Abrasion predictions for Francis turbines based on liquid–solid two-phase fluid simulations

Abstract

The runner blades and guide vanes of Francis turbines are worn by sediment in the flow. However, there are few studies about abrasion of the runner blade and guide vane for normal turbine operating conditions. This study investigated the relation between the wear rates on the surfaces of the runner blade and guide vane and the sediment concentration, and analyzed the distribution of the wear rates for normal turbine operating condition. An Eulerian–Lagrangian Computational Fluid Dynamics (CFD) procedure was used to simulate steady liquid–solid two-phase flow for various operating conditions. The Finnie model was then used to predict the abrasion. The conditions leading to abrasion in the inner flow passage components of a Francis turbine are clarified through analysis of the abrasion conditions for the runner blades and guide vanes. Field tests and simulations show that the relative wear rate on the runner blades and guide vanes increases with increasing sediment concentration, and the maximum wear on the runner blades occurs in a small opening region with the maximum increasing as the head increases. The maximum wear on the guide vanes occurs at the maximum output and the relative wear rate on the runner blades is much greater than that on the guide vanes. There is no good data, so the relative wear rates on the runner blades and the guide vanes can only be obtained numerically. Thus actual wear rates cannot be given and are beyond the scope of this paper. This paper shows the abrasion characteristics on the runner blades and guide vanes with sediment flow and provides reference data for predicting the abrasion conditions in the flow passage components of a Francis turbine.