Study on the Long-Term Sediment Erosion Characteristics of Turbines Considering Geometric Gradients

Abstract

To prevent long downtime accidents caused by runner erosion and failure in hydropower stations located in high-altitude areas with sediment-laden rivers, it is crucial to accurately assess and predict the erosion state of runners. Existing sediment erosion prediction methods, which are based on factors such as the erosion location, erosion rate, and sediment volume distribution, fail to consider the impact of progressive geometric boundary changes in the flow passage wall during erosion on the unit-time erosion rate. This makes it challenging to predict the actual amount of erosion during runner operation accurately. To address this technical challenge, this study proposed a numerical calculation method for predicting sediment erosion based on data from disk-type plane-flow sediment erosion experiments. This method accounts for the progressive geometric boundary changes in the runner flow passage wall during the erosion process and incorporates the erosion rate acceleration factor to correct for the impact of these changes on the erosion amount. A sediment erosion prediction model suitable for runners in sediment-laden river hydro-turbines was developed. Validation and comparison with actual measurements of turbine blade erosion after 5723 h of operation revealed that the proposed model, which considers progressive geometric boundary changes, improved the long-term erosion prediction accuracy by 28.33% compared with traditional models. The findings of this study can provide valuable guidance for the design, operation, maintenance, and prevention of sediment erosion of hydropower station turbines.

Keywords: Turbine runner, sediment erosion, erosion rate acceleration factor, numerical simulation