Control of Fluid Flow

front-matter......Page 1
Title page......Page 2
Copyright page......Page 3
Preface......Page 4
Acknowledgments......Page 5
Table of contents......Page 6
List of Symbols......Page 10
1 Introduction......Page 13
2 Weak Reverse-Flow Regions......Page 18
2.1.1 Separation Control Using Fluidic Forcing at High Frequencies......Page 19
2.1.2 Separation Control Using Fluidic Forcing at Low Frequencies......Page 23
2.1.3 Separation Control Using Mechanical Forcing at Low Frequencies......Page 25
2.2 Manipulation of Trailing Edge Separation on an HQ-17 Laminar Airfoil by Means of Two-Dimensional ZNMF-Actuators......Page 27
2.2.1 The Single Slot Configuration (xslot2/c = 0.66, b = 1.2mm)......Page 29
2.3 Manipulation of Closed Reverse-Flow Regions by Free-Stream Turbulence (FST)......Page 31
3 Strong Reverse-Flow Regions......Page 35
3.1 Manipulation of the Closed Reverse-Flow Region Downstream of a Fence......Page 36
3.2 Manipulation of Strong Reverse FlowCaused by a Trapped Vortex......Page 44
4 Conclusions......Page 51
References......Page 52
1 Introduction......Page 57
2 Experimental Apparatus and Procedure......Page 60
3 Modification of the Time-Averaged Aerodynamic Performance......Page 62
4 The Role of the Actuation Frequency......Page 65
5 Elements of the Dynamics of Flow Reattachment and Separation......Page 73
6 Pulse-Modulated Reattachment......Page 77
7 Conclusions......Page 82
References......Page 84
1 Introduction......Page 86
3 Passive Control Example: The Lobed Fuel Injector......Page 87
4 Active Control Methodologies......Page 91
5 Active Control Example: The Acoustically Resonant Dump Combustor......Page 95
6 Future Directions......Page 98
References......Page 101
1 Introduction......Page 106
2 Dynamic Models of Combustion Instability......Page 108
2.1 Linear Models......Page 109
2.2 Nonlinear Models of Combustion Oscillations......Page 112
2.3 Linear Models Using a System Identification Approach......Page 116
3 Control of Combustion Instability......Page 117
3.1 Linear Control......Page 119
3.1.1 Experimental Results......Page 120
3.2 Time-delay Control......Page 121
3.2.1 Simulation Results......Page 122
3.3.2 Adaptive Time-delay Control......Page 123
3.3.4 Extremum-seeking Control......Page 124
3.3.5 Observer-based Control......Page 125
3.4 Neural Control......Page 126
4 Summary......Page 127
References......Page 129
1 Introduction......Page 133
2 Control of Plane Waves in Ducts......Page 134
3 Controller Design and Implementation......Page 135
4 Control of Higher-order Modes in Ducts......Page 137
5 Control of Sound in Enclosures......Page 138
6 Control of Sound at Source......Page 141
7 Conclusions......Page 145
References......Page 146
1 Introduction......Page 148
2 The Acoustic Equation......Page 149
2.1.1 The Hamiltonian Flow Inside Ω......Page 152
2.1.2 Interaction with the Boundary......Page 153
3 Control and Observation......Page 154
4.1 Unstable Observations Estimates......Page 156
4.2 Propagation Along Rays and High Frequency Estimates......Page 158
5 Time Reversal Methods and Ergodicity......Page 160
References......Page 164
1 Introduction......Page 166
2 Problem Statement......Page 167
3 Boundary Feedback Laws......Page 169
4 The Result......Page 170
5 Proof of Theorem......Page 171
6 Numerical Simulation......Page 173
7 Simulations with Only Parts of the Wall Controlled......Page 176
References......Page 179
1 Introduction......Page 182
2 Exact Controllability from the Boundary of the Navier–Stokes System......Page 183
3.1 Formulation of the Problem......Page 185
3.2 Preliminaries......Page 187
4.1 Theorem on Extension......Page 190
4.3 Feedback Property......Page 191
5.1 Formulation of the Stabilization Problem......Page 192
5.2 Invariant Manifolds......Page 193
5.3 Final Results......Page 195
References......Page 196
1 Introduction......Page 198
2.1 Simple Vortical Configurations......Page 199
2.2 Vortex/Solid Body Interaction......Page 200
2.3 Control of the Wake Behind a Bluff Body......Page 201
2.4 Vortex Dynamics in Shear and Mixing Layers......Page 203
3 Towards Control of Vortex Merging......Page 204
4.1 Averaging for a Co-Rotating Vortex Pair......Page 205
4.2 Two Vortices Controlled by a Strain Field......Page 207
4.3 Two Vortices in a Source/Sink Field......Page 209
5 Control of a Pair of Vortex Patches......Page 211
5.1 Flat Coordinates......Page 212
5.2 Adiabatic Control......Page 214
Conclusions......Page 215
References......Page 216
1 Introduction......Page 222
2 Multi-Objective Optimization in Combustion Processes......Page 224
3 Cylinder Drag Minimization......Page 225
4 Aerodynamic Profile Design......Page 226
5 Micromixer......Page 229
6 Microchannel Flow......Page 230
7 Jet Mixing......Page 232
8 Aircraft Trailing Vortex Destruction
......Page 233
References......Page 235