Numerical Study of the Flow in Rotor-Stator of Francis Turbine

Abstract

This study focuses on the aspects of rotor-stator interaction in a realistic prototype Francis turbine for two main load settings. The study used a state-of-the-art computational fluid dynamics technique to simulate the flow in the whole turbine. The method used in this study is based on solving the Reynolds-averaged Navier-Stokes equations with the turbulence model k-. The flow parameters such as velocity and pressure are analyzed to show the main flow characteristics within the turbine components. Pressure signals at some points within the turbine are analyzed to find out the primary and the secondary frequencies of the pressure signal. Comparing the measurement of the pressure with the simulations revealed that the computational solution is in good comparison with the measurement. Fast Fourier transform algorithm is applied to the pressure signals sampled from some points in the turbine in order to find out the inherent frequencies. These pressure frequencies are important to find the resonance possibilities. The study gave two important deliverables for the operation and design of this specific Francis turbine. The first one is the actual geometry of the turbine and the second one is the database of the computational solution. These two deliverables can be used for future research and analysis of the Francis turbine.