Investigation into the aerodynamic e ects of simulated battle damage to a wing

218 Pages·2016·5.98 MB·English

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Investigation into the
aerodynamic effects of
simulated battle damage to a
wing
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• A Doctoral Thesis. Submitted in partial fulfilment of the requirements
for the award of Doctor of Philosophy of Loughborough University.
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Publisher: (cid:13)c Andrew Irwin
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INVESTIGATION INTO THE AERODYNAMIC EFFECTS OF
SIMULATED BATTLE DAMAGE TO A WING
by
Andrew J. lrwin, B.Eng
A Doctoral Thesis
Submitted in partial fulfilment of the requirements for the Award of
Doctor of Philosophy of Loughborough University
May 1999
©by An drew Irwin 1999
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Acknowledgements
Firstly, I would like to thank Dr.P.Render for his advice, guidance and support throughout all
the stages of this research, from original conception through to thesis submission, his
assistance has been invaluable. The same thanks and gratitude are also extended to
Prof.J.McGuirk, not only for his role as Director of Research, but also for his enthusiastic
support.
Sincere thanks go to Mr.P.Stinchcombe and Mr.G.Cunningham for their roles in supporting
the practical aspects of the research.
I would also like to acknowledge the valuable support of British Aerospace (Military
Aircraft) Ltd. throughout the project. In particular, Mr.B.Probert and Mr.P.Alonze for their
advice, encouragement and assistance throughout.
Finally, I wish to express my heartfelt thanks to my family and in particular Angela, without
whose support, encouragement and above all patience, this work could not have been
completed.
List of Contents
Synopsis i
Nomenclature
11
Chapter 1 Introduction I
1.1 Background I
1.2 The role of Battle Damage Survivability Assessments I
1.3 Historical Considerations of Battle Damage Effects 3
1.4 Threat Characteristics 6
1.4.1 Threat Types 6
1.4 .2 Damage Processes 8
1.5 Literature Review 11
1.6 General Scope of the Investigation 19
1.7 Programme Objectives 19
Chapter 2 Experimental Facilities and Techniques 20
2.1 Introduction 20
2.2 Tunnel Test Facilities 20
2.3 Wind Tunnel Wing Models 22
2.3.1 Wing Geometry 22
2.3.2 Wing Model Manufacture 23
2.4 Aerodynamic Force Measurement 25
2.4.1 Force Measurement Facilities 25
2.4.2 Experimental Test Procedures & Techniques 27
2.4.3 Wind Tunnel Data Corrections 28
2.4.4 Data Validation, Accuracy and Repeatability 32
2.4.5 Damaged Wing Data Presentation 37
2.5 Wing Surface Pressure Measurements 41
2.5.1 Pressure Tapping Equipment 41
2.5.2 Test Procedures 44
2.5.3 Data Processing 45
2.5.4 Pressure Data Accuracy 46
2.6 Flow Visualisation Techniques 49
2.6.1 Local Flow-field Smoke Visualisation 49
2.6.2 Surface Flow Visualisation 50
Chapter 3 Sensitivity of Test Aerofoil to Simulated Gunfire Damage 52
3.1 Introduction 52
3.2 Methods of modelling Gunfire Damage 52
3.2.1 Damage Occurrence 53
3.2.2 Extent of Penetration 53
3.2.3 Direction of Attack 53
3.2.4 Damage Shape 55
3.2.5 Damage Size 57
3.2.6 Location of Damage 57
3.2.7 Summary of Simulated Damage Characteristics 59
3.3 Leading Edge Damage; A Qualitative & Quantitative Investigation 60
3.3.1 Damage Cases Considered 60
3.3.2 Smoke Injection Flow Visualisation 60
3.3.3 Surface Flow Visualisation 63
3.3.4 Leading Edge Damage Effects on Aerodynamic Coefficients 65
3.4 Mid-Chord Damage; A qualitative & Quantitative Investigation 71
3.4 .I Damage Cases Investigated 71
3.4.2 Flow Structures Identified by Flow Visualisation Techniques 71
3.4.2.1 Weak-Jet Flow Observations 71
3.4.2.2 Strong-Jet Flow Observations 75
3.4.3 Half-Chord Damage Flow Structure Characteristics 80
3.4.4 Surface Pressure Data 81
3.4.4.1 Damage Centreline Pressure Data 81
3.4.4.2 Damage Spanwise Pressure Data 88
3.4.5 A comparison of Wing and Flat-plate Jet Mechanics 101
3.4.5.1 Published Characteristics of Jets-in-Crossflows 101
3.4.5.2 Comparison of Flat-plate and Damaged-wing Jet Effects 107
3.4.6 Variations in Aerodynamic Coefficients Resulting from Quarter-
Chord Damage 110
3.4.7 Half-chord Damage Aerodynamic Coefficient Changes 115
3.5 Trailing Edge Damage; A Qualitative & Quantitative Investigation 116
3.5.1 Surface Flow Visualisation 116
3.5.2 Trailing Edge Damage Effects on Aerodynamic Coefficients 118
3.6 Reynolds Number and Internal Modelling Effects 120
3.6.1 Reynolds Number Influence on Damage Characteristics 121
3.6.2 Influence of Aerofoil Construction on Damage Characteristics 123
Chapter 4 Interpolation Techniques for Simulated Gunfire Damage 125
4.1 Introduction 125
4.2 Damage Conditions with Minimal Effects 125
4.3 Leading Edge Damage Effects 128
4.3.1 Lift Loss Interpolation 128
4.3 .2 Drag Increase Interpolation 130
4.3 .3 Pitching Moment Interpolation 130
4.4 Mid-Chord Damage Effects 131
4.4.1 Lift Loss Interpolation 131
4.4.2 Drag Increase Interpolation 137
4.4.3 Pitching Moment Interpolation 139
4.4.4 Validation Test Case 140
4.5 Trailing Edge Damage Effects 142
4.5.1 Lift Loss Interpolation 142
4,5.2 Drag Increase Interpolation 145
4.S.3 Pitching Moment Interpolation 14S
4.S .4 Validation Cases 148
ChapterS The Effects of Simulated Multi-hit Gunfire Damage ISO
S. I Introduction ISO
S. 2 Superposition Prediction Method ISO
S. 3 Experimental Investigation ISI
S. 4 Comparison of Experimental & Predicted Results IS2
S.4.1 Multi-Hole Mid-chord Damage IS2
5.4.2 Effects of Enlarged Mid-Chord Damage IS4
S.4.3 Effects of Varying Damage Location IS6