Abstract

Absorption spectroscopy has been used to characterize the steady-state flame structure of solid propellants burning over a pressure range of 0.3 to 2.0 MPa. A high-intensity-xenon-arc-lamp light source and two spectrometer-intensified photodiode-array detectors formed the experimental setup from which NO and OH absorption spectra were acquired. Vibrationally resolved transitions in the A²Σ - X²Π (0,1) 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 A² Σ - X² Π (0,0) vibrational band system of OH from306to311nm comprise the absorption spectra from which luminous-flame temperatures are determined. These spectra can be least-squares fitted with respect to a variety of parameters, which include an instrument response function, an absorption baseline, as well as the temperature and concentration. Several different propellants that exhibit a dark zone have been studied as a function of pressure. The dark-zone temperatures ranged from 1300 K to 1500 K, and NO concentrations varied from 13 to 30 mole percent, depending on the propellant type and pressure. Temperatures in the luminous flame region reached adiabatic values.

© 1992 Optical Society of America