Obtain the lift and propulsive force coefficients of an airfoil given in Example 8.6, and compare the results with Problem 8.30. Assume the profile pitches about midchord.

Example 8.6

The NACA 0012 airfoil is pitching and plunging with a reduced frequency of 1 as given below

\[
\begin{aligned}
& h=0.65 \cos (\omega t) \\
& \alpha=20^{\circ}+20^{\circ} \cos (\omega t+\pi / 2)
\end{aligned}
\]

Show that the effective angle of attack remains under the dynamic separation angle of attack.

Problem 8.30

Derive Eq. 8.37 for the thrust coefficient of an airfoil in pure pitching about the point \(a\) with reduced frequency \(k\).

Eq. 8.37

Transcribed Image Text:

25 de 20 15 10 de 0 5 -5 -10 -15 -20 -25 5 tan (-h/U) 10 15 S 20