Performance assessment of an Indalma hydro-turbine

Hydro-turbines for small heads have recently attained considerable attention as they show the possibility of achieving a good power performance. In Brazil, electricity is highly dependent on the hydroelectric generation due to high water availability and low long-term cost. For generation at smaller scales, conventional turbines such as Kaplan, Pelton and Francis generally do not present satisfactory efficiency and they typically have a high installation cost. In this way, there are some alternatives for small hydropower plants; one of them is the Indalma turbine, which was invented and built in the eastern Amazon region. The differential of this turbine is the shape of the blades and the shape of the spiral casing, having its efficiency experimentally verified by the National Reference Center in Small Hydroelectric Plants (CERPCH/UNIFEI-MG-Brazil). Since the design of this turbine was performed almost empirically, there is a need for an in-depth study of the pressure and velocity fields, as well as other phenomena that commonly occur in hydraulic turbines. Thus, this work presents a performance assessment of an Indalma pico-turbine through computational fluid dynamics, using a Reynolds-averaged Navier-Stokes formulation. As a result, the Indalma turbine has a good performance among conventional turbines at the nominal operating point. The highest turbine efficiency of 80.8% is found at a flow rate of 0.012 m(3)/s and a rotational speed of 1460 rpm. Additionally, the results yield good agreement with experimental and theoretical data available in the literature, demonstrating that Indalma turbine is a good alternative for small hydropower plants.