改性铵油炸药连续爆速实验研究

采用连续速度探针研究改性铵油炸药在不同起爆条件下爆速和爆轰成长的连续变化.在起爆条件分别为雷管/160g起爆药柱、雷管/160g起爆药柱/有机玻璃隔板和仅采用雷管时,改性铵油炸药在稳定爆轰阶段的稳定爆速分别为4569m/s、4496m/、4559m/s,爆轰成长距离分别为3.5、7.3和20cm,爆轰成长时间分别为0.01、0.025和0.06ms.结果表明,在相同的装药约束条件下,起爆能量越大,改性铵油炸药爆轰成长时间和爆轰成长距离越短,即越容易发展为稳定爆轰.     

Performance Properties of Commercial Explosives

The aquarium test is a proven means of obtaining nonidial performance property data for commercial blasting agents. Optical data on the detonation velocity, shock wave in water, and expansion rate of the pipe enclosing the detonation products (in combination with the equilibrium thermodynamic chemistry code BKW) give the C-J state and degree of chemical reaction at the detonation front, as well as information on additional chemical reaction that occurs as the detonation products expand. Specific explosive systems that are studied are ammonium nitrate-fuel oil mixture (ANFO), aluminized ANFO, flaked trinitrotoluene (TNT), and several other commercial products in 10-cm-diam and 20-cm-diam pipes of Plexiglas and clay. Experimental shock pressure data are obtained with lithium niobate transducers placed in the water surrounding the explosive charge. These data show that the addition of ∼ 100-μm aluminum particles to ANFO significantly increases the initial peak shock pressure delivered to the surrounding medium. Peak shock pressures in the water, calculated from the shock-wave orientation, are also useful in comparing performance properties of various commercial explosives.     

A 3D Smoothed Particle Hydrodynamics Method with Reactive Flow Model for the Simulation of ANFO

ANFO (ammonium nitrate/fuel oil) is a widely used bulk industrial explosive mixture that is considered to be highly “non‐ideal” with long reaction zones, low detonation energies, and large failure diameters. Thus, its detonation poses great challenge for accurate numerical modeling. Herein, we present a numerical model to simulate ANFO based on improved smoothed particle hydrodynamics (SPH) method, which is a mesh‐free Lagrangian method performing well in simulating situations consist of moving interface and large deformation, as happened in high‐velocity impact and explosion. The improved three‐dimensional SPH method incorporated with JWL++ model is used to simulate the detonation of ANFO. Good agreement is observed between simulation and experiment, which indicates that the proposed method performs well in prediction of behavior of ANFO.     

Influence of Ammonium Nitrate Prills' Properties on Detonation Velocity of ANFO

Prilled/granulated ammonium nitrate is commonly used as a fertilizer and a basic ingredient of industrial explosives, especially of ANFO. One of the most important factors that affect the explosive properties of ANFO is the porosity of the prills/granules. This paper describes an attempt to manufacture ammonium nitrate prills of determined porosity in order to investigate its influence on the ANFO detonation velocity. A method of manufacturing porous ammonium nitrate prills with a high‐level of oil absorption (up to 20% by volume) was developed. The relations between porosity and granulometric distribution of ammonium nitrate prills versus the detonation velocity of ANFO were examined. It has been proved that the detonation velocity of ANFO increases significantly with higher porosity and smaller size of ammonium nitrate prills/granules. The influence of ANFO oxygen balance (researched by changing the content of fuel oil in the mixture) on detonation velocity has been determined for two kinds of ammonium nitrate prills–one with a low and another one with a high level of porosity.     

Flyer Plate Motion by Thin Sheet of Explosive

Acceleration of a metal plate by explosive energy at low value of charge to metal mass ratio has been studied by employing a new theoretical model based on uniform pressure and density of detonation products behind the flyer plate. Theoretical velocities of flyer plates have been compared with those measured by radiographic technique and found in good agreement. Comparing the relations for plate velocity, obtained from the present model and earlier Gurney model at low C/M values, an analytical expression for Gurney energy has been obtained in terms of detonation velocity of the explosive and adiabatic exponent of the detonation products.     

Energy release of mixed explosives during propagation of a nonideal detonation under conditions similar to the operation conditions of a blasthole charge

Detonation experiments were performed in a specially developed explosive device simulating a blasthole using charges of fine-grained and coarse-grained (granular) 30/70 TNT/ammonium nitrate mixtures of identical density 0.89 g/cm³ in steel shells with an inner diameter of 28 mm and a wall thickness of 3 mm at detonation velocities of 4.13 and 2.13 km/sec, respectively. Despite significant differences in detonation velocity (pressure), identical expansion of the charge shells was observed. On the other hand, numerical simulations of detonation propagation in the explosive device with the corresponding velocities ignoring the possibility of energy release behind the shock front show that the expansion of the charge shell is always greater in the case of a high-velocity regime. It is concluded that under the conditions simulating detonation propagation and the work of explosion products in a blasthole, effective additional energy release occurs behind the low-velocity (nonideal) detonation front. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 111–120, July–August, 2007.     

Detonation velocity of mechanically activated mixtures of ammonium perchlorate and aluminum

The detonation properties of mechanically activated mixtures of ammonium perchlorate and aluminum were studied. The deflagration-to-detonation transition for low-density charges was investigated. Dependences of the detonation velocity of pressed charges with different types of aluminum on the activation time, density, and diameter of the charges were obtained. For compositions with nanosized aluminum, it is was found that the detonation velocity depends nonmonotonically on the inverse charge diameter and remains almost unchanged in a certain range of charge diameters. It is shown that the joint use of mechanical activation and nanosized components of the composite explosive significantly increases the detonability, reduces the critical diameter, and shifts the maximum of the detonation velocity as a function of density to higher charge densities.     

Interactions of Impact Shock Waves in a Thin-Walled Explosive Container. I. Impact by a Flat-Ended Projectile

Interaction of impact shock waves that could detonate an explosive (Composition B) confined in a thin-walled container impacted by a cylindrical projectile is numerically studied, based on the Forest Fire explosive reaction rate model. After the impact, rarefaction waves from projectile periphery and front cover–explosive interface catch up the forward-moving shock fronts in the explosive as well as in the projectile. At a high impact velocity, the transmitted shock front induces detonation at the front cover–explosive interface. At an intermediate velocity, the rate of energy release from the shock-compressed volume in the explosive is such that the associated effects prevail over the effects caused by rarefaction waves, leading to detonation after the shock wave travels a certain distance in the explosive. There is a range of minimum impact velocities at which the effect of rarefaction waves prevails over the energy release; hence, the detonation is excited not behind the shock-wave front moving over the explosive but only after shock-wave reflection from the high-impedance back plate. It is suggested that, in interpreting the detonation behavior of an explosive confined by a high-impedance container, one should take into account the effects of shock-wave interaction with container walls.     

Corner Turning of Detonation Waves in an HMX‐based Paste Explosive

Detonation wave profiles have been determined for RX‐08‐HD (74% HMX paste) loaded in 3 mm square troughs after turning both acute 90° bends and bends with a 1.5 mm inner radius turn and a 4.5 mm outer radius. The explosive troughs were confined with either lucite or copper. We show that the shape of the detonation wavefront can be explained in terms of a Huygens' construction from the leading point to the outer radius. Turbulent behavior occurs between the leading point and the inner edge. The turbulence appears enhanced for the curved samples with copper confinement. The distance the detonation wave has to travel past the turn in order to regain its original symmetry was found to be governed by an exponential time constant of 0.6 µs. Analysis suggests that the leading point alone stays at the straight‐ahead detonation velocity throughout the turn.     

Detonation velocities of the Non-Ideal Explosive Ammonium Nitrate

In order to gain a better understanding of the detonation behaviour of the non-ideal explosive ammonium nitrate, the detonation velocities of low density prilled ammonium nitrate were measured in steel tubes with different diameters and wall thicknesses. It was found that the tube diameter has a much greater effect on the detonation velocity than the confinement. The highest value observed (3.95 km/s) coincides with the ideal detonation velocity as predicted by the TIGER code in combination with the JCZ3 equation of state.     

Simulation of Explosive Welding with ANFO Mixtures

The work described here arose from a study into explosive welding. As part of that study, the impact velocity of stainless steel and titanium plates to grazing detonation of ANFO/perlite, the velocity of detonation were measured. Computer simulation required a new model which copes with an equation of state of low explosives.     

Analytic Model of Reactive Flow

A simple analytic model allows prediction of rate constants and size effect behavior before a hydrocode run, if size effect data exist. It utilizes detonation velocity, average detonation rate, pressure and energy at infinite radius. This allows the derivation of a generalized radius, which becomes larger as the explosive becomes more non‐ideal. The model is applied to near‐ideal PBX 9404, in‐between ANFO and most non‐ideal AN. The power of the pressure declines from 2.3, and 1.5 to 0.8 across this set. The power of the burn fraction, F, is 0.8, 0 and 0, so that an F‐term is important only for the ideal explosives. The size effect shapes change from concave‐down to nearly straight to concave‐up. Failure is associated with ideal explosives when the calculated detonation velocity turns in a double‐valued way. The effect of the power of the pressure may be simulated by including a pressure cut‐off in the detonation rate. The model allows comparison of a wide spectrum of explosives providing that a single detonation rate is feasible.     

Detonation velocity of highly dispersed ammonium perchlorate and its mixtures with explosive substances

This paper describes the measurement of the detonation velocities close to ideal velocity relative to large charges of highly dispersed ammonium perchlorate (AP) and its mixtures with different explosive substances in thick-walled steel pipes. The relationship of the detonation velocity of AP with its density and the relationship between the detonation velocity of mixtures with the component ratios and oxygen coefficient of the mixtures are determined. The calculation of the detonation velocity of AP/explosive/Al three-component compositions is proposed for the first time.     

JBO-9021炸药初始密度对爆轰波阵面曲率效应的影响

采用高速扫描相机及电探针,在室温环境下对不同初始密度(1.894~1.901g/cm3)、不同半径(5.0、7.5、15.0mm)的钝感炸药JBO-9021药柱开展了曲率效应实验,获取了拟定态爆轰波阵面形状及波速,分析了其随炸药柱密度及半径的变化。结果表明,随着炸药JBO-9021的初始密度由1.894g/cm3增至1.901g/cm3,3种不同半径JBO-9021药柱的爆轰波拟定态波速均增大,拟定态波阵面形状变得更为平坦,波阵面中心点与边界点之间的波到达时间差降低;在小曲率范围内(κ0.2mm-1),JBO-9021药柱爆轰波波阵面法向波速Dn与当地曲率κ的关系(Dn(κ)关系)不受药柱半径及密度的影响,当曲率κ0.2mm-1时,Dn(k)关系随药柱半径及炸药密度呈现离散趋势,药柱半径及初始密度共同影响爆轰波波阵面大曲率的Dn(κ)关系。     

The Effects of Containment on Detonation Velocity

Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70 μs⁻¹. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For U_s/C_o≥1.2, where U_s is the detonation velocity and C_o the zero‐pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump‐off. For U_s/C_o≤1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The U_s/C_o≥1.2 cylinders saturate in detonation velocity for thick walls but the U_s/C_o<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15–0.5 power.     

Studies of Detonation Characteristics of Aluminum Enriched RDX Compositions

Research on the effect of aluminum contents and of its particle size on detonation characteristics of RDX‐based compositions containing 15–60% aluminum was carried out. Measurements of detonation velocity for different charge diameters and confinements were performed. To measure the shock curvature of the detonation wave, X‐ray photography was applied. Unconfined charges and charges confined with a water envelope were tested. The radius of the detonation front curvature was determined. The cylinder test results were the basis for determination of the acceleration ability and energetic characteristics of the detonation products of the mixtures. The Gurney energy describing the acceleration ability was found. The detonation energy of the mixtures tested was also estimated from the cylinder test data.     

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 Products as a Function of Initiation Strength,ambient gas and binder systems of explosives charges

The way of initiating an insensitive high explosive can influence the start of a detonation reaction remarkably. In order to study the extent of this influence, different boosters and different booster structures for the initiation of explosive mixtures containing TNT and nitroguanidine (NQ) have been used. The experiments have been conducted in a 1.5 m³ containment from which the detonation products could be taken and analyzed. In those cases where we only used a 10 g RDX booster together with a detonation cap no. 8, we had not a complete detonation reaction by initiating cylindrical charges of TNT/NQ and TNT/AN. This means that unreacted TNT was analyzed in the solid residue, mainly consisting of carbon soot. On the other hand, we had a complete detonation using an additional booster of about 18 g detonation sheet, placed on the front side of the cylindrical explosive, having the same diameter as the explosive charge. Another part of the investigations deals with the determination of the influence of different argon pressures on the composition of the detonation gas and the solid residue. Between vacuum and one bar argon a strong change not only of the gas but also of the soot residue was measured. A stronger influence on the products was found using a confinement with glass tubes. The investigation of Al-containing charges exhibited a very different behavior compared with charges without Al. No more influence of vaccum or of different ambient gas pressure could be observed. By investigation of two composite explosive charges (PBX) containing binder systems of different energies and different oxygen balances, a great influence on the reaction of Al was found. The PBX charges with the better O₂-balance containing the energetic GAP-binder reacted nearly completely with the Al, opposite to the charge containing the polyisobutylene (PIB) binder system.     

Effect of Shell Material on the Detonation of an Explosive Charge

The effect of shell material (copper and silicon carbide) on the detonation of a cylindrical explosive charge was analyzed. The wave patterns in the detonation products and the shells are substantially different, which is due to different sound velocities and the rapid destruction of the ceramic under explosive loading. The wave pattern at the explosive/ceramic interface was found to be affected by desensitization of the explosive due to its loading by an advancing wave from the shell side, resulting in a decrease in pressure, blurring of the detonation front, and an increase in particle velocity. Throughout the process, there is a continuous increase in the time of explosive decomposition near the interface between the explosive and the ceramic shell. An extended region with a constant pressure close to the Chapman–Jouguet pressure was observed on the axis of symmetry behind the detonation front of the explosive charge in the ceramic shell.     

Dynamics of the detonation-wave front in solid explosives

The important role of the shape of the front during detonation wave propagation in gas mixtures was substantiated by K. I. Shchelkin during construction of the theory of spinning detonation. Subsequently, a unique relationship between the curvature of the front and detonation wave parameters has been repeatedly confirmed in experiments, including for condensed high explosives (HEs). The existence of this relationship formed the basis of the theory of the dynamics of the detonation front which had been developed by the end of the 20th century. This paper presents the results of a study of detonation front propagation in cylindrical samples of a low-sensitivity HE of different diameters with one-point and plane-wave initiation. A unique relationship between the detonation velocity and the curvature of the detonation wave front has been found. Ordinary differential equations describing two-dimensional steady-state detonation front profiles for HE charges in the form of a plate, a cylinder, and a ring were derived assuming that the detonation velocity depends on the curvature of the front. It was taken into account that the boundary angle between the normal to the front and the HE edge is unique for each combination of HE and liner material. It was found that the same detonation front profile corresponds to several combinations of liner material and the determining size of the charge (plate thickness, radius of the cylinder or the inner radius of the ring). A comparison of experimental front profiles near the edges of HE charges for these combinations provides data on the dependence of detonation velocity on the curvature of the front at low velocities corresponding to shock-induced detonation regimes. Analysis of previously obtained data for detonating ring charges of low-sensitivity HEs shows that as the detonation velocity decreases, the total front curvature tends to a limit of about 0.05 mm⁻¹, i.e., of the order of the inverse critical diameter. The limit of the front curvature allows predicting the critical detonation diameter.