LES and experimental studies of cold and reacting flow in a swirled partially premixed burner with and without fuel modulation

In devices where air and fuel are injected separately, combustion processes are influenced by oscillations of the air flow rate but may also be sensitive to fluctuations of the fuel flow rate entering the chamber. This paper describes a joint experimental and numerical study of the mechanisms controlling the response of a swirled complex-geometry combustor burning natural gas and air. The flow is first characterized without combustion and LDV results are compared to large eddy simulation (LES) data. The nonpulsated reacting regime is then studied and characterized in terms of the heat release field. Finally the fuel flow rate is pulsated at several amplitudes and the response of the chamber is analyzed using phase-locked averaging and acoustic analysis. Results show that LES and acoustic analysis predict the flame dynamics in this complex configuration with accuracy when heat losses (radiation and convection) are accounted for. (c) 2007 The Combustion Institute. Published by Elsevier Inc. All rights reserved.