scholarly journals Hydroelectromechanical modelling of a piezoelectric wave energy converter

2016 ◽  
Vol 472 (2195) ◽  
pp. 20160715 ◽  
Author(s):  
E. Renzi
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Numerical Approach ◽  
Wave Energy Converter ◽  
Flexural Wave ◽  
Energy Converter ◽  
Flow Equations ◽  
Ocean Surface Waves ◽  
In Series ◽  
Surface Water Waves

We investigate the hydroelectromechanical-coupled dynamics of a piezoelectric wave energy converter. The converter is made of a flexible bimorph plate, clamped at its ends and forced to motion by incident ocean surface waves. The piezoceramic layers are connected in series and transform the elastic motion of the plate into useful electricity by means of the piezoelectric effect. By using a distributed-parameter analytical approach, we couple the linear piezoelectric constitutive equations for the plate with the potential-flow equations for the surface water waves. The resulting system of governing partial differential equations yields a new hydroelectromechanical dispersion relation, whose complex roots are determined with a numerical approach. The effect of the piezoelectric coupling in the hydroelastic domain generates a system of short- and long-crested weakly damped progressive waves travelling along the plate. We show that the short-crested flexural wave component gives a dominant contribution to the generated power. We determine the hydroelectromechanical resonant periods of the device, at which the power output is significant.

Numerical Verification of the Tuned Inertial Mass Effect of a Wave Energy Converter

2017 ◽  
Author(s):  
Ruriko Haraguchi ◽  
Takehiko Asai
Keyword(s):  
Wave Energy ◽  
Inertial Mass ◽  
Mass Effect ◽  
Dominant Frequency ◽  
Wave Energy Converter ◽  
Numerical Verification ◽  
Energy Converter ◽  
Numerical Studies ◽  
In Series ◽  
Band Limited

This paper introduces the mechanism of a buoy-type wave energy converter (WEC) with a tuned inertial mass (TIM) mechanism. The TIM mechanism consists of a rotational mass and motor connected in series with a tuning spring. While it is common to control the current of the power take-off system, the stiffness of the spring is tuned in addition so that the inertial mass part resonates with the dominant frequency of the wave motion. The method to design the parameters to maximize the power generation capability is introduced and numerical studies for both narrowband and broadband sea states are carried out. It is shown that the proposed device demonstrates better energy harvesting performance compared to the WEC without the TIM mechanism to band-limited stationary random vibration.

Stochastic Analysis of a Nonlinear Energy Harvester Model

2014 ◽  
Author(s):  
P. D. Spanos ◽  
A. Richichi ◽  
F. Arena
Keyword(s):  
Dynamic Analysis ◽  
Wave Energy ◽  
Water Waves ◽  
Nonlinear Dynamic Analysis ◽  
Nonlinear Effects ◽  
Wave Energy Converter ◽  
Statistical Linearization ◽  
Energy Converter ◽  
Domain Integration ◽  
Stiffness And Damping

Floating oscillating-bodies are a kind of wave energy converter developed for harvesting the great amount of energy related to water waves (see Falcão [1] for a review). Although the assumptions of small-wave and linear behavior of oscillating system are reasonable for most of the time during which a floating point harvester is in operation, nonlinear effects may be significant in extreme sea states situations. In this paper a nonlinear dynamic analysis of a point harvester wave energy converter is conducted. The model involves a tightly moored single-body floating device; it captures motion in the horizontal and vertical directions. The stiffness and damping forces, being functions of the displacement and velocity components, make the system nonlinear and coupled. For the input forces, the erratic nature of the waves is modeled by a stochastic process. Specifically, wind-generated waves are modeled by means of the JONSWAP spectrum. The method of statistical linearization [2] is used to determine iteratively the effective linear stiffness and damping matrices and response statistics of the system and to proceed to conducting a dynamic analysis of the harvester model. The reliability of the linearization based approach is demonstrated by comparison with time domain integration, Monte Carlo simulation, data. This approach offers the appealing feature of conducting efficiently a variety of parameter studies which can expedite preliminary evaluations, inter alia, of competing design scenarios for the energy converter in a stochastic environmental setting.

scholarly journals A Novel Method for Estimating Wave Energy Converter Performance in Variable Bathymetry Regions and Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2092 ◽  
Author(s):  
Kostas Belibassakis ◽  
Markos Bonovas ◽  
Eugen Rusu
Keyword(s):  
Wave Field ◽  
Wave Energy ◽  
Water Waves ◽  
Bottom Topography ◽  
Wave Energy Converter ◽  
Diffraction Radiation ◽  
Floating Bodies ◽  
Energy Converter ◽  
Coupled Mode ◽  
Energy Absorbers

A numerical model is presented for the estimation of Wave Energy Converter (WEC) performance in variable bathymetry regions, taking into account the interaction of the floating units with the bottom topography. The proposed method is based on a coupled-mode model for the propagation of the water waves over the general bottom topography, in combination with a Boundary Element Method for the treatment of the diffraction/radiation problems and the evaluation of the flow details on the local scale of the energy absorbers. An important feature of the present method is that it is free of mild bottom slope assumptions and restrictions and it is able to resolve the 3D wave field all over the water column, in variable bathymetry regions including the interactions of floating bodies of general shape. Numerical results are presented concerning the wave field and the power output of a single device in inhomogeneous environment, focusing on the effect of the shape of the floater. Extensions of the method to treat the WEC arrays in variable bathymetry regions are also presented and discussed.

Intermediate Ocean Wave Termination Using a Cycloidal Wave Energy Converter

2010 ◽  
Author(s):  
Stefan G. Siegel ◽  
Tiger Jeans ◽  
Thomas McLaughlin
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Optimal Parameter ◽  
Wave Energy Converter ◽  
Design Parameters ◽  
Intermediate Water ◽  
Main Shaft ◽  
Energy Converter ◽  
Incoming Wave ◽  
Conversion Efficiencies

We investigate a lift based wave energy converter (WEC), namely, a cycloidal turbine, as a wave termination device. A cycloidal turbine employs the same geometry as the well established Cycloidal or Voith-Schneider Propeller. The interaction of intermediate water waves with the Cycloidal WEC is presented in this paper. The cycloidal WEC consists of a shaft and one or more hydrofoils that are attached eccentrically to the main shaft and can be adjusted in pitch angle as the Cycloidal WEC rotates. The main shaft is aligned parallel to the wave crests and fully submerged at a fixed depth. We show that the geometry of the Cycloidal WEC is suitable for wave termination of straight crested waves. Two-dimensional potential flow simulations are presented where the hydrofoils are modeled as point vortices. The operation of the Cycloidal WEC both as a wave generator as well as a wave energy converter interacting with a linear Airy wave is demonstrated. The influence that the design parameters radius and submergence depth on the performance of the WEC have is shown. For optimal parameter choices, we demonstrate inviscid energy conversion efficiencies of up to 95% of the incoming wave energy to shaft energy. This is achieved by using feedback control to synchronize the rotational rate and phase of the Cycloidal WEC to the incoming wave. While we show complete termination of the incoming wave, the remainder of the energy is lost to harmonic waves travelling in the upwave and downwave direction.

Experimental Wave Generation and Cancellation With a Cycloidal Wave Energy Converter

2011 ◽  
Author(s):  
Stefan G. Siegel ◽  
Marcus Ro¨mer ◽  
John Imamura ◽  
Casey Fagley ◽  
Thomas McLaughlin
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Wave Generation ◽  
Wave Energy Converter ◽  
Design Parameters ◽  
Main Shaft ◽  
Energy Converter ◽  
Incoming Wave ◽  
Wave Flume ◽  
Wave Maker

We investigate a lift based wave energy converter (WEC), namely, a cycloidal turbine, as a wave termination device. A cycloidal turbine employs the same geometry as the well established Cycloidal or Voith-Schneider Propeller. The main shaft is aligned parallel to the wave crests and fully submerged at a fixed depth. We show that the geometry of the Cycloidal WEC is suitable for single sided wave generation as well as wave termination of straight crested waves using feedback control.The cycloidal WEC consists of a shaft and one or more hydrofoils that are attached eccentrically to the main shaft. An experimental investigation into the wave generation capabilities of the WEC are presented in this paper, along with initial wave cancellation results for deep water waves. The experiments are conducted in a small 2D wave flume equipped with a flap type wave maker as well as a 1:4 sloped beach. The operation of the Cycloidal WEC both as a wave generator as well as a wave energy converter interacting with a linear Airy wave is demonstrated. The influence that design parameters radius and submergence depth on the performance of the WEC have is shown. For wave cancellation, the incoming wave is reduced in amplitude by ≈ 80% in these experiments. In this case wave termination efficiencies of up to 95% of the incoming wave energy with neglegible harmonic waves generated are achieved by synchronizing the rotational rate and phase of the Cycloidal WEC to the incoming wave.

Efficient Dynamic Analysis of Floating Bodies Nonlinear Behavior in Wave Energy Conversion

2013 ◽  
Author(s):  
P. D. Spanos ◽  
A. Richichi ◽  
F. Arena
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Water Waves ◽  
Nonlinear Behavior ◽  
Time Domain Analysis ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Equivalent Linearization ◽  
Energy Converter ◽  
Stiffness And Damping

Floating oscillating-bodies are a kind of wave energy converter developed for harvesting the great amount of energy related to water waves; see Falcão [1] for a review. In this paper a particular energy converter model is considered. A nonlinear analysis of its dynamic behavior is conducted both in the time and the frequency domains. The model involves a tightly moored single-body floating wave energy converter. It captures motion in the horizontal and vertical directions. The nonlinear stiffness and damping forces are functions of the horizontal and vertical displacements and velocities and make the system a nonlinear one. In addition to the time-domain analysis of the nonlinear behavior of the system, the method of equivalent linearization is used to determine iteratively the effective linear stiffness and damping matrices and the response of the buoy in the frequency domain. The analysis pertains to the surge and the heave directions response of the wave energy converter under harmonic mono-frequency excitation (regular waves). The reliability of the linearization based approach is demonstrated by comparison with time domain integration data. This approach offers the appealing feature of conducting efficiently a variety of parameter studies which can expedite preliminary evaluations, inter alia, of competing design scenarios for the energy converter. Suggestions for extending this approach to the case of fully nonlinear and random irregular waves are also included.

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