Turbulent combustion modelling

Combustion synthesis is an attractive technique to synthesize a wide variety of advanced materials including powders and near-net shape products of ceramics, intermetallics, composites, and functionally graded materials. This method was discovered in the former Soviet Union by Merzhanov et al. (1971). The development of this technique by Merzhanov and coworkers led to the appearance of a new scientijc direction that incorporates both aspects of combustion and materials science. At about the same time, some work concerning the combustion aspects of this method was also done in the United States (Booth, 1953; Walton and Poulos, 1959; Hardt and Phung, 1973). However, the full potential of combustion synthesis in the production of advanced materials was not utilized. The scientijc and technological activity in thejeld picked up in the United States during the 1980s. The signijcant results of combustion synthesis have been described in a number of review articles (e.g., Munir and Anselmi-Tamburini, 1989; Merzhanov, I990a; Holt and Dunmead, 1991; Rice, 1991; Varma and Lebrat, 1992; Merzhanov, 1993b; Moore and Feng, 1995). At the present time, scientists and engineers in many other countries are also involved in research and further development of combustion synthesis, and interesting theoretical, experimental, and technological results have been reported from various parts of the world (see SHS Bibliography, 1996). This review article summarizes the state of the art in combustion synthesis, from both the scientijc and technological points of view. In this context, we discuss wide-ranging topics including theory, phenomenology, and mechanisms of product structure formation, as well as types and properties of product synthesized, and methods for large-scale materials production by combustion synthesis technique.

Combustion Synthesis of Advanced Materials: Principles and Applications

Porous burners for lean-burn applications

In honor of the fiftieth anniversary of the Combustion Institute, we are asked to assess accomplishments of theory in combustion over the past fifty years and prospects for the future. The title of our article is chosen to emphasize that development of theory necessarily goes hand-in-hand with specification of a model. Good conceptual models underlie successful mathematical theories. Models and theories are discussed here for deflagrations, detonations, diffusion flames, ignition, propellant combustion, and turbulent combustion. In many of these areas, the genesis of mathematical theories occurred during the past fifty years, and in all of them significant advances are anticipated in the future. Increasing interaction between theory and computation will aid this progress. We hope that, although certainly not complete in topical coverage or reference citation, the presentation may suggest useful directions for future research in combustion theory.

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Combustion theory and modeling

Combustion in porous media and its applications--a comprehensive survey.

Maximal energy accumulation in a superadiabatic filtration combustion wave

We consider planar, uniformly propagating combustion waves driven by the filtration of gas containing an oxidizer which reacts with the combustible porous medium through which it moves. We find that these waves are typically unstable with respect to hydrodynamic perturbations. For both forward (cofiow) and reverse (counterflow) filtration combustion (FC), in which the direction of gas flow is the same as or opposite to the direction of propagation of the combustion wave, respectively, the basic mechanism leading to instability is the reduction of the resistance to flow in the region of the combustion products, due to an increase of the porosity in that region. Another destabilizing effect in forward FC is the production of gaseous products in the reaction. In reverse FC this effect is stabilizing. We also describe an alternative mode of propagation, in the form of a finger propagating with constant velocity. The finger region occupied by the combustion products is separated from the unburned region by a f...

Instabilities, Fingering and the Saffman - Taylor Problem in Filtration Combustion

New results in the theory of filtration combustion

To determine the effects of gas-solid nonequilibrium on forced filtration combustion (FC) waves, a two-temperature model is employed, with separate temperature fields for the solid and gas particles. We consider heterogeneous (solid/gas) combustion in a porous sample with a prescribed gas flux at the inlet. If the reaction is initiated at the inlet (outlet) of the sample and the combustion wave travels in the direction of (opposite to ) gas filtration it is referred to as coflow (counterflow) FC. We determine the effects of gas-solid nonequilibrium on various aspects of forced FC waves. First, we consider coflow FC waves, in which case the gas infiltrating through the hot product region significantly enhances the propagation of the combustion wave. For a relatively small gas flux, the infiltrating gas delivers heat from hot product to the combustion layer, thus increasing the combustion temperature and, hence, the combustion rate. Propagation of such waves is controlled by conduction of the heat released ...

A. P. Aldushin

Papers

Maximal energy accumulation in a superadiabatic filtration combustion wave

Instabilities, Fingering and the Saffman - Taylor Problem in Filtration Combustion

New results in the theory of filtration combustion

Effects of gas-solid nonequilibrium in filtration combustion

On the transition from smoldering to flaming