Experimental and numerical evaluation of the drag and lift forces on a scaled-down airfoil

Abstract

Knowledge about the aerodynamic quality of a wing is an important factor in the design of aircraft. If the aerodynamic coefficients are not known, they must be evaluated using highly sensitive equipment. In this study, a low cost measurement system using load cells and strain gauges was developed and evaluated. It was used to measure the drag and lift forces acting on a reduced scale airfoil, when it was subjected to different flow velocities in a wind tunnel. The experimental values were compared with numerical results obtained using computational fluid dynamics (CFD) techniques. The OpenFOAM code was used to predict the turbulent flow behaviour around the airfoil, considering different turbulence models. It was established that the optimal mesh for this study has 3.26 million control volumes. The experimental values of the lift and drag forces were provided by several runs with different velocities using the measurement system, which proved to have enough accuracy. Numerical results showed good agreement for the prediction of the lift force. However, the predicted drag force showed noticeable differences. Among the models used, the Spalart-Allmaras model provided the best agreement with experimental values.