Subsurface Flows Preceding Flame Spread Over a Liquid Fuel

Abstract

Liquid fuel flows below a two-dimensional flame spreading at a steady rate are examined. Captured convection eddies develop, and their structure in terms of streamline and temperature fields is obtained by numerically solving the energy and vorticity transport equations. Surface tension and buoyancy effects are considered. Results are presented for given values of the surface tension parameter (S = –12,500) and the Prandtl number (Pr = 10). A range of Reynolds numbers (50 to 400) and Grashof numbers (0, 10⁴, 10⁵, 10⁶) is explored. The reverse surface velocity induced by the flame appears to be of the same order as observed flame spread rates regardless of the Reynolds number. This lends support to the contention that convection eddies may control the rate of flame spread.