Pressure Effects on the Turbulent Consumption Speeds of High H₂ Mixtures Available to Purchase

This paper describes measurements and correlations of turbulent consumption speeds, S_T,GC, of hydrogen/carbon monoxide (H₂/CO) fuel mixtures, with a focus on recently acquired elevated pressure data. Turbulent consumption speed data were obtained at mean flow velocities and turbulence intensities of 30 < U₀ < 50 m/s and 5 < u′_rms/S_L,0 < 30, respectively, for H₂/CO mixtures ranging from 30–90% H₂ by volume at 5 and 10 atm. Experiments were conducted where the mixture equivalence ratio, ϕ was adjusted at each fuel composition to have nominally the same un-stretched laminar flame speed, S_L,0. In comparing two blends with the same composition, S_L,0 value, and flow conditions, the 5 and 10 atm data have S_T,GC values that are consistently about 1.8 and 2.2 times larger than the 1 atm data, respectively. These data are also correlated with a scaling law derived from quasi-steady leading points concepts using detailed kinetics calculations of highly stretched flames. For a given pressure, these scalings do an excellent job in scaling data obtained across the H₂/CO fuel composition and fuel/air range. However, the pressure sensitivities are not captured by this scaling. This pressure sensitivity may be more fundamentally a reflection of the non-quasi-steady nature of the flame leading points. In support of this argument, we show that the spread in the data can largely be correlated with the ratio of a chemical time scale to a flow time scale.