An experimental study on the diffuser-enhanced propeller hydrokinetic turbines. (April 2019) - Nunes, Matheus M.
Abstract: In the present paper, wind tunnel experiments with horizontal axis propeller hydrokinetic turbine models are carried out. The turbine performance is assessed for different diffuser configurations and operational ranges. The present experiments evaluate the use of two different geometries of rear diffusers to enhance the power output of the free flow machine. The present paper reports an increase of the power coefficient of about 48 % –79 % . A discussion about the use of the diffuser technology is pointed out in a framework of a concept of the minimization of the volume of material contained in the turbine parts. It represents an important result that has to be taken into account in the design of hydrokinetic turbines. Highlights: The effect of the diffusers in the performance of a 4-blades horizontal axis hydrokinetic turbine was assessed. The analysis is performed for lens- CII and S1223 diffusers with a propeller hydrokinetic turbines. Wind tunnel experiments were carried out for two different diffusers geometries and for free runner case. The configurations with diffusers have shown an important gain of the power coefficientabout 48%–79%. The diffusers volumes were compared, finding a correlation between the diffusers viability and the power output gain.