Abstract
As one of the promising renewable energies, ocean renewable energy (ORE) in the form of tidal energy can be extracted through a horizontal-axis tidal turbine (HATT). HATT performance relies on various environmental factors, including the presence of waves, shear flow, blockage, and submersion depth. Several studies have been conducted regarding the effects of such factors on HATT’s performance. However, a coupled study on the mentioned environmental factors is yet to be performed. This study determines the effects of blockage and submersion depth on HATT’s performance designed for low-flow velocities experiencing shear flow with wave–current interaction through numerical simulations. The hydrodynamic analysis is done using CFD to determine the performance characteristics of the turbine, specifically the coefficients of thrust and power. For structural performance, a fatigue analysis is done through FEM to study the effects of stress loadings on the turbine. A wet epoxy/E-glass is utilized as the material of the turbine and a stress-life (S-N) analysis as the fatigue model. It is found that an increase in blockage ratio and submersion depth increases the coefficients of thrust and power, thus increasing the forces applied on the turbine blade. This result is due to the variation in fluid flow created by waves and current, which also leads to an increasing accumulation of stress and strain, with safety factors decreasing along with it. The parametric analysis shows a very strong relationship between the hydrodynamic and structural performance of the turbine, with absolute R-values ranging from 0.84 to 1.0. This study shows blockage ratio and submersion depth are essential considerations when designing HATTs.