Analysis of the air-water-sediment flow behavior in Pelton buckets using a Eulerian-Lagrangian approach

Abstract

One of the major concerns in developing high-head water resources, which usually uses Pelton turbines especially in geologically young and fragile mountains, is hydro-abrasive erosion caused by the entrained sediment particles. However, the fundamental analysis of the air-water-sediment flow in Pelton turbines remains largely unexplored. Here, a new Eulerian-Lagrangian (E-L) approach is proposed and applied firstly to simulate the transient air-water-sediment flow in Pelton buckets. An analytical model and a qualitative comparison with the field values were adopted to support the reliability of the proposed approach. Further, a detailed analysis of the instantaneous flow patterns and the particle distributions was conducted for this transient three-phase flow. Interestingly, the findings related to the separation behavior of particles from the fluid streamlines revealed that the particles preferentially accumulated at some regions in the water sheet of the buckets as the separation velocity was different in different regions. The particle separation velocity, however, strongly depends on the bucket curvature, particle positions, and velocity of the water sheet. The present paper demonstrated the ability of the E-L approach to satisfactorily simulate the three-phase flow as well as established the E-L approach as a promising tool for erosion prediction in Pelton buckets.