Soot formation and oxidation in technical relevant burner geometries

Abstract

Swirl-stabilized, non-premixed fuel/air flames were investigated at pressures up to 9 bar in order to provide validation data for numerical simulations and to contribute to a better understanding of soot formation and oxidation under gas turbine like conditions. The flames had a thermal power of up to 45 kW and were confined by a squared combustion chamber with quartz windows. Secondary air could be injected into the post-flame zone to study the influence of cooling air on the oxidation of soot. The good optical access to the flame enabled the application of optical and laser measuring techniques. Temperatures were measured by coherent anti-Stokes Raman scattering (CARS) and soot concentrations by 2D laser induced incandescence (LII). The influence of the flow field characteristics, known from previous measurements in similar configurations, on the soot distributions could be analysed. Furthermore, the effects of pressure, equivalence ratio and secondary oxidation air on the instantaneous and mean soot distributions were studied. Additionally, conventional probing techniques were applied on the axis of the combustor. All measurements were performed under well-defined and documented conditions, so that the data sets are suitable for the validation of numerical simulations.