以拍撲翼作為升力機制的微飛行器，現今已被廣用在軍事、救援、探勘等任務中，但是其飛行上的低高度、低速的飛行限制條件，造成抗風能力不足的現象，因此，探討低速陣風的影響已成為當前航空工業研究的重點。
	拜現今電腦技術快速發展所賜，透過增加網格數目來達到增加計算模擬的準確度，卻可以不增加運算時間。本研究首先以2D的拍撲翼面作為基準，將陣風的環境依照不同的方向、風速大小的變化與否做區分，再用動態網格的技術以Fluent這套軟體模擬出拍撲的動作。由我們的結果可以得到陣風環境會對上下翼面的渦流有很大的影響，更會直接影響拍撲翼的升力與阻力值，而陣風方向的不同影響更大。因此，本研究將會對拍撲翼面在陣風環境下性能分析有很大的幫助，更是未來研究微飛行器之抗風性的重要基石。
關鍵詞：拍撲翼，陣風，動態網格，延遲失速

Micro Aerial Vehicles (MAV) use flapping wing as their flying  
mechanism. Nowadays MAV have been used more intensively in daily
military, rescue, or reconnaissance missions, but their inherent nature of
low altitude, low speed operation envelope will lead to their weak wind
resistance ability, and thus the investigation of low level gust wind effect is
becoming the focus point in recent aeronautical research.
  By the rapidly development in recent computer technology, we can improve simulation accuracy without using more time, through escalating the grid’s number. In this thesis, first choose a standard 2D flapping airfoil as a benchmark, then we can implementing gusty environment in several different directions, and simulate the wind amplitude with both constant speed and sine wave forms by using the dynamic grid technique of software Fluent to generate flapping motion. Our results show that the gusty environment has a strong effect on the vortices both on the upper and the lower surfaces, and will have direct influence on the lift and drag values of the flapping wing. But most profound effect is from the wind direction. As a result, this research will be very helpful to learn about the flapping airfoil’s aerodynamic performance in gusty environment, and could be an important cornerstone in the wind resistance capability consideration of future flapping MAV.

CONTENTS	VI
LIST OF TABLES	VIII
LIST OF FIGURES	IX
CHAPTER 1  INTRODUCTION	13
1.1 THE HISTORY OF AVIATION	13
1.2 FLAPPING-WING VEHICLE	15
1.3 ENVIRONMENT INFLUENCE	16
CHAPTER 2  LITERATURE REVIEW	18
2.1 FLIGHT IN NATURE	18
2.2 MECHANISMS WITH FLAPPING-WING AERODYNAMICS	18
2.2.1 Leading-Edge Vortex	18
2.1.2 Pitch-Up	19
2.1.3 Wake Capture	20
2.1.4 Clap-and-Fling Mechanism	22
2.2 DRAGONFLY	22
2.3 FLAPPING MOTION	23
2.4 NUMERICAL SCHEME	24
CHAPTER 3  GUST ENVIRONMENT	26
3.1 GUSTS	26
3.2 POWER SPECTRAL DENSITY	26
3.3 SINUSOIDAL WAVE FUNCTION	28
CHAPTER 4 NUMERICAL METHOD	30
4.1 FLOW CHART	30
4.2 FLOW FIELD ASSUMPTIONS	31
4.3 GOVERNING EQUATIONS	31
4.4 PRE PROCESS	32
4.4.1 Wing Shape and Grid Generation	32
4.4.2 Dynamic Grid	34
4.4.3 Boundary Condition	34
4.5 SOLVER-FLUENT	34
4.5.1 Coupled Solution Method	35
4.5.4 QUICK Scheme	35
4.5.6 PISO	36
4.5.7 Pressure Interpolation Scheme	36
4.6 POST PROCESS	36
CHAPTER 5 RESULTS AND DISCUSSION	37
5.1 WINDLESS ENVIRONMENT	40
5.2 UNIFORM FLOW ENVIRONMENT	50
5.2.1 135-Degree Constant Inflow	51
5.2.2 45-Degree Uniform Inflow	60
5.3 SINUSOIDAL WAVE WIND ENVIRONMENT	71
5.3.1 45-Degree Sinusoidal Wave Inflow	71
5.3.2 135-Degree Sinusoidal Wave Inflow	77
5.4 FLAPPING WING F-FACTOR	82
CHAPTER 6 CONCLUSIONS	92
REFERENCES	94
APPENDIXⅠ	97

List of Tables
TABLE 5.1 MEAN LIFT FORCE AND MEAN DRAG FORCE COMPARE WITH [8], [10]	40
TABLE 5.2 MEAN LIFT FORCE AND MEAN DRAG FORCE COMPARE WITH [10]	51
TABLE 5.3 MEAN LIFT FORCE AND MEAN DRAG FORCE	61
TABLE 5.4 UNIFORM INFLOW MEAN LIFT FORCE AND MEAN DRAG FORCE	70
TABLE 5.5 MEAN LIFT FORCE AND MEAN DRAG FORCE	72
TABLE 5.6 MEAN LIFT FORCE AND MEAN DRAG FORCE	77
TABLE 5.7 MEAN LIFT FORCE AND MEAN DRAG FORCE FOR ALL DIRECTION	82
TABLE 5.8 THE SINE WAVE INFLOW’S MEAN F-FACTOR VALUE AT DIFFERENT DIRECTION	85

List of Figures
FIG. 1.1 THE GENEALOGICAL TREE OF AIRCRAFT	15
FIG. 2.1 THE LEV GENERATION PROCESS [4]	19
FIG. 2.2 EXPERIMENTAL AND NUMERICAL LIFT COEFFICIENTS FOR A FRUIT FLY-MODELED WING [6]	20
FIG. 2.3 EVIDENCE OF WAKE-CAPTURE MECHANISM AND ITS EFFECT ON FORCE GENERATION FOR A ROBOTIC FRUIT FLY-MODELED WING AT RE=136. [6]	21
FIG. 2.4 MOMENTUM TRANSFER IN A WAKE-CAPTURE INTERACTION. [6]	21
FIG. 2.5 ILLUSTRATION OF CLAP-AND-FLING MECHANISM [6].	22
FIG. 2.6 THE POSITIONS OF A WING ELEMENT IN ONE PERIOD AS MODEL HERE [8]	23
FIG. 2.7 DYNAMIC GRIDS DOMAIN [9]	24
FIG. 4.1 THE CFD FLOW CHART IN THIS THESIS	30
FIG. 4.2 THE STRUCTURE GRIDS	33
FIG. 4.3 THE TRIANGLE GRIDS	33
FIG. 5.1 THE TOTAL GRIDS ARE SMALLER THAN 0.45(GRID QUALITY FACTOR), ESPECIALLY THOSE NEARBY THE WING SURFACE	37
FIG. 5.2 THERE ARE LOTS OF GRIDS BIGGER THAN 0.45(GRID QUALITY FACTOR), ESPECIALLY THOSE NEARBY THE WING SURFACE	38
FIG. 5.3 USING DIFFERENT NUMBERS OF GRID TO CALCULATE LIFT FORCE PER FLAPPING CYCLE	39
FIG. 5.4 LIFT FORCE PER FLAPPING CYCLES COMPARE WITH [8], [10]	41
FIG. 5.5 DRAG FORCE PER FLAPPING CYCLES COMPARE WITH [8], [10]	41
FIG. 5.6 DRAG FORCE COMPONENT	42
FIG. 5.7 VORTICES CONTOUR (1/SEC)	46
FIG. 5.8 PRESSURE CONTOUR (PA)	50
FIG. 5.9 LIFT FORCE PER FLAPPING CYCLE COMPARE WITH [10]	52
FIG. 5.10 DRAG FORCE PER FLAPPING CYCLE COMPARE WITH [10]	52
FIG. 5.11 DRAG FORCE COMPONENT BY PRESSURE DRAG AND VISCOUS DRAG	53
FIG. 5.12 VORTICITY CONTOUR PER 0.05T (1/SEC)	57
FIG. 5.13 PRESSURE CONTOUR (PA)	60
FIG. 5.14 DRAG FORCE COMPONENT BY PRESSURE DRAG AND VISCOUS DRAG	61
FIG. 5.15 LIFT FORCE PER FLAPPING CYCLES	62
FIG. 5.16 DRAG FORCE PER FLAPPING CYCLES	62
FIG. 5.17 VORTICITY CONTOUR (1/SEC)	66
FIG. 5.18 PRESSURE CONTOUR (PA)	70
FIG. 5.19 DRAG FORCE COMPONENT BY PRESSURE DRAG AND VISCOUS DRAG	72
FIG. 5.20 LIFT FORCE PER FLAPPING CYCLES	73
FIG. 5.21 DRAG FORCE PER FLAPPING CYCLES	73
FIG. 5.22 LIFT FORCE PER FLAPPING CYCLES	74
FIG. 5.23 DRAG FORCE PER FLAPPING CYCLES	74
FIG. 5.24 VORTICITY CONTOUR (1/SEC)	75
FIG. 5.25 PRESSURE CONTOUR (PA)	76
FIG. 5.26 DRAG FORCE COMPONENT BY PRESSURE DRAG AND VISCOUS DRAG	77
FIG. 5.27 LIFT FORCE PER FLAPPING CYCLES	78
FIG. 5.28 DRAG FORCE PER FLAPPING CYCLES	78
FIG. 5.29 LIFT FORCE PER FLAPPING CYCLES	79
FIG. 5.30 DRAG FORCE PER FLAPPING CYCLES	79
FIG. 5.31 VORTICITY CONTOUR (1/SEC)	80
FIG. 5.32 PRESSURE CONTOUR (PA)	81
FIG. 5.33 THE F-FACTOR VS. FLAPPING CYCLES AT WINDLESS CONDITION	87
FIG. 5.34 THE F-FACTOR VS. FLAPPING CYCLES AT 0-DEGREE SINE WAVE CONDITION	87
FIG. 5.35 THE F-FACTOR VS. FLAPPING CYCLES AT 180-DEGREE SINE WAVE CONDITION	88
FIG. 5.36 THE F-FACTOR VS. FLAPPING CYCLES AT 45-DEGREE SINE WAVE CONDITION	88
FIG. 5.37 THE F-FACTOR VS. FLAPPING CYCLES AT 90-DEGREE SINE WAVE CONDITION	89
FIG. 5.38 THE F-FACTOR VS. FLAPPING CYCLES AT 135-DEGREE SINE WAVE CONDITION	89
FIG. 5.39 THE F-FACTOR VS. FLAPPING CYCLES AT 225-DEGREE SINE WAVE CONDITION	90
FIG. 5.40 THE F-FACTOR VS. FLAPPING CYCLES AT 270-DEGREE SINE WAVE CONDITION	90
FIG. 5.41 THE F-FACTOR VS. FLAPPING CYCLES AT 315-DEGREE SINE WAVE CONDITION	91
FIG. A1 LIFT FORCE PER FLAPPING CYCLES	97
FIG. A2 DRAG FORCE PER FLAPPING CYCLES	97
FIG. A3 VORTICITY CONTOUR (1/SEC)	98
FIG. A4 PRESSURE CONTOUR (PA)	99
FIG. A5 LIFT FORCE PER FLAPPING CYCLES	100
FIG. A6 DRAG FORCE PER FLAPPING CYCLES	100
FIG. A7 VORTICITY CONTOUR (1/SEC)	101
FIG. A8 PRESSURE CONTOUR (PA)	102
FIG. A9 LIFT FORCE PER FLAPPING CYCLES	103
FIG. A10 DRAG FORCE PER FLAPPING CYCLES	103
FIG. A11 VORTICITY CONTOUR (1/SEC)	104
FIG. A12 PRESSURE CONTOUR (PA)	105
FIG. A13 LIFT FORCE PER FLAPPING CYCLES	106
FIG. A14 DRAG FORCE PER FLAPPING CYCLES	106
FIG. A15 VORTICITY CONTOUR (1/SEC)	107
FIG. A16 PRESSURE CONTOUR (PA)	108
FIG. A17 LIFT FORCE PER FLAPPING CYCLES	109
FIG. A18 DRAG FORCE PER FLAPPING CYCLES	109
FIG. A19 VORTICITY CONTOUR (1/SEC)	110
FIG. A20 PRESSURE CONTOUR (PA)	111
FIG. A21 LIFT FORCE PER FLAPPING CYCLES	112
FIG. A22 DRAG FORCE PER FLAPPING CYCLES	112
FIG. A23 VORTICITY CONTOUR (1/SEC)	113
FIG. A24 PRESSURE CONTOUR (PA)	114
FIG. A25 LIFT FORCE PER FLAPPING CYCLES	115
FIG. A26 DRAG FORCE PER FLAPPING CYCLES	115
FIG. A27 VORTICITY CONTOUR (1/SEC)	116
FIG. A28 PRESSURE CONTOUR (PA)	117
FIG. A29 LIFT FORCE PER FLAPPING CYCLES	118
FIG. A30 DRAG FORCE PER FLAPPING CYCLES	118
FIG. A31 VORTICITY CONTOUR (1/SEC)	119
FIG. A32 PRESSURE CONTOUR (PA)	120
FIG. A33 LIFT FORCE PER FLAPPING CYCLES	121
FIG. A34 DRAG FORCE PER FLAPPING CYCLES	121
FIG. A35 VORTICITY CONTOUR (1/SEC)	122
FIG. A36 PRESSURE CONTOUR (PA)	123
FIG. A37 LIFT FORCE PER FLAPPING CYCLES	124
FIG. A38 DRAG FORCE PER FLAPPING CYCLES	124
FIG. A39 VORTICITY CONTOUR (1/SEC)	125
FIG. A40 PRESSURE CONTOUR (PA)	126
FIG. A41 LIFT FORCE PER FLAPPING CYCLES	127
FIG. A42 DRAG FORCE PER FLAPPING CYCLES	127
FIG. A43 VORTICITY CONTOUR (1/SEC)	128
FIG. A44 PRESSURE CONTOUR (PA)	129
FIG. A45 LIFT FORCE PER FLAPPING CYCLES	130
FIG. A46 DRAG FORCE PER FLAPPING CYCLES	130
FIG. A47 VORTICITY CONTOUR (1/SEC)	131
FIG. A48 PRESSURE CONTOUR (PA)	132

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