Detonation Velocity Deficits and Curvature Radius of Mild Detonation Cords

In order to study the detonation velocity deficits of wound mild detonation cords, a physical model and a theoretical mathematical equation for detonation velocity deficits of wound mild detonation cords were established based on the detonation wave’s corner effects and delay time phenomenon by using non‐dimensional analysis method. Besides, a semi‐empirical formula for detonation velocity deficit of wound mild detonation cords in the same charge size was obtained through experiments and curve fitting. Both the theoretical mathematical equation and the semi‐empirical formula show that the detonation velocity deficit of wound mild detonation cords and the reciprocal of the curvature radius have an exponential relationship.     

理想混合炸药模型的提出及其应用

通过建立“理想混合炸药”模型 ,发现理想混合炸药的爆速 Did与纯组分炸药的爆速 Di和质量分数 Wi之间存在着定量关系 ,据此发展了一种计算混合炸药爆速的新方法。对大量混合炸药的计算结果表明 ,爆速计算值与实验值的一致性令人满意 ,平均误差 1.37%。本文方法的提出 ,不仅提供了一种预测混合炸药爆速的方法 ,而且对高爆速混合炸药的研究具有一定的指导意义     

铝含量对RDX基含铝炸药爆压和爆速的影响

利用锰铜压力传感器和测时仪测量了不同铝含量的RDX基含铝炸药的爆压和爆速。拟合出爆压、爆速与铝含量的关系式,分析了铝含量对RDX基含铝炸药爆压、爆速的影响因素。结果表明,随着铝含量的增加,RDX基含铝炸药的爆压和爆速呈线性减小。计算了铝粉的质量分数在0~40%时所对应的PC-J=A(x)0ρD2中的A(x)值,拟合出A(x)值与铝含量的关系式,得到RDX基含铝炸药爆压与爆速之间的关系式。     

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.     

Detonation velocity deficit and curvature radius of flexible detonation fuses

The detonation velocity deficit in bending flexible detonating fuses is studied, based on the detonation wave’s corner effects and delay time phenomenon. A physical model and a theoretical mathematical equation of the detonation velocity deficit are established by using the dimensional analysis. Based on experimental data, a semi-empirical formula of the detonation velocity deficit for bending fuses in the same charge size is derived. It is shown that the detonation velocity deficit and the reciprocal of the curvature radius are in an exponential relationship.     

复合结构装药爆轰波爆速与曲率关系的数值模拟

为了研究复合结构中爆轰波传播速度和曲率的关系,利用通用有限元程序AUTODYN对钝感复合装药结构单点起爆的爆轰效应进行了数值模拟。分析说明了不同尺寸的装药结构爆速和曲率的对应变化情况,根据曲面爆轰波曲率和爆速的线性近似关系,描述了复合装药药柱的爆速与曲率的关系方程,并拟合得到了相关参数。     

一次引爆型云爆剂的爆速计算

以典型一次引爆型云爆剂为基础,根据炸药的热化学理论和爆轰理论,对一次引爆型云爆剂的爆速进行了理论分析和计算,并研究了组分配比及配方对爆速的影响.结果表明,一次引爆型云爆剂的理论爆速与金属粉含量有关,在一定范围内适当增加金属粉含量,可以提高爆速,且金属粉的热值越高,其一次引爆型云爆剂理论爆速也越高.     

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.     

Mean detonation velocity in poorly mixed gas mixtures

A method is proposed for calculating the mean velocity of the front of a plane detonation wave in a poorly mixed mixture of a gaseous hydrocarbon fuel and an oxidizer (oxygen or air). It is assumed that the chemical composition of the mixture exhibits periodic fluctuations in the detonation propagation direction, e.g., owing to gas charge stratification. The method is based on analyzing the functional dependence of the ideal (Chapman–Jouguet) detonation velocity on the molar fraction (normalized molar concentration) of the fuel. It is demonstrated that the mean detonation velocity can be appreciably (by 10–15%) smaller than the ideal detonation velocity. A dependence is found, which allows one to estimate the degree of mixing of the gas mixture on the basis of mean detonation velocity measurements.     

Effect of Mixing Methods on the Thermal Stability and Detonation Characteristics of Ammonium Nitrate and Sodium Chloride Mixtures

A study has examined the effect of mixing methods on the thermal stability and detonation characteristics of ammonium nitrate (AN) and sodium chloride (NaCl) mixtures. NaCl was mixed with AN by two methods. The thermal stability, detonation velocity and structural properties were investigated by differential scanning calorimetry (DSC), measurement of detonation velocity and X‐ray diffraction (XRD). For the mechanical mixing method, in all tested scope of proportions of NaCl in the mixtures, activation energies increase when the proportion of NaCl increases; for solution mixing method, the activation energies decrease first and then start to increase as the proportion of NaCl increases. The detonation velocity of AN‐NaCl mixtures prepared by two mixing methods also showed different results. The results indicate that the mixing methods significantly affect the thermal stability and detonation characteristics of AN.     

惰性气体对氢气/空气爆轰传播的抑制作用

常温常压条件下,在内径52 mm的不锈钢管道中开展了惰性气体对氢气/空气（H₂/air）爆轰的抑制实验研究,通过改变当量比（0.6、0.8、1.0、1.2、1.4）和惰性气体种类（CO₂、N₂、Ar）探讨了三种惰性气体对爆轰火焰速度的影响。结果表明,H₂/air爆轰通过可燃气与惰性气体分界面后,爆轰波发生解耦,火焰速度大幅度下降。整个速度下降过程分为快速下降、波动缓慢衰减、火焰消失三个阶段。三种惰性气体中CO₂的抑制效果最明显,其次是Ar和N₂。相较比热容差异影响,Ar和N₂的分子量差异在爆轰抑制中起到主导性作用。贫燃和富燃条件下爆轰在惰性介质中衰减程度均比化学计量比工况下明显,其中富燃条件下爆轰在惰性介质中的衰减更为明显。     

An empirical confinement model for ANFO explosive

Ammonium-nitrate-fuel-oil (ANFO) explosive, one of the most used mining explosives, exhibits highly non-ideal behaviour. The non-ideality of the detonation is manifested in the strong dependence of the detonation velocity on the charge radius and existence and the characteristics of confinement. This can lead to the detonation velocities as low as one-third of the ideal velocity. The literature reported experimental detonation velocities of cylindrical ANFO charges confined in different confiners (aluminium, copper, steel, polymethyl methacrylate, and polyvinyl chloride) are analysed in this paper. An empirical confinement model, which relates the detonation velocity to the charge radius and the mass of the confiner to the mass of explosive ratio per unit length, is proposed. The model predicts the detonation velocity of unconfined and confined ANFO charges with a mean average percentage error of 8.8 %.     

Possibility of the formation of diamonds as a result of the detonation of picric acid

The dependences of the detonation velocity and electrical resistance on the initial density of picric acid were determined for developing the conclusions made earlier for TNT- and RDX-based comjpositions concerning the effect of diamond formation on the detonation velocity and resistance of detonation products. A discontinuity of the dependence of the detonation velocity on the initial density and an increase of the resistance of the detonation products in the region of this discontinuity, which are related to diamond formation in the detonation wave, were found. The relative position of the dependences of resistance on density and of the discontinuities of the dependences of the detonation velocity on the density for various explosives is discussed.Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 117–121, July–August, 1991.     

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.     

Nanometric Aluminum in Explosives

Aluminum nanopowders, because of their larger surface area, can increase the burning rate of propellants. It has been suggested that the powders could also enhance the detonation properties of certain explosives. For these reasons, an experimental study was undertaken to compare the performance of nanometric and micrometric aluminum in various explosives. No enhancement of performance was found in plastic‐bonded explosives. In fact, a reduction of the detonation velocity was found in plastic‐bonded explosives that are based on an energetic binder system. No increase of the detonation velocity was found in mixtures of aluminum and either Composition B or Ammonium Nitrate Fuel Oil, but a small increase in the heat of detonation was measured. The mixture of TNT and nano‐aluminum demonstrated higher detonation velocities and heats of detonation. The increase was higher at small charge diameters. Nanometric aluminum was shown to reduce the critical diameter of such mixtures, and it is concluded that the nano‐aluminum reacts faster than regular micron‐size particles in TNT/Al compositions.     

Mathematical modeling of detonation suppression in a hydrogen-oxygen mixture by inert particles

The paper addresses the problem of searching for methods that can control, suppress, and attenuate explosive and detonation processes in homogeneous and heterogeneous media (mixtures of reactive gases and inert species). The analysis is performed by analytical and numerical methods. The problem of detonation suppression in a mixture of reactive gases and inert species (argon and sand particles) in a one-dimensional unsteady flow is formulated, and its solution is given. The effect of the particle diameter and concentration on the detonation velocity is determined; the parameters of the detonation wave in a stoichiometric hydrogen-oxygen mixture diluted by a chemically inert gas (argon) and particles is determined. The influence of the initial parameters of the mixture on the possibility of detonation suppression by inert particles is studied. It is shown that the detonation velocity substantially decreases with increasing volume fraction of particles. A decrease in the particle size with an unchanged volume fraction is also found to reduce the detonation velocity.     

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.     

A Low‐Sensitivity Composition Based on FOX‐7

1,1‐Diamino‐2,2‐dinitroethene (DADNE, FOX‐7) is considered to be an explosive combining comparatively high performance and low sensitivity. In the present study, FOX‐7 has been evaluated as a possible replacement of RDX in TNT‐based melt‐cast compositions. A composition containing FOX‐7, TNT, Al and wax, and a method of preparing it were proposed. Its sensitivity to impact, friction, shock wave, jet impact, fast heating, and its thermal stability were tested. Some detonation parameters like the detonation pressure, velocity and heat were measured. Moreover, the Gurney velocity, the so‐called effective exponent of the expansion isentrope and the JWL equation of state of the detonation products were determined from the results of a cylinder test. The detonation characteristics were compared with that obtained for cast TNT.     

Detonation characteristics of ammonium nitrate and activated fertilizer mixtures

To better understand the detonation characteristics of ammonium nitrate (AN) and activated additives mixtures, potassium chloride (KCl) and monoammonium phosphate (MAP) are mixed with AN by different mixing methods. The UN gap test and scanning electron microscopy are applied to study AN and AN-additive mixtures. For the mechanical mixing method, the detonation velocity of AN-additives decreases with increasing the additive proportion, while the detonation velocity of modified AN prepared by the solution mixing method shows the opposite tendency. It is proved that the sensitivity to shock waves increases as the size of AN particles decreases. The type of additives, the mixing methods, and the particle size distribution are important parameters that affect the detonation characteristics of AN.     

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.