The dynamic behavior of freely propagating premixed flames with large Lewis numbers was computationally simulated using a sixth-order central difference scheme and non-reflective boundary conditions. Results in the linear stage of the instability growth show that the growth rate dramatically decreases with increasing Lewis number and that the large activation energy excites the pulsating instab...

We report the use of a tunable ArF laser at 193.26 nm to record simultaneous single-laser-shot, planar images of molecular hydrogen and hot oxygen in a turbulent H(2)-air diffusion flame. Excitation spectra of fuel and oxidantrich flame zones confirm a partial overlap of the two-photon H(2) (6,0) Q(1) E, F ? X and single-photon O(2) (10,2) R(17) B ? X (Schumann-Runge) absorption bands. UV Rayle...

A situation in which a diffusion flame reaches an end at some position in a medium of non-premixed reactants is studied. The mixing of reactants that takes place ahead of the diffusion flame leads to the formation of a "triple-flame", a structure which consists of a fuel-rich premixed flame, a fuel-lean premixed flame. and a diffusion flame that starts where the two premixed flames meet. An imp...

The design and optimization of liquid-fuel rocket engines is a major scientific and technological challenge. Despite some sixty years of continuous development, basic features such as flame length, flame stabilization, ignition or the occurrence of combustion instabilities are still difficult to predict. The numerical simulation of such flows is made particularly challenging by the extreme ther...

In this study, the phase transition characteristics of flame-synthesized γ-Al2O3 nanoparticles to α-Al2O3 have been investigated. The nanoparticles were synthesized by using a coflow hydrogen diffusion flame. The phase transition and particle characteristics of the Al2O3 nanoparticles were determined by examining the crystalline structure and the shape of the collected nanoparticles before and ...

The problem of non-perturbative description of stationary flames with arbitrary gas expansion is considered. A general method for deriving equations for the flame front position is developed. On the basis of the Thomson circulation theorem an implicit integral of the flow equations is constructed. With the help of this integral the flow structure near the flame front is determined, and a closed...

Polymeric composite films with a high loading of nano-size silicates can hardly meet the increasingly stringent fireproof and smoke-free requirements during burning. Thus, it is desirable to prepare pure clay films that can block air, heat, and flame. Here we report an organic-free clay film capable of both flame- and heat-shielding. The film was prepared from the self-assembly of nanometer-thi...

A time-resolved numerical analysis of combustion dynamics of double-base homogenous solid propellant in a rocket motor is performed by means of a Large-Eddy Simulation (LES) technique. The physiochemical processes occurring in the flame zone and their influence on the unsteady flow evolution in the chamber are investigated in depth. A five-step reduced reaction mechanism is used to obtain the t...