混合炸药爆速加和公式的新描述及其应用

一、引言炸药的爆速是衡量炸药爆轰性能的一项主要指标,又是目前唯一能够准确测量的爆轰参数。国内外对影响爆速的各种因素及估算爆速的方法开展了大量的研究工作,先后发表了各种计算爆速的公式。但是,上述这些公式只适用于C-H-N-O系单质炸药或由这些单质炸药构成的混合炸药,而对含有惰性添加剂或金属粉的混合炸药则概不适用。     

混合炸药爆速加和公式的新描述及其应用

一、引言炸药的爆速是衡量炸药爆轰性能的一项主要指标,又是目前唯一能够准确测量的爆轰参数。国内外对影响爆速的各种因素及估算爆速的方法开展了大量的研究工作,先后发表了各种计算爆速的公式。但是,上述这些公式只适用于C-H-N-O系单质炸药或由这些单质炸药构成的混合炸药,而对含有惰性添加剂或金属粉的混合炸药则概不适用。     

从高效炸药的组成和结构预测它们的爆速

对于全部理想炸药,提出了一种理论最大密度下的爆速和因子F之间的简单经验线性关系,而因子F仅取决於炸药的化学组成和结构。这些炸药包括硝基芳香族化合物、环状和链状硝胺、硝酸酯和脂肪族硝基—硝酸基化合物,以及无氢炸药、无碳炸药和富氢炸药。在估算了爆速的64种炸药中,95％的炸药,其计算值与实测值的偏差在5％以内,98％的炸药在7％以内。唯独硝基甲烷严重地偏离计算爆速(-13％),全部炸药的绝对误差是±2.3％。     

从高效炸药的组成和结构预测它们的爆速

对于全部理想炸药,提出了一种理论最大密度下的爆速和因子F之间的简单经验线性关系,而因子F仅取决放炸药的化学组成和结构。这些炸药包括硝基芳香族化合物、环状和链状硝胺、硝酸酯和脂肪族硝基—硝酸基化合物,以及无氢炸药、无碳炸药和富氢炸药。在估算了爆速的64种炸药中,95%的炸药,其计算值与实测值的偏差在5%以内,98%的炸药在7%以内。唯独硝基甲烷严重地偏离计算爆速(-13%),全部炸药的绝对误差是±2.3%。     

工业炸药的爆轰性能研究

用有机玻璃法测定了岩石膨化、煤矿膨化、铵梯以及乳化炸药的爆速和爆压，同时用VLWR爆轰程序对岩11石膨化硝铵和铵梯炸药的爆轰参数及C—J产物的平衡组成进行了计算。结果表明，工业炸药具有低爆速和低爆压的非理想爆轰特征，而理论计算值和实验值比较接近，获得了较好的结果。     

RDX基铝薄膜炸药与铝粉炸药水下爆炸性能比较

为了减少铝粉炸药在生产过程中因铝粉对环境污染,降低铝粉炸药的撞击感度,提高含铝炸药的成型性及力学性能,将RDX用铝薄膜分层包裹得到新型的铝薄膜混合炸药。将铝薄膜混合炸药与铝粉炸药进行水下爆炸实验与爆速实验,得到两种炸药的爆速与压力时程曲线,经过分析计算得到两种炸药的压力峰值、冲量、冲击波能、气泡脉动周期与气泡能。结果表明：铝薄膜炸药药柱的轴向为RDX与铝薄膜独立贯通的结构,有利于降低混合炸药中添加物对基体炸药爆轰波传播的影响,从而使铝薄膜混合炸药的爆速高于铝粉炸药,导致铝薄膜炸药的冲击波损失系数高于铝粉炸药,使铝薄膜混合炸药的总能量、比气泡能与铝粉炸药相当情况下,其比冲击波能却降低了10.16%～10.33%,计算过程说明铝薄膜混合炸药的C-J压力计算公式具有合理性。     

炸药破甲威力与爆轰参数之间定量关系的探讨

探讨了炸药的破甲威力与爆轰参数之间的关系,发现在一定计算精度范围内,炸药的破甲威力与爆速Ｄ的关系比较复杂,而与爆压Ｐ的关系相对比较简单且具有较高的计算准确度,据此提出,爆压Ｐ与破甲深度ｈ、与破孔体积Ｖ之间的定量关系式。对单质炸药和混合炸药的计算结果表明,计算值与实验值的一致性令人满意。根据这一定量关系,可以确定提高炸药破甲威力的两条件途径,一是提高炸药的爆压,即提高炸药的能量,二是通过设计新型装药结构,提高炸药能量的利用率,应用本文定量关系,不仅能够预测炸药的破甲威力,而且对于寻求具有优良破甲威力的炸药及设计新型装药结构具有一定的参考价值。     

炸药爆轰参数与空中爆炸冲击波超压的关系

为研究炸药爆轰参数与空中爆炸冲击波超压之间的关系,设计了不同铝含量的RDX/Al、HMX/Al混合炸药,并进行了空中爆炸试验。根据爆炸相似理论,用相同条件下实测TNT超压数据,计算了冲击波超压的TNT当量。采用不同方法计算了炸药的爆轰参数。结果表明,炸药空中爆炸冲击波超压与爆热、爆容和爆速乘积TNT当量的1/3次方满足线性关系,且回归线在y轴上的截距为0,斜率与炸药的类型有关。对于TNT,斜率为1;对于RDX/Al混合炸药,斜率为1.053(R2=0.9996);对HMX/Al混合炸药,斜率为1.073(R2=0.9995),表明炸药的爆热、爆速和爆容对空中爆炸冲击波超压的影响相同。     

计算含能材料爆速的一种新方法

讨论了应用ＳｔｉｎｅＪＲ新方法计算单质炸药与混合炸药的爆速。结果表明，Ｓｔｉｎｅ方法的计算精度优于Ｋａｍｌｅｔ参数方法。     

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。     

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 %.     

Predicting Maximum Attainable Detonation Velocity of CHNOF and Aluminized Explosives

This paper describes a simple method to predict the detonation velocity of pure and mixed CHNOF explosives as well as aluminized explosives at their maximum nominal density as one of the most important detonation properties. The new correlation uses the contribution of some structural parameters to apply for a wide range of ideal and non‐ideal explosives. Aluminized explosives have non‐ideal behavior and the Chapman Jouguet detonation velocities significantly differ from those expected from existing thermodynamic computer codes for equilibrium and steady state calculations. With the presented method, there is no need to use any assumed detonation products, heat of formation and experimental data. Detonation velocities at maximum nominal density of explosives predicted by this procedure show good agreement with respect to experimental values. They are more reliable compared to the calculated results of well‐known empirical methods and computed outputs using BKWS equation of state for CHNOF and aluminized 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.     

Calculation of the Energy of Explosives with a Partial Reaction Model. Comparison with Cylinder Test Data

The energy delivered by explosives is described by means of the useful expansion work along the isentrope of the detonation products. A thermodynamic code (W‐DETCOM) is used, in which a partial reaction model has been implemented. In this model, the reacted fraction of the explosive in the detonation state is used as a fitting factor so that the calculated detonation velocity meets the experimental value. Calculations based on such a model have been carried out for a number of commercial explosives of ANFO and emulsion types. The BKW (Becker‐Kistiakowsky‐Wilson) equation of state is used for the detonation gases with the Sandia parameter set (BKWS). The energy delivered in the expansion (useful work) is calculated, and the values obtained are compared with the Gurney energies from cylinder test data at various expansion ratios. The expansion work values obtained are much more realistic than those from an ideal detonation calculation and, in most cases, the values predicted by the calculation are in good agreement with the experimental ones.     

Comparative brisant characteristics of some classes of industrial emulsion explosives

The four types of mixtures consisting of the two bases (aqueous solutions of ammonium nitrate and ammonium dinitroamide) and the two additions (hollow glass microballoons and gunpowder) are considered in this work. On the base of thermodynamic computations of an ideal detonation and accompanying processes (shock and rarefaction waves) there were obtained not only the dependences of detonation parameters on addition quantities to mixtures, but the pressure versus particle velocity diagrams, too, which in comparison with Hugoniots relatively soft (water) and hard (aluminium) substances allowed to determine values of pressure in the shock waves being produced in surroundings nearby the end-wall and lateral surface of a charge. It is proposed to characterize the brisant effect of an explosive by a value of relative brisance which is calculated as percentage ratio of pressures of shock waves generated in surroundings under the same conditions by detonation products of the given explosive and the standard one. It is shown that the brisant effect of the new emulsion explosives is comparable and even can exceed that of TNT of maximal density. It is shown as well that the brisant ability of industrial emulsion explosives can be raised by 60 and more percents by replacing ammonium nitrate with ammonium dinitroamide and hollow glass microballoons with powders being obtained as a result of military industry conversion and utilization of munitions.     

Predicting High Explosive Detonation Velocities from their composition and structure (II)

An earlier paper⁽¹⁾ described a simple linear relationship between detonation velocity of 64 ideal C,H,N,O type explosives at their theoretical maximum densities (TMD's) and a factor. F, that is dependent solely upon chemical composition and structure. Based upon available experimental data for nine fluorine-containing explosives, the equation for calculating the factor has been expanded to include compositional terms for fluorinated compounds. In addition, the reliability of the linear relationship has been further tested against seven more recently published C,H,N,O type explosive experimental detonation velocity data points. The calculated detonation velocity values for all 16 explosives lie within 6.0% of experimental with an absolute error of ± 3.0%.     

Prediction Method for Specific Impulse Used as Performance Quantity for Explosives

A novel method is presented to estimate the prediction of the specific impulse of mostly ideal and less ideal compositions of explosives. It requires only elemental compositions and some structural parameters of pure and composite explosives. There is no need to use the heat of formation of the explosive, which is an essential input parameter to compute the specific impulse through complicated computer codes. Moreover, there is no need to use any assumed decomposition products to calculate the specific impulse. The new simple method gives good results for any C_aH_bN_cO_d explosives, even with complicated molecular structures, and their composite mixtures. The calculated specific impulse can also be used to estimate detonation pressures and velocities of pure and mixed explosives at specified loading densities.     

Analytical and Numerical Study of the Shock Pressures in the Gap Test

This paper analyzes the functional relationship of pressure induced in the gap versus distance travelled. P = k e^−ax. An analytical shock matching calculation is described to evaluate the constant k as a function of the density and the velocity of detonation of the donor explosive. TDL code is used to check the values of the constants for several donor explosives, and to compute the decay constant a. Functions for pentolite are compared with experimental data from bibliography. The method can be used to predict equivalent gap test thicknesses for donor explosives different from the commonly used pentolite.     

Experimental study on the effect of titanium hydride content on the detonation performance of emulsion explosives

In order to improve the explosion characteristics of emulsion explosives, titanium hydride was added to emulsion explosives to produce a new type of hydrogen storage emulsion explosives. Charges with different contents of titanium hydride were evaluated through underwater explosion experiments and detonation velocity tests. The tests on underwater explosion and detonation velocity reveal that compared to pure emulsion explosives, the detonation parameters of emulsion explosives containing titanium hydride showed a trend of first increasing and then decreasing. When the mass ratio of titanium hydride in the emulsion explosive is 1 % to 3 %, all detonation parameters have been improved to a certain extent. When the mass ratio of titanium hydride in the emulsion explosive is 3 % to 10 %, only part of the detonation parameters (specific impulse, specific shock energy, specific total energy and volume energy density) has been improved. The maximum increase of specific impulse, specific shock energy, specific total energy and volume energy density of emulsion explosive containing titanium hydride is 7.06 %, 8.95 %, 3.97 % and 8.22 %, respectively. Based on the analysis, it is evident that though powdered TiH₂ participates in the detonation reaction process of the emulsion explosive, the majority of TiH₂′s energy is released during the secondary reaction occurring after the detonation wave front. Therefore, the detonation performance of emulsion explosives can be effectively improved by adding a certain mass ratio of titanium hydride.