Author(s): Calogero Picone; Marco Sinagra; Mabrouk Mosbahi; Tullio Tucciarelli
Linked Author(s): Tullio Tucciarelli, Calogero Picone
Keywords: Cross-Flow turbines nozzle PRS turbines Free Discharge turbines
Abstract: In recent years mini-hydro has gained much attention, mainly because of its low environmental impact. Inexpensive machinery, like PAT or Cross-Flow type turbines are often required to balance the low nominal power associated to this type of plants. Many recent papers have investigated the best geometry of the Cross-Flow turbines, including the profile of the internal wall of its distributor, named nozzle. All these studies assume that the blade profiles and their thickness have not impact on the profile design criterium and that the number of blades is large enough to make negligible the reduction of the exchanged power at the two channels overlapping the initial and the final point of the nozzle profile. In the submitted paper the mentioned reduction of exchanged power is first explained, in the two cases of a) traditional Cross-Flow with free discharge and b) PRS turbines. The effect of the singularity occurring at the final point of the nozzle profile is shown with reference to the runner of a PRS turbine which has been working for two years in the S. Giovannello plant, comparing the actual erosion spots with the simulated pressure and velocities. A different nozzle profile, leading to a reduction of the flow entering the initial and final channels and of the resulting singularities is finally proposed and tested with 2D modeling.
Year: 2025