Periodic combustion regimes for thermally coupled SHS systems with a thermocapillary melt flow

This paper presents a three-dimensional mathematical model of self-propagating high-temperature synthesis (SHS) of a three-layer “sandwich” sample. The layers are formed from gasless mixtures with the addition of an inert fusible component. The mathematical model is studied numerically using the finite-difference method. The unsteady periodic regimes of gasless combustion of the three-layer sample with square cross-section are revealed with account for melting and thermocapillary flow of the melted inert component of the mixture. The unsteady periodic combustion regimes are specified depending on the relative calorific value of the mixture in the inner layer. High-temperature points move along the side faces of the sample. The velocity of the points’ motion along the combustion surface is much higher than the average burning velocity of the sample. An increase in the melt flow velocity leads to the equalization of the temperature field and stabilization of the combustion regime. The quasi-stationary regimes of control and fusion are studied during the combustion of the sample with an active inner layer, when the intrinsic burning velocities of the donor and acceptor mixtures are close to each other.