Numerical study of the turbulent diffusion flame on the horizontal surface of PMMA

The development of new polymer materials with new properties (including reduced flammability) requires refined approaches to investigating their combustion behavior. A new algorithm was tested for calculating the parameters of the turbulent diffusion flame propagation over the PMMA (polymethylmethacrylate) horizontal surface. To solve the coupled problem, an algorithm was used combining the calculation of laminar flame characteristics with the use of a modified OpenFOAM package and the simulation of turbulent gas-phase combustion using FDS (Fire Dynamics Simulator). The computational domain was divided into two zones. The first was the near-wall zone (including the solid combustible material). In the zone, a coupled problem was solved for two-dimensional transport equations describing the laminar regime of the reacting gas-phase flow and heat transfer in the solid material. For solving the problem, the following parameters were used: elliptic formulations of conservation equations for both condensed and gaseous phases, finite-rate chemical kinetics, radiative heat transfer when necessary, and coupled thermal feedback between gas-phase reactions and solid decomposition. The second zone was the outer zone, where three-dimensional equations were solved to describe the turbulent transport and turbulent combustion using the LES method. The dimensions of the coupling interface zone were refined, the coupled problem was calculated using the proposed algorithm, and a comparison was made between the flame spread rates obtained by purely laminar calculations and by the coupled approach.