Study on cavitating vortex rope characteristics of reversible pump-turbine under part load turbine condition

Pressure fluctuations in the draft tube mainly arise from rotational motion of vortex rope. The formation and development rope are significantly influenced by cavitation. However, precise mechanism underlying progression cavitation its initial weak state to a more severe level remains unclear. objective this study is investigate pump-turbine operating under part load turbine conditions. Numerical simulations were conducted analyze impact coefficient on various parameters, including vapor volume, efficiency, head. With increasing degree cavitation, rope's pattern undergoes transition helical type torch-like type. This consequently leads shift dominant frequency pressure within tube. Furthermore, exhibits higher speed compared rope, thereby causing pronounced effect field. factors contributing morphological explored, with particular emphasis accelerating reverse axial flow reduction tube's circumferential velocity. Additionally, examined swirl number pattern, while also assessing entropy production. These findings provide valuable insight into control pump-turbines Moreover, they carry significant implications for design optimization systems.