Hydrodynamic coefficients and wave loads for a WEC device in heaving mode

Abstract

Abstract-This paper deals with the hydrodynamic parameter computation of a Wave Energy Converter (WEC) that consists of a cylindrical buoy sliding along a partially submerged platform made up of a plate and a column. The computed parameters are particularly needed for the development of a simple hydrodynamic time-dependant model based on the Cummins formulation. This model is intended to be used for WEC control purposes. A semi-analytical approach is therefore proposed for the computation of the hydrodynamic coefficients and the excitation forces. The boundary value problem is solved using variable separation and matched eigenfunction expansion methods. Analytical expressions for the velocity potential are then obtained for each subdomain. Using afterwards these expressions enables the hydrodynamic coefficients and the excitation force to be computed. Numerical results are given for different radiuses of the buoy, column and plate and are compared with previously published models.

Heave Buoy Energy Converters; Simulation of Heave Buoy Response to Wave in Malaysian Water

“…For stationary cylinder, total force is related to the hydrodynamic damping coefficient and defines by following formula: For deep water, group velocity is given as: (6) Then formula for the exciting force is (7) Thus, the wave forces are estimated to produce as much as 4x10 5 kW/m at 10 second as shown below. In figure 8 (a), the positive real response is about 0.5 at longer period in shows the buoy is moving up and down in regards of phase with the wave.…”

“…The most challenge in wave power convertors is to reach the accepted conceptual design and theory that appropriate for the application [4][5][6]. Recent studies discuss the theoretical hydrodynamic coefficient for WEC in heaving mode but merely on cylindrical buoy [7]. Hence, there is a need to extend the theory to make it applicable to such cases.…”

Experimental Studies of Interaction Forces Affect the Position of Vertical Plates on Oscillating Heave Plates with Cylindrical Bodies in Regular Waves

“…The dynamics of heave coupling in WECs have been taken into consideration by several authors (Davis, Thomson, Mundon, & Fabien, 2014;Olaya, Bourgeot, & Benbouzid, 2013;Rhinefrank et al, 2013;Ruehl, Michelen, Kanner, Lawson, & Yu, 2014). The dynamics of heave coupling in WECs are taken into consideration by several authors (Davis, Thomson, Mundon, & Fabien, 2014;Olaya, Bourgeot, & Benbouzid, 2013;Rhinefrank et al, 2013;Ruehl, Michelen, Kanner, Lawson, & Yu, 2014). A literature review reveals two patents and no technical papers that specifically focus on heave plates (Bull, Gerber, & Powers, 2011;US patent no.…”

“…Olaya et al (Olaya et al, 2013) investigated the hydrodynamic parameter computation of a WEC that consists of a cylindrical buoy sliding along a partially submerged platform made up of a plate and column. The computed parameters particularly needed for the development of a simple hydrodynamic time-dependent model were based on the Cummins' formulation.…”

Optimal control for a self-reacting point absorber: A one-body equivalent model approach

“…Hydrodynamic coefficients, i.e. added mass, radiation damping, and wave excitation force, that are required in the identification process, are computed in the frequency-domain by a semi-analytical method described in [11] and also in [12].…”