THREE-DIMENSIONAL FLOW FIELD AROUND A ROTATING CYLINDER FOR SPIRAL-FIN MAGNUS WIND TURBINE

A Magnus wind turbine uses the Magnus effect to generate electricity. Spiral Magnus wind turbines are unique in that they rotate with cylinders that have fins coiled around them, instead of the more common propeller-type blades. In a previous study, lift force was measured by testing three models (cylinder with no fins, cylinder with straight fins, and cylinder with spiral fins) in a wind tunnel, and it was confirmed that the greatest lift force was generated by the cylinder with spiral fins. In this study, to investigate the reasons for the spiral fins exhibiting superior lift generation performance, three-dimensional flow field was measured using a stereoscopic particle image velocimetry method. A strong vortex from the interaction of a free stream with spiral fins exists close to the cylinder surface; thus, the cylinder with the spiral fins can generate the greatest lift of all three models.