Flexibility Increase on Hydro Installed Base

HYDRAULIC PHENOMENA AT STAKE ON FRANCIS AND PSP RUNNERS Dynamic Hydraulic Phenomena / Mechanical Fatigue Cavitation / Material Erosion The operation is limited by two main phenomena that are demanding for the runner and that may result in the accelerated consumption of its lifetime: Dynamic phenomena and cavitation which can generate cracks and erosion, respectively. damaging Discharge PART LOAD Head Dynamic Strain DEEP PART LOAD damaging damaging 2 1 1 2 3 3 HIGH LOAD: ROPE + ROTOR STATOR INTERACTION (RSI) 4 5 4 5 Helical vortex rope Interblade vortex Axial vortex rope Operation Area Freevortex rope zone H opt 1 0.2 0.6 Head Operation Area Freevortex rope zone H opt DESIGN Inlet suction side cavitation (erosive) Interblade cavitation vortex (IBCV) (erosive) Inlet pressure side cavitation (limited erosion) Outlet cavitation (erosive) Potentially erosive area Climate change with more frequent drought and/or flooding can lead to change in hydraulic conditions (net head variation, change in upstream/downstream water level), which can lead the actual turbine to operate under cavitation regime; to continue to deliver the rated power or also to generate power under very low flow conditions (e.g. generate power with the ecological flow). The unit operates under condition for which it was not originally designed for. Discharge 1 0.2 0.6