Distribution Features of Flow Patterns and Pressure Pulsations of Pump-Turbine in Five Operating Modes on the Four-Quadrant Plane

To meet the demand of power grid for flexible regulation, pump turbines have to frequently and fleetly stop, start, transition between different modes, causing many instability problems. solve problems, understanding complex flow pressure pulsation features in working conditions is prerequisite. In this study, patterns, pulsations, cavitation characteristics, runner forces a prototype pump-turbine under five operating modes were displayed analyzed based on computational fluid dynamics simulations. It shown that when points are near turbine design points, smooth, with small without cavitation; however, deviate from optimal ones, patterns become worse appears. pump-brake mode, hits blades violently, obvious force fluctuations. hump region, has strong impact guide vanes, rotating stall vortices apparent vane area. S-shaped pulsations highest prominent rotor–stator interaction stall. Under similar conditions, larger guide-vane opening corresponds amplitude. On spatial distribution, largest happen vaneless space.