In the episode 10 of fire fundamentals together with David Morrisset, a nearly graduated PhD student from the University of Edinburgh, we explore the intricate dynamics of flame spread and its crucial role in fire safety engineering. David helps us differentiate between the two primary modes of flame spread, concurrent (imagine upward spread) and opposed (imagine downward spread), and explains how understanding these mechanisms can significantly enhance building safety and fire risk mitigation.

In this episode, we take a closer look at various materials like PMMA and timber and their unique fire behaviors. We also examine the complexities of flame spread on charring solids such as timber, discussing how pyrolysis and the resulting char layer influence heat transfer and flame behavior.

Lastly, we dissect the heat transfer mechanisms in various materials, from foams to solid slabs, and how factors like orientation and material properties affect flame spread rates. David highlights the balance between gas phase and solid phase heat transfer and the importance of precise modeling to predict flame behaviors accurately.

Phemonena discussed here:

• flame spread definition
• concurrent vs opposed flame spread
• regimes of flame spread
• driving mechanisms of flame spread

Further reading:

• Quantifying the controlling mechanisms of opposed flow flame spread: Influence of orientation, material, and external heating
• Characterization of Flame Spread Over PMMA Using a Temperature Reconstruction Method
• The relative position of pyrolysis onset and flame front location for downward flame spread

And even though we did not have time to discuss diagnostics in the episode, you can check this crazy paper of David:

• Assessment and application of phosphor thermometry for spatially resolved surface temperature measurements during downward flame spread

Cover image: edited from Figure 1 in https://doi.org/10.1016/j.firesaf.2023.104048

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