Numerical Study of Control Rod's Cross-Section Effects on the Aerodynamic Performance of Savonius Vertical Axis Wind Turbine with Various Installation Positions at Suction Side

The substantial rise in atmospheric pollutants attributed to the use of fossil fuels has driven the development of renewable energy sources as a burgeoning industry. Subsequently, amidst the ongoing quest for sustainable energy sources, wind energy has emerged as a reliable alternative. This has resulted in the development of various types of wind turbines. One of the most common types of vertical axis wind turbines is Savonius VAWTs. Despite possessing advantages, these turbines are less efficient compared to others. However, this shortcoming can be remedied by enhancing the aerodynamic performance of the turbines. This two-dimensional study examined the impact of placing an external object as a control rod at the rotor upstream or on the suction side by computational fluid dynamic methods. The rod was designed with circular, oval, dimpled, and bumpy cross-sections. The study evaluated different stagger angles for various diameter and distance ratios. The results showed that using a circular cross-section at a stagger angle = 30°, S/D = 1.5 and D/d = 2 increased efficiency by 40%. Implementing an oval cross-sectional design with stagger angle = 60° and S/D = 1 enhanced the rotor's efficiency to 90%. Using a bumpy cross-section yielded a jump in efficiency and expanded the operating range of the Savonius VAWT up to a tip speed ratio of 0.8.