FLAME STRETCH MEASUREMENTS DURING THE INTERACTION OF PREMIXED FLAMES AND KARMAN VORTEX STREETS USING PIV

Flame stretch measurements in a premixed, lean methane-air, V-flame in teracting with a Karman vortex street have been made using a particle image velocimeter. The flame curvature and strain rate along the flame have been measured over the range of -2.0-1.0 mm(-1) and -175-175 s(- 1), respectively, which corresponds to a range of flame stretch from - 475-200 s(-1). Results indicate that the curvature and strain rate are statistically independent. Flame stretch statistics based on individu al flames are also considered since each flame represents a particular phase within the regular and periodic interaction cycle studied. Thes e results indicate that for a particular flame the average stretch rat e becomes independent of the average flame strain rate. A comparison a mong PIV measurements, OH planar laser-induced fluorescence (OH-PLIF) measurements, and numerical simulation reveals similar flame stretch s tatistics. Qualitative measurements concerning flame shape and the rel ative location of vortices within the reactant flow are also discussed .