关键词: 冲击式水轮机, 含沙三相流, 磨损预测, 冲击特性, 数值计算

Abstract: Sediment erosion is one of the main reasons for the failure of hydraulic components of a Pelton turbine. Especially in sediment season, sediment concentration increases greatly and the process of sand-carrying three-phase flow on the surface of the runner bucket is complicated, so the erosion problem is usually more severe. The Pelton turbine at the Zixia hydropower station in Tibet, planned for construction, is examined in the present work as a case study. This paper focuses on numerical simulations of its flow process of sediment particles on the bucket surface, using the Mansouri erosion model and the Euler-Lagrange method, based on its measured sediment characteristics data provided by the design institute. The characteristics of sediment particle flow and erosion distribution over the bucket surface under high sediment concentration in sediment season are examined. The numerical predictions of surface erosion distribution agree well with previous measurements in literature. The predictions show the bucket erosion concentrates near the water outlet edge of the root and the cutout edge of the bucket. The highest similarity occurs between the distributions of sediment erosion and the impact number, so the impact number imposes a great effect on sediment erosion.

Key words: Pelton turbine, gas-solid-liquid flow, erosion prediction, impact characteristics, CFD