Flow Characteristics of Preliminary Shutdown and Startup Sequences for a Model Counter-Rotating Pump-Turbine

Pumped Hydropower Storage (PHS) is the maturest and most economically viable technology for storing energy regulating electrical grid on a large scale. Due to growing amount of intermittent renewable sources, necessity maintaining stability increases. Most PHS facilities today require geographical topology with differences in elevation. The ALPHEUS H2020 EU project has aim develop flat topologies. present study was concerned initial design low-head model counter-rotating pump-turbine. machine numerically analysed during shutdown startup sequences using computational fluid dynamics. rotational speed individual runners decreased from point stand-still increased back point, both pump turbine modes. As speeds were close zero, flow field chaotic, separation occurred by blades runners. Rapid load variations runner reverse encountered mode as lost ability produce head. loads less severe sequence. Frequency analyses revealed that blade passing frequencies their linear combinations yielded strongest pulsations system.