Phase-resolved chemiluminescence of an acoustically forced jet flame at frequencies <60 Hz

Abstract

-The California Institute of Technology's Combustion Acoustics Facility is used to measure the response of a partially premixed jet flame to acoustic forcing at frequencies ranging from 22 Hz to 55 Hz. The facility generates bulk acoustic modes that simulate unstable combustor conditions. This same facility and burner has been previously used to measure the phase-resolved response of the OH PLIF field. In this experiment, phase-resolved chemiluminescence measurements are recorded and analyzed. Flame base oscillations are quantified and compared for two different burner configurations. The chemiluminescence also shows that frequencies that exhibit stronger acoustic coupling to the flame tend to have decreased luminosity in the flame stabilization zone, while frequencies with weaker coupling tend to produce greater luminosity at the base of the flame.

Flame Response to Equivalence Ratio Fluctuations — Relationship between Chemiluminescence and Heat Release

“…(25) (26) Note that, for a chosen fuel and fixed operating conditions, the sensitivities, s L1 and h R1 are functions of the mean equivalence ratio alone and vary spatially due to the spatial variations in the mean equivalence ratio. However, these sensitivities change with preheat temperature, pressure, and other variables.…”