A. G. Merzhanov

Gasless Combustion of Ti–Al Bimetallic Multilayer Nanofoils

Ti–Al multilayer foils were produced magnetron vacuum deposition. The microstructure period varied in the range of 5–110 nm, the number of layers was 150–4700, and the total thickness of a multilayer foil reached 15–20 μm. The gasless combustion of the foils was studied. Steady‐state and pulsating combustion regimes were revealed; combustion temperatures were determined for both regimes. It was shown that the most probable mechanism of the self‐propagating reaction is the diffusion of Al in β‐Ti at a temperature close to the temperature of the α → β transition.

Three-dimensional spinning waves in the case of gas-free combustion

Spinning waves represent a spiral-helix motion of a localized combustion center, which occurs along the lateral surface of a cylindrical sample [1, 2]. After their discovery, these waves stimulated a lot of investigations. Solving unsteady two-dimensional equations of heat conduction and kinetics in the case of combustion of a thin adiabatic shell, authors of [3] have performed for the first time computer modeling of a spinning wave. Then, the two-dimensional approach started to be used in other theoretical studies as well (see, e.g., [4, 5]). However, processes that occurred inside a solid sample in the presence on its lateral surface of a spinning wave remained yet unknown. Attempts to consider threedimensional models [6, 7] have not yield desired results, because computational algorithms chosen led to rather difficult calculations.

Principles of the spin mode of combustion front propagation

A mathematical model of the spin mode of combustion propagation on a cylindrical surface is developed. The model is a system of two-dimensional nonlinear partial differential equations, which are solved numerically by an implicit conservative two-dimensional difference scheme and a cross-drive method. Parametric effects in the spin combustion process are examined, and theoretical results are compared with experimental data.

Nonstationary Regimes of Transformation of Multilayered Heterogeneous Systems

A nonstationary mathematical model of thermal propagation of flame in a layered heterogeneous system is proposed. The structure and dynamics of the frontal exothermal transformation in quasihomogeneous, transitional, and relay-race regimes are studied. Averaged characteristics of the front and dynamics of transformation of individual elements of a “discrete” combustion wave are analyzed using the model proposed. A correlation is established between the combustion of a model medium and real heterogeneous compositions. It is shown that the maximum combustion velocity is reached at an intermediate level of medium dispersion in a transitional parametric region. Key words: combustion waves, heterogeneous systems, multilayered nonstationary regimes, modeling.

Influence of pressure on the laws governing the combustion of molten heterogeneous systems

This article examines the possibility of controlling the combustion of highly exothermal heterogeneous systems by means of excess pressure. Experiments were performed in a constant pressure bomb with argon at pressures of 0-100 atm. The linear steady combustion rate was measured by means of photorecording. A BESM-6 computer was used for a thermodynamic calculation of the composition of the final combustion products. The combustion products of graphite, amorphic boron, and carbon black were investigated. It is determined that the character of the combustion and the state of the final products depend on the pressure and combustion temperature.

Laws and mechanism of diffusional surface burning of metals

As shown in [1], burning metal powders in a nitrogen medium is an effective means of obtaining the highmelting nitrides widely used in modern technology. Accordingly, the study of the combustion mechanism of metal-gas systems is of considerable interest . The laws of diffusional metal combustion were first studied in [2, 3]. On the basis of the experimental data obtained certain ideas about the combustion mechanism were formulated. The limit regime of diffusional surface burning, in which gas is supplied to the combustion front solely through the ends of the specimen, and the lateral surface is impermeable, was subjected to a detailed theoretical study in [ 4-6].

Three-Dimensional Unsteady Solid Flame Combustion under Nonadiabatic Conditions

The effect of heat losses on solid flame combustion characteristics is considered. New steady-state three-dimensional periodic regimes are found that do not occur under adiabatic combustion conditions. The essence of these regimes is explained using as an example the regime with six spots moving on helical lines in the near-surface layers of a cylinder. The spots are localized in the near-surface layers of a cylinder and do not intersect the central (located along the axis) zone of the sample. The interior of the cylinder (core) burns in a steady-state regime; i.e., along the cylinder axis, the front propagates at a constant velocity. An explanation is given for the existence of such regimes.

Validity of experimental and theoretical modeling of combustion of high-energy materials

Problems of theoretical and experimental modeling of combustion of high-energy materials in technological devices are considered. Requirements for modeling, validation criteria of modeling, and similarity criteria of combustion conditions are formulated. Classification of the validity of theoretical and experimental modeling is considered taking into account the features of intrachamber combustion of high-energy materials in technological devices.

Influence of Microgravity on Self-Propagating High-Temperature Synthesis of Refractory Inorganic Compounds

The self-propagating high-temperature synthesis was applied for the production of foam materials under the conditions of microgravity aboard the Mirstation. The materials obtained have a porous bimodal structure. The results of space experiments predicted using the interpolation method are checked. An unpredicted phase separation of the combustion products is discovered. The autowave combustion of suspended nickel-clad aluminum solids is observed for the first time. The combustion products were found to have a frame structure.

Two-temperature models of combustion of heterogeneous systems

Combustion is generally characterized by signifi� cant nonlinearity, nonstationarity, and a combination of numerous processes: chemical and phase transfor� mations, heat and mass transfer, etc. [1–10]. Here, we consider spatially structured systems. It is often prac� tically important to study specific features of combus� tion in systems in which a fuel and an oxidant are sep� arated: e.g., the oxidant is over or, vice versa, within the combustible material. In this work, we proposed the simplest model of combustion of heterogeneous systems and identified