基于爆能等效原理大型模爆器燃气爆炸冲击加载的数值模拟

运用非线性显式动力有限元程序LS-DYNA,基于多物质Euler算法,对TNT炸药和乙炔-空气混合气体两种爆炸源在自由大气场中爆炸产生的冲击波荷载特征参数进行数值模拟,比较两种爆源产生的冲击波压力传播规律。基于爆能等效原理,按超压相等的原则给出了气体爆炸名义比例距离计算公式。结果表明,基于Euler算法可以较好地描述乙炔-空气混合气体爆炸空气冲击波传播规律,爆炸压力随着距爆源距离的增大而迅速衰减,且两种爆源产生的冲击波超压峰值误差随着冲击波传播距离的增大而逐渐减小。采用名义比例距离公式修正后,气体爆炸与炸药爆炸冲击波计算误差可以得到有效控制。当爆炸冲击波超压小于0.5MPa时,可以采用乙炔-空气混合气体代替化学炸药进行模爆器内爆炸实验加载。     

温压炸药在野外近地空爆中的冲击波规律

为了研究温压炸药在敞开空间爆炸中冲击波的规律,选取典型温压炸药制成不同量级的裸药柱进行野外近地空爆实验,同时用TNT进行对比实验,获取温压炸药与TNT的冲击波参数并拟合得到相似律公式。结果表明,温压炸药的冲击波超压峰值在中远场略高于TNT;在相同对比距离处,温压炸药的比冲量明显高于TNT,在对比距离小于2 m/kg1/3的近场,温压炸药的比冲量达到TNT的2倍。引入超压-比冲量曲线描述冲击波特征,表明当超压峰值相同时,温压炸药比冲量更大, 超压峰值在20~50 kPa的中度以下毁伤范围时,温压炸药的比冲量比TNT高40%~60%,可产生更严重的毁伤效应。冲量是爆炸冲击波的重要毁伤元素,应建立与冲量有关的方法评价温压炸药的威力。     

钢筋混凝土排架结构的抗爆破坏等级

为了研究钢筋混凝土排架结构在大当量爆炸冲击波下的破坏规律，依据最大TNT当量为3 t的爆炸试验，对排架主体结构的抗爆破坏等级进行数值模拟研究。通过量纲分析得到1/2缩比模型的荷载参数和结构尺寸。基于Abaqus有限元软件，利用CONWEP方法实现爆炸加载，分别计算装药0.5 t爆距33 m和装药3 t爆距33 m两种工况下排架结构的破坏形态，并与试验结果进行对比。进一步通过控制药量和距离，计算不同超压和冲量下缩比模型的破坏形态。研究结果表明，排架的关键破坏特征为中间承重柱的倾覆转动；数值计算与试验破坏形态吻合较好，特征位移和特征转角的最大相对误差分别为5.6%和4.6%。以承重柱的倾覆角作为划分依据，将计算结果分为3种破坏等级，拟合得到的超压-冲量曲线和药量-距离曲线可用于厂房安全距离和仓库容量设计以及意外爆炸下的破坏程度预估。     

柱形装药空中爆炸冲击波荷载研究

受比例距离、装药长径比、起爆方式、方位角、冲击波入射角以及反射面相对位置等多种因素的影响,球形装药空中爆炸冲击波荷载的计算方法不适用于柱形装药。为探究柱形装药空中自由场爆炸冲击波入射和反射荷载,首先,开展柱形TNT装药单端起爆的空中爆炸试验,并基于显式动力学分析软件AUTODYN进行数值模拟,通过与试验和规范进行对比,验证了采用的有限元分析方法的适用性。进一步开展考虑比例距离、长径比、起爆方式、方位角和刚性反射等因素的1 000余组柱形装药空中爆炸工况的数值模拟。基于模拟结果,揭示了柱形装药空中爆炸入射冲击波峰值超压和最大冲量及其形状因子的分布特征,提出峰值超压和最大冲量临界比例距离的判定准则和确定方法,阐明了刚性反射冲击波峰值超压和反射系数的变化规律。最后,提出柱形装药空中爆炸入射和反射冲击波荷载的计算方法,并得到360余组试验数据的验证。该方法可快速计算作用于建筑结构上的爆炸荷载,并为弹药毁伤效能评估、结构动态响应和破坏分析及其抗爆设计提供参考。     

云爆药剂爆炸超压测试及威力评价

借助压力测试系统,在自由场及地面布置压力传感器,分别测量了熔铸TNT、一次云爆药剂和二次云爆药剂在自由场和地面的爆炸场冲击波超压,经分析处理后拟合得到适用于3种炸药的自由场和空中爆炸超压发展公式,并计算云爆药剂的TNT当量。实验结果表明:实验选用的二次云爆药剂的自由场和地面平均TNT当量相比一次云爆药剂分别提高了60%和69%,说明二次云爆药剂比一次云爆药剂具有更大的超压作用效果;3种药剂的自由场超压峰值都比地面小10%左右,说明地面的反射效应依旧存在,在实际超压威力评估时应采用一定的修正系数。实验结果可丰富云爆药剂和传统炸药的小当量实验对比数据,为云爆药剂爆炸场参数的研究和威力评估提供参考。     

固态燃料空气炸药空爆实验研究

通过四组无约束固态燃料空气炸药(FAE)装置与等质量的TNT在野外开放空间的一次起爆对比实验,测得了不同配方组份FAE装置在不同距离的爆炸超压分布,FAE装置峰值超压比相同距离的TNT高1.14~1.6倍;并运用空气冲击波峰值超压公式计算出了FAE的等效爆炸TNT当量随距离的变化关系,在爆炸场边缘区,FAE装置爆炸当量达到了3.88倍TNT当量;通过高速摄影的图片得到了爆炸产生火球的持续时间和最大作用范围,与等质量TNT爆炸火球相比,FAE的优势明显;运用粉尘爆炸下极限浓度估算了云雾爆轰区半径,并分析了测量到的固态FAE爆炸场的压力分布单调衰减的原因;建议在保持超压不变的情况下,把提高爆温作为提高FAE爆炸性能的主要途径。     

空中强爆炸冲击波地面反射规律数值模拟研究

为准确预测空中强爆炸产生的冲击波载荷分布，基于欧拉坐标系建立了能够模拟具有高密度比、高压力比的强激波问题的二维多介质流体数值方法。结合网格自适应技术，对1 kt TNT当量的空中强爆炸在不同爆炸高度下的冲击波地面反射过程进行了数值模拟，并考虑了真实气体状态方程和空气随高度不均匀分布的影响。计算得到了地面上距爆心投影点大尺度范围内的反射超压和冲量等冲击波载荷分布，并给出了冲击波载荷随爆高的变化规律。     

近场近地爆炸下建筑柱爆炸荷载分布规律及简化模型

为了快速评估近场近地爆炸荷载下建筑柱的动力响应和破坏模式,通过数值仿真方法,探究了近场近地爆炸工况下冲击波在建筑柱迎爆面的分布规律,并提供了该工况下的爆炸荷载简化模型。为此,首先利用已有实验数据验证数值模型,并建立典型近地近场爆炸工况的数值模型,然后研究比例爆距和比例爆高对建筑柱冲击波特征参数的影响规律,最后拟合出柱迎爆面反射冲量和正相超压持续时间的计算公式,将柱迎爆面各点爆炸荷载转化为等效三角形荷载模型,为工程实践中建筑柱遭受近场近地爆炸作用下的抗爆设计提供荷载输入。研究结果表明：当比例爆高小于0.3 m/kg^1/3、比例爆距在0.4～0.6 m/kg^1/3范围时,最大反射冲量沿柱高可简化为三折线分布;当比例爆距在0.6～1.4 m/kg^1/3范围时,最大反射冲量沿柱高可近似简化为双折线分布;在同一比例爆距和比例爆高工况下,随着炸药当量的增加,柱迎爆面相同比例高度处反射超压峰值保持不变而反射冲量正比于当量的立方根。     

温压炸药坑道内爆炸冲击波的数值模拟研究

基于二次反应理论,采用AUTODYN程序对温压炸药(RDX/AP/AL/粘合剂=20/43/25/12,质量比)坑道内爆炸冲击波进行了数值模拟研究。将温压炸药与传统炸药TNT的计算结果进行了比较,结果表明:①在爆炸近区,温压炸药比TNT的爆炸冲击波超压峰值低。但在爆炸远区,温压炸药的爆炸冲击波超压峰值则逐渐超过了TNT,最高达到了TNT的1.48倍;温压炸药爆炸冲击波的冲量峰值始终高于TNT,约为TNT的1.33～1.43倍。②最小二乘拟合得到了温压炸药坑道内爆炸冲击波超压峰值随距离衰减的计算公式,具有一定参考价值。     

复合装药空气中爆炸冲击波传播特性

为了研究复合装药超压爆轰时的径向能量输出特性,选择典型的TNT、JO-8、海萨尔等理想、非理想高能炸药,进行了单一装药、内外层复合装药冲击波超压测试实验。采用自由场压电传感器测量了距爆心2、3、4 m处的冲击波压力,通过Origin软件对实验数据进行去除“零漂”和积分处理,获得了冲击波超压、冲量随距离的变化规律,分析了装药结构、装药类型对实验结果的影响。研究结果表明:与同体积单一装药相比,内外层复合装药对提高径向冲击波超压无优势,但对径向冲击波冲量增益显著,且冲量随传播距离的增加而增大;装药类型对内外层复合装药径向冲击波冲量增益影响较大,非理想/理想复合装药在4 m处的冲量增益大于20%,比理想/理想复合装药更有利于提高战斗部的径向输出威力。     

Optical measurement and scaling of blasts from gram-range explosive charges

Laboratory-scale experiments with gram-range explosive charges are presented. Optical shadowgraphy and high-speed digital imaging are used to measure the explosive-driven shock-wave position as a function of time. From this, shock Mach number-versus-distance from the explosion center can be found. These data then yield the peak overpressure and duration, which are the key parameters in determining the potential damage from an explosion as well as the TNT equivalent of the explosive. Piezoelectric pressure gage measurements of overpressure duration at various distances from the explosive charges compare well with theoretical calculations. A scaling analysis yields an approach to relate the gram-range blast to a large-scale blast from the same or different explosives. This approach is particularly suited to determining the properties and behavior of exotic explosives like triacetone triperoxide (TATP). Results agree with previous observations that the concept of a single TNT equivalence value is inadequate to fully describe an explosive yield, rather TNT equivalence factor and overpressure duration should be presented as functions of radius.      

Analysis of reflected blast wave pressure profiles in a confined room

To understand the blast effects of confined explosions, it is necessary to study the characteristic parameters of the blast wave in terms of overpressure, impulse and arrival time. In a previous study, experiments were performed using two different scales of a pyrotechnic workshop. The main purpose of these experiments was to compare the TNT equivalent for solid and gaseous explosives in terms of mass to define a TNT equivalent in a reflection field and to validate the similitude between real and small scales. To study the interactions and propagations of the reflected shock waves, the present study was conducted by progressively building a confined volume around the charge. In this way, the influence of each wall and the origins of the reflected shock waves can be determined. The purpose of this paper is to report the blast wave interactions that resulted from the detonation of a stoichiometric propane-oxygen mixture in a confined room.     

固态燃料小型FAE装置空中爆炸场效应分析

通过一次引爆固态复合粉尘燃料小型FAE装置与等质量TNT在自由空间的爆炸对比实验,获得了不同距离的峰值超压值,并运用粉尘爆炸下极限浓度对云雾爆轰区半径进行了估算。结果表明,固态燃料小型FAE装置空爆峰值超压分布规律不同于TNT,云雾爆轰区内的峰值超压不呈现单调减的特征,而是在有限范围内呈现波动趋势;云雾爆轰区外的峰值超压随距离增大迅速衰减,但固态燃料小型FAE装置的峰值超压大于相同距离处等质量的TNT。高速摄影观测结果显示,固态燃料小型FAE装置爆炸的化学反应持续时间大于等质量TNT。     

Studies of the TNT equivalence of silver azide charges

Schlieren photographs and shadowgrams have been evaluated to provide the radius-time histories of the shocks generated by explosions of silver azide charges with masses in the milligram range. Series of photographs of the flow field produced by a single explosion were obtained with an image converter camera, to yield a time history of the shock trajectory. These data were used to determine the shock Mach number and subsequently the peak hydrostatic overpressure as a function of radius. The pressure-radius profile was compared with that from a unit charge of TNT to determine the TNT equivalence of silver azide as a function of peak pressure and of distance from the centre of a silver azide charge. The shock radius and time were also determined from single-shot visualizations of silver azide explosions. A new method of analysis was developed so that the charge mass and the TNT equivalence of an explosion could be derived from such a single radius-time measurement. The TNT equivalence factor for silver azide was shown to vary from 0.3 to 1.4, depending on the distance from the centre of the explosion. This agrees well with the generally reported equivalence factor of about 0.4 (Baker et al. 1983), which was probably based on the chemical composition of the material. Procedures are described by which the TNT equivalence factor can be calculated at any specified distance from a silver azide charge of known mass, or from a measurement of the shock radius and time, even when the charge mass is not known. This factor can then be used to determine the physical properties of the TNT blast wave which best describe those from the silver azide charge at the specified distance. A further result of these studies was that the scaling laws for blast waves, whose validity has been verified for charge masses ranging from a few grams to hundreds of tons, i.e., for charge masses varying over more than nine orders of magnitude, also apply for charges with masses of the order of one milligram.Received: 7 April 2003, Accepted: 1 July 2003, Published online: 5 August 2003     

Investigating ground effects on mixing and afterburning during a TNT explosion

In this paper, the unconfined and semi-confined condensed phase explosions of TNT will be studied using large eddy simulations based on the unsteady, compressible, reacting, multi-species Navier–Stokes equations to gain further understanding of the physical processes involved in a condensed phase explosion and the effect of confinement on the physical processes involved. The analysis of the mixing and afterburning of TNT explosions in free air (unconfined) and near the ground (semi-confined) indicates that the combustion region of detonation products and air is determined by the vorticity patterns, which are induced by the Richtmeyer–Meshkov instabilities that arise during the explosion. When the explosive is detonated in the vicinity of a surface, the surface affects the shock propagation by creating complex shock systems, thereby changing the orientation of the vorticity, giving the afterburning a mushroom shape, and increasing performance of an explosive charge by prolonging the existence of the mixing layer and thereby the afterburning.     

FAE爆炸场超压与威力的实验研究

利用现场测试系统动态灵敏度标定技术,分别等精度测试了FAE和TNT爆炸场峰值超压。在此基础上获得了各自的爆炸波峰值超压随传播距离的拟合曲线和TNT当量比。结果表明:FAE爆炸场超压分布规律与TNT有显著区别,前者属于大体积云雾爆炸,爆炸场可划分为云雾爆轰区、云雾边缘区和冲击波作用区;在云雾爆轰区,超压平均值在2.6MPa左右,在小于2/3云雾半径的范围内比同质量的TNT低,在大于2/3的云雾半径范围则显著大于TNT;在冲击波作用区,环氧丙烷燃料的FAE爆炸超压约是TNT爆炸效果的5倍,超压均呈衰减趋势,但FAE衰减比TNT缓慢许多。