Enhancement efficiency of Michell-Banki turbine using NACA 6512 modified blade profile via CFD

Abstract

The small hydroelectric power plants (SHPP) are implemented in non-interconnected zones (NIZ) of developing countries. In which, the provision of electrical energy from the national interconnected system is not economically feasible. Therefore, in the literature, hydroelectric generation technologies have been implemented taking advantage of the energy available in the rivers. One of these technologies is the Michell-Banki type cross-flow turbines (MBT), which, despite having lower efficiencies than turbines such as Pelton and Francis, maintain their efficiency although fluctuations in site conditions. For this reason, different studies have been made to increase the efficiency of the MBT by making geometric modifications to both the nozzle and the rotor.
 The purpose of this study is to determine numerically the effect of the geometry of the blades that form the runner on the efficiency of Michell-Banki Turbine (MBT). For this, two (2) geometries were studied corresponding to a circular sector of a standard tubular profile and an airfoil NACA 6512 modified in curvature profile and chord length, according to the profile of the standard tubular blade. For this study, transient simulations for multiphase water-air flow were implemented using a k-ε turbulence model in the Ansys 2020R1® CFX software. The two (2) turbine models were configured to the same hydraulic conditions of head and volumetric flow corresponding to 0.5 m and 16.27 L/s, respectively. Variations in rotational speed were configured between 100 and 200 RPM with 20 RPM steps. It was found that using the modified 6512 hydrodynamic profile, at 140 RPM increased efficiency by 6 %, compared to the conventional tubular type blade geometry

Effect of Blade Angle and Number on the Performance of Bánki Hydro-Turbines: Assessment using CFD and FDA Approaches

“…The inlet boundary condition used is the incoming fluid velocity, which is 3 m/s 12) . The boundary conditions at the outlet have used the opening boundary condition type 28) . The condition used is a static pressure of 1 atm 29) .…”

The Blade's Angle Affects Banki-Turbine Performance as an Alternative Design for Clean Energy Generation

“…Parameters that affect banki-turbine performance are the number of blades, diameter ratio, and blade design [7]. Research on changes in the blade's shape that has been done can increase by 1% -7.3% the performance with a regular blade shape [20]. In another study, modifying the blade's shape increased the power coefficient by 7.23% [21].…”

“…Changes in geometry are still the primary research to improve turbine performance, such as PSA [13], Aspect Ratio [14], Number of blades [8,15], Overlap ratio [16], Number of stages [6], and shape of blade [3]. However, apart from the geometric aspect, several other factors also influence, such as the rotor material factor [17][18][19][20].…”