Opposed Flow Flame Spread over Degrading Combustible Solids

ABSTRACT

A macroscopic model of opposed flame spread based on the SIMPLE algorithm was examined. Features of flames spreading over thick degrading combustible materials were described utilizing the moving boundary method. Numerical predictions of flame spread speed showed good agreement with the experimental data. Comparisons were made, for flame spread over thermally thick samples of PMMA for several flow velocities, with numerical predictions for the primitive quantities temperature, velocity field, and surface regression. Quantities derived from primitive variables included the mass flux, the surface heat flux and the heat loss from the solid. The velocity gradient in the airflow boundary layer and the temperature gradient in the solid interior were examined. Other quantities also examined were the wall heat flux and the burning rate of the regressing pyrolyzing surface along with their relation to the rate of supply of oxidizer (air).

KEYWORDS:

• Opposed flow
• flame spread
• degrading solids
• surface regression
• heat and mass transfer
• numerical simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was supported by Sun Yat-sen University and Michigan State University and also by the Chinese National Science Foundation [grant number 51606226]; Guangdong Natural Science Foundation [grant number 2016A030313347]; and the Guangdong Provincial Key Laboratory of Fire Science and Technology [grant number 2014B030301034].