Effect of sprays of water and NaCl-water solution on the extinction of laminar premixed methane-air counterflow flames

The response of laminar premixed fuel-lean methane-air counterflow flames to the combined effects of stretch and cooling by a fine spray of water and NaCl-water as well as surfactant-water solution is studied experimentally. Results show that flame extinction is promoted both by increased flame stretch and by a higher concentration of liquid. An unexpected finding is that at a given concentration an NaCl-water solution is significantly more effective than pure water in causing flame extinction. On the other hand, at the concentration studied, results from a spray of water containing a surfactant (Synperonic PE/L62) are indistinguishable from those with pure water.