CORDIS

The AFC4Hydro project addresses the development of a novel Active Flow Control (AFC) system for improving off-design operation of hydraulic turbines by mitigating deleterious flow phenomena during steady and transient operation including ramping of produced load. The main effect being increased reliability and flexibility, and reduced wear and tear. More specifically, this innovative and affordable AFC solution, allowing efficient utilization of existing hydraulic turbines, is planned to be validated at small scale in a model turbine and at large scale in two prototype turbines. A combination of technologies will be used to reduce the pressure and load fluctuations exerted on the machine induced by the draft tube flow using: (1) injection of pulsating momentum (IPM) with a specific frequency, amplitude and phase by means of actuators; (2) injection of continuous momentum (ICM) in the form of water jets with controlled speed and orientation directed against the swirling flow. A structural health monitoring (SHM) system will be developed to evaluate the effects of the injection systems in the structural response of the rotor, generator and bearings. These measurements will be used to optimise the machine performance. For that, a Controller will be programmed and tuned to reduce pressure fluctuations, structural loads and induced vibrations in real-time operation by continuously adjusting the injection systems. The final AFC system will also be tested against demanding transients like ramp up and ramp down. Special attention will be given to mitigate the powerful and dangerous flow instability provoked by the vortex rope breakdown. The success of the proposal will permit to extend the operating range of already existing turbines beyond the stablished safety limits, to increase their efficiency at off-design operation, to be able to face more frequent transients and to reduce the maintenance and operating costs.