Laminar Flame Speeds of Hydrocarbons with Helium Dilution at Raised Pressures and Temperatures

Difficulties with flame stability arise when hydrocarbon fuels are burned with air at elevated pressures. The use of helium dilution abates these instabilities to allow the measurement of flame speeds at these elevated pressures. This study inspects the effects of said helium dilution at elevated temperatures and pressures to construct a reliable database for hydrocarbon mixtures at these conditions and to validate a chemical kinetics model. Seven different fuel and oxidizer mixtures were studied at 5 atm and 473 K including pure methane and both 80/20 and 60/40 blends of each methane/propane and methane/ethane. The model accurately predicts the flame speed data at each condition with high accuracy. Furthermore, the Lewis numbers and Markstein lengths explain the stable flames seen in this study.