Phase-resolved no planar laser-induced fluorescence of a jet flame in an acoustic chamber with excitation at frequencies <60 Hz

The California Institute of Technologys Combustion Acoustics Facility is used to measure the changes in the creation of NO in a partially premixed jet flame due to acoustic forcing at frequencies ranging from 22 to 55 Hz. The facility generates bulk acoustic modes that simulate unstable combustor conditions in the absence of velocity fluctuations. This facility and a similar burner have been previously used to measure the phase-resolved response of the OH field. In this experiment, phase-resolved NO planar laser-induced fluorescence measurements are recorded. The location and phase coupling of the NO field are analyzed, and the production and transport of NO are compared with previously reported OH field measurements. The NO levels increase for frequencies that exhibit stronger acoustic coupling to the flame. The NO concentration variations with the phase of the chamber pressure lead the OH field variations. This is probably a result of the greater NO sensitivity to temperature.