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A review on concepts, theories and literature about wind and wind turbine technology is made. It is intended for performance evaluation of turbine blade modified by leading edge protuberance and forward sweep. Best efficiency attainable by a wind turbine is 59.3% at tip speed ratio of 7-8. Hypothesis is modifying turbine blade with leading edge protuberance and forward sweep would improve the aerodynamic performances of the turbine in low wind speed regime. From literature, airfoils with leading edge protuberances and forward swept airfoils have achieved aerodynamic advantages. Researches on leading edge protuberances on aircraft wing and other airfoil span sections have indicated decrease in lift at low angles of attack, but increase of up to 48% in lift at angles of attack beyond 16o, and up to 44% decrease in drag or no drag penalty. The amplitude of leading edge protuberance plays significant effect in the lift and drag performances, while wavelength has negligible effect. Researches on forward swept airfoil sections identified improved performance including lower speed aircraft handling characteristic, increased resistance to span departure, and reduced stall speed for fixed wings. Also, lift and drag coefficients diminish with an increase in forward swept angles and aerodynamic characteristics for forward swept are more stable at low speed. For laminar flow wing, the reduction in sweep in the case of forward swept wing leads to more stable laminar boundary layer concerning transition because of cross flow instability and attachment. Literature reflects a consensus that forward swept geometry gives potential for the following advantages in the part load operational range of rotor blades: improvement of efficiency, increase of total pressure peak, and extension of stall-free operating range by improving stall margin. The findings of the current review suggest that investigation into wind turbine blade with leading edge protuberance and forward sweep would lead to improved aerodynamic performance of wind turbines in low wind speed regime.
