CFD modelling of a small–scale fixed multi–chamber OWC device

Abstract

Wave Energy Converters (WECs) have excellent potential as a source of renewable energy that is yet to be commercially realised. Recent attention has focused on the installation of Oscillating Water Column (OWC) devices as a part of harbor walls to provide advantages of cost-sharing structures and proximity of power generation facilities to existing infrastructure.In this paper, an incompressible three-dimensional CFD model is constructed to simulate a fixed Multi-Chamber OWC (MC-OWC) device. The CFD model is validated; the simulation results are found to be in good agreement with experimental results obtained from a scale physical model tested in a wave tank. The validated CFD model is then used for a benchmark study of 96 numerical tests. These investigate the effects of the PTO damping caused by the power take-off (PTO) system on device performance. The performance is assessed for a range of regular wave heights and periods. The results demonstrate that a PTO system with an intermediate damping can be used for all chambers in the MC-OWC device for most wave period ranges, except for the long wave periods. These require a higher PTO damping. An increased incident wave height reduces the device capture width ratio, but there is a noticeable improvement for long wave periods.

Wave-to-Wire Model of an Oscillating-Water-Column Wave Energy Converter and Its Application to Mediterranean Energy Hot-Spots

“…In these modeling approaches, the OWC hydrodynamic coefficients are analytically [27,28], numerically [29,30], or experimentally [31,32] determined. Recently, models based on CFD are experiencing a great expansion for analyzing the interaction between incident waves and OWC structures, including the nonlinear and viscous effects [33][34][35][36][37][38]. The aforementioned modeling approaches were applied to study the effect of different design parameters of the primary conversion efficiency.…”

“…However, a holistic approach is needed, going into the direction of a combined optimization of the converters for specific wave conditions. Indeed, the optimal damping for the OWC chamber depends on its geometry and the local characteristics of the incident wave and, in turn, the performance of the air turbine depends on the pressure difference made available by the chamber [11,35,38,48]. For these reasons, analytical wave-to-wire models are the most suited solution for the primary design of OWC wave energy converters, allowing for investigation of a wide variety of design solutions with the need of reduced computational power and time.…”

Experimental investigation on the hydrodynamic performance of a multi-chamber OWC-breakwater

“…[33] followed up with an experimental study and observed the existence of two different resonant frequencies corresponding to the inner-and outer-chambers, and concluded that the combination of the two different resonant frequencies of inner and outer chambers lead to a wider frequency region. Shalby et al [34][35] proposed a new type of MC-OWC wave energy device, which has four chambers along the incident wave direction. Numerical 3-D studies with focus on the capture width ratio and free surface elevation were presented.…”

The Wave-to-Wire Energy Conversion Process for a Fixed U-OWC Device

“…However, one-dimensional models are unable to give an insight of the different hydrodynamic processes that occur in the proximity of, and inside the U-OWC system. To overcome the intrinsic limits of these one-dimensional models, a numerical approach based on CFD simulations has been proposed by the authors [18,19] and by others (e.g., [20][21][22][23]). The performance of an OWC device under a range of wavelengths for different wave steepness was analyzed by Kamat et al [21] by means of CFD simulations.…”