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Accueil du site > Thèmes de recherche > Combustion & systèmes réactifs > 1.5 Dynamique des flammes laminaires & turbulentes > 1.5.3 Turbulent flames

1.5.3 Turbulent flames Non-premixed turbulent flames
Turbulent hydrogen – air non premixed flames (or hydrogen enriched methane – air flames) are of interest because of their lowest risk potential in burners or gas turbines, compared to premixed hydrogen mixtures. An experimental study has been conducted on the characterisation of high pressure H2/air and H2 enriched methane – air flames in the framework of a joint PhD with the Polytecnico di Milano (TH1). A specific burner has been developed for this purpose and adapted to the ICARE high pressure turbulent combustion facility. The role of pressure and hydrogen enrichment rate has been identified on flame dynamics and sooting characteristics. These flames have also been studied numerically using the FLUENT code with adapted mixing and turbulence models and chemical kinetics for the studied flames (ACL, 116, 130). Premixed turbulent flames
During the last years, research at ICARE on turbulent premixed flames has concentrated on the structure and dynamics of high pressure methane-air flames, either enriched by hydrogen or diluted by CO2. The high pressure turbulent combustion facility of ICARE has been used for this purpose together with relevant diagnostics such as LDV and PIV and laser induced Mie and Rayleigh scattering techniques. For H2 enriched flames, the increase of the flame surface density both by the increase of pressure and the enrichment rate has been demonstrated and analysed using several turbulent combustion models (ACTN1, COM22, ACL118, ACL119, ACL125, ACL129). For CO2 diluted flames, the pressure effect remained the same, but the detailed structure of the flame was found insensitive to the dilution rate, except of course the reduction of the laminar flame propagation velocity and the ensuing reduction of the global combustion rate (TH6 ; ACTI27, ACL128). These studies were mainly conducted in the framework of the FP5 project AFTUR (2003-2008) and the PIE CNRS project HyTAG (2005-2007), both coordinated by ICARE. This research axis is presently continuing namely in the context of turbulent syngas – air flames studies and by using biplanar laser induced Rayleigh scattering technique in order to resolve the 3D effects when determining the instantaneous flame front thicknesses.