This paper presents the measurements of mean and fluctuating forces on an NACA0012 airfoil over a large range of angle (α) of attack (0–90°) and low to small chord Reynolds numbers (Rec), 5.3 × 103–5.1 × 104, which is of both fundamental and practical importance. The forces, measured using a load cell, display good agreement with the estimate from the LDA-measured cross-flow distributions of velocities in the wake based on the momentum conservation. The dependence of the forces on both α and Rec is determined and discussed in detail. It has been found that the stall of an airfoil, characterized by a drop in the lift force and a jump in the drag force, occurs at Rec ⩾ 1.05 × 104 but is absent at Rec = 5.3 × 103. A theoretical analysis is developed to predict and explain the observed dependence of the mean lift and drag on α.
International Journal of Heat and Fluid Flow Vol. 32, Issue 1, p. 329-339