Control of intrinsic thermoacoustic instabilities using hydrogen fuel

A conceptual numerical study was carried out to explore a possible strategy for control of unstable intrinsic thermoacoustic (ITA) modes. Addition of hydrogen fuel was proposed as a means of control. The effect of incremental addition to the fuel mixture on the stability of a laminar slit flame was investigated using various approaches. First, the ITA frequencies were estimated by a chemical kinetics solver for hydrogen fuel content up to 50% of the total fuel mass flow. Second, DNS was performed for each case and the Flame Transfer Function (FTF) was computed, from which the ITA mode frequencies and their stability can be estimated. Additionally, for each case the unstable flame was computed to confirm the estimated ITA mode frequencies. Third, an acoustic network model was utilized, which uses the FTF and predicts the stability limits observed by the DNS. Comparison with DNS data showed very good agreement and allowed to model the impact of hydrogen on the stability of the combustor.