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Experimental studies of combustion stability to the local excess of the component in a dispersed mixture of titanium and carbon powder are presented. It is shown how the spreading of a melt of a low-melting or liquid reaction product affects the stability of combustion transition through a solid and perforated carbon powder target. The melt motion direction with respect to the front propagation direction is revealed. It is indicated that the stability of the combustion transition through the target is determined by thermal interaction between the combustion wave and the target and is not directly related to the convective heat transfer by the melt. [ABSTRACT FROM AUTHOR]

A computational and experimental study of the passage of a gasless combustion wave through a wedge-shaped inert obstacle was performed. The stability of the transient combustion process to a change in the thermophysical and geometric parameters of the obstacle and the energy-kinetic parameters of chemically active layers was studied. By the region of stable transient combustion process is meant the range of parameters in which the passage of the combustion wave through the contact boundary ends with the establishment of its steady-state propagation regime in the ignited composition. The dynamics of transient combustion under near-critical conditions of its existence was investigated. [ABSTRACT FROM AUTHOR]

The transition of the combustion wave of a titanium powder layer in air through an inert shaped obstacle has been experimentally studied. It has been shown that an inhomogeneous wave-like structure of the combustion front can form due to the limited supply of gaseous reagents and the thermal instability of combustion of the titanium powder layer. Conditions of the optimal transient combustion mode in the presence of gaseous impurities affecting gas exchange in the reaction zone and the stability of the front in the layered system are obtained. It is shown that there exists a phenomenological criterion for assessing the nature of the transient combustion mode of titanium powder depending on the shape of the inert obstacle and the combustion front. [ABSTRACT FROM AUTHOR]

The paper describes the formation of the combustion zone structure of a titanium powder layer in inclined rectangular air channels with natural gas filtration. It is shown that heterogeneous combustion near the critical conditions of its existence with limited supply of gaseous reagent in the reaction zone and under the effect of gravitational forces is accompanied by rearrangement of the plane homogeneous front into more complex wave structures: cellular, cross-cellular, and heterogeneous. The features of the process under study is the presence of gaseous impurities affecting the gas exchange in the reaction zone, the destabilization of the plane front, and the formation and propagation of heterogeneous and cellular wave structures. [ABSTRACT FROM AUTHOR]

External manifestations of the heterogeneous combustion front are characterized. Gasdynamic aspects of the phenomenon are considered, and experimental data on the change of combustion modes during natural filtering of an air mixture are analyzed. Results of an investigation of the bifrontal structure of the combustion zone in a horizontal plane layer during convective gas transfer are presented. [ABSTRACT FROM AUTHOR]

The cellular filtration combustion of porous energetic compositions that interact with an active gas reagent and form condensed reaction products is studied for titanium powder combustion as an example. A simple and visually accessible quasi-experimental analysis of the nonlinear propagation of the combustion front with adjustable filtration transport of gas is proposed. Under conditions of a deficiency of the gas reagent and instability, the flat front of filtration combustion is divided into isolated cells of exothermic chemical reaction propagating in a pulsating mode. The results obtained are interpreted within a model of thermal filtration stability of the filtration combustion front. [ABSTRACT FROM AUTHOR]

The combustion of Ti-C mixtures of bulk density under inert gas blowing conditions produced by evacuation of one end of the reaction cell was studied for the first time. The experiments showed that the tested mixtures in quartz cups were not ignited and did not burn without the inert gas (argon) flow. Increasing the rate of gas evacuation from the sample increased the rate of steady-state combustion of the mixture of titanium with carbon black, and for the mixture of titanium with graphite, stabilization of the flat combustion front was observed. It is shown that the presence of small pressure difference (up to 105 Pa) allows control of the combustion process and confirms the basic postulates of the convective-conductive theory of combustion for heterogeneous condensed systems. [ABSTRACT FROM AUTHOR]

The filtration combustion of a layered porous fill consisting of alternating layers of a mixture of Ti + 0.5C a titanium powder with forced concurrent filtration of nitrogen was studied for the first time. The gas flow through the sample was provided by a vacuum pump attached to the lower end of the fill. The presence of the concurrent gas flow radically changes the character of propagation of the combustion front and the structure and composition of the products obtained. The layers consisting of carbonitride and titanium nitride make a single unit. The experiments provided scientific bases for the production of new laminated and composite ceramic materials by dynamic filtration combustion. [ABSTRACT FROM AUTHOR]

The specific features of dynamics of the thermal explosion in systems porous reagent- active gas-solid product under conditions where the heat-transfer and mass-transfer regions are separated from the ambient medium are considered. In addition to the competition of heat release and heat removal, the process of initiation of exothermal chemical interaction in these systems under normal pressures depends significantly on conditions of filtration transport of the gaseous reagent. The induction and post- induction periods of the thermal explosion are studied. The theoretical analysis of thermal-explosion issues is supplemented by an experimental study of the process for the porous titanium-nitrogen-titanium nitride system. [ABSTRACT FROM AUTHOR]

Numerical results of an experimental study of burning through steel tubes in a water medium by thermite-combustion products are presented. Based on the analysis of experimental data, recommendations on the optimal organization of the process are given, and an empirical formula for calculating the thermite mass necessary for burning through a steel wall is derived. [ABSTRACT FROM AUTHOR]