Wave energy harvesting performance of a novel Dual-mode Oscillating Buoy- Parabolic Oscillating Water Column (DOB-POWC) hybrid system

Incident, reflected, and transmitted wave energies are the primary types of wave energy interacting with marine structures. This paper proposes an innovative hybrid system that integrates an Oscillating Water Column (OWC) device with a cylindrical Oscillating Buoy (OB). The front wall of the OWC is designed with a parabolic shape to collect and focus reflected waves to enhance the power capture performance of the OB device; therefore, it is referred to as the Parabolic Oscillating Water Column (POWC). The OB can harvest energy from both heave and pitch modes and connects to the POWC through a hinge mechanism, known as the Dual-mode Oscillating Buoy (DOB). The proposed DOB-POWC hybrid system can absorb incident wave energy via the DOB, capture transmitted wave energy through the POWC, and converge reflected wave energy within a region using the parabolic wall. Numerical simulations indicate that positioning the DOB at the focal point of the parabolic front wall significantly enhances the capture factor of the hybrid system, with a maximum capture factor reaching 160.63%. Furthermore, the hybrid system combining DOB and POWC features a broad effective bandwidth and can continuously absorb wave energy across a wider range of wave periods, offering a wider capture bandwidth.