Laminar hydrocarbon flames, which have adiabatic flame speeds on the order of a meter per second, are conventionally described by a leading convective-diffusive zone followed by an energyreleasing reactive-diffusive region. On the other hand, combustion induced by a strong shock wave is typically modeled as a convective-reactive balance with negligible diffusion, which may be called a convectiv...

Detailed understanding of turbulent combustion in liquid rocket engines (LRE) requires an ability to predict the coupling between the transient features, acoustics, vortex/shear layer dynamics and the unsteady combustion heat release. Conventional and ad hoc models that mimic or match one set of conditions but fail in another test case cannot be used for reliable predictions. This paper present...

In this study, methane-ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to investigate the effects of acoustic excitation frequency and mixed fuel on nanomaterial formation. Acoustic output power was maintained at a constant value of 10 W, while the acoustic excitation frequency was varied (f = 0-90 Hz). The results show that the flame could...

A dominant factor in determining the burning rate of a premixed turbulent flame is the degree to which the flame front is wrinkled by turbulence. Higher turbulent intensities lead to greater wrinkling of the flame front and an increase in the turbulent burning rate. This picture of turbulent flame dynamics must be modified, however, to accommodate the affects of variations in the local propagat...

In this paper, a one dimensional premixed laminar methane flame is subjected to acoustic oscillations and studied. The purpose of this analysis is to investigate the effects of acoustic perturbations on the reaction rates of different species, with a view to their respective contribution to thermoacoustic instabilities. Acoustically transparent non reflecting boundary conditions are employed. T...

A computational study is performed to investigate the effects of hydrogen addition on the fundamental characteristics of stretched methane/air premixed flame in an opposed flow configuration. The problem is of interest as a potential application to gas turbines and spark-ignition engines, where it has been anticipated that addition of a small amount of hydrogen will extend the lean flammability...

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...

Minimum ignition energies and flame radii as a function of time were measured for near-limit, limit, and sublimit fuel-lean methane-air mixtures burning at one-g and zero-g. Minimum ignition energy values were the same at one-g and zero-g except for mixtures very near the zero-g flammability limit and leaner, where the zero-g values were much higher than the one-g values. For sublimit mixtures ...

We present three-dimensional, time-dependent simulations of the flowfield of a laboratory-scale slot burner. The simulations are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second-order projection formulation that conserves both species mass and total enthalpy. The methodology incorporates detailed chemical kinetics and a mixture model for differen...