Design of Archimedes screw turbine: exploring the influence of pitch ratio, radius ratio, and inclination angle on outer diameter size

Archimedes screw turbine is a hydropower machine with a cylindrical shaft and a helical screw-shaped blade. This study determines the appropriate outer diameter of the turbine by considering internal parameters, such as pitch ratio and radius ratio, along with the influence of inclination angle and varying flow rates. A procedural design calculation method is proposed, integrating existing models for power output, flow rate capacity, and losses from various previous literature. The findings reveal that the pitch ratio significantly affects the outer diameter, indicating that higher pitch ratios correspond to smaller diameters. Furthermore, the radius ratio exhibits a minimum point at 0.45, resulting in the smallest diameter. The inclination angle also impacts the outer diameter, with larger angles leading to increased diameters. For instance, at the highest flow rate of 1.0 m³/s, an inclination angle of 50° yields an outer diameter of 4.94 m, while an angle of 20° results in 1.76 m. The study identifies an optimum efficiency of nearly 0.91 at a 34° inclination angle, with efficiency sharply declining beyond 40°. Designing Archimedes screw turbine for higher flow rates increases outer diameter, enhancing torque production and overall efficiency. The proposed calculation procedure ensures an appropriate design to accommodate flow rates and prevent overflow leakage. This study provides insights into determining the outer diameter of Archimedes screw turbines. By considering internal parameters, inclination angle, and varying flow rates, the proposed design calculation method enables proper turbine design. These findings offer practical insights for implementing Archimedes screw turbine designs.