Numerical Study of the Turbulent Diffusion Flame on the PMMA Surface using FDS

Abstract

This study investigates the complex processes involved in the propagation of turbulent flames over solid combustible materials. Employing the Large Eddy Simulation (LES) technique within the Fire Dynamics Simulator (FDS), a detailed numerical investigation of flame structure and propagation were conducted. Obtained results reveal significant influences of turbulence on the flame's behavior, including fluctuations in temperature, velocity, and species concentrations. A notable finding of this study is the presence of a distinct laminar-like sublayer adjacent to the burning surface. This region exhibits significantly reduced turbulence intensity and is characterized by more stable temperature and species profiles compared to the fully turbulent regions of the flame. The coexistence of laminar and turbulent regimes within the flame has important implications for understanding flame spread rates and heat transfer mechanisms. Furthermore, our simulations highlight the role of buoyancy-driven flow in shaping the overall flame structure and propagation. The interaction between buoyancy forces and turbulent fluctuations leads to complex flow patterns and enhances mixing within the flame. Comparing our numerical results with experimental data, was demonstrated the ability of the LES model to accurately capture the essential features of turbulent flame spread. The findings of this study provide valuable insights into the underlying physics of turbulent flame spread. The detailed understanding of flame structure and propagation mechanisms gained from this work can be leveraged to develop more accurate and predictive models for fire safety engineering. Future research can focus on exploring the effects of different material properties, ambient conditions, and flame geometries on turbulent flame spread.