- Author
- Butler, G. | Carrier, G. | Fendell, F.
- Title
- Modeling of Wind-Aided Flame Spread. Final Report. September 21, 1982 to April 30, 1985.
- Coporate
- TRW Space and Technology Lab., Redondo Beach, CA
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
- TRW-39641-6001-UT-00, 1985, 53 p.
- Contract
- NB-825BCA1662
- Keywords
- soot | ceilings | char
- Abstract
- A fundamental engineering approach to the theoretical modeling of wind-aided flame spread across a polymeric ceiling in a structure is undertaken. Three areas are identified that require significant progress before qualitative prediction of spread rate (and detailed description of the spread mechanism) can be expected, and advances are attempted in each of these three areas. First, a tractable but physically adequate formation for a thin char layer between the gas phase and the still-intact interior of the ceiling slab is required. It is proposed that the char layer be treated as a porous carbonaceous matrix, formed on the lower-temperature boundary contiguous to the interior (by a sublimation-like endothermic interfacial process), and eroded at the other higher-temperature boundary contiguous to the gas phase by any of serveral possible interfacial mechanisms. Second, a capacity to estimate the amount of soot formed, and the amount of soot oxidated, in connection with the gas-phase diffusion flame is required to account for radiative transfer of heat. It is proposed that a semiempirical approach to interpret results from a particular sequence of experiments, carried out with the counterflow geometry, could yield in the near term the information required to incorporate soot-associated radiative transfer. Third, and efficient means of integrating the nonlinear parabolic boundary-/initial-/eigen-value problem in two spatial dimesions and time is required to permit adequate parametric investigation. Because it is not clear that a previously implemented integral-equation-type approach to the unconventional Stefan-type problem is amenable to tractable generalization, a direct numerical approach using implicit finite-difference methods is undertaken and results are reported.