Design and optimisation of cross-flow turbine for enhanced efficiency in electricity generation using free-flow water from reinforced tank

Urban and industrial water systems are neglected renewable energy source, even as demand for energy has risen and sustainability targets push back on fossil fuel power generation. In order to fill this research gap, this study aims to design and optimise the vertical free-fall water flow from reinforced concrete (RC) tanks for electricity generation through the crossflow hydro turbine. The impact of blade quantity (15, 25, and 30 blades) and blade angles (20°, 25°, 30°, 35°, 40°, and 45°) on turbine performance was evaluated. A 3D model of the turbine was created in SolidWorks, including detailed blade-geometry considerations to optimise the turbine. The pressure distribution and the efficiency of energy conversion were investigated using computational fluid dynamics (CFD) simulation in ANSYS Fluent based on 36 configurations of turbine, where the inlet velocity was kept constant at 18.26 m/s (corresponding to a head of 0.8 m). The results indicated that both a low blade angle (20°–25°) and a high blade number (30 blades) showed the highest performance, and the 30-blade, 25° configuration generated the maximum pressure of 319,336.3 Pa, torque of 3257.230 Nm, angular velocity of 22.687 rad/s and power output of 73.896 kW. The results serve as a comparative benchmark for future experimental and practical studies into the generation of small-scale hydropower. The correct positioning of the outlet of the RC tank with respect to the turbine is identified as a critical parameter for reducing losses and improving efficiency in successive design versions.