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. The research methodology is based on numerical modelling supported by small-scale laboratory experiments performed by Crema et al. (2016) and further experiments from the literature, which are used to better understand the involved processes and to validate the Computational Fluid Dynamics models. A comparative analysis of the results from the validated CFD codes applied at full-scale (1:1) and three smaller scales (1:25, 1:10 and 1:5) is performed in order to assess the errors induced by neglecting the effect of air compressibility for each scale and to derive the aforementioned correction factors which are valid for the range of considered flow regime in terms of the Mach number (Ma=0.05-0.15). Indeed, for the air pressure levels considered in the simulations (up to 350 Pa at model scale 1:50), the effect of ...


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    Titel :

    Optimization of oscillating water column wave energy converters - a numerical study ; Optimierung von Wellenkraftanlagen mit oszillierender Wassersäule: eine numerische Studie


    Beteiligte:

    Erscheinungsdatum :

    2017-11-24



    Medientyp :

    Hochschulschrift


    Format :

    Elektronische Ressource


    Sprache :

    Englisch



    Klassifikation :

    DDC:    6 / 62 / 627 / 690