which is another advantage of Darrieus runner. Authors have been clarified the design guideline and the characteristics of Darrieus turbine to obtain the higher
performances [2,3]. A peculiar characteristic of the Darrieus runner is variations in generated blade torque in one revolution. Matsushita et al. [4] proposed a runner casing with inlet nozzle which was optimized the torque variation, then achieved higher turbine performances. In addition,