Evaluation of the influence of the number of blades on a Michell Banki turbine on the power generated under given flow and head conditions

Rural areas often face electricity supply challenges due to high costs and low population density, making small hydraulic turbines a viable solution. Michell Banki turbines are a cost-effective alternative, but their efficiency depends on blade count, and most studies rely on commercial software, limiting accessibility. This study evaluates the influence of blade count on power output using open-source computational fluid dynamics (CFD) tools. A numerical simulation approach was employed with FreeCAD and its CFDof module to model five rotor configurations (15, 20, 25, 30, and 35 blades) under different flow conditions (25 %, 50 %, 75 %, 100 %, and 125 %). The k-ω SST turbulence model within a Reynolds-Averaged Navier-Stokes (RANS) framework was applied, alongside a mesh convergence study to optimize computational efficiency. Velocity fields, pressure distribution, and forces on the blades were analyzed to calculate torque and power. Results show that blade count significantly affects efficiency, with the 30-blade rotor achieving the highest power output of 5253.89 W at 100 % flow rate. While rotors with 25, 30, and 35 blades performed best, excessive blades increased friction losses, reducing efficiency. The study validates the 30-blade configuration as the most appropriate for Michell Banki turbines under given conditions. Lower blade counts yield suboptimal energy conversion, while excessive blades cause friction losses. The findings align with prior research and demonstrate that open-source CFD tools offer a cost-effective alternative to commercial software