Wave energy harvesting of a floating membrane carpet tethered by array-arranged power take-off units

Abstract

Flexible-structure-based wave energy converters (WECs) present a cutting-edge technology to efficiently harvest wave energy through the utilization of generalized elastic modes. This paper proposes a novel WEC consisting of a floating elastic carpet moored by a Power Take-Off (PTO) system. A numerical carpet-covered flume is developed to investigate the hydroelastic effect on wave energy conversion. The carpet is simulated as a uniform elastic thin membrane using the Finite Element Method (FEM). The Computational Fluid Dynamics (CFD) is adopted to model the two-phase flow motion. The bi-directionally coupled fluid-structure interaction is achieved by enforcing interface conditions at each time step. After convergence and validation, detailed hydrodynamic characteristics are examined via parametric analysis. The wave energy absorption of the floating carpet can be enhanced by the multi-mode elastic deformation, which is constructive for both wave energy extraction and wave attenuation. Symmetrical PTO placements yield better performance by striking a balance between energy extraction and structural deformation. When the number of PTO units exceeds a certain threshold, i.e., a continuous PTO distribution, the improved cost-effectiveness is not offered. The energy harvesting is augmented with increasing the PTO placement range. A larger carpet aspect ratio significantly improves efficiency, especially in medium- and long-period waves.