Radiative heat feedback in a toluene pool fire

Abstract

A purged radiometer was used to measure directional heat flux incident on the fuel surface in a 30 cm diameter toluene fire. A new approximate method for the treatment of the effects of turbulence on radiation was evaluated using these data. The average emissive power and the average transmittance are the two local properties needed for the approximate method. These quantities were obtained from transient local measurements of temperatures and soot volume fractions based on emission at two wavelengths. Soot volume fractions based on absorption were also measured for comparison. The results showed that a large fraction of the soot particles observed by the absorption probe were at relatively low temperatures. The predictions of directional heat fluxes showed systematic errors with angle when compared to measurements. These errors are related to the absorption of energy by fuel vapor in the central core and the higher spatial resolution needed in the necking-in region of the fire. The directional total flux data and predictions were integrated to obtain total radiative heat feedback to the surface. Comparisons between measurements and predictions of total heat flux were reasonably good.