Fire Safety Science Digital Archive

Measurements are reported of the line of sight averaged soot volume fraction as a function of height within pool fire flames fueled by polystyrene (PS) and polymethylmethacryl ate (PMMA) No- lip pools with diameters of 7.5 cm and 15 cm were examined and compared with Markstein's result s at 31 cm and 73 cm. The multi-wave length laser transmission technique used has been previously described. PS and PMMA represent two distinct cases. For the optically thick PS the soot volume fraction, fv, appears to be independent of fuel scale at 3.3 ppm. For the optically thin PMMA, fv increases substantially with fuel scale from- 0.2 t o - 0.7 ppm. For both fuels, fV decreases only slightly with height and is well approximated as uniform throughout the flame. The correlation, fv/fvmax = 1.5 ( K L ) O * ~f o~r KL < 0.3 and = 1 for KL > 0.3, where KL is the flame optical thickness, is inferred from this scant data base. It may provide fv f o r any fuel at any scale as well as estimates o f the maximum possible conversion of fuel carbon to soot.