Diffusion-flame dynamics in von Karman boundary layers

Experimental and theoretical results are reported for fiat diffusion flames adjacent to a spinning fuel disk in on oxidizing atmosphere. Disk-shaped f lames are observed. the radii of which increase or decrease with time, depe nding on whether an appropriate Damkohler number is large or small. Experim entally, initially large flame disks expand at sufficiently high Damkohler numbers, while at sufficiently small Damkohler numbers, initially small fla me disks contract, as predicted by theory. A stability map is derived theor etically in a plane of the Damkohler number and the flame-disk radius norma lized by a diffusion length scale, showing regimes of disk growth and shrin kage. (C) 2001 by The Combustion Institute.