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Numerical Study of Opposed-Flow Flame Spread Over Charring Solids.


pdf icon Numerical Study of Opposed-Flow Flame Spread Over Charring Solids. (312 K)
Park, W. C.; Atreya, A.; Baum, H. R.

E1 - Fire Research/Paper E03;

Combustion Institute/Western States, Central States and Eastern States. Fourth (4th) Joint Meeting of the U.S. Sections. Hosted by The Eastern States Section of the Combustion Institute and Drexel University. E1 - Fire Research/Paper E03. March 20-23, 2005, Philadelphia, PA, 1-6 pp, 2005.

Keywords:

combustion; solids; charring; flame spread; equations; thermal decomposition; kinetics; temperature; pressure; temperature distribution

Abstract:

Numerical calculations were performed on thermal decomposition of charring solids undergoing opposed-flow flame spread and the results are compared with analytical models developed by Baum and Atreya. The objective was to understand the effect of finite rate kinetics on the temperature and pressure inside the solid. The analytical solution, while exact, assumes infinite kinetics, i.e. abrupt decomposition at a known pyrolysis temperature. The numerical results using finite and infinite rate kinetics showed good agreements with the analytical model in terms of char depth and temperature distribution. For the solution of the pressure equation, numerical results showed good agreements with analytical gas transport model from surface to char/virgin solid interface. However, the numerical result using finite kinetics implies that pressurized region in real situation is larger than that of infinite kinetics assumption. Numerical analysis using infinite kinetics showed pressure fluctuation due to lack of the information of the interface shape inside a cell.