Investigation of oxy-fuel flame structure by laser diagnostics

The PhD project is a part of the BIGCO2 project coordinated by SINTEF Energy Research. The focus of this project is to study oxy-fuel flames whose reactants are methane and O2/CO2 mixtures, under standard conditions. The investigation will allow identifyi ng the difference with conventional air supported combustion, and highlight the influence of turbulence-chemistry interactions at various levels of local temperature induced by the atmosphere composition. Different oxidizer mixtures are tested to study the dynamic and chemical structure of the flames burning in a varying composition O2/CO2 atmospheres. The range of oxygen percentage within the oxidizer is from 20% to 100%. The focus is set only on the flame itself in O2 excess conditions. The temperatur e field, the turbulent velocity field and the chemical species at different locations within the turbulent, non-premixed, axisymmetrical flame are to study. This is performed by using laser diagnostics, especially Laser Raman scattering and Laser Doppler Velocimetry. A potential issue during such measurements is that the local soot concentration present in O2 enriched combustion is quite high. One of the challenges will be the alteration of the Raman signal directly due to the presence of soot. This top ic is currently investigated by Robert Barlow from Sandia National Laboratories, California. His purpose is to set up a process to withdraw the signal emitted by soot particles from the signal collected to obtain a clear Raman signal. A stay at Sandia Nat ional Laboratories during the second year of the PhD is planned to familiarize with this process and to then apply it to the experimental results. The measurements obtained will provide an experimental data library in standard conditions, most useful for the validation of combustion, turbulent, and kinetic models, still to be tested in oxy-fuel configurations.