Spatial distribution of rigid vorticity in pump-turbine under turbine mode with different guide vane openings

Abstract

Abstract Under non-design operating conditions, pump-turbines often exhibit notable instabilities within their runner regions. This study endeavors to investigate the spatial distribution patterns of vortex structures occurring between runner blade channels, focusing on different guide vane opening conditions in the turbine mode of a model pump-turbine. Based on rigid vorticity vectors, the large-scale vortex structures in the channels were analysed. Additionally, this study proposes a novel approach that utilizes the relative streamline coordinates of the blade skeleton to conduct flow analysis. This method offers a quantitative description of the spatial distribution of rigid vortices and associated physical quantities within the blade channels along the streamwise, circumferential, and spanwise directions. Finally, the causes of rigid vortices were analysed. The paper presents a pioneering and advanced theoretical tool and research methodology, serving as a valuable resource for the analysis and understanding of unstable flow structures within pump-turbines.