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Modeling of the Flame/inhibiting particles interaction

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Required Education : Master ou école d'ingénieur
Start date : 1 March 2023
Mission duration : 6 mois
Deadline for applications : 15 January 2023
Salary : 650 euros/mois

Context:

Until the 1970s, industrial safety processes relied heavily on chlorofluorocarbon gases as fire suppressants in ground, sea and air systems. Since then, the threat to Earth's ozone of such gases has been established and their production prohibited. Following this ban, intensive research has been conducted to find efficient halon replacements. Alkali metal compounds, such as (IHCO3)s and(I2CO3)s with I = {K, Na}, have received considerable attention because of their higher effectiveness per mass basis compared to the halon 1301 (CF3Br). The flame inhibition (flame speed reduction) and flame suppression abilities of these products have been shown experimentally, which led to their wide commercial use as chemical fire suppressants. Recently, their suitability for gas explosion mitigation was also demonstrated.

The efficiency of these inhibiting powders depends strongly on the capacity of the alkali metal particles to decompose inside the flame front. Even though the overall thermal decomposition mechanism is well documented in the literature, little is known about the parameters controlling the time/length scales associated to the thermal decomposition and its intermediate steps. The objectives of this internship are two-fold: (1) to improve the current modeling and understanding of this thermal decomposition step, based on recent investigations [1,2,3]  on the flame/inhibitor interaction problem at CERFACS and available experimental data in the literature; (2) evaluate the effectiveness of these inhibitors on highly reactive mixtures like H2/air.

Mission:

The internship will go through the following steps:

  • Literature review on experimental data on the decomposition of inhibiting particles;
  • Development of a thermal decompostion model for the inhibitors in CANTERA(Open-source chemistry code: cantera.org) and AVBP(CFD code developed at CERFACS: https://www.cerfacs.fr/avbp7x/);
  • Validation on flame/inhibitor interaction cases in canonical setups;
  • Demonstration test case: deflagration in obstructed/smooth channel with presence of inhibitors.

References:

  • [1] O. Dounia, O. Vermorel, T. Poinsot, Theoretical analysis and simulation of methane/air flame inhibition by sodium bicarbonate particles, Combust and Flame 193 (2018);
  • [2] O. Dounia, O. Vermorel, T. Jaravel, T. Poinsot, Time scale analysis of the homogeneous flame inhibition by alkali metals, Proceedings of the Combustion Institute 38 (2021);
  • [3] O. Dounia, O. Vermorel, T. Jaravel, On the controlling parameters of the thermal decomposition of inhibiting particles: A theoretical and numerical study, Combust and Flame 240 (2022).

Contacts: