Pressure Pulsation Characteristics and Flow-induced Vibration Optimization in a Turbine Runner under Low Flow Conditions

Hydropower systems, as core components for electricity regulation in renewable energy infrastructures, are increasingly operating under off-design conditions, such as high- and low-flow scenarios. Pressure pulsations induced by off-design operation have posed severe threats to the stability and reliability of flow-passing components. In this study, a 24 MW bulb turbine was selected as the research object. A transient fluid-structure interaction (FSI) method based on the finite element method (FEM) and finite volume method (FVM) was employed to investigate pressure variations and abnormal pulsations within the runner region. The reliability of the flow field analysis was validated through experimental data. The structural response of flow-passing components under complex pressure distributions was evaluated, and a multi-parameter collaborative optimization model was developed. An improved structural design was proposed to mitigate pressure pulsations under off-design conditions. Results show that, under flow-induced pressure mapping, the optimized structure achieved an average increase of 4.04% in prestressed modal frequency and 58.45% in wet modal frequency compared to the original structure, along with a significant alleviation of stress concentration phenomena. This study provides valuable insights into enhancing the safe operation of hydraulic turbines within multi-energy complementary renewable energy systems.