title: Laser-induced incandescence measurements of soot in turbulent pool fires.
abstract: We present what we believe to be the first application of the laser-induced incandescence (LII) technique to large-scale fire testing. The construction of an LII instrument for fire measurements is presented in detail. Soot volume fraction imaging from 2 m diameter pool fires burning blended toluene/methanol liquid fuels is demonstrated along with a detailed report of measurement uncertainty in the challenging pool fire environment. Our LII instrument relies upon remotely located laser, optical, and detection systems and the insertion of water-cooled, fiber-bundle-coupled collection optics into the fire plume. Calibration of the instrument was performed using an ethylene/air laminar diffusion flame produced by a Santoro-type burner, which allowed for the extraction of absolute soot volume fractions from the LII images. Single-laser-shot two-dimensional images of the soot layer structure are presented with very high volumetric spatial resolution of the order of 10(-5) cm3. Probability density functions of the soot volume fraction fluctuations are constructed from the large LII image ensembles. The results illustrate a highly intermittent soot fluctuation field with potentially large macroscale soot structures and clipped soot probability densities.
authors.affiliation: Engineering Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: Kraig
authors.initials: K
authors.lastname: Frederickson
authors.forename: Sean P
authors.initials: SP
authors.lastname: Kearney
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Grasser
mesh_terms: D000465:Algorithms; D004784:Environmental Monitoring / Q000379:methods*; D005390:Fires; D007834:Lasers; D008163:Luminescent Measurements / Q000379:methods*; D017711:Nonlinear Dynamics; D010783:Photometry / Q000379:methods*; D053260:Soot / Q000032:analysis*; D014867:Water
chemical_list: D053260:Soot; D014867:Water