Minimum pressure coefficient criterion applied in axial-flow hydraulic turbines

The recent development of computer-based tools with more efficient algorithms has allowed a substantial improvement in hydraulic turbine design. The definition of an initial geometry capable to assist certain characteristics of turbine performance is a first step for useful numerical turbine analysis. This paper presents an application of the minimum pressure coefficient criterion for axial flow hydraulic turbines cascade geometry design. In recent works, the criterion was tested for axial fan and it was showed that it is suitable to define the initial geometry for machine design. The global parameters that supply the principal dimensions of the turbine are obtained from the literature as based upon statistical data of installed power plants. The grid of the simulation domain was generated with CFX-TURBO grid software package and the results were obtained using the commercial package Navier-Stokes 3-D CFX-TASC flow to analyze the fluid flow through blade runner. Using this procedure, a study was carried out on a small axial-flow turbine, specifically designed to operate in a small river in the Amazon region. An interpretation of the flow through the turbine's hydraulic channels is presented for nominal flow rate operation points. Finally, the results are evaluated to hydraulic efficiency prediction of blade runner turbines.