Faculty of Engineering and Applied Science

Faculty of Engineering and Applied Science

Fluids Mechanics II – Engineering 5912

Winter 2002

Laboratory # 2 – Lift and Drag on Airfoils

In this laboratory, you will measure the lift and drag characteristics of a finite airfoil at various angles of attack and at least three flow speeds (Reynolds #’s). Using the measured data, you will compute the lift and drag coefficients and compare with theoretical predictions. Prepare a plot of the non-dimensional lift and drag coefficients. How well do these results compare, with theoretical equations.

Fig. 1 – Airfoil Dimensions (From Fluid Mechanics, By F.M. White, 2000)

The lift and drag coefficients are defined as follows:

The theoretical lift coefficient for an infinite airfoil may be computed from the following expression in your notes:

where:

and h is the maximum camber. Determine the circulation G where the lift is related to the circulation by means of

Plot all of the lift and drag coefficient data versus angle of attack. How well do the data compare with the theoretical prediction of the lift coefficient. What factors may be affecting the results? The thickness effect of airfoils has not been well verified by experiment. As a result it is traditional to drop the term (1+0.77t/c) from the equation. What effect does setting this group equal to unity, have on the theoretical predictions? In your write up tabulate the lift and drag coefficients in addition to providing a plot of each. Include on the plot for the lift coefficient, the theoretical curve. What is the percent deviation from the infinite airfoil theory? On another plot, present the lift to drag ratio versus angle of attack.