Investigations Of Offshore OWC On Structure Optimization Of Front And Rear Wall And Wave Load Under Focused Wave

Among the rich ocean renewable energy,wave energy has the characteristics of huge energy reserves and high energy-flux density,which has very promising developments and prospects.The oscillating water column(OWC)wave energy converter has become the most widely used wave energy conversion device in the world benefited from its simple structure form and functional diversity.Many achievements have been made in the research and development of OWC while the problem of low power generation efficiency still remains.At the same time,there is a lack of research on the survival ability of OWC in extreme wave conditions.Numerical simulations of wave-OWC interaction are studied in this paper based on the open-source computational fluid dynamics(CFD)platform OpenFOAM.The hydrodynamic performance of OWC is studied and optimized in order to improve the energy conversion efficiency and study the survival ability of OWC in extreme wave conditions.The main contents are as follows:First of all,based on waves2 foam solver a two-dimensional numerical model is established,which can accurately simulate the interaction between waves and structures.The verification of wave generation is conducted,and subsequently the interactions of wave-OWC is carried out,both are compared with the theoretical values and experimental ones.The results show a good reliability and accuracy of the numerical model and lays a foundation for the following study.Secondly,the hydrodynamic performances of two-dimensional offshore OWC in regular wave conditions are studied.By compared with the traditional OWC model,the effects of asymmetric arrangement of front and rear walls and smooth bottom corner treatment on the energy capture efficiency of OWC device and the scatter of nearby flow field are studied.The results show that the combination of asymmetric layout and smooth bottom corner can suppress the generation of vortices at the front and rear walls,thus reducing energy dissipation and improving the energy conversion efficiency of the OWC device.Finally,the wave load of the two-dimensional offshore OWC in focusing wave conditions is studied by analyzing the impact forces and pressure distribution along the walls of OWC,which is compared with the forces in regular wave conditions.The results show that the strong nonlinearity of focusing waves will intensify the oscillation of the water column in the chamber,causing waves reach the upper side of OWC and having an adverse impact on the normal operation of the turbine at the opening;the violent oscillations of the water column will also lead to a large impact pressure both at the inner side of the front wall and the upper roof of the chamber,which will seriously affect the safety and stability of the structure.