Influence of Vortex Generator Height on Dynamic Stall of Wind Turbine Airfoil
Based on transition SST k-ω turbulence model,the DU91-W2-250 airfoil is used to study the effect of the height of vortex generator(VG)on the dynamic stall.The flow control effects of VG with four heights of h=5,6,7.5 and 10 mm are discussed in terms of lift-drag coefficient,velocity profile,stream-wise vortex and vortex field.The findings indicate that an increase in VG height significantly improves lift,maximizes the increase in drag,and enhances drag reduction during the down pitch phase.Compared to a smooth airfoil section,the airfoil section with VG exhibits greater kinetic energy in the boundary layer and smaller boundary layer thickness.The higher the height of VG generate increased streamwise vortex strength and are less affected by the angle of attack,with higher vortex core altitude and less dissipation.Overall,It is found that the VG with h=7.5 mm has the most significant effect on lift-increasing and resistance reduction in the down pitch phase,and increases the boundary layer fluid kinetic energy to a greater extent,and its stream-wise vortex chordal control is wider and less dissipative,which can effectively suppress the flow separation.
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