بررسي عددي و آزمايشگاهي تاثير شكل بستر بر كارآيي هيدروديناميكي مبدل انرژي امواج از نوع ستون آب نوساني

With the depletion of fossil fuel resources an‎d growing environmental concerns associated with their consumption, renewable energy has become a primary option for meeting future energy deman‎ds. Among the various renewable energy resources, ocean wave energy has attracted considerable attention due to its high energy density an‎d widespread availability. Oscillating Water Column (OWC) wave energy converters have received particular interest because of their compatibility with breakwaters, relatively low construction cost, an‎d simple power take-off mechanism. Nevertheless, their complex hydrodynamic behavior remains one of the main obstacles preventing their widespread commercialization. In this study, for the first time, the Laplace equation governing the wave velocity potential of an OWC wave energy converter was solved using the meshless Method of Fundamental Solutions (MFS). Under the assumptions of an ideal, incompressible, an‎d irrotational fluid, the proposed method provides an efficient solution to the boundary value problem while significantly reducing the computational time compared with conventional numerical approaches. Moreover, it enables accurate prediction of the hydrodynamic performance of OWC converters. Initially, the problem was investigated under linear free-surface boundary conditions, an‎d several seabed configurations, including sloping bottoms, were eva‎luated. Two key geometric parameters, namely the opening ratio (o) an‎d the seabed slope angle (θ), were identified as the dominant factors affecting the performance of sloping-bottom OWC converters. The results demonstrated that increasing the seabed slope while reducing the opening ratio decreases the hydrodynamic efficiency for short waves but enhances the converter performance under long-wave conditions. Based on these findings, two innovative seabed configurations, namely dual-slope an‎d parabolic seabeds, were proposed. Furthermore, a fully nonlinear numerical model was developed to investigate the nonlinear wave–structure interaction by considering the three primary sources of nonlinearity: the movement of free-surface boundary nodes, the nonlinear kinematic free-surface boundary condition, an‎d the nonlinear dynamic free-surface boundary condition. To validate an‎d further optimize the numerical findings, an experimental investigation was conducted on both conventional an‎d dual-slope OWC converters at Dalian University of Technology, China. The experimental results confirmed that the dual-slope configuration improves the converter efficiency under long-wave conditions while mitigating the reduction in efficiency for short waves. In addition, as the dimensionless wave amplitude (Ai/d) increased, the dual-slope converter consistently outperformed the conventional configuration. For instance, at Ai/d=0.02, its efficiency was up to 7% lower than that of the conventional converter, whereas at Ai/d=0.04, it achieved an efficiency improvement of up to 14%. Overall, this research not only presents a fast an‎d accurate numerical framework for analyzing OWC wave energy converters but also proposes effective design strategies for improving their hydrodynamic performance.

محمدنويد مقيم , بشير موحديان عطار

شهريار منصورزاده , مجتبي ازهري , محمود فغفور مغربي