university of florida thesis or dissertation formatting template

More documents

Recommendations

Info

the upper surface. However, on the upper surface, there is a more defined shock character in the 60-70% chord region for the tip-launcher case. There is also see a shift aft in the shock location. These features are attributed to the presence of the tip launcher. Upon examining Figure 6-43 and animating the Cp for all iterations on the upper surface, a rapid suction build-up with increasing AOA is revealed at the 50-70% chord location. As AOA decreases, there is a rapid loss of suction which progresses from the aft portion of the wing forward. The motion of this loss resembles that of a double hinged door slamming shut; the first near 70% chord and the second near 60% chord. This is an indication of the hysteresis behavior in the shock structure. Significant pressure differences occur on the lower surface for the both cases in the 0-30% chord region. Similar results where encountered on for the Grid4 tip-launcher case with LE antenna. This is indicative of the aerodynamic influence of the LE antenna. Based on this significant influence from a small component, small aerodynamic differences between stores can cause significant changes in the flow-field, possibly influencing the occurrence of LCO. This may explain why nearly identical configurations have different LCO flight test results which are not predicted by classical flutter analyses. However, it is known from flight testing experience that the LE antenna is not a driving force behind the LCO mechanism. Therefore, future grids will most likely not include the LE antenna so as to avoid distraction from the true contribution to the LCO mechanism. Lissajous Analysis Figure 6-44 shows the set of Lissajous plots (-Cp vs. local displacement from the upper surface of the airfoil at various chord vs. span locations) for one cycle of pitching 8Hz ±0.5° oscillation. A low pass filter is applied to the data at 100 Hz to filter out the noise due to turbulence effects. The top of the figure is the tip launcher, the bottom the wing root; and the left side is the LE and the right side the TE of the wing. The red circles indicate the starting point of 96
the roll cycle, and the black arrows indicate the direction of rotation of the Lissajous. The set of Lissajous plots for the tip-launcher case is slightly different from the clean-wing case seen in Figure 6-31. First, the tip-launcher plots include two extra span stations, one on the tip launcher and one at the LE antennae. The Lissajous figures for the pitch oscillation cases are very different from the roll oscillation cases. However, the overall trends are similar for the tip- launcher Grid8 and clean-wing Grid9 pitch cases. In the lower left-hand potion of the plot, a 0° to 45° phase shift is observed with counter-clockwise rotation. The phase suddenly shifts to 180°, essentially mapping out the pitch axis. There is also a corresponding phase shift on the tip launcher (LAU) for Grid8 at the 13% chord location indicative of the pitch axis. The phase then shifts to 180° with clockwise rotation, with a delayed shift in the 42-59% span, 28-68% chord region, and begins to open up aft along the wing with 90° phase shift along the inboard, TE portion of the wing. The phase maintains a 180° phase shift near and along the tip for Grid8. A transition from clockwise to counter-clockwise rotation is apparent in the 78% chord region at the root and extending back to the 68% chord region near the tip. This shift in rotational direction can be attributed to the shock transition. It is interesting to note that the rotational directions for the pitch cases are opposite of those of the roll cases. This has to do with the roll beginning left-wing-up and the pitch beginning left-wing-down. Additionally, the region of change is much further forward moving toward the tip launcher. The tip-launcher plots show a more narrow nature in the shock transition region than the rounder clean-wing case, and a more open nature near the tip. There are also a few regions on the wing, mostly near the tip launcher and shock transition, where the Lissajous plots form a figure-eight shape, indicating a continuous phase variation within 1 cycle. Overall, the Lissajous figures for both pitch oscillation cases differ significantly near the tip (88-100% span) and shock transition region. 97
Page 1 and 2:
TEMPORAL ANALYSIS OF TRANSONIC FLOW
Page 3 and 4:
To Dodjie 3
Page 5 and 6:
TABLE OF CONTENTS ACKNOWLEDGMENTS .
Page 7 and 8:
Summary ...........................
Page 9 and 10:
LIST OF FIGURES Figure page 2-1 F-1
Page 11 and 12:
6-9 Lissajous plots of upper surfac
Page 13 and 14:
6-45 2-D (left column) and 3-D (rig
Page 15 and 16:
incrementally since this capability
Page 17 and 18:
are not sufficient to provide an an
Page 19 and 20:
4. Contribute to the work of others
Page 21 and 22:
Classical aircraft flutter is chara
Page 23 and 24:
Popular methods for finding the sol
Page 25 and 26:
LCO amplitude but not the mechanism
Page 27 and 28:
speed for the particular configurat
Page 29 and 30:
Denegri 23 explains the flutter fli
Page 31 and 32:
Doublet-lattice Denegri 1, 7,12,13
Page 33 and 34:
Batina’s work and uses an F-16 ha
Page 35 and 36:
As a result of Denegri’s previous
Page 37 and 38:
Figure 2-1. F-16 store stations. Fi
Page 39 and 40:
Figure 2-5. Flutter flight test bui
Page 41 and 42:
Stokes (RANS) equations on hybrid u
Page 43 and 44:
CHAPTER 4 ANALYSIS TECHNIQUES Intro
Page 45 and 46: time-localization cannot be determi
Page 47 and 48: A B C D E Figure 4-3. Analysis of s
Page 49 and 50: (CFD) analyses in order to capture
Page 51 and 52: the appropriate time step for the n
Page 53 and 54: Wing1, is the wing-only (no fuselag
Page 55 and 56: similar to DES but with modificatio
Page 57 and 58: Figure 5-1. Time step comparison of
Page 59 and 60: A B Figure 5-3. Flow results for 8
Page 61 and 62: A B Figure 5-5. Flow results for 8
Page 63 and 64: Figure 5-7. Turbulence model compar
Page 65 and 66: Figure 5-9. CFD vs. wind tunnel com
Page 67 and 68: Figure 5-11. CFD vs. wind tunnel co
Page 69 and 70: Figure 5-13. CFD vs. wind tunnel co
Page 71 and 72: server cluster comprised of 5,120 p
Page 73 and 74: of oscillation. The 88% span locati
Page 75 and 76: since it is proportional to lift, a
Page 77 and 78: of phase. Figure 6-10 B) and D) are
Page 79 and 80: The instantaneous Cp measurements p
Page 81 and 82: D Lissajous plots with time being t
Page 83 and 84: frequency of 8Hz. The wavelet plot
Page 85 and 86: vortex is observed travelling outbo
Page 87 and 88: near 70% chord and the second near
Page 89 and 90: expected from a lift curve slope. A
Page 91 and 92: shape of this Lissajous is nonlinea
Page 93 and 94: occurring at harmonics, and assumes
Page 95: the same direction of rotation on t
Page 99 and 100: B) shows the fast Fourier transform
Page 101 and 102: is that shock separation aft of the
Page 103 and 104: on the upper surface, a much larger
Page 105 and 106: Figure 6-1. F-16 wing planform with
Page 107 and 108: A C B Figure 6-4. DDES of F-16 in s
Page 109 and 110: Cp (Non-dimensional) Cp (Non-dimens
Page 111 and 112: -Cp (Non-dimensional) A -Cp (Non-di
Page 115 and 116: -Cp (Non-dimensional) A Time (sec)
Page 117 and 118: A B Figure 6-14. DDES-SARC of F-16
Page 121 and 122: Figure 6-18. Lissajous plots of upp
Page 123 and 124: -Cp (Non-dimensional) Frequency (Hz
Page 125 and 126: -Cp (Non-dimensional) A Frequency (
Page 127 and 128: A B Figure 6-24. DDES-SARC of F-16
Page 143 and 144: A B D Figure 6-40. DDES of F-16 in
Page 147 and 148:
Figure 6-44. Lissajous plots of upp
Page 149 and 150:
-Cp (Non-dimensional) A Time (sec)
Page 151 and 152:
-Cp (Non-dimensional) A Time (sec)
Page 153 and 154:
A B Figure 6-50. DDES-SARC of F-16
Page 155 and 156:
Figure 6-52. Lissajous plots of upp
Page 157 and 158:
Impact on Future Design of Aircraft
Page 159 and 160:
The size of the Mach=1 iso-surface
Page 161 and 162:
these cases in order to identify th
Page 163 and 164:
15. Dawson, K. S., and Sussinham, J
Page 165 and 166:
41. Thomas, J. P., Dowell, E. H., a
Page 167 and 168:
67. Cunningham, A. M., Jr., and den
Page 169 and 170:
93. Parker, G. H., Maple, R. C., an
Page 171 and 172:
121. Travin, A. K., Shur, M. L., Sp
show all

university of florida thesis or dissertation formatting template

Create successful ePaper yourself

Delete template?

Save as template?