Optimum performance of a horizontal axis tidal current turbine: A numerical parametric study and experimental validation

One of the most essential parameters contributing to the performance of hydrokinetic tidal current turbine is its geometry. In this study, the effect of curvature, thickness, and blade pitch angle (BPA(0)) with a glimpse at the turbine performance considering the probability of fatigue loading presence are investigated. Six different airfoils based on possessing the acceptable lift to drag ratio were selected and used to design turbine blades using the blade element momentum theory. Computational fluid dynamic was employed for simulation the performance of turbines at diverse tip speed ratios (TSR)s and BPA(0)s so that the condition for obtaining the maximum performance was determined. An experimental setup was fabricated to validate the computational results. The question is: To what extent this maximum performance condition is possible to be implemented in practice? To answer this question, a parameter called superiority of maximum power coefficient (SCPmax) was introduced to assess the usefulness of employment of each airfoil based on maximum power coefficient (C-Pmax), thrust coefficient (C-Th), and the percentage of airfoil thickness (%t) and exhibit the utility of maximum performance against the probability of fatigue hazard. Results indicated that at higher values of BPA(0)s, by increasing the thickness, the maximum amount of torque enhances. Furthermore, the augmentation in the TSR leads to increase in C-Pmax at the lower value of BPA(0) so that the difference between the lowest (for NACA 65(3)-618) and highest (for NACA 4412) C-Pmax is around 66%. In contrast, the maximum value of SCPmax belonged to the NACA65(3)-618 due to lower C-Th and more %t, while the minimum amount of SCPmax appertained to the NACA2410 which has the minimum %t.

Automated summary

The geometry of hydrokinetic tidal current turbine is crucial for its performance. This study investigates the effect of curvature, thickness, and blade pitch angle on turbine performance, considering the probability of fatigue loading. Different airfoils with acceptable lift to drag ratios were used to design turbine blades, and computational fluid dynamics was employed to simulate turbine performance under various conditions. An experimental setup was also used to validate the computational results. Results indicate that increasing thickness at higher blade pitch angle values enhances the maximum torque, while increasing the tip speed ratio improves the maximum power coefficient. The parameter SCPmax is introduced to assess the usefulness of each airfoil based on various factors and demonstrate the utility of maximum performance against fatigue hazard.