G463
Publisher: European Wave and Tidal Energy Conference
Date: 02-09-2023
Publisher: Elsevier BV
Date: 05-2023
Publisher: Allerton Press
Date: 03-2011
Publisher: Springer Berlin Heidelberg
Date: 2013
Publisher: CRC Press
Date: 30-10-2017
Publisher: MDPI AG
Date: 22-09-2021
Abstract: As it was shown earlier, a wide class of nonlinear 3-dimensional (3D) fluid flows of incompressible viscous fluid can be described by only one scalar function dubbed the quasi-potential. This class of fluid flows is characterized by a three-component velocity field having a two-component vorticity field. Both these fields may, in general, depend on all three spatial variables and time. In this paper, the governing equations for the quasi-potential are derived and simple illustrative ex les of 3D flows in the Cartesian coordinates are presented. The generalisation of the developed approach to the fluid flows in the cylindrical and spherical coordinate frames represents a nontrivial problem that has not been solved yet. In this paper, this gap is filled and the concept of a quasi-potential to the cylindrical and spherical coordinate frames is further developed. A few illustrative ex les are presented which can be of interest for practical applications.
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5063561
Abstract: We revise the solutions of the forced Korteweg–de Vries equation describing a resonant interaction of a solitary wave with external pulse-type perturbations. In contrast to previous work where only the limiting cases of a very narrow forcing in comparison with the initial soliton or a very narrow soliton in comparison with the width of external perturbation were studied, we consider here an arbitrary relationship between the widths of soliton and external perturbation of a relatively small litude. In many particular cases, exact solutions of the forced Korteweg–de Vries equation can be obtained for the specific forcings of arbitrary litude. We use the earlier developed asymptotic method to derive an approximate set of equations up to the second-order on a small parameter characterising the litude of external force. The analysis of exact solutions of the derived equations is presented and illustrated graphically. It is shown that the theoretical outcomes obtained by the asymptotic method are in a good agreement with the results of direct numerical modeling within the framework of forced Korteweg–de Vries equation.
Publisher: Springer Science and Business Media LLC
Date: 24-06-2019
Publisher: Institution of Engineering and Technology (IET)
Date: 02-05-2021
DOI: 10.1049/RPG2.12192
Publisher: No publisher found
Date: 2014
Publisher: European Wave and Tidal Energy Conference
Date: 07-10-2022
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.
Publisher: American Society of Mechanical Engineers
Date: 05-06-2022
Abstract: Recently, cyclorotors, utilizing lift rather than buoyancy forces for energy extraction, have been proposed and inherit many of the appealing features characteristic of modern wind turbines. In particular, the ability to spill energy though foil pitching allows the device to remain at rated power despite significant variations in input power level, while additional cyclorotor features, including variable submergence depth and rotor radius, also permit a significant degree of modulation of the device structure, and energy absorption characteristics, offering considerable flexibility. These configuration flexibilities, in addition to torque control of the rotor/generator shaft (also characteristic of wind turbines) offers the control engineer considerable freedom in adjusting the device characteristics to maximise the effectiveness of the device in capturing wave power, while maintaining structural integrity and minimizing harmful stresses on system components. However, such flexibility also provides a significant challenge in the form of a multivariable control problem for a system described by significantly nonlinear hydrodynamics. This paper describes a proposed hierarchical control system for a cyclorotor wave energy device, utilizing submergence depth, rotor radius, foil pitch angles, and shaft torque as control inputs. The hierarchy involves the separation of the control actuators into two classes: structural (or slow) control effectors, and wave-by-wave (or fast) control effectors. In particular, the paper will examine the interaction between the two levels of the control hierarchy and the need, if any, for simultaneous optimisation of the control parameters at both levels.
Publisher: Springer Berlin Heidelberg
Date: 2011
Publisher: Cambridge University Press (CUP)
Date: 11-09-2020
Publisher: IEEE
Date: 05-06-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2022
Location: Russian Federation
Location: No location found
No related grants have been discovered for Andrei Ermakov.