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occurring at harmonics, and assumes a periodic response. The wavelet plot in C) reveals non-<br />

periodic features that are not seen in the FFT. The blue region at time=0.23 sec c<strong>or</strong>responds to<br />

the wide peak region and consists <strong>of</strong> a range <strong>of</strong> frequencies, whereas the green region at time=0.3<br />

sec c<strong>or</strong>responds to the narrow trough region and consists <strong>of</strong> one, clear frequency.<br />

Flow Visualization<br />

Tip-Launcher Pitch Oscillations<br />

The FSR flow-field break-down is now extended by perf<strong>or</strong>ming f<strong>or</strong>ced, rigid body pitch<br />

oscillation f<strong>or</strong> a fine F-16 Grid8 with f<strong>or</strong>ebody bump, diverter, ventral fin, fuselage gun p<strong>or</strong>t,<br />

leading edge antenna, and tip launchers. An 8Hz ±0.5° rigid-body pitch oscillation is examined<br />

at the same flow conditions (AOAi=1.34°, Mach=0.9, 5000 feet) with the same turbulence model<br />

(DDES-SARC) f<strong>or</strong> direct comparison to the clean-wing Grid9 case.<br />

Figure 6-39 and Figure 6-40 illustrate a sequence <strong>of</strong> images visualizing the flow computed<br />

f<strong>or</strong> 8Hz ±0.5° sinusoidal pitching motion depicting instantaneous Mach = 1 boundary and<br />

v<strong>or</strong>ticity magnitude iso-surfaces col<strong>or</strong>ed by pressure, respectively, at the upward stroke (between<br />

pitch angles <strong>of</strong> 135° and 180°) <strong>of</strong> the 8 Hz ±0.5° sinusoidal pitching cycle. The left set <strong>of</strong> images,<br />

A) upper and B) lower surfaces, display the tip-launcher Grid8 case results, and the clean-wing<br />

Grid9 comparisons are presented in C) upper and D) lower surfaces. The AOA is shown as a<br />

function <strong>of</strong> time in the center <strong>of</strong> each pair <strong>of</strong> images. Additionally, BL159 (88% span location) is<br />

indicated along the LE <strong>of</strong> each <strong>of</strong> the images f<strong>or</strong> reference purposes.<br />

Just like f<strong>or</strong> the roll cases, it can be seen from that the addition <strong>of</strong> the tip launcher<br />

significantly influences the nature <strong>of</strong> the Mach=1 boundary and v<strong>or</strong>ticity magnitude iso-surfaces<br />

f<strong>or</strong> the pitch cases. It is observed from Figure 6-39 that the trends between the tip-launcher and<br />

clean-wing cases are similar; such as the Mach=1 iso-surfaces at their maximum sizes at the top<br />

<strong>of</strong> the oscillation, and that the aft extent <strong>of</strong> the upper-surface Mach=1 iso-surface maintains a<br />

93

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