Calculation of the induction period of thermal explosion

Formulas for the induction period obtained for various source and heat-transfer functions are presented. The formulas are applicable over the entire range of supercritical parameters. For each case considered, the generalities and peculiarities of variation in the induction period are established. The range of the determining parameter in which heat transfer has an effect on the induction period is estimated. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 1, pp. 3–11, January–February, 1997.     

Dynamics of phase-formation processes during self-propagating high-temperature synthesis in the thermal explosion regime

Specific features of formation of temperature and concentration fields during self-propagating high-temperature synthesis in the thermal explosion regime in a cylindrical reactor are studied by methods of mathematical modeling. The calculations are performed with allowance for melting of one (chemically active) component in the approximation with the high-melting component being non-soluble in the melt of the low-melting component. It is shown that the conditions of complete conversion of the original components in the volume of the reacting mixture depend on relations between the Biot criterion of the system, the ambient temperature, and the thermal effect of the reaction. After the thermal explosion, which occurs when the melting front reaches the geometric center of the reactor, a front of complete conversion is formed. This front moves from the cylinder centerline to the periphery with a gradually decreasing velocity. The diagram of the critical values of the Biot criterion at which the components burn down completely in the entire reaction volume is calculated. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 4, pp. 31–38, July–August, 2008.     

Hot-spot thermal explosion in deformed solids

A model for hot-spot thermal explosion is proposed taking into account the coherence of deformation and temperature fields and the dependence of the reaction rate on the work of the deformation force. The problem is considered in terms of thermal elasticity theory. The solution is performed using matched asymptotic expansions in various particular cases. The temperature, displacement, deformation and stress fields, the hot-spot radius corresponding to the boundary of ignition and extinction regimes, and the ignition time are determined under critical conditions.Tomsk. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 4, pp. 3–13, July–August, 1993.     

Dynamics and scaling of explosion cratering in granular media

Granular cratering is a ubiquitous phenomenon occurring in various natural and industrial contexts. Although impact‐induced granular cratering has been extensively studied, fewer experiments have been conducted on granular cratering via low‐energy explosions. Here, we study the dynamics and scaling of explosion granular cratering by injecting short pulses of pressurized air in quasi‐two‐dimensional granular media. Through an analysis of the dynamics of explosion processes at different explosion pressures, explosion durations, and burial depths, we identify two regimes, the bubbling and the eruption regimes, in explosion granular cratering. Our experiments explore the distinctive dynamics and crater morphologies of these regimes and show the energy scaling of the size of explosion craters. We compare high‐energy and low‐energy explosion cratering as well as explosion and impact cratering in terms of their energy scalings. Our work illustrates complex granular flows in explosion cratering and provides new insights into the general scaling of granular cratering processes. © 2017 American Institute of Chemical Engineers AIChE J, 64: 2972–2981, 2018     

Synthesis of Ti-Al-based materials by thermal explosion

Ti-Al-based materials reinforced with TiC and TiB₂ particles were prepared by thermal explosion in compacted (Ti + 0.3B₄C) + xAl and (Ti + 3Al) + yB₄C blends. The structure/properties of synthesized materials were characterized by XRD, SEM, and mechanical testing. An increase in x was found to affect the microstructure of products (lower grain size) and to have no influence on reaction temperature. An increase in y was found to decrease reaction temperature and to change the structure/composition of products toward better viscoelastic behavior.     

Degenerate thermal explosion regimes of autocatalytic reactions

Conclusions We have analyzed the laws of degeneracy of thermal explosion for autocatalytic reactions close to and remote from the ignition limit over a broad range of variation of the parameters β and γ. The characteristic features of degeneracy for reactions with different autocatalysis numbers η₀ have been noted. Fizika Goreniya i Vzryva, Vol. 4, No. 4, pp. 563–567, 1968     

Features of thermal explosion in systems with strong self-retardation

The features of self-ignition of heterogeneous systems with a logarithmic law of interaction of reacting components are studied. The physical pattern of the process is considered, and critical conditions of thermal shock are obtained. The region of parameters for which thermal shock degenerates is found.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 4, pp. 77–79, July–August, 1996.     

On the validity of the thermal explosion model in shock wave initiated nitromethane

By means of Perot Fabry Velocimetry (PFV) we recorded material velocities generated by an intense shock wave (P > 70 kbar) in pure nitromethane. Our experiments show that nitromethane does not behave according to the Campbell-Travis model for detonation in liquid explosives. We do not find any evidence for a so-called superdetonation, which would start behind and overtake the pressure shock wave. Our recordings of material velocities show a behavior of the liquid explosive very similar to that of solid polycrystalline explosives and are compatible with the heterogeneous decomposition scheme.