Numerical comparison and efficiency analysis of three vertical axis turbine of H-Darrieus type

Hydropower is an important source of energy in Latin America. Many countries in the region, including Brazil, Peru, Colombia, and Chile, rely heavily on hydropower plants to meet their energy needs. However, there are also challenges related to the use of hydropower in the region, such as the construction of dams that can have negative impacts on ecosystems and local communities. A new alternative is the production of energy through hydrokinetic turbines because they are a clean and renewable energy source that does not emit greenhouse gases. In addition, its production is predictable and can be generated in a variety of environments, from coasts to rivers and canals. Within the hydrokinetic turbines are the H-Darrieus turbines although they are still under development, they are seen as an important opportunity to diversify the energy matrix and reduce dependence on fossil fuels. The main purpose of this study is to determine and compare the efficiency of three Darrieus H-type vertical axis hydrokinetic turbines numerically. The turbines were configured with different solidities. The NACA 0018 profile was used for the turbine design. The study was carried out using the ANSYS® Fluent 2022R2 software, two-dimensional (2D) simulations set up constant operating conditions. Rotation speed variations have been set between 21 and 74 RPM with 10 rpm increments. Furthermore, the General Richardson extrapolation method is used for the analysis of mesh convergence, monitoring the turbine power coefficient as a convergence parameter. The numerical results show that the turbine H-Darrieus with a solidity of 1.0, a wider operating range, and lower power and torque coefficient. At low TRS, the largest solidity provided the best efficiency and the greatest self-starting capability, but it also had the smallest operating rang

Physical compensation of phase curvature in digital holographic microscopy by use of programmable liquid lens

Quantitative phase measurements obtained with digital holographic microscopes are strongly dependent on the optical arrangement of the imaging system. The nontelecentric operation provides phase measurements affected by a parabolic phase factor and requires numerical postprocessing, which does not always remove all the perturbation. Accurate phase measurements are achieved by using the imaging system in telecentric mode. Unfortunately, this condition is not accomplished when a commercial microscope is used as the imaging system. In this paper, we present an approach for obtaining accurate phase measurements in nontelecentric imaging systems without the need for numerical postprocessing. The method uses an electrically tunable liquid lens to illuminate the sample so that the perturbing parabolic wavefront is cancelled out. Experimental holograms of a Fresnel lens and a section of the thorax of a Drosophila melanogaster fly are captured to verify the proposed method

METODOLOGÍA DE DISEÑO Y SIMULACIÓN HIDRODINÁMICA DE UNA MICROTURBINA TIPO KAPLAN USANDO HERRAMIENTAS COMPUTACIONALES

En este trabajo se utiliza un modelo de simulación de una microturbina tipo Kaplan de 6 álabes; con éste, se analiza el efecto causado por la variación del paso de la turbina en la obtención de potencia de eje a la salida, implementando paramétricamente diferentes velocidades de giro de ésta con respecto al flujo de agua circundante. La geometría es simplificada con el fin de reducir el tiempo de procesamiento en la discretización y análisis del modelo; la simulación fue realizada bajo condiciones de frontera definidas y empleando dinámica de fluidos computacional. Con los datos obtenidos, se busca generar curvas de rendimiento 2D y 3D, que permiten caracterizar el comportamiento de la microturbina tipo Kaplan, tomando en consideración la inclinación de sus álabes y la velocidad de giro del rodete, con el fin de determinar los rangos de operación en los cuales se obtiene la mayor entrega de potencia

2D numerical analysis of an H-Darrieus hydrokinetic turbine with passive improvement mechanisms

H-Darrieus hydrokinetic turbines are an alternative for small hydroelectric plants. These turbines are considered to have a low environmental impact as they do not require reservoirs. However, they have limited self-starting capacity, which limits their use. Nevertheless, the configuration of passive mechanisms in the H-Darrieus turbines affects their performance, as they tend to increase the flow velocity. This study is part of a project with the aim to design and build a turbine to generate energy in the Colombian river scenario in non-interconnected zones. The objective of this study is to analyze the performance through numerical simulations of four H-Darrieus rotors to be configured with passive improvement mechanisms. The study was conducted using ANSYS® Fluent software, employing transient, two-dimensional models under constant operating conditions. Overlapping meshes were used for the stationary and rotating domain configuration. The results show that increased solidity leads to decreased tip speed ranges and increased maximum rotor power. Improvement in the self-starting capability was found with passive mechanisms employing a diffuser geometry. Among the tested configurations, the rotor configured with a Venturi-shaped mechanism achieved a remarkable 660% improvement in the power coefficient compared to configurations without such mechanisms

La investigación en la USTA, Sede Villavicencio: capacidades CTeI desde los grupos de investigación

El libro presenta un balance de la memoria histórica de lo que ha sido la investigación en la Universidad Santo Tomás, sede de Villavicencio, desde el 2007, año en que la Universidad inicia labores académicas en la región de los Llanos con cuatro programas académicos. El trabajo de investigación y sistematización se realiza desde sus 15 grupos de investigación; en el documento se evidencia su constitución y formalización a partir de la creación de los programas de pregrado y postgrado; asimismo, se refleja el quehacer académico e investigativo que sus docentes han gestado en el transcurso del tiempo, las líneas de investigación que han abordado y las políticas públicas desde las cuales se han conformado, así como su interacción con el currículo, la docencia y la proyección social