Spatially Resolved Combustion Species and Temperatures of Solid Propellant Flames Using Snapshot Spectroscopy

Report No. ARL-TR-2060
Authors: Homan, Barrie E.; Vanderhoff, John A.
Date/Pages: October 1999; 32 pages
Abstract: Experimental improvements have been made in the ultraviolet (UV)- visible absorption spectroscopy technique applied to propellant flame diagnostics. The two-dimensional (2-D) feature of an intensified charge-coupled device (ICCD) detector was used to simultaneously record multiple, spatially distinct absorption spectra over a region of 0.35 cm. Temporal resolution has been increased to 1 ms by pulsing a simmering xenon arc lamp. The resulting increase in the light intensity by 30 to 70 times over the nonpulsed output provides the necessary light flux to achieve single-pulse, multiple absorption spectra. Species with low concentrations can be measured with the inclusion of multiple-pass optics to increase the effective path length through the combustion region. Due to broadband UV-visible absorption observed in propellant flame spectra, only 20% of the incident light is typically transmitted. However, inclusion of a calibrated neutral density filter during the measurement of the incident intensity (I sub 0) allows the dynamic range of the detector to be effectively increased by a factor of 5. With these improvements, temperature and OH and NO concentration maps, with 1-ms temporal resolution, have been determined for two different propellant flames.
Distribution: Approved for public release
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Last Update / Reviewed: October 1, 1999