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PhD Position Available at the University of Poitiers and University of Maryland


  PhD Research Project

Modeling of finite rate chemistry effects in the combustion of solid fuels relevant to fire safety problems

Points of contact:

–‐          Prof.  Thomas  Rogaume,  Franck  Richard,  Jocelyn  Luche,  Department  Fluides,  Thermique,Combustion, Institut Pprime (UPR 3346 CNRS), University of Poitiers, Isae–‐ENSMA, Poitiers, FRANCE.

–‐          Prof.  Arnaud  Trouvé,  Department  of  Fire  Protection  Engineering,  University  of  Maryland,College Park, USA.

Email : thomas.rogaume@univ–‐poitiers.fr, atrouve@umd.edu

Location : the PhD position will take place both in France and the USA : 18 months at the University of Maryland, USA, and 18 months at Institut Pprime, FRANCE.

Background :

Fire safety engineering makes extensive use of CFD–‐based simulation software, for instance the Fire Dynamics Simulator (FDS) and FireFOAM. CFD–‐based fire models provide a description of the thermal decomposition  of  solid  fuels,  of  the  turbulent  flow,  mixing  and  combustion  processes,  and  the resulting convective and radiative heat transfer that control flame spread and fire growth. In FDS and FireFOAM, the thermal decomposition of solid fuels is typically described using simplified single–‐step chemistry models and the combustion is described assuming fast equilibrium chemistry. The present project is aimed at bringing more detailed information on solid decomposition chemistry and gas–‐ phase combustion chemistry into  CFD–‐based  fire  models.  Detailed  information  on  chemistry  is required for a description of ignition and extinction phenomena as well as a description of soot formation and the emission of toxic products.

The proposed work will take place in a succession of four major phases:

 ·             Phase  1  will  focus  on  the  combustion  chemistry  of  fuel–‐air  mixtures  characterized  by different fuels and different fuel–‐air ratio conditions, ranging from well-ventilated to under-ventilated.  The  selected  fuels  will  be  representative  of  the  pyrolyzate  gas  produced  by thermally–‐degrading solid materials. The combustion conditions will vary from fast to slow chemistry. A finite rate, detailed chemical kinetic model taken from the literature will be selected and implemented into the CFD fire model FireFOAM. Phase 1 will take place at the University of Maryland during months 1–‐10 of the PhD project.

 ·              The  detailed  chemical  kinetic  model  selected  in  phase  1  will  then  be  evaluated  by comparison with experiments performed in a controlled atmosphere cone calorimeter. The cone calorimeter will be instrumented with a flame imaging system, thermocouples and gas analysis.  The experiments  will  use  wood.  The  experimental  campaign  will  be  aimed  at characterizing the gas–‐phase combustion and emission processes as a function of radiant loading and oxidizer composition. Phase 2 will take place at Institut Pprime during months 11–‐22 of the PhD project.

 ·              The comparison between experimental data and FireFOAM results obtained with a detailed chemical kinetic model performed in phase 2 will then provide the basis for developing a reduced (skeletal) kinetic model adapted to a CFD–‐based description of combustion of the pyrolyzate   gas   produced   by   thermally–‐degrading   wood   materials   in   configurations representative of fire problems. Phase 3 will take place at Institut Pprime during months 23–‐ 28 of the PhD project.

 ·              In a final phase, the reduced kinetic model will be implemented into FireFOAM and tested. The series of test will focus on the ignition and extinction limits of combustion fueled by thermally–‐degrading solid materials. Phase 4 will take place at the University of Maryland during months 29–‐36 of the PhD project.

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