S. I. Torunov

Detonation characteristics of diluted liquid explosives: Mixtures of nitromethane with methanol

Detonation in mixtures of nitromethane with methanol as an inert (nonexplosive) diluent is studied. Ignition experiments with mixtures in steel tubes of various diameters provided information on the effect of the degree of dilution on detonability. Mass velocity profiles with a chemical spike characteristic of detonation waves were recorded at the unsteady detonation front in all mixtures studied. This made it possible to distinguish the Chapman-Jouguet state and obtain a fairly complete set of detonation parameters. The dependence of the pressure in the detonation products on the methanol concentration is determined, which is required, in particular, to find the true (absolute) limit of detonation propagation for the concentration of diluted liquid explosives using the method proposed and validated by A. N. Dremin. Some results were found to be inconsistent with one-dimensional detonation theory.

Detonation properties of diluted liquid explosives: A mixture of nitromethane with nitrobenzene

A set of data characterizing the detonation process in mixtures of nitromethane with nitrobenzene is determined with the use of an electromagnetic method. The dependence of the pressure of detonation products on nitrobenzene concentration is established. Information on the effect of dilution ratio of nitromethane by nitrobenzene on detonability was obtained in experiments on mixture explosion. The results are compared with the results of previous similar studies of mixtures of nitromethane and methanol.

Determination of detonation parameters of liquid high explosives

An experimental study of the detonation parameters and structure of the reaction zone for liquid high explosives (HEs), such as bis(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), and nitromethane (NM) is performed. For each of these HEs, the time corresponding to the position of the Chapman-Jouguet point is determined: for FEFO, from experiments conducted at different charge diameters (≈300 ns); for TNM, at a fixed diameter but at different lengths (≈200 ns); and for NM, at the same diameter and length of the shell, but with detonation being initiated by different HE charge (≈50 ns). The particle velocity and pressure at the Chapman-Jouguet point for these explosives were measured. For TNM and NM, the dependence of the detonation velocity on the charge diameter was obtained

Instability of detonation waves in FEFO/methanol solutions

A VISAR interferometer and a high-speed streak camera are used to study the structure of detonation waves in bis-(2-fluoro-2,2-dinitroethyl)-formal (FEFO) mixtures with methanol, whose mass concentration varied in the range of 0–35%. It is shown that the two types of instability existing in liquid explosives, which are the one-dimensional instability of the detonation front and the reaction failure wave instability on the edge of the charge, can be implemented in any combination. The reaction time of the studied mixtures is determined, and the different character of the dependence of the critical diameter of detonation and the reaction time on the diluent concentration is demonstrated.

Instability of detonation waves in FEFO–methanol mixtures

The stability of one-dimensional flow, which occurs at the absence of influence of the boundaries, and instability at the edge of the charge has been investigated in liquid high explosive bis-(2-fluoro-2.2-dinitro-ethyl)-formal (FEFO) and in the mixtures of FEFO with methanol. The structure of the detonation wave was recorded by a VISAR interferometer and by high-speed streak camera. For FEFO it was found strong velocity oscillations in chemical reaction zone but the boundary at the edge of the charge was smooth. When the methanol concentration changes in the interval 10-20%, the stabilization of detonation front is observed and failure reaction waves are occurred at the edge of the charge. Further increase of the concentration of the inert diluent results in the instability of the detonation front at existing of the reaction failure waves. Obtained results show, therefore, that the failure reaction waves and stability of one-dimensional detonation front appear, in general, independently.

The stabilization of unstable detonation waves for the mixture of nitromethane/methanol

Using a laser interferometer VISAR the measurements of the particle velocity profiles in detonation waves for nitromethane/methanol mixtures with additions of a sensitizer diethylenetriamine were conducted. It is shown that the detonation front in a mixture of nitromethane/methanol is unstable and sensitizer is an effective method for the flow stabilization. If the diluent concentration is less than 10%, the detonation front is stabilized by adding of 1% diethylenetriamine. At higher concentrations of methanol, the sensitizer does not reject instability, but the amplitude of oscillations decreases in several times. An increase of the limit concentration of methanol at the addition of diethylenetriamine to the mixture was found.

Instability of a detonation waves in nitromethane and FEFO

The stability of detonation waves in nitromethane and FEFO was studied in experiments using a VISAR laser interferometer and an SFR high-speed photorecorder. It is shown that the relationship between various types of instability of the detonation front in liquid explosives is not strictly deterministic. Waves of reaction failure exist in the case of a stable detonation front (no cellular structure) and are absent in the case of an unstable detonation front.

Experimental study of the relief of the front of steady detonation in liquid high explosives

The instability of detonation waves in a 81 : 19 nitromethane-acetone mixture is experimentally studied. The amplitude of the irregularities caused by detonation instability and the typical reaction time are estimated using a VISAR laser interferometer, which makes it possible to measure the particle velocity profiles at the explosive-window interface. The characteristic transverse dimensions of the irregularities are measured with the help of a CORDIN camera operating in the single shooting mode to record the intrinsic emission of the detonation front or the light of an outside source reflected from it.