 | Schwithal J. Lidar-based wake identification and impact alleviation: Diss. … Dr.-Ing. / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Flugsystemtechnik, Braunschweig. - Köln: DLR, 2017. - [12], xii, 188 p. - (Forschungsbericht; 2017-59). - Res. also Germ. - Bibliogr.: p.165-175. - ISSN 1434-8454
Шифр:(Pr 1120/2017-59) 02
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1 Introduction ................................................. 1
1.1 Overview and Motivation ................................. 1
1.2 State of the Art ........................................ 6
1.3 Objectives of this Thesis .............................. 13
1.4 Structure of the Thesis ................................ 15
2 Physical Background of Wake Vortices ........................ 17
2.1 Basic Principles of Wake Vortices ...................... 17
2.2 Wake Deformation and Decay ............................. 20
2.3 Wake Vortex Models ..................................... 22
2.4 Impact of Wake Vortices on Encounter Aircraft .......... 24
3 Doppler Lidar Sensor ........................................ 25
3.1 Measurement Principle .................................. 25
3.1.1 Direct Detection and Coherent Doppler Lidars .... 27
3.1.2 Emission and Focusing Methods ................... 29
3.2 Measurement Uncertainty ................................ 30
3.3 State of the Art of Doppler-lidar-based Wake Vortex
and Turbulence Detection ............................... 34
4 Simulation Environment ...................................... 39
4.1 Model of Encountering Aircraft ......................... 39
4.1.1 Dynamic Aircraft Model .......................... 39
4.1.2 Aerodynamic Interaction Model ................... 40
4.2 Wake Vortex Model ...................................... 41
4.3 Lidar Simulation Model ................................. 42
4.4 Encounter Scenarios .................................... 47
4.5 Assessment Metrics for Wake Impact Alleviation ......... 48
5 Concept for the Alleviation of Wake Vortex Impacts on the
Basis of Remote Lidar Measurements .......................... 51
5.1 The OWIDIA Concept for Wake Impact Alleviation ......... 51
5.2 Online Wake Identification ............................. 52
5.2.1 Activation Criterion ............................ 56
5.2.2 Maximum Likelihood Estimation of Wake
Parameters ...................................... 57
5.2.3 Identification Model ............................ 58
5.2.4 Initialization of the Parameter Estimation
Procedure ....................................... 63
5.2.5 Plausibility Check .............................. 65
5.3 Wake Impact Alleviation Control ........................ 68
5.3.1 Initial WIAC Design ............................. 68
5.3.2 Interaction of WIAC with Basic Control System ... 71
5.3.3 Improved Combination of WIAC and Basic control
System .......................................... 76
5.3.4 Further Possible Improvements for the
Combination of Wake Impact Alleviation and
Basic Control System ............................ 83
6 Separate Performance Analysis of Wake Impact Alleviation
Control Module .............................................. 85
6.1 Analysis of WIAC Performance with Ideal Wake Vortex
Model .................................................. 85
6.1.1 Influence of Encounter Geometry ................. 88
6.1.2 Influence of Vortex Strength .................... 93
6.2 Sensitivity of Wake Impact Alleviation Performance
with respect to Wake Vortex Parameter Accuracy ......... 98
7 Wake Impact Alleviation Performance of Complete OWIDIA
System ..................................................... 105
7.1 Examplarily Wake Impact Alleviation Performance of
the OWIDIA System based on three Different Lidar
Sensors ............................................... 105
7.2 Performance Improvement by Increased Buffer Capacity .. 109
7.3 Sensitivity Study of Lidar Parameters ................. 111
7.4 Detailed Study of Selected Lidar Parameter Sets ....... 126
7.4.1 Assessment Methodology ......................... 126
7.4.2 Analysis of Selected Parameter Sets at
Different Encounter Altitudes .................. 130
7.4.3 Influence of an Increased Number of Vertical
Measurement Axes on the Alleviation
Performance .................................... 131
7.4.4 Influence of an Increased Vertical Field of
View of the Lidar on the Alleviation
Performance .................................... 135
7.4.5 Variation of Measurement Noise Level ........... 139
7.4.6 Variation of Encounter Geometry ................ 143
7.5 Application to LES Vortices ........................... 147
7.6 Estimation of Possible Reduction of Separation
Minima ................................................ 153
8 Summary and Outlook ........................................ 157
8.1 Summary ............................................... 157
8.2 Outlook ............................................... 162
References ................................................. 165
A Wake-Vortex-Based Separation Minima ........................ 176
В Modeling of Measurement Volume of Doppler Lidar Sensor ..... 180
С Analytical Wake Vortex Models .............................. 181
D Transformation between Wake Vortex Parameters used within
Parameter Estimation Process and in WIAC Module ............ 182
E Wake Impact Alleviation without Actuatator Dynamics and
Limits ..................................................... 184
F Characteristics of Sensor Configurations of Section 7.1 .... 185
G Models for Wake Identification of Deformed Wake Vortices ... 186
G.l Model of Curved Wake Vortices ......................... 186
G.2 Model of Vortex Rings ................................. 188
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