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Reconstruction of OH* for direct comparison between measurements and simulations in H2/air flames

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Required Education : Master or Engineering school
Start date : 1 February 2023
Mission duration : 6 montths
Deadline for applications : 31 December 2022
Salary : 650 euros/mois

Context

Hydrogen is seen as a promising fuel to decarbonize industrial processes and most specifically combustion processes. But burning H2 raises several technological and scientific challenges due to the specific features of the H2 molecule with respect to standard hydrocarbon fuels. Indeed, H2 flames are barely visible with human eyes compared to hydrocarbon fueled flames [3], but their strong OH* natural emission in the UV band around 310 nm is easily detectable by many optical devices (cameras and photomultipliers adapted to UV collection) already available in industry. This makes OH* an ideal candidate to deduce information on the combustion state and locate H2/air flame region in a combustor. However the exact relation between OH*emission intensity and other flame quantities is not established. This relation is even more difficult to interpret in laminar flows when the reactants are not fully premixed and/or for real-like systems operating at high turbulence levels or elevated pressures. In addition OH* – being an excited state of OH – is usually not computed in numerical simulations, preventing from direct comparison with measurements.

The TOHREAU (Simulation of OH* light emission from H2/air flames in real burners) project supported by the French National Research Agency (ANR, 2022-2026) gathers 3 laboratories expert in chemistry, diagnostics and simulations (IMFT, ICARE and CERFACS) to experimentally and numerically investigate the OH* signal in order to better understand H2/Air laminar and turbulent flame structures in academic test-rigs. This internship is part of the TOHREAU project, and a PhD position will be open on this topic to be started Fall 2023.

Internship program

Hence, the goal of this internship will be to propose a methodology to numerically simulate the OH* signal in practical hydrogen/air burners experimentally measured by IMFT and ICARE within the TOHREAU project. First, canonical H2/air flame simulations (fully premixed and diffusion) will be carried out using the open-source chemical kinetics software CANTERA and existing detailed H2/air chemistry from the litterature including OH* sub-mechanism to investigate the link between heat release rate and OH*. Then, the in-house reduction code ARCANE co-developed with Cornell University will be used to produce a reduced H2/air chemistry including OH* compatible with CFD. Finally, Direct Numerical Simulation (DNS) of laminar H2/air M- and V-flames measured at IMFT will be carried out using AVBP, the combustion code developed at CERFACS, to analyse flame/turbulence interactions.

The internship program is hereafter detailed:

  • Bibliography study and training on numerical combustion, CANTERA and AVBP.
  • 1D simulations in CANTERA of premixed and diffusion H2/Air flames using detailed chemical mechanisms and including OH* sub-mechanism. Validation with measurements found in literature. Study of the link between OH* and heat release rate.
  • Derivation and validation of a reduced chemical mechanism to be used for CFD using ARCANE (https://chemistry.cerfacs.fr/en/arcane/).
  • DNS with AVBP (https://www.cerfacs.fr/avbp7x/) of laminar H2/air M- and V-flames.

Contacts: