목차

Abstract i
Table of contents iv
List of tables ⅵii
List of figures ix
Nomenclature xv
Chapter 1 Introduction 1
1.1. Objects and Goals 1
1.2. The combustion instability evaluation 2
1.3. The stabilization of the laminar diffusion flame 3
1.4. Application of dynamic mode decomposition (DMD) in dynamical system analysis 4
1.5. Determine the triggering time of combustion instability 5
1.6. Organization of the thesis 5
Chapter 2 Numerical and experimental study of vortex formation near the nozzle of laminar jet diffusion flame 8
2.1. Background 8
2.2. Introduction 9
2.3. Experiment and numerical simulation 12
2.4. Results and discussions 17
2.4.1 Effect of fuel density 17
2.4.2 Effect of jet velocity 20
2.4.3 Effect of coflow air velocity 21
2.4.4 Effect of fuel inlet temperature 24
2.4.5 Effect of flame temperature 26
2.4.6 Effect of nozzle diameter 27
2.5. Validation of the hypothesized physical mechanism 29
2.6. Conclusions 31
Chapter 3 Improvement on the accuracy of dynamic mode decomposition method for combustion instability analysis 33
3.1. Background 33
3.2. Introduction 34
3.3. Methodology 36
3.3.1. The methodology of the CDMD method 36
3.3.1.1 Algorithm 36
3.3.1.2 Model reconstruction 40
3.3.2 The methodology of the HDMD method 43
3.3.2.1 Initialization 43
3.3.2.2 The HDMD algorithm 44
3.4. Application and results 46
3.4.1 CFD model for DMD analysis 46
3.4.2 DMD accuracy evaluation 48
3.4.3 Comparison of DMD results between CDMD and HDMD 52
3.4.4 Comparison of mode shapes between CDMD and HDMD method 52
3.5. Conclusions 59
Chapter 4 Combination of post-processing tools for analysis of combustion instability in a combustor 61
4.1. Introduction 61
4.2. Methodology 64
4.2.1. DMD method 64
4.2.2. Short Time Fourier Transform (STFT) method 65
4.2.2.1. Introduction of STFT method 65
4.2.2.2. Application of window in STFT method 68
4.2.2.3. Effect of window functions on the STFT result 71
4.2.2.4. Function of overlapping data in STFT method 77
4.2.2.5. Function of window length in STFT method 78
4.2.2.6. Optimization of window length in STFT method 79
4.2.3. Recurrence theory for synchronization analysis of coupled oscillators 80
4.3. Application and results 82
4.3.1. Computational model of model chamber 82
4.3.2. DMD, STFT and RP analysis for model chamber 83
4.4. Conclusions 92
Chapter 5 Conclusions 94
Chapter 6 References 97
Chapter 7 Abstract (in Korean) 107
Chapter 8 Acknowledgement 110