Vortex Characteristic of The Conical Basin for Gravitational Vortex Water Turbine (GVWT)

Due to the fossil fuel depreciation and the intensive growth of energy demand, the research on alternative energy resources is attractive, including hydropower. The emergence of GVWT is a promising technology for low-head hydroelectric power generation. The energy extraction of GVWT depends on the formation of eddies in the basin. The study was conducted to analyze the characteristics of the eddies in the GVWT basin through CFD simulations and validated by experimental results. The impact of basin design on the vortex heigh, the air-core diameter, and the water velocity is presented as the basic consideration in determining the GVWT design. Due to the small basin cross-section near the outlet, the tangential and axial velocities increase with increasing depth. The increase in tangential velocity varies with a value of 8 - 26% for every 10% increase in depth. The conical basin without deflectors produces asymmetrical eddies and secondary flow. The deflector is used to improve the eddies structure in conical basins since it contributes to generating axisymmetric eddies and secondary flows. The highest tangential velocity is obtained at a notch angle of 19°. Therefore, the use of a basin with a deflector in the GVWT is recommended to improve its performance.