Diseño y construcción de un prototipo del sistema de distribución de flujo para la turbina Kaplan didáctica de un banco de pruebas

Abstract

The growing world demand for electric power has led to the need to develop multiple technologies to meet energy requirements in multiple conditions and contexts. In Colombia, a country with large water sources, it is essential to implement turbines to take advantage of the energy coming from waterfalls. In this context, Kaplan turbines become one of the most versatile and efficient alternatives in different conditions of flow, pressure and energy demand because their blades are adjustable, which allows them to operate in conditions of low head and variable flow. The mechanism that makes it possible to regulate the guide vanes corresponds to the flow distributor and its operation provides the possibility of modifying the flow rate, pressure, fluid inlet angle to the runner and, consequently, the efficiency of the turbine. This paper deals with the redesign of the flow distributor of a didactic Kaplan turbine located at the Universidad Escuela Colombiana de Ingeniería Julio Garavito, which presents a reduced opening range of the guide vanes and problems in their synchronization. A prototype developed by means of polymer additive manufacturing technologies, specifically PLA (poly lactic acid) 3D printing, is proposed. The designed device has a greater amplitude of the guide vanes and optimizes the cost of materials and manufacturing processes according to the hydraulic and structural requirements of the turbine, where the feasibility of implementing the development of parts in turbo machines using this process will be evaluated. A bibliographic analysis of different researches, models and prototypes of hydraulic turbines manufactured by means of additive manufacturing technologies is developed within the document. In relation to the development of the device, the analysis of the properties of the 3D printer used and the parameters configured in the development of the parts, which modifies the mechanical and physical properties of the material, are discussed. Taking into account the above, tensile, bending and expansion tests of the material are implemented to specimens developed under the same conditions of the parts to be manufactured, in order to evaluate the feasibility of the designed prototype and apply the necessary parameters and adjustments to meet the initial geometric conditions of the rest of the turbine. Additionally, the behavior and efficiency of the turbine in question is evaluated for five opening angles of the guide vanes of the flow distributor, using analytical methods and the simulation of the turbine in ANSYS software. Finally, the manufacturing and validation of the prototype mechanism designed in relation to the opening and closing of the guide vanes in a range equal to or greater than 45° is carried out.