Experimental flow visualization over a two-dimensional airfoil at low Reynolds number

This paper presents a set of fluid flow patterns obtained by oil flow visualization method over a low Reynolds number airfoil at angle of attack = 4°, 8°, 12° and 15°. The experiments were conducted in a low speed wind tunnel at Reynolds number = 60,000 and 100,000. The aerodynamic performance of the airfoil is also shown for direct comparison with the flow features. The experimental results showed that with increase in both the Reynolds number and the angle of attack, the extent of the laminar separation bubble diminish and at the same time progress towards the leading edge. At angle of attack ≈ 12° shorter bubble at the leading edge was found to burst and reform into a rather longer bubble causing major increase in drag values.