Article Dans Une Revue Journal of Engineering for Gas Turbines and Power Année : 2025

Thermo-Acoustic Instabilities and Shape Bifurcations of a Pilot-Only Spray Flame in a Staged Burner

Résumé

Abstract Aircraft engine manufacturers develop new combustion technologies to comply with stricter regulations on pollutant emissions, such as nitrous oxides or soot. Staged systems coupled with lean premixed combustion show promising prospects to reduce these emissions through correct mixing of the fuel ahead of the combustion chamber, but are more prone to thermo-acoustic instabilities. Hence, guaranteeing the stability over the entire operating range is more challenging. The thermo-acoustic behavior of lean staged systems is investigated experimentally on the laboratory-scale BIMER combustor, an atmospheric pressure test rig composed of a two-stage swirled injector reminiscent of industrial systems and fueled with liquid dodecane. It uses a simplex atomizer in the pilot stage, multipoint injection in the main stage, and can be externally forced using a siren device located upstream of the injector. This study focuses on the thermo-acoustic behavior of the pilot stage of the BIMER combustor. Flame response to acoustic perturbations at different preheating temperatures (ranging from 383 to 473 K) is assessed. To this end, flame describing functions (FDF) are measured using acoustic forcing, a photomultiplier with an OH* filter for heat release rate fluctuation measurements and the multimicrophone method to determine acoustic velocity fluctuations. An acoustic network model of the combustor using the L-ζ model for the injector is used to compute acoustic velocity fluctuations at the base of the flame. This model is parameterized using only the burner geometrical configuration, with no tuning to fit reference experimental data. The accuracy of the model prediction is discussed. Measurements also display flame shape bifurcations from V to Tulip-shape flames generated by acoustic forcing at certain frequencies and amplitudes. High-speed imaging of flame chemiluminescence in the visible range is used to describe these bifurcations. The role of acoustic forcing is highlighted through phase-averaging.

Dates et versions

hal-05403270 , version 1 (08-12-2025)

Identifiants

Citer

Quentin Buisson, Antoine Renaud, Laurent Zimmer, Guillaume Fournier, Abel Faure-Beaulieu, et al.. Thermo-Acoustic Instabilities and Shape Bifurcations of a Pilot-Only Spray Flame in a Staged Burner. Journal of Engineering for Gas Turbines and Power, 2025, 147 (12), ⟨10.1115/1.4069464⟩. ⟨hal-05403270⟩
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