Abstract
Three dimensional computational fluid dynamics (3D-CFD) had been carried out to simulate the flow field around an aluminium circular-blade butterfly wind turbine (ACBBWT), which is a vertical axis type with four circular blades and whose diameter is 2.06 m. Under the assumption of a loss factor of 0.8 due to generator and AC-DC converter and so on, the CFD results agreed with the experimental results. Although vortex shedding corresponding to tip-vortex was observed at the top and bottom portions of blades, the vorticity intensity was weaker than the straight-bladed rotor case and the vorticity-distribution shape seemed to be elliptic unlike a circle. In the cases of low tip speed ratio, vortex shedding was observed at the downwind half-cycle as well as the upwind half-cycle.
