- Author
-
Shaddix, C. R.
- Title
- Development of Diode Laser Diagnostics for Soot and Species Measurements in Fires. BFRL Fire Research Seminar. VHS Video.
- Coporate
- Sandia National Labs., Livermore, CA
- Report
-
Video
December 13, 1999
- Keywords
-
soot
|
lasers
- Abstract
- Visible and near-infrared diode laser sources are well-suited to a variety of diagnostic or sensor applications in harsh industrial environments and in fire research, due to their ready-coupling to inexpensive, transmissive fiber-optic cabling. Unfortunately, weak molecular absorptions in this spectral region, coupled with reduced gas densities and further weakened transitions at high temperatures, make detection and quantification of species concentrations very difficult in fire environments. Over the past two years, we have endeavored to develop a diode-laser-based system to measure major gas-phase species concentrations, together with soot concentration and temperature, in order to evaluate mixing phenomena, gas-phase radiation interactions, and soot formation and oxidation chemistry in large pool fires. An initial suite of candidate species for detection has been selected and important high-temperature spectral information has been obtained, allowing the selection of the best spectral locations for their detection. In addition, a high-speed, sensitive technique for simultaneously measuring the concentrations of several different species has been developed and demonstrated. Finally, an open-architecture, multipass probe design has been developed to improve the measurement sensitivity over small physic al pathlengths. This probe design has been evaluated for beam-steering and attenuation effects in unsteady, buoyant diffusion flames. Preparations are under way for initial field testing of this system in 2-m JP8 pool fires at Sandia's FLAME facility in Albuquerque.