Effects of Hydrogen Power Ratio on Combustion Oscillation Characteristics of Hydrogen-Enriched Methane

In order to explore the impact of hydrogen-rich methane on combustion oscillations in engineering applications，experimental research was carried out around the centrally-staged flame of hydrogen-rich methane on the BASIS burner. The effects of main stage equivalent ratio，pilot stage equivalent ratio，and the hydrogen power ratio of main stage on combustion oscillation are conducted and analyzed. In this study，the air flow of pilot stage is 2g/s and that of main stage is 10g/s. 128 groups of tests under 24 working conditions are carried out with three major varying parameters：equivalence ratio of main stage，equivalence ratio of pilot stage and hydrogen power ratio. The pressure fluctuation is measured and analysed combining with the flame macrostructure. It is found that under most of the equivalence ratio conditions，hydrogen-enriched flame occurs in the same thermos-acoustic mode，and the flame stratification is obvious with no combustion instability. When main=0.6 and 0.55，the pulsation amplitude of hydrogen rich methane flame increases first and then decreases with the increase of hydrogen power ratio. Combustion oscillation occurs under 42% and 32% working conditions respectively. When main=0.5，combustion oscillation occurs only under high pilot and high hydrogen power ratio，and combustion oscillation occurs only under 7% working conditions. In order to achieve higher carbon reduction ratio，the combus-tor should be carried out under very lean combustion conditions of the main and pilot stage to avoid strong combustion instabilities. And in some working conditions，adding hydrogen can weaken the intensity of thermoacous-tic oscillation. © 2023 Journal of Propulsion Technology. All rights reserved.