Fractal structure and features of energy-release (combustion) processes in heterogeneous condensed systems

Abstract

In this work, the theory of fractals has been used to describe the structure of heterogeneous condensed systems (HCS). Features of energy-release processes with variation of the initial structure parameters have been investigated. The microstructure of HCS and the dynamics of its change have been studied as functions of the proportion and properties of their components. It is shown that particles of the components form fractal structures, which are characterized by fractional dimensions. The obtained images of the microstructure reflect the presence of the geometric phase transition “fractal cluster-percolation cluster.” Regularities of reaction-front propagation are determined. It is found that the concentration limits of energy release and combustion are associated with the evolution of fractal structures and the formation (disruption) of a continuous reaction surface. The electrical conductivity of the starting compositions is measured as an indicator of the formation of fractal structures of one or another configuration. Electrical and thermal-physics properties of the samples and energy-release (combustion) parameters are analyzed. The systems exhibit similar behavior in different processes. Near the critical point, the dependence of the parameters studied on concentration has an exponential character. The exponent is close to that determined in percolation theory. A computational algorithm for the contact surface of the components is developed and implemented. The computation results allow one to distinguish the “base block” that influences the combustion rate and to determine the critical concentrations of the components. The study of HCS in the context of the new direction in the geometry of disordered systems—the theory of fractals—is promising for generalization of available experimental data and for predicting the parameters of energy release in HCS with variation in the structural parameters.