Sand Abrasion and Particle Motion in the Bucket Flow

Abstract

One important issue in the operation of Pelton turbines is the sand abrasion in the rotating buckets, which is often called hydroabrasive wear or hydro. The problem becomes serious, when the water is richly loaded with suspended sediment particles. This is always encountered where the water from glaciers or river water during/after floods, for instance, is guided to Pelton turbines without previously passing a lake. The sand abrasion often leads to serious mechanical damages on components of Pelton turbines, including the injector nozzles and the buckets. Figure 22.1 shows the sand abrasion on the surface of an injector needle. The sand erosions at the bucket main splitters and on the inner surface of the buckets have been shown in Fig. 5.17. In Chap. 5 (see Sect. 5.10), the effect of eroded main splitters of Pelton buckets on the efficiency drop has been evaluated. Significant such efficiency drops could occur, especially at large relative widths of the eroded bucket splitters (see Figs. 5.22 and 5.23).