Rehabilitation of Francis Turbines of Power Plants with Computational Methods

Abstract

Rehabilitation of existing hydroelectric power plants (HEPP) by redesigning the hydraulic turbines is usually more elaborate than designing a tailor-made turbine for a new plant. Some of the parts are buried and the space is limited with the size of the old turbine; therefore, this increases the number of constraints imposed on the design. This article presents a Computational Fluid Dynamics (CFD) based rehabilitation procedure involving the state of the art redesign of the turbine of a hydroelectric power plant for better performance at design and off-design conditions of several head and flow rates. Runner and guide vanes of the Francis turbine are designed per the design head and flow rates available for the turbine at the site. The simulations for the designed parts are performed both separately and using all turbine parts as full turbine analyses. Both the design and off-design conditions are simulated for the newly designed and existing turbines for comparison purposes. Cavitation performance of the new design is also determined. The proposed methodology is applicable to any Francis type turbine and any HEPP that needs rehabilitation.