ABSTRACT
The Wells turbine appears in different configurations: with or without guide vanes, with contrarotating rotors, biplane and others. The efficiency of this turbine is limited by the aerodynamic conception of the turbine itself. Its efficiency curve versus pressure head is characterized by a sharp drop at a critical value of the flow rate above which aerodynamic stall at the rotor blades drastically reduces the turbine power. The peak efficiency achieved experimentally may attain about 75% for large models and high Reynolds numbers and for the best designs Curran and Gato (1997); Gato and Curran (1996). Wells turbines are characterized by relatively large blade tip speed and small torque. More information about Wells turbines can be found in Falcão and Gato (2012); Shehata et al. (2017).
