| dc.description.abstract | Ocean current turbines are one of many environmentally friendly, prospective energy sources out there, however, it is still at an embryonic stage in development. This thesis aims to build on the existing knowledge in the field, by investigating the design of two Savonius type ocean current turbines, both with- and without surrounding structures that augment their performances. The two profiles evaluated were the semi circular- and the elliptic blade profile. For this purpose, the computational fluid dynamics software, OpenFOAM, was utilised, with the geometry and mesh created in \textsc{Solidworks} and Gmsh, respectively. The Reynolds Average Navier-Stokes equations were used, employing the $k-\omega$ SST turbulence closure model, together with the PIMPLE pressure-velocity coupling algorithm. Wall functions were implemented to estimate the flow parameters in the wall boundaries, using an average $y^+$ value of 300. However, results show that this approach provided inaccurate results, most likely due to poor estimations of flow separation. Augmentations increased the power coefficient of the semi circular turbine by 50.78\%, from 0.258 to 0.389, whereas the elliptic profile saw a 79.71\% increase in power coefficient, from 0.276 to 0.496. Future work regarding this thesis should look at further enhancement of the elliptic profile, optimizing the augmentation around it. Moreover, a finer grid should be implemented. | |
