A single toroidal, laminar vortex in created and a laminar premixed flame is propagated over the vortex in order to study the fundamental interaction process and to compare results with the numerical solutions of the Navier-Stokes equations obtained by Poinsot, Veynante, and Candel. Results quantify the degree of flame rollup, the flame perimeter increase due to wrinkling, the minimum vortex si...

Imaging scheme based on Acetone-OH simultaneous PLIF (Planer Laser-Induced Fluorescence) is applied for diagnostics of reactive zone over the premixed flames and the reactive zone imaging are demonstrated for turbulent premixed flame conditions. In the present study, visualization of reactive zone is brought by simultaneous measurement of unburned zone through acetone (seeded into the fuel flow...

INTRODUCTION Theoretical analysis, experimental observations, and numerical simulations have all indicated that flame-vortex interactions play an important role in the propagation and extinguishment of turbulent flames in microgravity [1]. Most studies of flame-vortex interactions ignore the effects of gravity and experiments are usually conducted in Earth gravity. Recently, Sinibaldi et al. [2...

Lean premixed hydrogen flames are thermodiffusively unstable and burn in cellular structures. Within these cellular structures the flame is locally enriched by preferential diffusion of H2. This local enrichment leads to hot spots in which the flame burns with considerably more intensity than the corresponding laminar flame. In this paper we investigate the impact of this local enrichment on th...

Extinction limits and flame bifurcation of lean premixed dimethyl ether-air flames are investigated numerically using the counterflow flame with a reduced chemistry. Emphasis is paid to the combined effect of radiation and flame stretch on the extinction and flammability limits. A method based on the reaction front is presented to predict the Markstein length. The predicted positive Markstein l...

The lagrangian point of view is adopted to study turbulent premixed combustion. The evolution of the volume fraction of combustion products is established by the Reynolds transport theorem. It emerges that the burned-mass fraction is led by the turbulent particle motion, by the flame front velocity, and by the mean curvature of the flame front. A physical requirement connecting particle turbule...

Large eddy simulations (LES), where the large-scale motions are explicitly computed, is a promising tool for numerical simulations of reactive flows which generally exhibit large coherent structures. Nevertheless, subgrid-scale models have to be developed to describe the effects of the smaller flow motions not resolved in the simulation. An experimental method is presented for validation and de...

Tomographic analysis is used to provide a correction to low-pressure stoichiometric premixed CH(4)/O(2) flame temperatures measured with tunable diode laser absorption spectroscopy employing CO two-line thermometry. It is shown that flame temperatures measured with line-of-sight-based two-line thermometry are always too low and that the correction to the observed temperature is a nonlinear func...

Three-dimensional direct numerical simulation of lean premixed hydrogen flames is used to explore the influence of species and thermal diffusion and viscosity on the flame structure and turbulent flame response. The leadingorder flame response is shown to be due to the global Lewis number with little influence from the other species. The previously-reported observation of decorrelation of fuel ...