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A mathematical model is proposed to analyze the effect of compression and stretching of the filtration combustion front highly of porous metal samples. The processes of structuring of a quasi-isobaric wave of combustion of a titanium powder layer with a change in the transverse size of the layer in the direction of the movement of the front are experimentally studied. [ABSTRACT FROM AUTHOR]

The unstable propagation of combustion of a layer of titanium powder in horizontal and inclined channels under conditions of natural gas filtration is experimentally studied. The critical conditions for the disruption and restructuring of the combustion modes with an abrupt change in heat loss during the combustion of a layer on an inert substrate of variable composition is analyzed. The influence of the convective removal of impurity and inert gases on the processes of the passage of the combustion front over the boundary of dissimilar substrates is studied. The results are interpreted in the model of the heat-filtration stability of combustion in porous media. [ABSTRACT FROM AUTHOR]

Using a two-dimensional mathematical model, the dynamics of the transition of a combustion wave between layers of a multilayer system through an inert barrier, taking into account the influence of the geometric characteristics of the barrier's elements and heat loss, are analyzed. The characteristic parameters of the process, which determine the transition and establishment of a stationary wave mode of combustion behind the obstacle, are revealed. The optimal geometric characteristics of the wedge-shaped obstacle, which ensure the stability of the transition of the combustion wave under nonadiabatic conditions, are found. [ABSTRACT FROM AUTHOR]

Experimentally and theoretically (using mathematical modeling) the combustion of the undeformed porous matrix of cylindrically symmetric forms, in which the active gas reagent is fed from outside through the permeable surface part owing to difference between outside and inside pore pressure in the reaction zone, has been studied. It has been shown that under conditions of the instability of many-dimensional filtration combustion separate cells of exothermic chemical combustion form, which propagated in self-sustained mode. Structure of cellular waves, distribution dynamics and moving direction are determined by totality of factors: temperature field, gas pressure gradients, intensity of exothermic heat release, geometric parameters of porous layer, and heat loss value. The cellular combustion modes of the titanium powder layer were experimentally studied in the circular bath as the flat dish. The comparative analysis of theoretic and experimental results of combustion dynamics of cylindrical sample under cellular mode is given. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the effect of impurity and inert gases on the formation and propagation of cellular-combustion regimes for their inhomogeneous distribution above the surface of the reacting metal layer. The gas-dynamic aspects of the formation and steady propagation of inhomogeneous wave structures in the combustion of a titanium powder layer in through and semi-closed inclined air canals and in channels with uneven loading are considered. The gas composition heterogeneity over the reaction zone and the gas stratification, i.e., the stratification of a gas mixture of different densiies above the reacting layer, are shown to lead to the formation of inclined non-uniform and cellular fronts under conditions of a lack of active gas in the reaction zone and the loss of stability of the planar front. [ABSTRACT FROM AUTHOR]

In this paper, using mathematical modeling, we study combustion wave stability in transition through the interface of gasless systems. The effect of a gas layer separating two chemically active gasless layers on the combustion wave stability was studied at all stages of the transition. Using the criteria obtained, we estimate the stability conditions of the transition combustion wave. The nonstationary dynamics of the combustion wave transition through the gas gap is studied with allowance for competing mechanisms of heat transfer, such as conductive and radiant transfer. We analyze the effect of radiation heat transfer in the gas gap on the characteristics and stability of the transient combustion process. The failure region of the igniter combustion wave is determined through the approach to the ignition system, while estimates of temperature and heat flux at the interface of the systems are given with respect to the time of the igniter combustion completion under conditions of dominant conductive and radiant heat transfer. [ABSTRACT FROM AUTHOR]

The paper summarizes the results of experimental studies of the structuring of the infiltration combustion front in a burning titanium powder layer. The unsteady processes of formation and propagation of cellular and nonuniform combustion waves in heterogeneous media in straight-through and semi-closed channels in conditions of restricted gas exchange and presence of inert gaseous impurities are analyzed. The structural characteristics of cellular combustion waves in a metal powder layer under conditions of natural gas infiltration are reported. [ABSTRACT FROM AUTHOR]

The study examines the modes of propagation of cellular infiltration combustion waves through a high-porosity layer of an energetic composition yielding condensed reaction products. Under conditions of instability, a planar infiltration combustion front breaks into individual exothermic reaction cells, which propagate through the heterogeneous mixture in the pulsation mode. Based on video records and theoretical analysis of the process, the dynamics of propagation of a pulsating cellular front is investigated. The dependences and mechanisms of transformation of cellular combustion modes are established. The evolution of a cellular frontal structure within a separate pulsation period is investigated. [ABSTRACT FROM AUTHOR]

The experimental results on the unsteady propagation of cellular waves during the infiltration-controlled combustion of a titanium powder layer are presented. The modes of frontal combustion of a porous medium with a nonuniform thermal structure that arise because of the loss of stability of the front under conditions of controlled gas transport into the exothermic reaction zone are examined. The conditions of transformation of an irregular combustion front into a cellular combustion wave are determined. The effects of the key thermal parameters of the heterogeneous system on the structure of the irregular and cellular fronts and on the characteristics of the oscillatory dynamics of their propagation are examined. [ABSTRACT FROM AUTHOR]