Research on the Technical Improvement of the Turbine Runner of a Power Station Based on Improving Stability

Abstract

In view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations and tests was adopted to improve the operational stability of power station units without changing other parts of the flow. The optimization of the turbine runner blade shape involves optimizing the stress release zone at the water edge of both the upper crown and lower ring, along with adjusting the blade thickness. Calculation and testing demonstrate an enlargement of the high-efficiency zone, resulting in enhanced efficiency. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and leafless area, with a maximum decrease of approximately 50%. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 m/s to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high efficiency zone, decreases wear, and enhances the operational stability of the unit. Given the common occurrence of similar conditions in power stations domestically and internationally, the proposed technical transformation method and research outcomes hold significant guiding implications for comparable technical upgrades in other power stations.

Keywords: Francis turbine, technical transformation, numerical calculation, experiment, pressure fluctuation, stability