A new method of analysis

Abstract

Absorption spectroscopy has been used to characterize the steady-state flame structure of solid propellants over a pressure range of 0.3 to 2.0 MPa. An arc-lamp light source and two spectrometer-intensified photodiode-array detectors formed the basic experimental setup from which NO and OH absorption spectra were acquired. Vibrationally resolved transitions in the A2Σ-X2II electronic system of NO from 230 to 250 nm comprise the absorption spectra from which temperatures and absolute NO concentrations are determined in the dark-zone region of the solid-propellant flames and rotationally resolved transitions in the A2Σ-X2II (0,0) vibrational band system of OH from 306 to 311 nm comprise the absorption spectra from which limunous-flame temperatures are determined. Both NO and OH are sufficiently well characterized that the spectra can be least-sequeres fitted with respect to a variety of parameters which include an instrument response function, an absorption baseline, a wave-length nonlinearity as well as the temperature and concentration. Three different propellants (JA-2, M9, and HMX2) that exhibit a dark zone have been studied as a function of pressure. The dark-zone temperatures ranged from about 1300 K to 1500 K and NO concentrations varied from 13 to 30 mole per cent depending on the propellant type and pressure. Temperatures in the luminous flame region reached values in agreement with the computed equilibrium, adiabatic flame temperatures.