On the Mechanism of Detonation Combustion of Nanostructured Silicon with a Solid-Phase Oxidant
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 6, November, 2020
HEAT AND MASS TRANSFER IN COMBUSTION PROCESSES ON THE MECHANISM OF DETONATION COMBUSTION OF NANOSTRUCTURED SILICON WITH A SOLID-PHASE OXIDANT P. N. Krivosheyev, V. N. Mironov, O. G. Penyazkov, and S. I. Futko
UDC 662.612.2, 662.311.1
The physical mechanism of detonation combustion of nanostructured silicon with a solid-phase oxidant at a velocity of the combustion front of 1000–3000 m/s has been proposed. Thermodynamic characteristics of combustion of model solid-phase mixtures "silicon–ammonium perchlorate" with different equivalent ratios of their components have been calculated at different pressures. It has been established that a characteristic feature of detonation combustion of nanostructured silicon with a solid-phase oxidant is the stationary velocity of motion of the detonation front with a significant defect (10–15%) with respect to the Chapman–Jouguet detonation velocity. The detonation (supersonic) and subsonic regimes of combustion of nanostructured silicon with a solid-phase oxidant have been determined. Keywords: detonation combustion, nanostructured silicon, solid-phase oxidant, gas suspension of particles, ammonium perchlorate, Chapman–Jouguet detonation, mathematical modeling. Introduction. Beginning with the pioneering works on combustion of nanostructured silicon with various solidphase oxidants, the attention of researchers has been attracted to explosive regimes of such combustion [1–5]. The works that followed studied experimentally high-velocity regimes of combustion of nanostructured silicon with a combustion-front velocity of 1000–3000 m/s [6–12]. In these experiments, use was usually made of small nanostructured thin layers of porous silicon with the solid-phase oxidant embedded in them, which were ignited at one end, and quasi-stationary regimes of propagation of the combustion front along the sample depending on its porosity, the etching regime, and the ratio of the fuel and the oxidant in it were recorded using a high-speed video camera. The present work seeks to investigate thermodynamic and kinetic characteristics of high-rate combustion of nanostructured silicon with a solid-phase oxidant, the physical mechanism of such combustion, and its regimes. Physical Mechanism of Detonation Combustion of Nanostructured Silicon with a Solid-Phase Oxidant. Figure 1 gives the diagram of detonation combustion of nanostructured silicon with an embedded solid-phase oxidant (ammonium perchlorate), which reflects the physical mechanism of such combustion. When the combustion of a layer of nanostructured silicon with sodium perchlorate of height Δn-Si/NaP is initiated by heating it externally, gas-phase products of thermal perchlorate are intensely formed, in which a major portion is accounted for by molecular oxygen. Efficient gas generation in this layer produces a pressure increase in its pores, and large temperature gradients (of the order of 107–108 K/m) over the layer height and rather fast oxidation of silicon
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