Study on the influence of restricted distance on fixed-width discrete of discontinuous flame spread

Abstract

This study investigates the impact of varying distances between vertical walls on the propagation of discrete flames in PMMA (Polymethyl Methacrylate) slabs. The primary objective is to analyze the dynamics of flame spread in confined spaces, with a particular focus on how the spacing between vertical walls and the number of PMMA slabs influence flame characteristics. Experimentally, flame spread rate, mass loss rate, heat release rate, and pyrolysis front dynamics are examined under different confined space distances ranging from 1 to 5 cm using thermally thick PMMA slabs. The findings reveal a significant influence of confined space distance on flame propagation. In narrower spaces (1 to 2 cm), a stack effect leads to a rapid increase in flame height and mass loss rate. As the confined distance increases, this effect gradually diminishes, resulting in a decrease in flame height and mass loss rate. Additionally, the flame spread rate initially rises with increasing confined distance, reaching a peak at 2 cm, before decreasing. Through the application of the law of conservation of energy, the dominant mechanisms of flame spread are deeply analyzed under various confined space conditions. These insights are crucial for understanding and predicting fire spread in confined spaces.