A new regulation system for Crossflow type turbines for water management industry

Mini-hydro hydropower plants have recently gained much attention from energy providers, more than traditional turbines installed downstream of artificial hydrological basins. The reason is that mini-hydro plants do not require significant water storage and the construction of dams or weirs with significant environmental impact. However, the occurring large flow rate variability requires a great care in the design of the mobile parts of the distributor, like guide-vanes in Kaplan and Francis turbine types, or the Cink flap in Crossflow type. In the present work, a new regulation system for Crossflow turbines is proposed, which is aimed to maintain high efficiency inside a large range of flow rate values. This goal is achieved by regulating the width of the inlet section of the nozzle, which allows maintaining an almost constant velocity ratio without changing the rotational velocity of the runner. The proposed system can be applied to all the Crossflow type turbines; in the present research paper it is finalized to Power Recovery System (PRS) turbines, a Crossflow type turbine with pressurized output, used for in-line installations. The new system was studied using CFD analysis and the results were validated with laboratory tests on a 2 kW prototype.