We report on the development of a novel diode laser thermometry technique permitting temperature measurements in flames based on the fluorescence lineshapes of an atomic tracer species. The technique, which we term OLAF (one-line atomic fluorescence) requires only a single diode laser source for excitation, is simple to implement, and has excellent spatial resolution. Temperatures are deduced f...

A large eddy simulation (LES)/probability density function (PDF) method is proposed for modeling turbulent spray combustion. The PDF method has the advantage that the chemical source term appears closed but requires models for the small scale mixing process. The transport equation for the joint-scalar PDF is high dimensional and solved using a Lagrangian technique. A stable and consistent numer...

Quasi-steady and unsteady propagations of methane and propane–air premixed flames in a mesoscale divergent channel were investigated experimentally and theoretically. The emphasis was the impact of variable cross-section area and the flame-wall coupling on the flame transition between different regimes and the onset of flame instability. Experimentally, for the first time, spinning flames were ...

Reduction of nitric oxides (NOx) in aircraft engines and in gas turbines by lean combustion is of great interest in the design of novel combustion systems. However, the stabilization of the flame under lean conditions is a main issue. In this context, the present work investigates the effects of sinusoidal dielectric barrier discharge (DBD) on a lean inverse diffusive methane/air flame in a Bun...

Changes in flow strain and mixture composition on the order of a flame time scale are characteristic of many practical combustion processes. Accurately predicting the unsteady reponse of burning to these changes requires detailed modeling of species transport and chemical kinetics. This thesis formulates a detailed one-dimensional computational model for arbitrary unsteady conditions of strain ...

In experiments of hot surface ignition and subsequent flame propagation, a puffing flame instability is observed in mixtures that are stagnant and premixed prior to ignition. By varying the size of the hot surface, power input, and combustion vessel volume, it was determined that the instability is a function of the interaction of the flame, with the fluid flow induced by the combustion product...

Premixed combustion in an enclosed chamber is susceptible to large-scale acoustic instability, which manifests as intense pressure fluctuations with predominant peaks at the characteristic acoustic frequencies of the combustor. Such an instability can occur in aeroand rocket engines as well as in land-based gas turbines (e.g., Harrje & Reardon 1972; Yu, Trouve & Daily 1991; Richards & Janus 199...

A well-defined plasma assisted combustion system with novel in situ discharge in a counterflow diffusion flame was developed to study the direct coupling kinetic effect of non-equilibrium plasma on flame ignition and extinction. A uniform discharge was generated between the burner nozzles by placing porous metal electrodes at the nozzle exits. The ignition and extinction characteristics of CH4/...

Cooktop burners are widely used nowadays. In cooktop burner design, nozzle efficiency and greenhouse gas(GHG) emissions mainly depend on heat transfer from the premixed flame to the impinging surface. This is a complicated issue depending on the individual and combined effects of various input combustion variables. Optimal operating conditions for sustainable burner design were rarely addressed...

the premixed counterflow flames propagation in combustion of mixture which is a uniform mixture of fuel particles and air is analytically studied. this analysis framework is based on thermal-diffusion model with assumption that the lewis number is unit and the strain rate is constant. velocity profile is assumed as a function of one variable like x. the structure of the flame is presumed to con...