Various flame tracking techniques are often used in hydrodynamic simulations. Their use is indispensable when resolving actual scale of the flame is impossible. We show that parameters defining “artificial flame” propagation found from model systems may yield flame velocities several times distinct from the required ones, due to matter expansion being ignored in the models. Integral effect of m...

The propagation speed of a thin premixed flame disturbed by an unsteady fluid flow of a larger scale is considered. The flame may also have a general shape but the reaction zone is assumed to be thin compared to the flame thickness. Unlike in preceding publications, the presented asymptotic analysis is performed for a general, multi-step reaction mechanism and, at the same time, the flame front...

In this paper, we study the performance of a testing apparatus that could be used for evaluating the effectiveness of gaseous suppressants and solid fuel retardants under opposed flame spread conditions. A narrow channel, 3 mm in height, 110 mm in width and 375 mm in length, constitutes the most important component of this apparatus. To establish the flow and flame spread parameters in this app...

The characteristics of triple flames in a hydrogen–air mixing layer are studied using direct numerical simulation with detailed chemistry. Triple flames are initiated by imposing a temperature ignition source in the center of a scalar mixing layer of nonuniform thickness, thereby forming a pair of freely propagating triple flames. Two different fuel streams are studied: pure hydrogen and hydrog...

Mechanisms for flame retardation are reviewed and general principles developed. Approaches for utilizing flame retardants in various systems are discussed. Structure and flammability relationships are developed. Recent developments in flame retardants are presented. Market forecasts and directions are reviewed.

Since most of the practical combustion devices operate in turbulent environments, study of turbulent combustion is fundamentally appealing and practically important. Turbulence enhances the flame propagation by wrinkling an otherwise laminar smooth flame, leading to an increase in the flame surface area and hence the total burning rate. There have been number of studies performed to achieve a s...

The effect of gravity and thermal expansion on the propagation of a triple flame in a horizontal channel. Combustion and Flame Submitted (2013). [3] Al-Malki, F and Daou, J. Triple-flame propagation against a Poiseuille flow in a channel with porous walls. Submitted (2013). [4] Daou, J. Strained premixed flames: effect of heat-loss, preferential diffusion, and the reversibility of the chemical ...

A simplified model describing acoustically-generated parametric instability in a spherical chamber is developed for quasi-one-dimensional, low-Mach flames. We demonstrate how sound waves generated by a centrally-ignited, outwardly-propagating accelerating flamefront can be incorporated into a theory of self-similar flame acceleration in free space developed previously. Being reflected from the ...

An experimental and computational investigation on the liftoff characteristics of laminar partially premixed flames (PPFs) under normal (1-g) and microgravity (μ-g) conditions is presented. Lifted methane–air PPFs were established in axisymmetric coflowing jets using nitrogen dilution and various levels of partial premixing. The μ-g experiments were conducted in the 2.2-s drop tower at the NASA...