Experimental Investigation of Spherical-flame Acceleration in Lean Hydrogen-air Mixtures

Large-scale experiments examining spherical-flame acceleration in lean hydrogen-air mixtures were performed in a 64 m3 constant-pressure enclosure. Equivalence ratios ranging from 0.33 to 0.57 were examined using detailed front tracking for flame diameters up to 1.2 m through the use of a Background Oriented Schlieren (BOS) technique. From these measurements, the critical radii for onset of instability for these mixtures, on the order of 2–3 cm, were obtained. In addition, the laminar burning velocity and rate of flame acceleration as a function of radius were also measured.