Numerical Simulation of Downward Flame Propagation in Discontinuous Region of Solid Fuel

This paper presents a numerical model that investigates the characteristics of flow, heat, and mass transfer on downward flame propagation in the discontinuous region of solid fuel. Simulations were carried out for various discontinuous distances to analyze the morphology of the flame front and the competition between the "jump" of flame spread and heat transfer from the flame to the unburned area. The results demonstrate that there is a "jump" in the flame propagation in the discontinuous zone, with the flame front exhibiting a defined "acute angle" that undergoes a process from large to small during the flame spreading in the discontinuous area and deflects towards the discontinuous area of the material. The temperature in the discontinuous zone reaches a peak, and the average flame spread rate initially increases and then decreases with the increase of discontinuity distance until the flame spread stops. The study provides valuable insights into the growth and development of fires involving discretely distributed combustible materials.