Comparison of the Flow Field of a Swirl Stabilised Premixed Burner in an Annular and a Single Burner Combustion Chamber

An experimental investigation of the flow field of a 12 burner annular combustor and a single burner combustor with the same burner was performed. It has revealed the aerodynamic effect which causes the discrepancies in the flame transfer function behavior measured at the same operating conditions in the single and the annular combustion chambers. The results have shown significant differences in the flow field. In particular it is seen that for the investigated system in the annular combustor a free swirling jet flow forms while in the single burner configuration a swirling wall jet flow regime exists. In this paper we discuss the physical mechanism and show how to generalize an earlier finding which identified a critical confinement value for a given swirler. We propose a new correlation for co-swirling burners which explains the changes found for the investigated system. It compares also well with experimental data from other burner geometries. The correlation should allow to design single burner tests as to match the annular combustor flow regime.