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Kinematic coupling effects on heat-release transfer function of a premixed flame
Published in American Institute of Aeronautics and Astronautics Inc.
Volume: 21
Issue: 4
Pages: 591 - 599
The effect of acoustic excitation on the heat-release characteristics of a two-dimensional premixed flame is studied. Past researchers have assumed that the acoustic nearfleld and kinematics of the flame surface are un-coupled. However, recent studies by the authors have shown that the acoustic nearfleld is significantly affected by flame-surface wrinkling and hence the coupling between flame-surface kinematics and the acoustic field cannot be neglected. The acoustic-velocity nearfield of the flame surface is determined by using a boundary integral equation (BIE) modified to include the effects of flame-front wrinkling on the acoustic field. A linearized G equation is solved to obtain an expression for the flame-surface wrinkling in terms of the acoustic velocity at the flame front. This equation is then solved simultaneously with the BIE by using a Newton-Raphson scheme to obtain simultaneously the flame-surface shape and the acoustic-velocity variation for the case of a two-dimensional dump-stabilized flame. The results show that the transfer function is controlled by two parameters, the flame Strouhal number and the half-angle at the apex of the flame, θ. The computed transfer function is compared with the transfer functions from two other models. The first model assumes a one-dimesional variation of acoustic velocity along the axial direction. The second model assumes a two-dimensional acoustic-velocity field while neglecting kinematic coupling. The inclusion of kinematic coupling leads to the prediction of a different value of the magnitude of the transfer function at low frequencies. This difference in predicted magnitudes depends on the excitation velocity amplitude. The predicted magnitudes increase with decrease in θ. The predicted phase is observed to be insensitive to changes in θ. Kinematic coupling also results in the reduction of the predicted spatial variation of the magnitude of the normalized acoustic velocity along the flame.
About the journal
JournalData powered by TypesetJournal of Propulsion and Power
PublisherData powered by TypesetAmerican Institute of Aeronautics and Astronautics Inc.
Impact Factor1.868
Open AccessNo
Citation Styleunsrt
Sherpa RoMEO Archiving PolicyGreen
Concepts (11)
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    Perturbation techniques
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    Transfer functions
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    Premixed flame
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