Influence of the molecular structure of explosives on the rate of formation,yield, and properties of ultradisperse diamond

The dependence of the detonation rate and electrical resistance of the detonation products on the initial density of 2,4-dinitro-2,4-diazapentane is recorded. Investigation of the solid detonation products of DNP and its alloys with hexogen shows that the content of diamond in these products and the dimensions of its particles and microcrystallites are considerably smaller than for alloys of TNT with hexogen.Institute of Chemical Physics, 142432 Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 2, pp. 102–106, March–April, 1994.     

Dependences of the detonation velocity and propellant performance of metallized explosives on the charge density and additive content

The dependences of the detonation velocity and the propellant performance measured using the M-40 technique on the charge density for aluminized explosives with different mass fraction of Al were studied. The fractions of the energy of Al combustion utilized during the chemical reactions and during the acceleration of the flyer plate were estimated. Regression dependences of the detonation velocity and the propellant performance on the charge density were obtained. The effect of the addition of particulate Al, Ti, Zr, and W in an amount of 5–30% on the detonation velocity of high-density explosive charges based on plasticized RDX was investigated. It is found that the reduction in the detonation velocity with the addition of various metallic additives is determined by the longitudinal sound velocity of the additive, and not by its density. Simple formulas for calculating the detonation parameters of high-density metallized explosives were obtained.     

Detonation characteristics of emulsion explosives

The detonation properties of a water-emulsion explosive are studied. The shock adiabat is determined for a density of 1.38 g/cm³. The critical diameter and the detonation velocity are found as functions of the initial density of the charge and the shock heating temperature is calculated.D. I. Mendeleev Moscow Institute of Chemical Technology, Moscow, 125190. Translated from Fizika Goreniya i Vzyrva, Vol.30, No. 3, pp. 86–91, May–June, 1994.     

Limits of detonation propagation in a suspension of propellant particles in vacuum in a tube

The problem of stationary detonation in vacuum with monopropellant particles propagating in a tube is formulated and analyzed numerically. It is shown that friction and heat removal onto the tube walls affect the structure of a disperse wave. The dependences of the detonation velocity on the tube diameter, the size of the propellant particles, and on their mass concentration have been determined, and the limits of detonation propagation have been found.Lavrent'ev Institute of Hydrodynamics, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 2, pp. 76–84, March–April, 1994.     

Detonation of Secondary Explosives in a Vacuum Suspension

The existence of self–sustaining detonation in an evacuated suspension of the particles of a secondary explosive is shown experimentally. The experiments with HMX were performed in a vertical shock tube of diameter 0.07 m and length 7 m in the range of volume–average particle concentrations 0.32—0.9 kg/m³. It is shown that the vacuum–detonation velocity does not almost depend on the volume–average concentration of particles and it is (1750±50) m/sec and that the pressure profile of a vacuum–detonation wave is smooth. The data on the electric conductivity of vacuum–detonation products and the length of the reaction zone are given.     

Formation of diamond from the liquid phase of carbon

Results are presented for synthesis of the diamond phase of carbon during detonation of the high-temperature explosive benzotrifuroxan (BTF)-C₆N₆O₆. The detonation products of this nonhydrogenic explosive have a high temperature which initially falls in the region of thermodynamic stability of the liquid phase of carbon. A two-stage synthesis process is proposed: drops of liquid carbon with diameters 0.1–1.0 m are formed initially, and these drops subsequently crystallize into the diamond structure. The experimental results given here confirm this hypothesis.Novosibirsk. Chelyabinsk. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 4, pp. 131–134, July–August, 1993.     

Physical–chemical model of processes at detonation synthesis of nanodiamonds

This article presents a principally new physical–chemical model of nanodiamond formation at explosion, which describes adequately all the existing experimental data on detonation synthesis of diamonds. According to this model, the detonation wave performs activation rapidly; then the reaction mixture composition keeps varying. In the diagram C – H – O this process results in continual motion of the point imaging the reaction mixture composition. The ratio of the diamond phase amount to the condensed carbon quantity in the explosion products is defined by the width of the section this point passes over in the diamond formation zone. Motion of the point in the area below the line H – CO results in decrease of the condensed carbon (CC) amount. Diamonds are formed by the free-radical mechanism in the unloading wave.     

Approximate calculation of the parameters of one-dimensional deflagration for an arbitrary velocity of the flame front

Analytical dependences are obtained which allow one to determine with high accuracy the distribution of all flow parameters for one-dimensional deflagration of gas mixtures with an arbitrary propagation velocity of the flame front up to the normal detonation regime.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 2, pp. 38–45, March-April, 1996.     

Investigation of Gas Detonation in Over-Rich Mixtures of Hydrocarbons with Oxygen

Detonation in mixtures of acetylene, ethylene, and propylene with oxygen in the range of fuel component concentrations with possible formation of carbon condensate in detonation products is studied both experimentally and theoretically. In contrast to the traditional method of studying detonation in a quiescent mixture located in a closed tube, the present investigations are performed in a tube with an open end (for exhaustion of detonation products) under the conditions of separate injection of the components and their mixing after injection into the detonation tube through the ignition chamber. The components are injected into the tube from a computercontrolled multichannel system of gas injection of the CCDS2000 detonation spraying setup. The detonation cell size and detonation velocity are measured; these parameters are also calculated by the BEZOPASNOST (SAFETY) computer program. A comparison of the computed and experimental dependences testifies to a complicated character of transformation of detonation products from a purely gaseous to heterogeneous state and to its effect on the detonation wave.     

On the detonation velocity in a sensitive-explosive particle suspension in vacuum

In this paper we study the conditions of self-sustaining wave propagation upon combustion of a monofuel particle suspension in vacuum. We employ a two-velocity model of the flow of reaction products behind the detonation wave (DW). Essentially new conditions behind the DW front are obtained that ensure its propagation with a velocity higher than the velocity of ideal Chapman-Jouguet detonation in particle suspension in vacuum. The results agree qualitatively with the experimental data on the detonation velocity of lead azide in vacuum.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 1, pp. 71–74, January–February, 1996.     

Calculation of the Cellular Structure of Detonation of Sprays in an H2—O2 System

On the basis of the mathematical model of a two–phase two–velocity medium, detonation of a cryogenic mixture (gaseous hydrogen—drops of liquid oxygen) was studied numerically. The dynamics of formation and the special features of the structure of the two–dimensional reaction zone of the detonation wave are discussed. The cellular structure of detonation is modeled for the first time for a cryogenic hydrogen—oxygen spray.     

Configuration of a cloud of detonation products during expansion in air

Shadowgraph techniques are used to record the configuration of detonation products in air from various kinds of high-explosive charges with spherical and cxlindrical geometries. It is established that the cloud of detonation products from a cylindrical charge after expansion to its maximum size departs considerably from a spherical configuration. The cloud of detonation products attains its ultimate size at a distance of 25–30 times the initial radius, contrary to numerical results, which indicate that this distance does not exceed 15 or 16 times the initial radius of the charge.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 121–126, July–August, 1991.     

Problem of detonation suppression by means of blankets and foams

The subject of investigation was the effect of an injection of water vapor on the detonation of fuel-air mixtures. It is shown that the injection of mass into the detonation wave reaction zone leads to a lowering of the velocity and to a disruption of detonation. The possibility of a suppression of detonation with moderate water-mechanical foams density was investigated experimentally.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 6, pp. 116–124, November–December, 1991.     

Existence of stationary self-maintained combustion of porous and channel propellants

It is shown theoretically that in channel and porous propellants there exists a stationary self-maintained regime of propagation of a convective flame front. The existence of a spherical structure of the combustion zone results in the appearance of a qualitatively new propagation regime — subsonic relative to the condensed phase and supersonic relative to the gas phase ahead of the front. The final states of the reaction products lie on the branch of the detonation adiabat corresponding to weak detonation. It is shown that in a propellant with constant average density and thermal conductivity the velocity of the wave is variable and can be regulated by adjusting the size of the individual channels.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 18–24, July–August, 1991.     

Model of bubble detonation

A model of detonation in a two-phase heterogeneous mixture consisting of bubbles of chemically reacting gas in a chemically inert liquid is proposed. The model takes account of the compressibility and viscosity of the liquid, the presence of an induction period of the chemical reaction, and shift of the chemical equilibrium. The initiation of the wave and its approach to steady conditions are calculated. The calculation results agree with experiment. It is shown for the first time that wave propagation at supersonic (relative to the frozen sound velocity) velocity is possible with large initial pressures in the mixture. The structure of the wave in sub- and supersonic conditions is significantly different. In the first case, there is smooth pressure variation in the compression wave; in the second, there is a pressure discontinuity at the leading shock front of the wave.Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 129–136, July–August, 1992.     

Equation of state of the detonation products of RDX

Summary Experimental data and theoretical ideas concerning the detonation adiabat and the thermodynamic properties of real gases have been used to find the equation of state of the detonation products of RDX in the density range 0–2.3 g/cm³. The equation of state relates mainly to the region of thermodynamic parameters corresponding to adiabatic expansion of the explosion mines the pressure at given values of the density and energy in this region correct to 5–10%.Fizika Goreniya i Vzryva, Vol. 2, No. 4, pp. 85–96, 1966     

Possibility of detonation wave propagation in the Chapman-Jouguet regime in inhomogeneous media

We consider detonation wave propagation in an inhomogeneous fuel gas mixture at rest, whose initial state is characterized by values of pressure and density that are in the general case, functions of the spatial and time coordinates. The distance form the plane, axis or center of symmetry can be used as the spatial coordinate. The sources of mass, pulse, and energy are assumed to be present behind the detonation front. The appropriate necessary conditions for the detonation wave to propagate in the Chapman-Jouguet regime are determined. The relations obtained are analyzed for some inhomogeneous media: media with variable density, media with heat release varying with distance, and media with burnout sources behind the detonation front.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 2, pp. 98–109, March–April, 1993.     

Detonation wave structure in a vacuum with unitary fuel particles

The structure of steady state detonation in a vacuum with unitary fuel particles is studied. It is shown that the detonation structure lacks a shock wave frozen in the gas, and that the detonation wave zone consists of a contact discontinuity with jump in gas temperature and continuous pressure, a compression relaxation wave with contact discontinuity in the ignition plane and adjacent combustion zone. Parameters of the two-phase flow in the reaction zone are calculated.Novosibirsk. Translated from Fizika goreniya i Vzryva, Vol. 27, No. 6, pp. 109–115, November–December, 1991.     

Dependence of the Shape of a Detonation Wave Front on the Detonation Wave Velocity upon Detonation of a Cylindrical Charge

The transition of a system of partial differential equations which describe the stationary flow behind the shock–wave front of a detonation complex upon detonation of a cylindrical charge to a system of ordinary differential equations is performed by means of the series expansion in terms of the radial variable. The necessary equations for determination of the derivatives of solutions with respect to the parameters and the initial conditions for them are formulated. Imposing the condition of continuous extendibility of the solutions leads to equations that allow one to determine the shape of a shock–wave front as a function of wave velocity.     

Effect of the density of an emulsion explosive on the reaction zone width

This paper presents experimental dependences of the width of the reaction zone and detonation critical diameter on the initial density with a variation in the density of an emulsion high explosive from 0.5 to 1.33 g/cm³. Glass microballoons were used as a sensitizer. The emulsion explosive is characterized by an U-shaped dependence of the critical diameter on the density, and the reaction time and the width the reaction zone increase monotonically with the density of the explosive. The detonation pressure of the studied compositions varies in the range of 0.6–12 GPa.