Axisymmetric flame spread across propanol pools in normal and zero gravities

Axisymmetric ignition and dame propagation across propanol pools is investi gated numerically with finite-rate one-step chemical kinetics, variable pro perties, and an adaptive finite-difference gridding scheme without forced g as-phase flow. Propanol fuel is allowed to evaporate into the air after filling the fuel t ray and before the igniter is activated. The propanol vapor profile in the gas phase is examined numerically as a function of time. At 1-g(0), a stead y fuel vapor-concentration boundary layer is established in the gas phase 5 s after filling a fuel tray. Conversely, at 1-g(0), the profile of fuel va por concentration is always unsteady and keeps growing in the gas phase as time elapses. Axisymmetric flame spread over a shallow circular pool is examined as a fun ction of oxygen concentration. The flame spread rate at 1-g(0) is comparabl e to but lower than that at 0-g(0) for chi(O2),(infinity) greater than or e qual to 21% and T-0 = 22.1 degrees C with Delta t(PI) = 5 s, where Delta t( PI) denotes the time lapse between filling the fuel tray and activating the igniter. As the oxygen concentration is reduced to 17.5% with the same Del ta t(PI) the dame at 1-g(0) pulsates whereas the flame at 0-g(0) extinguish es. At 1-g(0), the flame spread rate does not change for Delta t(PI) greate r than or equal to 5 s; on the other hand, at 0-g(0), the flame spread rate increases as Delta t(PI) is increased. Flame propagation is also examined as a function of initial pool temperatur e T-0 both for axisymmetric and two-dimensional configurations with pool de pth 2 mm in normal gravity. For the uniform spread regime, flame spread rat e in the axisymmetric configuration is nearly identical to that in the two- dimensional configuration except for a short initial time. For the nonunifo rm (or pulsating) spread regime, flame spread in the axisymmetric configura tion is quite different from flame spread in the two-dimensional configurat ion. The axisymmetric flame spreads very slowly without pulsation for some initial time depending on T-0 and then either spreads with pulsations or re mains stationary as long as the igniter is activated.