Development and application of numerical methods for design of hydraulic turbines

Hydropower, the largest source of renewable energy, is a clean and very efficient way to generate electricity. Hydraulic turbines are turbo machines which produce electricity from hydraulic energy. Francis type turbines are the most common one in use today. The design of these turbines is called tailor-made due to their unque head and discharge and and it requires high engineering effort. Francis turbines are traditionally designed by means of experiments, measurements and model tests, but this process requires a great deal of time and money. Increasing computational power of computers and developing numerical methods during the last decades, Computational Fluid Dynamics (CFD) has become a very important tool at the design process of hydraulic machines. CFD is able to solve complex, three- dimensional and turbulent flows occurring in turbines and the performance of the turbine can be easily predicted. In this study, the design of a Francis turbine is accomplished by using a design methodology integrating theoretical and experimental fundamentals of hydraulic machines with commercial CFD codes. The design process begins with the selection of initial dimensions of turbine components. Required improvements on turbine are carried out to improve the overall hydraulic efficiency and obtain the final turbine specifications by solving the flow in the turbine with CFD tools. The results obtained at the final design show that the performance of a turbine can be predicted accurately and applied CFD-based design methodology is successful at turbine design.