Vortex rope patterns at different load of hydro turbine model

Kutateladze Institute of Thermophysics, Department of Heat Power Engineering, 630090, Novosibirsk, Russia

^* Corresponding author: skripkin.s.g@gmail.com

Abstract

Operation of hydraulic turbines beyond optimal conditions leads to formation of precessing vortex core in a draft tube that generates powerful pressure pulsations in a hydraulic system. In case of resonance it leads to stability decreasing of hydraulic unit and electrical grid on the whole. In present work, such regimes are explored in a conical part of simplified turbine model. Studies are performed at constant flowrate Q = 70 m³/h and varying the runner rotational speed to explore different loads of the hydroturbine unit. The experiments involve pressure measurements, high speed-visualization and velocity measurements by means of laser Doppler anemometer technique. Interesting finding is related with abrupt increasing precession frequency at low swirl parameter of flow near optimal regime.