Propellant dark zone concentrations via multichannel ir absorption

A multichannel infrared absorption technique has been developed and applied to the study of steadystate, self-sustained combustion of solid propellant flames at elevated pressure. An infrared light source. windowed pressure chamber, and spectrometer-diode array detector formed the basic experimental setup with which in situ absorption measurements were made. Spectra were obtained over the wavenumber range of 2300 to 6000 cm−1. Within this range, absorptions for HCN, H2O, N2O, CO, CO2, and CH4 have been detected through the use of a 1024-element platinum silicide array detector with the ability to read complete spectra in 10 ms. Experimental dark zone results for a nitramine, propellant (XM39) and a double-base-like propellant (JA2) have been obtained, and these absorption spectra analyzed with a full spectrum, multivariate, nonlinear, least-squares-fitting pe program that makes use of the HITRAN data base for the required molecular information. In some cases, the absorption spectra of the molecule had sufficient detail and fidelity to allow determination of both temperature and absolute concentration. This occurred for HCN and H2O in XM 39 propellant and for H2O and CO in JA2 propellant. Dark zone temperatures (1185 K for XM39 and 1433 K for JA2) obtained in this fashion are in good agreement with reported values. All six of the species were found in XM39, and absolute concentration or upper limits are given. No evidence of HCN or N2O absorption was observed in the dark zone of JA2, thus, four dark zone species concentrations are reported for this propellant. Comparisons of species concentration and dark zone temperature measurements are made with other published measurements under conditions of steady-state. self-sustained propellant combustion.