Flame Flashback Within Turbulent Streams of Lean Homogeneous Fuel Mixtures and Air

The flame flashback limit represents the minimum concentration of the fuel in the stream of homogeneous mixtures of fuel and air at which a flame can propagate upstream against the direction of the flow. Information about these limits is important in the assessment of the safety of operation in situations where a flowing homogeneous fuel-air mixture is present. The present work examines the flame flashback in turbulent homogeneous fuel-air streams with Reynolds number up to 16,000. The flashback limits were established for a number of common gaseous fuels, such as methane, propane, hydrogen, ethylene, and their binary mixtures. Taking into consideration the wide use of low heating value fuels, the effect of the presence of diluents (nitrogen and carbon dioxide) in the fuel on the flashback limit was also investigated. Correlations were proposed to calculate the flashback limits of fuel mixtures and their accuracy is discussed.