Session: 04-24 Combustion Dynamics - Flame Response

Paper Number: 152124

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

Aircraft engine manufacturers develop new combustion technologies to comply with stricter regulations on pollutant emissions such as nitrous oxides (NOx) or soots. 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 behaviour of staged lean 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 fuelled with liquid dodecane. It uses a simplex atomizer as the pilot stage, multipoint injection as the main stage and can be externally forced using a siren device located upstream of the injector. The complex flame dynamics of this system includes multi-stability, hysteresis phenomena and thermo-acoustic instabilities.

 

This study focuses on the thermo-acoustic behaviour of the pilot stage of the BIMER combustor. Flame response to acoustic perturbations at different pre-heating temperatures (ranging from 383 to 473K) is first assessed. Flame Describing Functions (FDF) are then measured using acoustic forcing, a photomultiplier with an OH* filter for heat release rate measurements and the multi-microphone method to measure acoustic velocity fluctuations. Measurements display flame shape bifurcations from V to Tulip-shape flames generated by forcing at certain frequencies and amplitudes. High-speed imaging of flame chemiluminescence is used to describe these bifurcations and the role of acoustic forcing through advanced post-processing such as phase-averaging and Dynamic Mode Decomposition (DMD).

Presenting Author: Quentin Buisson EM2C Laboratory

Presenting Author Biography: My name is Quentin Buisson. I'm a PhD student working on the thermo-acoustic behaviour of liquid-fuelled flames at EM2C laboratory in CentraleSupélec and Safran Aircraft Engines in France.

Authors:

Quentin Buisson EM2C Laboratory
Antoine Renaud EM2C Laboratory
Laurent Zimmer EM2C Laboratory
Guillaume J. J. Fournier Safran Tech
Abel Faure-Beaulieu Safran Aircraft Engines
Yoann Méry Safran Aircraft Engines
Sébastien Ducruix EM2C Laboratory