Negative lift characteristics of NACA 0012 aerofoil at low Reynolds numbers

Numerical investigations on the flow over NACA 0012 aerofoil are carried out to provide better understanding of the unusual lift characteristics exhibited by this aerofoil at low Reynolds numbers. Computations are carried out at Re = 10,000–100,000, for different values of angles of attack and freestream turbulence intensity. There exists a narrow range of these parameters where the net circulation around this symmetrical aerofoil is negative, leading to the generation of negative lift at positive angles of attack. Different flow regimes are identified and physical explanations are given for this unusual behaviour of negative lift, and the influence of different flow parameters is discussed.