The Design, Fabrication, and CFD-Based Performance Analysis of a Gravitational Water Vortex Turbine

Abstract

Gravitational Water Vortex Turbines (GWVTs) provide a cost-effective and sustainable solution for rural electrification under low-head conditions. This research presents the fabrication and experimental evaluation of a cylindrical basin prototype (50 cm diameter, 50 cm height) to study the influence of vortex height, blade position, and orifice-to-basin diameter ratios on turbine performance. Orifice sizes of 8, 10, 12, and 14 cm (16–28% ratios) were tested with blade placements at 2 cm, 7 cm, and 10 cm, across vortex heights ranging from 18–48 cm. Results show that vortex height is the primary driver of performance, with Revolutions Per Minute (RPM) and power output increasing up to 40–43 cm before plateauing due to turbulence. The stable performance was leading to 24% orifice-to-basin ratio with the maximum power output of approximately 2.3mW as well as an overall hydraulic to mechanical energy conversion efficiency of approximately 8.8% at a vortex height of 35 cm, whereas the speed of the turbine was approximately 115 RPM at 40 cm. The blades' position of 22 cm maximized torque capture, whereas deeper blades generated higher speeds (125-155RPM) but minimized electrical power. Smaller orifice ratios (16–20%) concentrated flow and performed better at higher vortex heights, while the 28% ratio showed efficiency losses from turbulence. Overall, the findings confirm that a 24% orifice-to-basin ratio with mid-range vortex heights (30–40 cm) and blade depths of 10–22 cm provides the most effective balance of RPM, power, and efficiency, making GWVTs a practical low-head micro-hydro technology for decentralized rural energy generation.