Accession Number : ADA107590


Title :   Modeling of Ceiling Fire Spread and Thermal Radiation.


Descriptive Note : Final rept. 25 May 79-Mar 81,


Corporate Author : FACTORY MUTUAL RESEARCH CORP NORWOOD MASS


Personal Author(s) : Alpert,R L ; Mathews,M K ; Modak,A T


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a107590.pdf


Report Date : Oct 1981


Pagination or Media Count : 105


Abstract : The pressure modeling technique is used to study fire spread under five different ceiling materials and analytical and numerical techniques are used to compute thermal radiation to floor level from the resultant layer of hot gases near the ceiling. In the physical modeling part of the study, measurements are obtained at one atmosphere (full-scale) and at elevated air pressure characterizing fire growth in a ceiling channel exposed to a developing PMMA wall fire. Pressure modeling predictions of flame spread rates under a PMMA ceiling and flame lengths under an inert ceiling are found to be in reasonable agreement with full-scale behavior. Although fire spread under aircraft material ceilings occurs only at elevated pressure and not at one atmosphere (due to charring effects and the use of full-scale material thickness in the models), exponential growth factors characterizing fire spread rates, mass loss rates and radiant heat loss in the model tests are used to group the five ceiling materials according to fire growth hazard. In the second phase of the study, an exact, numerical solution technique is formulated for computing the radiant flux from hot gas layers with arbitrary, three-dimensional variations in gas temperature and absorption coefficient. A simplified analytic approximation involving the use of a suitably averaged gas temperature and absorption coefficient is compared with the exact technique for the calculation of radiant flux to targets below the ceiling gas layer. It is found that the analytic approximation is adequate even when the gradients in temperature are much larger than those expected from real aircraft cabin fires. (Author)


Descriptors :   *MODELS , *FLAME PROPAGATION , *AIRCRAFT FIRES , *THERMAL RADIATION , PREDICTIONS , PHYSICAL PROPERTIES , RATES , GASES , NUMERICAL METHODS AND PROCEDURES , AIR PRESSURE , ABSORPTION COEFFICIENTS , CEILING , RADIANT HEATING , AIRCRAFT CABINS


Subject Categories : Aircraft
      Safety Engineering
      Combustion and Ignition


Distribution Statement : APPROVED FOR PUBLIC RELEASE