Study of Vortex Flow Phenomena in a Vortex Turbine Basin with Cone Angle Variations

Abstract

Vortex turbines are widely developed due to their main advantages, namely their ability to operate at low flow heads and their simple construction design, making them suitable for application in mountainous rivers. The working principle of a vortex turbine is to utilize the energy of the vortex flow to rotate the turbine runner, thereby generating mechanical power for the vortex turbine. The runner blade profile functions to extract vortex flow energy into mechanical energy through momentum transfer, while the vortex turbine basin plays an important role in creating free vortex flow. Vortex turbine basins are generally cylindrical and conical in shape. Conical basins produce higher vortex turbine output power compared to cylindrical basins. cone angle of the conical basin significantly influences the vortex flow velocity gain. this study aims to analyse the phenomenon of free vortex flow pattern formation with variations in the cone angle basin with a constant d/D ratio and vortex head. The free vortex flow pattern study utilized Ansys software to conduct computational fluid flow (CFD). Cone angle variation of 10° produces a more even distribution of velocity and pressure. Dominant tangential velocity vector occurs in the cone angle variation of 10. The cone angle variation of 10 produces the highest average pressure value at the 66% basin position. Vortex flow analysis and applicative consideration aspects, it can be recommended to use a conical basin with cone angle of 10° to produce optimal turbine performance.

Introduction

The text discusses the importance of energy sustainability and the transition from fossil fuels to renewable energy sources, with a focus on hydropower and vortex turbines. Vortex turbines are suitable for low-head water resources due to their simple design and ability to operate efficiently in mountainous rivers. Their performance is strongly influenced by runner blade profiles and the geometry of the turbine basin, particularly the basin shape, cone angle, and the outlet-to-inlet diameter ratio (d/D), which affect vortex flow formation and energy conversion.

Previous studies show that conical basins generally outperform cylindrical ones, with specific d/D ratios and cone angles producing stronger vortex flows and higher output power. However, limited research has examined detailed pressure distribution and flow patterns inside the basin. To address this, the present study investigates free vortex flow formation in turbine basins with varying cone angles (0°, 5°, 10°, 15°, and 20°) under constant head and d/D ratio conditions, using CFD simulations without a turbine runner.

The methodology involves CFD modeling with Ansys Fluent, employing a poly-hexcore mesh, k–ω SST turbulence model, and theoretical maximum flow rates calculated using Bernoulli and continuity equations. Simulation results show that conical basins generate higher flow velocities than cylindrical basins. A 10° cone angle provides the most uniform pressure and velocity distribution, while a 20° cone angle yields the highest velocity but with uneven distribution and no stable air core formation. The findings suggest that moderate cone angles, particularly around 10°, are more effective for forming stable and efficient vortex flows, offering useful guidance for optimal vortex turbine basin design.

Conclusion

The cone angle variation of 10° produces a more even distribution of velocity and pressure compared to variations of 0°, 5°, 15° and 20°. The dominant tangential velocity vector occurs in the cone angle variation of 10. The cone angle variation of 10 produces the highest average pressure value at the 66% basin position compared to variations of 0°, 5°, 15° and 20°. From the vortex flow analysis and applicative consideration aspects, it can be recommended to use a conical basin with cone angle of 10° to produce optimal turbine performance.

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Copyright

Copyright © 2025 I Putu Widiarta, Made Suarda, Made Sucipta, I Gusti Ketut Sukadana. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.