Repetitively pulsed, nonequilibrium plasma discharges are studied for their ability to ignite and stabilize methane jet flames in cross flow air. The placement of the discharge is surveyed to optimize the flame duty cycle (stability). We find that flame ignition is not achieved when the discharge is located in the potential core region of the fuel jet or on the windward side of the most upstrea...

The transient behavior of burner-supported spherical diffusion flames was studied in the transport-induced limit of low mass flow rate and the radiation-induced limit of high mass flow rate which characterize the isola response of flame extinction. Oscillatory instability was observed near both steady-state extinction limits. The oscillation typically grows in amplitude until it becomes large e...

The effects of dimethyl ether (DME) addition on the high temperature ignition and burning properties of methane–air mixtures were studied experimentally and numerically. The results showed that for a homogeneous system, a small amount of DME addition to methane resulted in a significant reduction in the high temperature ignition delay. The ignition enhancement effect by DME addition was found t...

Combustion under high-pressure conditions holds the potential for improved thermodynamic efficiency, enhanced power generation, and reduced emission of some pollutants. It underlies the technology of internal combustion engines such as the automotive engine, the gas turbine, and the rocket engine, for which the operating pressure can reach as high as 100s atm. At such high-pressure conditions, ...

This study has assessed the validity of the commercially available turbulent flame speed models within ANSYS Fluent as applied to hydrogen/methane/air combustion, with 5 different fuel compositions considered from 100% methane to 100% hydrogen. It was found that existing turbulent flame speed models were capable of producing accurate predictions up to 60% hydrogen with the Zimont model being th...

The effects of dimethyl ether (DME) addition on the high temperature ignition and burning properties of methane-air mixtures were studied experimentally and numerically. The results showed that for a homogeneous system, a small amount of DME addition to methane resulted in a significant reduction in the high temperature ignition delay. The ignition enhancement effect by DME addition was found t...

In this work, the effects of the electric fields on the flame propagation and combustion characteristics of lean premixed methane–air mixtures were experimentally investigated in a constant volume chamber. Results show that the flame front is remarkably stretched by the applied electric field, the stretched flame propagation velocity and the average flame propagation velocity are all accelerate...

Turbulent methane flames exhibit a change in Markstein number as the equivalence ratio changes. In this paper, we demonstrate how these changes in Markstein number are related to shifts in the chemistry and transport. We focus on the analysis of simulations of two-dimensional premixed turbulent methane flames at equivalence ratios φ=0.55 and φ=1.00 computed using the GRI-Mech 3.0 mechanism. The...

Recent advances in automation of systematically reduced mechanisms are reported here with the aim to accelerate the development process. A computer algorithm has been developed enabling fast generation and testing of reduced chemistry. This algorithm has been used to develop various reduced mechanisms of methane-air combustion for modelling of turbulent combustion. A 10-step reduced chemistry h...

The interaction of a premixed methane/air flame with a counter-rotating vortex pair is analyzed using a parallel low-Mach-number computational model that is based on a detailed C1C2 chemical mechanism. Attention is focused on the transient response of the heat release rate and the flame structure at the centerline of the vortex pair. Results are obtained for vortex pairs of different strengths ...