Mooring Analysis of a Floating OWC Wave Energy Converter

Abstract

This investigation focuses on the modelling of a floating oscillating water column (FOWC) wave energy converter with a numerical code (ANSYS AQWA) based on potential flow theory. Free-floating motions predicted by the numerical model were validated against experimental data extrapolated from a 1:36 scale model device in regular and irregular sea states. Upon validation, an assessment of the device’s motions when dynamically coupled with a four-line catenary mooring arrangement was conducted at different incident wave angles and sea states ranging from operational to survivable conditions, including the simulation of the failure of a single mooring line. The lack of viscosity in the numerical modelling led to overpredicted motions in the vicinity of the resonant frequencies; however, the addition of an external linear damping coefficient was shown to be an acceptable method of mitigating these discrepancies. The incident wave angle was found to have a limited influence on the magnitudes of heave, pitch, and surge motions. Furthermore, the obtained results indicated that the mooring restoring force is controlled by the forward mooring lines under the tested conditions.

Integrated Framework for Real-time Sea State Estimation of Stationary Marine Units Using Wave Buoy Analogy

“…Therefore, to increase the threshold dynamicity extension and to include lengthier response periods in the SSE model, a former mechanism has been further upgraded, where it can select the range within [20,40,60,80] sec. It ought to be noted that for the model taut lashing, as comprehensively discussed in (Gubesch et al, 2021), the mooring system impacts the response characteristics substantially, in which higher exciting forces do not influence the response periods, but they affect response amplitudes. The moored nature also introduces many uncertainties in higher-order wave responses that cannot be quantified accurately.…”

Floating Oscillating Water Column Wave Energy Converters: A Review of Developments

“…Recently, the hydrodynamic performance of a box-type moored OWC was studied numerically and experimentally. Specifically, in [189], the developed numerical modeling was compared against experimental data obtained from a test campaign in the wave basin with a 1:36 scale model. The study demonstrated that the wave direction significantly impacted sway, roll, and yaw motions while exerting a minimal effect on heave and pitch motions.…”

Wave Energy Conversion through Oscillating Water Columns: A Review

“…Theoretical studies play a crucial role in revealing hydrodynamic characteristics, primarily using linear water wave theory. The practicality and efficiency of the linearized approach have led to the continuous development of theoretical studies for OWC devices [54][55][56][57][58][59][60]. [24] investigated the behavior of the OWC device near an impermeable wall using the Galerkin technique (see Figure 6).…”