Issue |
La Houille Blanche
Number 8, Décembre 2001
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Page(s) | 11 - 15 | |
DOI | https://doi.org/10.1051/lhb/2001083 | |
Published online | 01 July 2009 |
Dynamique des interactions acoustique-combustion
Dynamics of interactions between acoustics and combustion
Abstract
The work presented in this document belongs to a set of studies concerning the prediction of acoustic instabilities in real combustion systems. The dynamic response of a laminar conical flame to modulations of the fresh gases is first determined. A theoretical modeling of the transfer function between heat release fluctuations and acoustic modulations is derived in an axisymmetrical configuration. An experimental study is performed and measurements are compared with modeling, in order to determine the model limitations. This model is then adapted to the two-dimensional case. The flame transfer function is compared with numerical simulations of acoustic-flame interactions. It is also possible to use the resonance properties of the burner cylindrical cavity, in order to generate strong interactions between acoustic waves, the flow and the flame. The first longitudinal eigenmode is used. Its frequency is around 900 Hz. Acoustic levels are very high and this configuration leads to a strong coupling between acoustics and combustion and to a severe modification of the mean velocity field. The stability domain of the flame from is also studied. Premixed flames with large curvature effects can be obtained using a conical flame submitted to peculiar low-frequency acoustic modulations. Curvature modifies laminar flame behavior. This fundamental problem has immediate practical interests. This situation makes it possible to study the Markstein length, which describe the flame response to stretch effects.
© Société Hydrotechnique de France, 2001