Numerical Simulation of the Dynamics of Turbulent Swirling Flames

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Identification of Flame Transfer Functions using LES/SI To analyze the dynamics of the flames by the different thermal conditions at the combustor wall, a harmonic excitation at 100 Hz for both thermal conditions is carried out. The flame response for the harmonic excitation is also in good agreement in amplitude and phase with the one obtained using system identification as shown in Fig. 5.24. The flame response for both cases in a complete cycle of the heat release fluctuation is illustrated in Fig. 5.25. For the V-flame, the perturbations travel along the flame and at the moment of maximum heat release (in (b)), the flame is elongated along the combustor walls, creating an increase of flame surface area. In (c), the flame tip is rolled up by the vortices produced at the burner exit [11, 44, 136], followed by a reduction on the flame surface in (d). Additionally, the flame tip in (d) falls in the outer recirculation zone due to the roll-up, inducing some reaction in the outer shear layer. Strong flame-wall interaction is observed during all the sequence. For the M-flame, the interaction with the wall is small, but strong interaction between flames in the inner and outer shear layer is observed. In (b), the flame is elongated and the flames in the inner and outer shear layer get closer to each other, creating annihilation between them. The same effect was shown in laminar flames by Schuller et al. [180] and Durox et al. [44]. In (c) and (d), the continuous reduction of flame surface is observed including annihilation between flames. Additionally, in both cases, the flame angle is also modified not only by the unsteady flapping behavior of flame, but also by the presence of swirl number fluctuations [78, 103, 137, 141]. These sequences showed the different flame dynamics between both flame topologies, leading to different flame transfer functions. 5.5 Influence of Swirler Position on the Flame Transfer Function Komarek and Polifke [103, 104] carried out an experimental and RANS-based study showing the impact of swirler position on the FTF. Their investigations are extended in this work to a LES context. Investigations are carried out for two varied positions of the swirler: One with the swirler at 30 mm upstream the burner exit (position 1), and the other with the swirler at 130 mm upstream the 94
5.5 Influence of Swirler Position on the Flame Transfer Function Figure 5.25: Instantaneous reaction rate for one cycle of a harmonic excitation at 100 Hz using adiabatic and nonadiabatic combustor walls with 30 kW. Excitation=9.5% U . 95
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Technische Universität München In
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gas turbine combustion during my in
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Zusammenfassung Die Dynamik von per
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CONTENTS 3.3.3 Influence of Swirler
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CONTENTS A.7.4 Inlet . . . . . . .
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LIST OF FIGURES 3.2 Scheme of deter
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LIST OF FIGURES 5.21 Instantaneous
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LIST OF FIGURES 5.47 FTFs from expe
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List of Tables 2.1 LES Combustion M
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Nomenclature R i j Two-point veloci
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Nomenclature M MF O prop r stoich S
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xxiv Nomenclature
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Introduction Figure 1.1: Left: Worl
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Introduction Figure 1.4: Illustrati
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Introduction fluctuations of the he
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Introduction tor walls, increasing
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Turbulent Reacting Flows Figure 2.1
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Turbulent Reacting Flows time scale
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Turbulent Reacting Flows instantane
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Turbulent Reacting Flows as the pro
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Turbulent Reacting Flows where s L
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Turbulent Reacting Flows 2.4.2 Fund
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Turbulent Reacting Flows 2.4.2.1 Mo
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Turbulent Reacting Flows Some of th
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Turbulent Reacting Flows Table 2.1:
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Turbulent Reacting Flows port equat
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3 Response of Premixed Flames to Ve
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Response of Premixed Flames to Velo
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Page 68 and 69: Response of Premixed Flames to Velo
Page 76 and 77: System Identification put, the heat
Page 78 and 79: System Identification Figure 4.2: U
Page 80 and 81: System Identification 4.2 The Wiene
Page 82 and 83: System Identification Figure 4.3: S
Page 84 and 85: System Identification 4.3 The LES/S
Page 86 and 87: System Identification A flow chart
Page 88 and 89: Identification of Flame Transfer Fu
Page 146 and 147: 6 Stability Analysis with Low-Order
Page 148 and 149: Stability Analysis with Low-Order N
Page 160 and 161: Summary and Conclusions series gene
Page 162 and 163: Summary and Conclusions • The ide
Page 164 and 165: Outlook tion. The system identifica
Page 166 and 167: BIBLIOGRAPHY [8] H. Büchner, C. Hi
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BIBLIOGRAPHY [28] P.J. Colucci, F.A
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BIBLIOGRAPHY [48] D. Fanaca. Influe
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BIBLIOGRAPHY [65] M. Germano, U. Pi
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BIBLIOGRAPHY [83] A. Huber. Impact
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BIBLIOGRAPHY [102] T. Komarek. Priv
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BIBLIOGRAPHY [122] L. Ljung. System
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BIBLIOGRAPHY [141] P. Palies, T. Sc
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BIBLIOGRAPHY [163] S.B. Pope. Compu
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BIBLIOGRAPHY [183] F. Selimefendigi
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BIBLIOGRAPHY [200] L. Tay Wo Chong,
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BIBLIOGRAPHY [223] B.T. Zinn and T.
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Appendices Figure A.1: Evaluation o
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Appendices Table A.1: One Step Reac
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Appendices and isotropic, the energ
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Appendices Figure A.2: DRBS Input s
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Appendices (a) The flow is homentro
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Appendices ends of the duct, the fo
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Appendices Figure A.6: Scheme for f
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Appendices Expressing Eqs. (A.59) a
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Appendices Figure A.7: Scattering M
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Appendices ping [45] is used. The i
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Appendices 4. Load in TECPLOT only
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Numerical Simulation of the Dynamics of Turbulent Swirling Flames

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