Effect of Airfoil Thickness on Flow Over the Cambered Airfoils

In this research, an experimental study for NACA2412, NACA2415, and NACA2418 airfoils was carried out at angles of attack of 0°, 4°, 8 and at
$\mathbf{Re}=\mathbf{1}.\mathbf{5}\times \mathbf{10}^{\mathbf{5}},\ \mathbf{Re}=\mathbf{2}.\mathbf{5} \times \mathbf{10}^{\mathbf{5}}$
. The oil-flow visualization technique and force measurement were used for experiments to analyze laminar separation bubble (LSB), separation and reattachment formations over the airfoil. According to the experimental results, the length of the LSB declined significantly with the raising Reynolds number for each airfoil. Over the NACA2418 airfoil, which is the thickest of the three airfoils, the LSB characteristics changed and the short bubble was observed at all angles of attack and Reynolds numbers. At the same Re number, aerodynamic force performance raised as the thickness of the cambered airfoil increased, but in NACA2418 airfoil, the trailing edge separations began and the lift force coefficient decreased due to the increase in the adverse pressure gradients.