Numerical Modeling of Flame Shedding and Extinction behind a Falling Thermoplastic Drip

Caiyi Xiong, Xinyan Huang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

The dripping of molten thermoplastics is a widely observed phenomenon in cable and façade fire, where the large drips can often carry a blue chain flame during the free fall to ignite other flammable materials and escalate the fire hazard. This work simulated the flame evolution behind a falling thermoplastic drip with the DNS model and finite-rate flame chemistry. The accelerated free-fall of drip was modeled by fixing the position of drip, increasing the upward airflow, and setting a fuel jet on the top of the drip. Modeling reproduces the dripping flame and reveals the flame shedding to be a combination of a lifted flame and a vortex street, where the lifted flame caused by the gravity acceleration of drip is identified as the critical factor that governs the shedding formation. As the diameter of drip decreases, the falling drip becomes difficult in forming a stable shedding structure in the wake region, so that the dripping extinction occurs due to the dilution and cooling of airflow, agreeing well with the experimental observation. This work reveals the underlying mechanism of stabilizing the dripping flame and helps evaluate the fire risk and hazard of dripping phenomena.

Original languageEnglish
Pages (from-to)745-758
Number of pages14
JournalFlow, Turbulence and Combustion
Volume107
Issue number3
DOIs
Publication statusPublished - 27 Feb 2021

Keywords

  • DNS
  • Dripping flame
  • Extinction
  • Flame shedding
  • Moving fuel

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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