Quantitative impact of a micro-cylinder as a passive flow control on a horizontal axis wind turbine performance

Adding micro-cylinder as a passive flow control is a new trend to enhance the power output of wind turbines. The impact of adding micro-cylinder, with different configurations, around horizontal axis wind turbine blade (HAWT) is examined using 3-dimensional simulations. The conventional turbine National Renewable Energy Laboratory (NREL Phase II) straight-bladed wind turbine is selected to validate the present numerical arrangements, where it hasn't been tested before with adding micro-cylinder. The Reynolds Average Navier-Stokes (RANS) equations for steady-state incompressible flow combined with Shear Stress Transport (k-u SST) turbulence model are employed for the current numerical analysis. In this study, a parametric study is conducted for different diameters and locations of micro-cylinder. In total, seven cases are examined. The influence of micro-cylinder size is examined by changing the cylinder diameter (three different diameters, diameter/chord 1/4 0.0131, 0.0175, 0.022). It has been found that the output power increases with decreasing the micro-cylinder diameter. The effect of micro-cylinder locations is investigated by introducing four different cases (four different locations around the leading edge). The power output increases for all cases. Additionally, it has been found that locating the micro-cylinder on the pressure side has less effect on the power output comparing to locating it on front of the blade leading edge.