Large eddy simulation calculated flame dynamics of one F-class gas turbine combustor

Abstract

Thermoacoustics in modern gas turbines is often accompanied by lean premixed combustion. A flame transfer function (FTF) is an important quantity for quantifying thermoacoustics. However, the FTF is often considered a black box and used in the final development phase. This study conducted principal component analysis (PCA) and dynamic mode decomposition (DMD), which are normally used in hydraulic instability analysis, to overcome the limitations of FTF. Results of the comparison of frequency response and mode shape indicated the flame was stable under the presence of coherent structures in the flow field. The transfer function (TF) between the first three modes and overall heat release rate was calculated to confirm the relationship between the mode shapes and FTF. Results indicated that the potential risk of pulsation originated from the flame itself rather than from flow instability. Additional tests should utilize a finite element method or perform a high-pressure test to calculate unstable operating points and obtain a definitive conclusion.