Sharif Digital Repository

Darrieus turbines are one of the most widely used turbines in extracting energy from tidal currents. This study aimed to investigate the effect of utilizing helical blades and variable solidity ratio on the efficiency of Darrieus tidal turbines. For this purpose, three types of helical turbines with different solidity ratios have been designed, and computer simulation has been used to investigate the effect of the mentioned parameters on the efficiency of the Darrieus turbines. According to the simulation results, the helical turbine has less efficiency than the straight blade Darrieus turbine. The maximum hydrodynamic efficiency of the Darrieus turbine with straighted blades is 38.5,...