The gravitational water vortex turbine is an alternative to renewable energies, it transforms the hydrokinetic energy of the rivers into electric energy and it does not require a reservoir. According to studies carried out, the hydraulic efficiency can increase or decrease according to the turbine geometrical configuration. This paper presents a numerical (CFD) and analytical comparison between conical and cylindrical designs for the outlet. The results show a higher performance for conical geometry than the cylindrical tank. The fluid behavior in CFD and analytical studies presents a tangential velocity increase near to air core and outlet hole (similar behavior). The maximum theoretical power generated was 167 W and 150 W for conical and cylindrical design respectively. The differences between geometries of the outlet holes using CFD and analytical models were 11 and 7%, respectively. However, the closest results to the CFD model had different values of 31 and 29% for conical and cylindrical design, respectively. The furthest result regarding the CFD study was 55%. The principal difference is due to tank geometry, the change in discharge zone, as well as the ratio of diameter tank and outlet hole can increase or decrease the tangential velocity and make a stronger and more stable vortex formation. The theoretical power generated is a good parameter to select the height to place the rotor.

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

The main objetive of this study is to compare numerically the torque generated at 50, 75, 100, and 125 rpm by H-Darrieus turbine as a rotor for Gravitational Vortex Turbine. The rotational flow into the gravitational vortex turbine tank helped to decrease the negative torque in H-Darrieus rotor. The study was developed in ANSYS® CFX, where the model was configured at constant operating conditions. The highest torque was 0.117 Nm at 50 rpm, and the torque decreased with increasing rpm. The H-Darrieus works with increasing lift force, however, the rotor inside the Gravitational Vortex Turbine interacts with drag force.

This work presents the optimization of a Coandă-effect air ejector used widely in industry through computational fluid dynamics. This optimization was developed in ANSYS FLUENT® software V16.2. Two 3D models of the commercial ejector (ZH30-X185 by SMC®) were carried out for the simulation procedure, varying the size of the separation of 0.3 and 0.8 mm in the walls of the nozzle, which communicates the high-pressure region and the mixture zone. In the experiment designed, the feed pressure applied to the ejector take values of 0.20, 0.25, and 0.30 MPa and the dynamic fluid behavior was analyzed for the two geometries mentioned. For the numerical and fluid behavior analysis, a mesh study was conducted to guarantee the independence of the results with the number of discretization cells. The k-ε RNG turbulence model was implemented with treatment of walls, solving in stationary manner the phenomenon occurring within it, given that the temporal evolution is quite rapid. Increased secondary mass flow (extracted) relations with respect to the primary mass flow (injected) were found when the separation communicating the high-pressure zone and the mixture zone diminished. With increased feed pressure of the primary flow, a decrease was found in the secondary mass flow relation with respect to the primary mass flow.Keywords: Compressible Flow, ANSYS, Fluent, Turbulence. ResumenSe presenta la optimización de un eyector de efecto Coandă para aire utilizado ampliamente en la industria mediante la dinámica de fluidos computacional CFD, esta optimización desarrollada en el software ANSYS FLUENT® V16.2. Para el procedimiento de simulación se realizaron dos modelos tridimensionales del eyector comercial ZH30-X185 de la marca SMC® en los cuales se variaron el tamaño de la separación en las paredes de la tobera que comunica la región de alta presión y la zona de mezcla de 0.3 mm y 0.8 mm. Se diseñó un experimento en el cual la presión de alimentación aplicada al eyector toma los valores de 0.20, 0.25 y 0.30 MPa y se analizó el comportamiento fluido dinámico para las dos geometrías anteriormente mencionadas. Para el análisis numérico y fluido dinámico se realizó un estudio de malla para garantizar la independencia de los resultados con el número de celdas de la discretización, se implementó el modelo de turbulencia k-e RNG con tratamiento de paredes y se resolvió de manera estacionaria el fenómeno que ocurre dentro de este, debido a que evolución temporal es muy rápida. Un aumento en las relaciones de flujo másico secundario (extraído) respecto al flujo másico primario (inyectado) fue encontrado cuando se disminuyó la separación que comunica la zona de alta presión y la zona de mezcla. Con el aumento de la presión de alimentación del flujo primario, se encontró una disminución en la relación del flujo másico secundario respecto al flujo másico primario.

El siguiente estudio propone el análisis de una turbina hidrocinética de eje vertical tipo H-Darrieus que puede ser implementada en las regiones no interconectas al sistema eléctrico colombiano en especial las zonas costeras. El objetivo del estudio es analizar el número de álabes en la eficiencia de la turbina hidrocinética, para esto se proponen 27 tipos de rotores, en los cuales, se varia el número de álabes desde 2 hasta 10 para 3 valores de solidez diferentes. Concluyendo que a partir de 3 álabes se reducen los torques negativos producidos, incrementando la capacidad de autoarranque, sin embargo, cuando el número de álabes aumenta el torque total generado por la turbina disminuye lo que conlleva a una disminución en la eficiencia.