Optimization of Oscillating Water Column Wave Energy Converters - A numerical study

This PhD research aims at the study of the combined effect of the structure geometry and of the damping applied by a non-linear turbine (i.e., an impulse turbine) on the performance of a fixed Oscillating Water Column (OWC) device for harvesting wave energy. The improved knowledge base regarding the still not well-understood optimal OWC geometry and the optimal turbine damping, specifically for moderate wave climates such as in the Mediterranean Sea, contributes to fill one of the current gaps of knowledge. Moreover, the scale effect induced by neglecting the air compressibility in modelling OWC devices at small-scale is evaluated, and correction factors for the results from small-scale laboratory testing of OWC devices as well as for the results of incompressible numerical models are provided, thus contributing to fill a further recognized knowledge gap. Further, a conceptual model allowing to predict the capture width ratio of the OWC based on the geometrical parameters (e.g. chamber width and front wall draught), the damping applied by the turbine and the incident wave conditions is proposed. The proposed conceptual model might be applied as a design tool in the process of the OWC device optimization.