Example: Pitching NACA0012

We consider now a pitching motion. Thanks to the linearity of the problem, the combined plunging and pitching motion can be obtained by superposition of the solutions of the two motions. The following pitching motion is considered:

a(t) = a0 + Sa sin(wt) (5.39)

where a0 = 4°, Sa = 8.3°, f = 30Hz, U = 98.8 m/s and the profile chord is c = 0.1° m. This corresponds to the reduced frequency k = fc/U = 0.03. Results of the numerical simulation are compared with experimental results of Wood [2] in Fig. 5.8. The normal force coefficient is defined as Cn = Cl cos a + Cd sin a and represents the component of the force perpendicular to the profile chord. The agreement is good for the lower incidences, a < 2.5° but differences occur at high incidences due to viscous effects.

Fig. 5.8 Normal force coefficient comparison