Effect of design parameters on the performance of helical Darrieus hydrokinetic turbines

Abstract

This study aims to explore the effect of various design parameters, such as maximum airfoil thickness, maximum camber in the blade profile, maximum camber position, helical pitch, blade pitch angle, solidity, and number of blades, on the performance of helical Darrieus hydrokinetic turbines (HDHKTs). An experimental and numerical performance analysis was conducted, corresponding to free-stream velocity of 0.5 m/s. The performance increased with increasing airfoil thickness, up to a maximum of 21%. Effects of the maximum camber and position of the maximum camber on the performance of the turbine were insignificant. The analysis was extended to different helical pitch angles on the NACA 4421 profile. The performance increased with increasing helical pitch angle; however, the operating range of tip speed ratio decreased. The blade pitch angle had an insignificant effect on the turbine performance. Furthermore, the HDHKT of the NACA 4421 blade profile consist of two-, three-, four-, five-, and six-blade turbine performances was examined for different solidity values. For solidity values of 0.10, 0.15, and 0.20, the three-blade HDHKT performed the best. For solidity values greater than 0.20, the four-blade HDHKT performed the best. The four-blade HDHKT had the highest coefficient of power among all the HDHKTs.