06.08.2013 Views

university of florida thesis or dissertation formatting template

university of florida thesis or dissertation formatting template

university of florida thesis or dissertation formatting template

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

shape <strong>of</strong> this Lissajous is nonlinear with a phase closer to 135°. This is due to shock f<strong>or</strong>mation.<br />

The 3-D plot in F) exhibits a loop feature in the first quarter <strong>of</strong> the cycle.<br />

Wavelet Analysis<br />

Wavelet analysis is applied to points <strong>of</strong> interest on the wing in Figure 6-33, Figure 6-34,<br />

and Figure 6-35 f<strong>or</strong> the clean-wing Grid0 1Hz pitch case; and in Figure 6-36, Figure 6-37, and<br />

Figure 6-38 f<strong>or</strong> the clean-wing Grid9 8Hz pitch case, in <strong>or</strong>der to gain further insight into the<br />

temp<strong>or</strong>al nature <strong>of</strong> the results. In each set <strong>of</strong> figures, A) gives the time hist<strong>or</strong>y <strong>of</strong> the Cp variation,<br />

B) shows the fast Fourier transf<strong>or</strong>m (FFT) <strong>of</strong> the data, and C) illustrates the wavelet transf<strong>or</strong>m<br />

view <strong>of</strong> frequency vs. time.<br />

Figure 6-33 contains the 1Hz Grid0 results at 93% span vs. 67% ch<strong>or</strong>d which c<strong>or</strong>responds<br />

to the shock recovery region as seen in Figure 6-27 C). The time hist<strong>or</strong>y plot in A) reveals a<br />

fairly periodic response in upper wing surface Cp. The FFT plot in B) shows broad-band energy<br />

f<strong>or</strong> 1-5Hz. The wavelet plot in C) illustrates large energy concentration occurring at 3Hz at<br />

time=0.82 sec and 1.82 sec. The wavelet analysis also confirms a periodic response as predicted<br />

by the FFT.<br />

Figure 6-34 contains the 1Hz Grid0 results at 88% span vs. 72% ch<strong>or</strong>d which also<br />

c<strong>or</strong>responds to shock recovery region as seen in Figure 6-28 C). The time hist<strong>or</strong>y plot in A) again<br />

reveals a fairly periodic response in upper wing surface Cp. The FFT plot in B) shows a<br />

prominent peak at the input frequency <strong>of</strong> 1Hz. The wavelet plot in C) illustrates most <strong>of</strong> the<br />

energy concentration occurring at 1Hz with higher frequency energy occurring on the upstroke<br />

and downstroke <strong>of</strong> the oscillation. The wavelet analysis also confirms a periodic response as<br />

predicted by the FFT.<br />

Figure 6-35 contains the 1Hz Grid0 results at 88% span vs. 81% ch<strong>or</strong>d which also<br />

c<strong>or</strong>responds to the area aft <strong>of</strong> shock recovery region as seen in Figure 6-28 C). The time hist<strong>or</strong>y<br />

91

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!