In low-velocity areas, the Savonius turbine offers an attractive, economical, and ecologically beneficial method of generating electricity. However, due to the fact that scientists are still looking for a solution to the primary issue of the Savonius turbine's poor efficiency, this turbine has not yet been properly investigated. To increase the efficiency of the Savonius turbine the nozzle system can be utilized. In the present study, a 2-dimensional numerical simulation using the computational fluid dynamics (CFD) method was conducted for a Savonius vertical axis wind turbine (VAWT). This study aims to investigate the effect of different nozzle installation angles and nozzle wall lengths on the performance of the Savonius turbine and for this purpose, six different nozzle designs are investigated. In order to observe the performance of the mentioned turbine, the power coefficient (Cp) is calculated, and their values are compared in the different tip speed ratios (TSR). The results show that the highest efficiency of Savonius VAWTs is achieved with a nozzle installation angle of 55°. After that in optimum nozzle installation angle, the nozzle length of 1900 mm exhibits better performance compared to other nozzle lengths at a TSR of 0.5. پرونده مقاله