The flashback or propagation of premixed flames along the near-wall low-velocity region at the base of a laminar boundary layer of a reactive mixture has been studied numerically. The analysis, carried out using the constant density approximation for an Arrhenius overall reaction, accounts for the effects of the Lewis number of the fuel. The flow field, as seen by an observer moving with the fr...

Spectroscopic diagnostic technique are applied for the determination of excitation temperature Texc and electron density in Air Acetylene premixed laminar flame. A group of FeI spectral lines has been used to estimate Texc using Boltzmann plot. Electron number density was determined from atom ion line pairs for Cd and Zn using Saha Boltzmann equation after substitution the obtained value of exc...

Premixed turbulent flames, encountered in power generation and propulsion engines, are an archetype of a randomly advected, self-propagating surface. While such flame is known to exhibit large-scale intermittent flapping, the possible intermittency its small-scale fluctuations has been largely disregarded. Here, we experimentally reveal inner premixed V-flame, while clearly distinguishing this ...

Enthalpy (fuel mass fraction and/or temperature) fluctuations in the oncoming mixture are known to have important impacts on premixed combustion and in particular on combustion instability. Theoretical modeling has primarily been following an empirical approach. In Part I of the present study, an asymptotically reduced first-principle theory was derived from the reactive Navier-Stokes equations...

The dynamics of radiative, near-limit, stretched premixed flames was investigated analytically and numerically, with emphasis on pulsating stability for sub-unity Lewis numbers. The analysis includes both flame stretch and order-unity heat loss, and yields a dispersion equation for the stability of radiative stretched flames subjected to symmetrical and asymmetrical perturbations. The dispersio...

Nonpremixed turbulent reacting flows are intrinsically difficult to model due to the strong coupling between turbulent motions and reaction. The large amount of heat released by a typical hydrocarbon flame leads to significant modifications of the thermodynamic variables and the molecular transport coefficients and thus alters the fluid dynamics [1],[4]. Additionally, in nonpremixed combustion,...

Modern combustion devices are designed to balance the need for efficient performance with the need for robust performance. Presently available design techniques are capable of meaningfully informing how this balance should be struck. To truly optimize the efficiency and robustness of a combustor, however, the predictive capabilities of numerical simulations will have to be more heavily relied u...

An experimental and numerical investigation of counterflow prevaporized partially premixed n-heptane flames is reported. The major objective is to provide well-resolved experimental data regarding the detailed structure and emission characteristics of these flames, including profiles of C1–C6, and aromatic species (benzene and toluene) that play an important role in soot formation. n-Heptane is...

The Stochastic Fields approach is an effective way to implement transported Probability Density Function modelling into Large Eddy Simulation of turbulent combustion. In premixed turbulent combustion however, thin flame-like structures arise in the solution of the Stochastic Fields equations that require grid spacing much finer than the filter scale used for the Large Eddys Simulation. The conv...

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...