Session: 04-36: Combustion Dynamics - Spray Flames

Paper Number: 103105

103105 - Flame Dynamics of Rich and Lean Kerosene Flames in the Primary Zone of an Air-Staged Combustion Test-Rig 

In this study the thermoacoustic behavior of non-premixed kerosene flames from rich to lean combustion conditions is investigated. Flame transfer functions measured purely acoustically are compared against results based on flame chemiluminescence. OH*, CH*, C₂* and CO₂* were selected as potential measures for representing steady and fluctuating heat release when burning non-premixed kerosene. In addition, their ability for the quantification of equivalence ratio fluctuations will be highlighted. The measurements were performed in the primary zone of an atmospheric RQL (rich-quench-lean) combustion test-rig. The new experimental approach allows an independent characterization of the primary zone from the secondary zone. Rich and lean operating points were analyzed by fueling an aero-engine prototype injector with and without acoustic excitation. To improve the quality of the acoustic wavefield reconstruction a thermocouple correction method was implemented. The resulting flame dynamics exhibit a frequency and equivalence ratio depending effect for rich combustion conditions using the multimicrophone method. The results for the steady behavior of the chosen radicals by altering equivalence ratio and thermal power indicate proportionality of the chemiluminescence to thermal power. Furthermore, the CH*/C₂* ratio is found to be a promising indicator for the global equivalence ratio in the combustion chamber. The flame transfer functions based on chemiluminescence show a good qualitative agreement with the multimicrophone method. Based on the experimental findings a calibration curve for the different radicals to obtain quantitatively correct flame transfer functions concludes the study.

Presenting Author: Martin March Technical University of Munich

Presenting Author Biography: Master Degree with distinction in Mechanical Engineering from the Technical University of Graz, Austria
Ph.D. Student at the Chair of Thermodynamics, Technical University of Munich, Germany
Research project on combustion instabilities in aero-engines with air-staging (RQL)

Authors:

Martin March Technical University of Munich
Julian Renner Technical University of Munich
Thomas Sattelmayer Technical University of Munich