Flame Spectra of a Turbulent Liquid-Fueled Swirl-Stabilized LDI Combustor

Abstract

of the air flow rate, the equivalence ratio, preheat temperature, and pressure. Procedures for determination of the instantaneous heat release rate and the instantaneous equivalence ratio along the flame front are developed. For both combustion instability and forced flame responses, the errors between measurements and estimation are within 2.0% for the mean heat release rate, the mean air consumption rate, and the mean equivalence ratio. The assumption that chemiluminescence is proportional to the instantaneous heat releaser rate is generally invalid. Probably the proportionality is valid only in the weakly turbulent or wrinkled flamelet region in the absence of equivalence ratio variations and strong acoustic oscillations. For forced flame responses under fuel modulations, the gain difference between the heat release rate and CH * chemiluminescence can be more than 20%, and the phase difference can be more than 90 o above 400 Hz. For self-excited combustion instability, the phase difference can be more than 10 o , while the gain difference can be up to 20%. Nomenclature