Features of the precessing vortex control in the Francis turbine model via jet injection

Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia

^* Corresponding author: d.suslov@g.nsu.ru

Abstract

The study elucidates the mechanisms involved in actively controlling vortex phenomena within hydraulic turbines, particularly prevalent during partial load operations, leading to severe pressure fluctuations within the draft tube. Employing laser Doppler anemometry alongside acoustic sensors, the research delves into the flow structure and pulsation characteristics within the conical section of a Francis hydraulic turbine model under the influence of supplementary control jets injected through the runner streamline body. It was observed that orientation of the control jet has a discernible effect on reduction in pressure pulsations emanating from the precessing vortex core (PVC). An optimal injection strategy for diminishing pressure fluctuations while maintaining high turbine efficiency is identified. The findings align with earlier theoretical predictions derived from linear stability analysis of flow perturbations.