The Effect of Chemical Kinetic Mechanisms on the Flame Transfer Function

Abstract

This paper reports the investigation of the effect of chemical kinetic mechanisms on the thermoacoustic behaviour of a premixed combustor test rig. This was done by exploring the flame transfer function (FTF) of three chemical kinetic mechanisms; a global (6 species, 2 reaction) mechanism, a reduced (19 species, 55 reaction) mechanism and a detailed (53 species, 325 reaction) mechanism. Chemistry was computed using a tabulated chemistry approach, and FTF’s were computed using a large eddy simulation (LES) along with a system identification method (SI). The LES results of each of the 3 chemical mechanisms were quite similar for mean results, but the dynamic (and hence thermoacoustic) results depended significantly on the chosen chemical mechanism. Despite this, the global and detailed mechanisms showed similar FTF results, which indicated that significant computational savings may be achieved in the pre-processing step of pre-tabulation provided that the global mechanism can compute the unit impulse response (UIR) with sufficient accuracy. These computational savings will allow rapid assessment and optimization of future clean energy systems.