Laminar flame speeds of natural gas blends with hydrogen at elevated pressures and temperatures

Recently there has been a push for more fuel flexibility in gas turbine engines. Designers need base-line data, such as laminar flame speed, to effectively design said engines. Engineers also need these data at a variety of conditions such as elevated pressures and temperatures. This study examined the effect of fuel blending as well as initial conditions on laminar flame speed. Natural gas-based fuels that contain high hydrogen content have recently become of interest in the gas turbine industry. This study examined flame speed data resultant from a blending of natural gas and hydrogen at various initial conditions. A parametric sweep of equivalence ratios, 0.7- 1.3, was conducted at each condition. The hydrogen content was varied from 50-90%. The initial temperature and pressure were also varied from 300-450 K and 1-5 atm, respectively. Experiments conducted above atmospheric pressure utilized a 1:6 oxygen-to-helium ratio to curb the hydrodynamic and thermal instabilities that arise when conducting laminar flame speed experiments. A heated, constant-volume combustion vessel was utilized to experimentally determine flame speed. The experimentally determined flame speeds were also compared to the latest AramcoMech chemical kinetics models. These chemical kinetics models are being developed by Curran and coworkers at National University of Ireland Galway. The experimental data matches well with the calculated flame speed from the mechanism. The discrepancies between the model and experimental data can be mostly justified when taking into account the uncertainty of the experimental flame speed.