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 ...

Since a large number of physical variables are involved in the combustion process occurring in complex swirl stabilized combustors, simple systems (burner stabilized laminar flat flames) were initially studied (see chapters 5 and 6). Having understood the dynamics of laminar flat flames and developed methodologies to build reduced order flame dynamic models, the technique developed to measure t...

Flame stability inside a cylindrical micro-combustor was studied. Considering occurrence of heat recirculation, the respective relations were written and with parameters such as motion speed of reactants, flame propagation speed and thermal conductivity of the combustor’s wall, flame stability and its location inside micro-combustor were studied. It was found that for each thermal conductivity ...

Investigation of combustion instabilities in gas turbine combustors require the knowledge of flame transfer functions. Those can be obtained by experimental measurement or by Large Eddy Simulations (LES). Since calculations are usually limited to a portion of the whole combustor, boundary conditions are of crucial importance. It is common practice to inject acoustic perturbations for the flame ...

Abstract: The laminar combustion characteristics of blends of isooctane and C1–C5 primary alcohols (i.e., methanol, ethanol, n-propanol, n-butanol and n-pentanol) were investigated using the spherical expanding flame methodology in a constant volume chamber at various equivalence ratios and volume fractions of alcohol. The stretch effect was removed using the nonlinear methodology. The results ...

The combustion characteristics of both pure propane hydrates and the mixtures of hydrates and quartz sands were investigated by combustion experiments. The flame propagation, flame appearance, burning time and temperature in different hydrate layers were studied. For pure propane hydrate combustion, the initial flame falls in the “premixed” category. The flame propagates very rapidly, mainly as...

We consider the competition of the different physical processes that can affect the evolution of a flame bubble in a Type Ia supernovae — burning, turbulence and buoyancy. Even in the vigorously turbulent conditions of a convecting white dwarf, thermonuclear burning that begins at a point near the center (within 100 km) of the star is dominated by the spherical laminar expansion of the flame, u...