The explosion of a Type Ia supernova (SNIa) begins as a turbulent flame deep within a 1.4 solar-mass white dwarf. Initially the burning happens in the flamelet regime where turbulence only serves to wrinkle and fold an essentially laminar burning front. However, as the star expands and the flame moves outwards, it encounters regions of lower density. At ∼ 2 × 10g cm, the flame transitions to a ...

diffusion flame in a dust cloud combustion in a counterflow configuration is investigated in this research. it is presumed that the fuel particles vaporize first to yield a gaseous fuel to oxidize with the gas phase. the reaction rate is assumed to be of the arrhenius type. conservation equations for the non-unity lewis number are solved and the flame temperature with the variations of differen...

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...

Spherical diffusion flames supported on a porous sphere were studied numerically and experimentally. Experiments were performed in 2.2 s and 5.2 s microgravity facilities. Numerical results were obtained from a Chemkin-based program. The program simulates flow from a porous sphere into a quiescent environment, yields both steady-state and transient results, and accounts for optically thick gas-...

One strategy for reducing US dependence on petroleum is to develop new combustion technologies for burning the fuel-lean mixtures of hydrogen or hydrogen-rich syngas fuels obtained from the gasification of coal and biomass. Fuel-flexible combustion systems based on lean premixed combustion have the potential for dramatically reducing pollutant emissions in transportation systems, heat and stati...

Diffusive transport of mass occurs at small scales in turbulent premixed flames. As a result, multicomponent diffusion, which is often neglected direct numerical simulations (DNS) combustion, has the potential to impact both turbulence and flame characteristics scales. In this study, we evaluate these impacts by examining enstrophy dynamics internal structure for lean hydrogen-air neglecting se...

The effect of turbulence on mixing in prototype reaction-diffusion systems is analyzed here in the special situation where the turbulence is modeled ideally with two separated scales consisting of a large-scale mean flow plus a small-scale spatiotemporal periodic flow. In the limit of fast reaction and slow diffusion, it is rigorously proved that the turbulence does not contribute to the locati...

Momentum and energy integral analysis of planar and axisymmetric laminar, buoyant diffusion flames is presented with the objective of describing the flame properties and ambient air entrainment. The analysis follows the traditional momentum/energy integral technique utilizing the Howarth–Dorodnitzyn transformation for variable density flows and description of the velocity profiles through the f...

Ignition, flame propagation and stabilisation have been simulated and analysed in a turbulent jet of non-premixed methane and air. The first order Conditional Moment Closure (CMC) turbulent combustion model was fully coupled with a Reynolds-Averaged Navier Stokes (RANS) flow simulation. A CMC model was developed to account for spark ignition. The over-prediction of turbulent flame propagation w...