1.School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China；
2.Key Laboratory of Transients in Hydraulic Machinery, Ministry of Education, Wuhan University, Wuhan 430072, China
Abstract：A novel wave energy converter (WEC) was studied and its nonlinear hydrodynamics characteristics were analysed. Based on potential flow theory, the influences of WEC’s irregular shape (asymmetry, non-constant waterplane area) and position variation on restoring force were considered, and the Morison model was introduced to analyze added inertial effect and drag effect of fluid viscosity. Therefore, the complete nonlinear dynamics model was proposed, consisting of main linear and nonlinear hydrodynamics and describing processes from wave energy capture to conversion. The numerical wave tank was established using Computational Fluid Dynamics (CFD) method to accurately simulate WEC’s responses. The results of CFD and nonlinear dynamics model were compared to investigate nonlinear hydrodynamics effect and identify coefficients. The results show that conventional linear model overestimates performance of WEC and nonlinear model significantly improves evaluation accuracy of free decay motion and wave-WEC interaction; the Morison model coefficients vary with working conditions; response amplitude operator is more sensitive to Morison model coefficients near resonance frequency; the study can provide guidance for assessing WEC performance correctly and conveniently.
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