We present an asymptotic study of the effect of volumetric heat loss on the propagation of triple flames in a counterflow configuration at constant density. Analytical results for the speed, the local burning rate, the shape and the extent of the flame front are derived in the asymptotic limits of weak strain rates and large activation energies and for Lewis numbers that are near unity. The res...

A direct Path Flux Analysis (PFA) method for kinetic mechanism reduction is proposed and validated by using high temperature ignition, perfect stirred reactors, and steady and unsteady flame propagations of n-heptane and n-decane/air mixtures. The formation and consumption fluxes of each species at multiple reaction path generations are analyzed and used to identify the important reaction pathw...

The combination of in situ X-ray absorption spectroscopy, X-ray diffraction and on-line catalytic data provided insight into the structure-performance relationship of a flame-made Pd/ZrO(2) catalyst during the total oxidation of methane: upon heating, a sudden reduction accompanied by sintering of the Pd-particles, leads to a significantly lower catalytic activity and a hysteresis during coolin...

Nonpremixed jet flames of dimethyl ether (DME) were studied both experimentally and theoretically to investigate flame liftoff near unity Schmidt number. It was found experimentally that although the DME nonpremixed flames have a Schmidt number larger than unity it cannot be lifted directly by increasing the flow rate. Lifted flames can only be established by igniting the mixture in a narrow re...

A numerical study of the supercritical combustion of a liquid oxygen (LOX) droplet in a stagnant environment of hot hydrogen is carried out with a detailed chemistry model. Special attention is devoted to ignition process and diffusion flame structure. Ignition consists typically of the propagation of a premixed flame which is initiated in the H,-rich hot side. Propagation takes place in a nonh...

Please cite this article in press as: L. Qiao, Com A detailed numerical study was conducted to understand the transient flame propagation process and the flame-speed oscillation phenomenon in a carbon dust cloud. The modeling included the solution of a set of time-dependent conservation equations developed for the gas phase and the particle phase in a spherical coordinate. The gas-phase reactio...

In this paper, the implication of various grades of hydrogen rich gas on the in-cylinder flame speed, and on the knock propensity, are discussed. The laminar flame propagation speed of methane with various grades of hydrogen-rich gas addition has been calculated. The effect of adding hydrogen, hydrogen rich gas from an ideal reformer (synthesis gas), as well as that from a non-catalytic plasmat...

The present work addresses unsteady flame dynamics in a lean-premixed swirl-stabilized combustor, with attention focused on the transition of flame structure from a stable to an unstable state. It was found that the inlet temperature and equivalence ratio are the two most important variables determining the stability characteristics of the combustor. A slight increase in the inlet mixture tempe...

In an opposed-jet diffusion flame experiment, under certain conditions, after the extinction of the diffusion flame, an edge flame can be obtained. This ring-shaped edge flame was first reported in 1959 by Potter and Butler but received little attention. It was reported again recently in a numerical and an experimental work and is responsible for an interesting transition between two distinct b...

The effect of O(3) on C(2)H(4)/synthetic-air flame propagation at sub-atmospheric pressure was investigated through detailed experiments and simulations. A Hencken burner provided an ideal platform to interrogate flame speed enhancement, producing a steady, laminar, nearly one-dimensional, minimally curved, weakly stretched, and nearly adiabatic flame that could be accurately compared with simu...