Experimental measurement of energy release from an initiating layer in an insensitive explosive

When subjected to a shock of insufficient strength to trigger prompt reaction, heterogenous condensed phase explosives can form regions where significant amounts of the explosive remain unreacted for times much greater than the reaction time of the detonating explosive. This phenomena is observed for the explosive PBX 9502 (95 wt% TATB) both for planar and oblique input shocks. In this work, we build on previous results by performing cylinder expansion (CYLEX) tests where the explosive charge is comprised of a faster core of PBX 9501 (95 wt% HMX) inside a slower annulus of PBX 9502. The detonation in the faster PBX 9501 drives an oblique shock into the adjacent PBX 9502, and an annular transverse initiating layer (IL) results. In the test geometry, the IL travels steadily down the length of the test after a short run distance. At radial positions beyond the IL, an annular region of detonating PBX 9502 is observed. Using standard CYLEX test diagnostics, we infer the total energy release of this experiment. By making the assumptions that (1) the combined energy release is comprised of contributions from detonating PBX 9501, detonating PBX 9502, and the IL in the PBX 9502 and (2) mass-specific energy release for the detonating explosives is approximately the same as typically observed for each explosive, the IL energy release and reaction efficiency can be computed. Results are compared to prior results for a similar geometry, and indicate that while shock deadened PBX 9502 does not detonate promptly, it does eventually release a significant portion of its chemical potential energy over longer timescales on the order of 10 µs.     

Experimental and modeling analysis of detonation in circular arcs of the conventional high explosive PBX 9501

We examine the diffraction dynamics of a two-dimensional (2D) detonation in a circular arc of the conventional HMX-based, high performance, solid explosive PBX 9501, for which the detonation reaction zone length scale is estimated to be of the order of 100–150 µm. In this configuration, a steady propagating detonation will develop, sweeping around the arc with constant angular speed. We report on results from three PBX 9501 arc experiments, exploring the variation in linear speed on the inner and outer arc surfaces for the steady wave along with the structure of the curved detonation front, as a function of varying inner surface radius and arc thickness. Comparisons of the properties of the motion of the steady wave for each arc configuration are then made with a spatially-distributed PBX 9501 reactive burn model, calibrated to detonation performance properties in a 2D planar slab geometry. We show that geometry-induced curvature of the detonation near the inner arc surface has a significant effect on the detonation motion even for conventional high explosives. We also examine the detonation driving zone structure for each arc case, and thus the subsonic regions of the flow that determine the influence of the arc geometry on the detonation propagation. In addition, streamline paths and reaction progress isolines are calculated. We conclude that a common approximation for modeling conventional high explosive detonation, wherein the shock-normal detonation speed is assumed equal to the Chapman–Jouguet speed, can lead to significant errors in describing the speed at which the detonation propagates.     

高能炸药爆速曲率关系的一种计算方法

研究平面爆轰波爆轰化学能和状态方程之间的关系,得到平面爆轰波关系式和CJ条件.基于柱坐标系下的一维流体力学方程组,采用坐标变换方法得到含曲率的爆轰波关系式及广义声速条件.在反应区内采用压力平衡和温度平衡的混合规则,在给定的复杂状态方程和复杂反应率下求解,得到PBX9404和PBX9502炸药的爆速和曲率的关系.已知炸药...     

PBX-9502炸药爆轰反应速率模型研究

利用高能炸药爆轰反应的拉格朗日分析方法,得到了一个形式简单的PBX-9502炸药的爆轰反应速率方程。运用该速率方程,计算了PBX-9502炸药爆轰波反应区的纵向结构,并与三项式点火增长模型的计算结果及实验结果进行比较。结果表明:该爆轰反应速率方程能很好地模拟PBX-9502炸药爆轰波反应区的纵向结构。     

Calibration of the Pseudo-Reaction-Zone model for detonation wave propagation

An approach for the calibration of an advanced programmed burn (PB) model for detonation performance calculations in high explosive systems is detailed. Programmed burn methods split the detonation performance calculation into two components: timing and energy release. For the timing, the PB model uses a Detonation Shock Dynamics (DSD) surface propagation model, where the normal surface speed is a function of local surface curvature. For the energy release calculation and subsequent hydrodynamic flow evolution, a Pseudo-Reaction-Zone (PRZ) model is used. The PRZ model is similar to a reactive burn model in that it converts reactants into products at a finite rate, but it has a reaction rate dependent on the normal surface speed derived from the DSD calculation. The PRZ reaction rate parameters must be calibrated in such a way that the rate of energy release due to reaction in multi-dimensional geometries is consistent with the timing calculation provided by the DSD model. Our strategy for achieving this is to run the PRZ model in a detonation shock-attached frame in a compliant 2D planar slab geometry in an equivalent way to a reactive burn model, from which we can generate detonation front shapes and detonation phase speed variations with slab thickness. In this case, the D _n field used by the PRZ model is then simply the normal detonation shock speed rather than the DSD surface normal speed. The PRZ rate parameters are then iterated on to match the equivalent surface front shapes and surface phase speed variations with slab thickness derived from the target DSD model. For the purposes of this paper, the target DSD model is fitted to the performance properties of an idealised condensed-phase reactive burn model, which allows us to compare the detonation structure of the calibrated PRZ model to that of the originating idealised-condensed phase model.     

某PBX炸药的动态力学性能研究

 PBX炸药作为现代武器的主装药,它的力学行为决定着武器的生存能力。为了研究PBX炸药的动态力学特性,采用分离式霍普金森压杆（Split Hopkinson Pressure Bar,SHPB）作为加载手段,结合半导体应变片测试技术和压电晶体监测技术,保证了实验数据的有效性。利用SHPB加载波整形技术,实现了材料两端应力平衡和常应变率加载,得到了不同应变率（90~410 s^-1）下材料的应力-应变曲线。根据材料的模量、破坏强度和破坏应变随应变率的变化规律,采用粘性修正的Sargin模型,得到了该PBX炸药在单轴压缩下的唯象本构模型,模拟结果与实验曲线符合较好。     

On the experimental verification of the semiconductor model of detonation

An experiment for verifying the semiconductor model of detonation is described. Within this model, the electron thermal conductivity is the decisive parameter in initiating the detonation of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), a low-sensitivity explosive. The idea of the experiment is to detect an increase in the electron concentration in the conduction band and to estimate the electron thermal conductivity from the electrical conductivity of TATB compressed by shock waves of subthreshold intensity.     

Compressive Behavior of TATB Grains inside TATB-Based PBX Revealed by In-Situ Neutron Diffraction

We investigate the(002)lattiee strain evolution of triaminotrinitrobenzene(TATB) grains inside one TATB-based plastic bonded explosive(PBX) through the in-situ neutron diffraction. By comparing the untreated specimen with the thermal-treated one, it is found that the volume-average response of measured TATB grains remains nearly elastic during quasi-static uniaxial compression. The observed changes in TATB(002) lattice strains correlate tightly with the evolution of damage. A damage parameter defined by the macroscopically determined residual strain is further used to describe the damage degree of PBX, which suggests that the compressive behavior of TATB-based PBX is significantly influenced by the damage evolution.     

炸药爆轰的连续介质本构模型和数值计算方法

假定炸药和爆轰产物处于局部热力学平衡状态, 即它们的压力和温度相同, 利用热力学基本关系建立炸药爆轰过程的连续介质本构模型的一般理论框架. 在此框架下, 炸药爆轰本构模型由一组常微分方程构成, 包括炸药和爆轰产物的状态方程、简单混合法则、化学反应速率方程和能量守恒方程, 易于由成熟的计算方法如梯形法等进行求解. 一组广义Maxwell型非线性固体本构形式的微分方程描述了压力和温度随时间的演化速率与应变率和化学反应速率的关系, 借助简单混合物理论, 其中的系数由炸药和爆轰产物的材料参数确定. 未反应的炸药和爆轰产物采用JWL状态方程, 化学反应率方程采用Lee-Tarver点火-燃烧二项式模型, 模拟PBX-9404炸药的一维冲击波起爆过程和爆轰波传播过程. 计算结果表明了本文给出的本构模型和相应计算方法的有效性. 关键词： 炸药爆轰 本构模型 化学反应率方程 数值模拟     

180°圆弧形钝感炸药的爆轰波传播

 采用贴体坐标下与Level Set方法相结合的爆轰冲击波动力学（DSD）计算方法,研究了180°圆弧形钝感炸药中非理想爆轰波的传播过程。通过数值模拟计算和实验测量的对比分析,得到了180°圆弧形炸药中爆轰波传播的一些规律：圆弧形钝感炸药可以实现定常爆轰,即在极坐标中整个爆轰波以固定角速度转动。这种定常阵面的形状和角速度与圆弧的外半径无关,定常体系依赖于圆弧形炸药的内半径和覆盖圆弧的外壳物质。对描述圆弧形炸药中爆轰波传播规律的经验公式进行了研究,结果表明这些经验公式能够准确描述爆轰波速度的变化,在实验测量和预估方面具有一定的参考价值。     

Peel-off case failure in thermal explosions observed by the deflagration cylinder test

We have discovered a previously unidentified thermal explosion mode using the Los Alamos deflagration cylinder test (DFCT). The DFCT is a “pipe bomb”-style test similar to the detonation cylinder test (DTCT), which has been used for many years to calibrate detonation product equations of state. The shot is heated in an oven to a uniform test temperature. The pre-heated high explosive (HE) is triggered by a hot wire initiator on one end. The tube is back-illuminated by a bright light source, and its combustion-driven deformation and subsequent break-up are observed by a high-speed framing camera. Like the DTCT, the DFCT tube wall motion provides the primary diagnostic. A variety of reactive responses are possible, including quasi-steady deflagration and deflagration-to-detonation transition. This paper focuses on the behavior of the HMX-based explosive PBX 9501 at 155 °C. Under this condition burning appeared to occur only at the HE/tube interface, causing the tube to peel away from the HE core. Peel-off propagated as a wave that traveled along the tube at 500 m/s. This failure mode resulted in vigorous case venting, but the response was otherwise benign. We derive a steady peel-off-wave model that reproduces the essential observed features for realistic PBX 9501 parameter values.     

猛炸药RHT-901和钝感炸药IHE-2的爆轰波直角绕射

 采用高速转镜分幅相机和电探针技术研究了猛炸药RHT-901和钝感炸药IHE-2的爆轰波直角绕射图像和不同位置上的爆轰波传播时间。从研究得出，两种炸药都在拐角顶点附近绕射，爆轰波传播时间增长，爆速变小。但是两种炸药绕射爆轰波的状态不一样，钝感炸药IHE-2中爆轰波绕过直角时，在拐角顶点附近约10 mm范围内炸药未完全反应，猛炸药RHT-901中爆轰波绕过直角时未出现类似现象。两者相比，钝感炸药中绕射爆轰波速度变化大，波阵面曲率半径小，而猛炸药的绕射爆轰波速度变化小，波阵面曲率半径大。这说明炸药的爆轰波绕射与炸药的冲击感度、反应区宽度有关。     

Front shock behavior of stable curved detonation waves in rectangular-cross-section curved channels

The propagation of curved detonation waves of gaseous explosives stabilized in rectangular-cross-section curved channels is investigated. Three types of stoichiometric test gases, C₂H₄ + 3O₂, 2H₂ + O₂, and 2C₂H₂ + 5O₂ + 7Ar, are evaluated. The ratio of the inner radius of the curved channel (r_i) to the normal detonation cell width (λ) is an important factor in stabilizing curved detonation waves. The lower boundary of stabilization is around r_i/λ = 23, regardless of the test gas. The stabilized curved detonation waves eventually attain a specific curved shape as they propagate through the curved channels. The specific curved shapes of stabilized curved detonation waves are approximately formulated, and the normal detonation velocity (D_n)?curvature (κ) relations are evaluated. The D_n nondimensionalized by the Chapman–Jouguet (CJ) detonation velocity (D_CJ) is a function of the κ nondimensionalized by λ. The D_n/D_CJ?λκ relation does not depend on the type of test gas. The propagation behavior of the stabilized curved detonation waves is controlled by the D_n/D_CJ?λκ relation. Due to this propagation characteristic, the fully-developed, stabilized curved detonation waves propagate through the curved channels while maintaining a specific curved shape with a constant angular velocity. Self-similarity is seen in the front shock shapes of the stabilized curved detonation waves with the same r_i/λ, regardless of the curved channel and test gas.     

氢化镁储氢型乳化炸药的爆炸特性研究

 通过理论计算和水下爆炸实验,初步研究了MgH₂敏化储氢型乳化炸药的爆炸特性和爆轰反应机理。结果表明：与玻璃微球敏化的乳化炸药相比,MgH₂敏化的乳化炸药水下爆炸的冲击波超压、比冲量、比冲击波能、比气泡能及水下爆炸比总能量显著增加,其中冲击波超压和水下爆炸总能量分别增加了20.5%和31.0%。MgH₂储氢型乳化炸药的爆轰机理与玻璃微球敏化乳化炸药不同,MgH₂在乳化炸药中起到了敏化剂和含能材料的双重作用,即MgH₂在乳化基质中水解产生均匀分布的氢气泡,起到了敏化作用,同时氢气参与爆炸反应,提高了炸药的爆炸能量和做功能力。     

On the structure and accuracy of programmed burn

Accurate computation of the evolution of a (typically curved) detonation front in a complex geometry, and of the state behind it, is a practical problem in the design of devices that use high-energy explosives. Direct numerical simulations are infeasible: accuracy demands high resolution of the smallest scale (the reaction zone), which is typically several orders of magnitude smaller than the device scale. Programmed burn is an engineering alternative that has been shown to produce acceptable results at a fraction of the cost. The underlying algorithm prescribes the trajectory of the detonation front a priori and replaces the actual reaction zone by a mock up that is a few computational cells thick and in which the reaction rate is taken to be a constant. The state of the explosive at the end of the reaction zone is thereby computed at a relatively modest cost, and the bulk of the computational effort is reserved for the region behind the reaction zone wherein the products of detonation perform useful work. The reasons for the remarkable fidelity to which the physical situation is captured by the programmed burn are not well-understood. This investigation, aimed at achieving such an understanding, considers a model problem for a steady, curved detonation propagating down a rate stick. It examines the pseudo-reaction-zone structure of the programmed burn, studies the sensitivity of the state of the reaction products to the choice of the reaction zone length, and compares the results to those for the actual, physical reaction zone. Conclusions are drawn as to the causes behind the success of the programmed-burn algorithm. The analysis is based on the asymptotic limits of small front curvature and small departures from the Chapman–Jouguet speed. Results are presented for ideal as well as nonideal explosives.     

爆轰波在弯管内传播过程数值分析

应用基元反应模型和频散可控耗散格式(DCD)对氢氧爆轰波在弯管内的传播过程进行了数值模拟.计算中氢氧混合物化学反应采用了8种组分20个反应方程式.在处理化学反应引起的刚性问题时采用了时间算子分裂的方法.计算结果表明,在弯管小曲率半径壁面附近,由于膨胀稀疏作用,爆轰波强度减弱,在局部出现前导激波与放热反应区的解藕以及二次起爆现象;在弯管大曲率半径壁面上爆轰波在马赫反射和正规反射之间相互转变,使爆轰波加强.弯管内的爆轰现象与弯管曲率半径有关.     

JB-9001钝感炸药冲击Hugoniot关系测试

 利用“压力对比法”实验技术，通过锰铜压力计测试待测炸药样品和LY12铝样品在LY12铝飞片的同时撞击下的界面压力p_exp和p_Al，从冲击波关系式和正交回归直线拟合分析，确定了JB-9001钝感炸药的冲击Hugoniot关系。     

Modelling detonation of heterogeneous explosives with embedded inert particles using detonation shock dynamics: Normal and divergent propagation in regular and simplified microstructure

This paper discusses the mathematical formulation of Detonation Shock Dynamics (DSD) regarding a detonation shock wave passing over a series of inert spherical particles embedded in a high-explosive material. DSD provides an efficient method for studying detonation front propagation in such materials without the necessity of simulating the combustion equations for the entire system. We derive a series of partial differential equations in a cylindrical coordinate system and a moving shock-attached coordinate system which describes the propagation of detonation about a single particle, where the detonation obeys a linear shock normal velocity-curvature (D_n–κ) DSD relation. We solve these equations numerically and observe the short-term and long-term behaviour of the detonation shock wave as it passes over the particles. We discuss the shape of the perturbed shock wave and demonstrate the periodic and convergent behaviour obtained when detonation passes over a regular, periodic array of inert spherical particles.     

炸药球壳中长程绕射爆轰波的传播行为

 进行了一点引爆的塑料粘结炸药（HMX/TATB=87/7）球壳中长程绕射爆轰波传播实验。针对实验结果给出一种简便的近似计算方法,它能准确地重现炸药球壳中长程绕射爆轰波的非理想传播行为。     

凝聚炸药爆轰波在高声速材料界面上的折射现象分析

凝聚炸药爆轰在边界高声速材料约束下传播时,爆轰波会在约束材料界面上产生复杂的折射现象.本文针对凝聚炸药爆轰波在高声速材料界面上的折射现象展开理论和数值模拟分析.首先通过建立在爆轰ZND模型上的改进爆轰波极曲线理论给出爆轰波折射类型,然后发展一种求解爆轰反应流动方程的基于特征理论的二阶单元中心型Lagrange计算方法来数值模拟典型的爆轰波折射过程.从改进爆轰波极曲线理论和二阶Lagrange方法数值模拟给出的结果看出,凝聚炸药爆轰波在高声速材料界面上的折射类型有四种:反射冲击波的正规折射、带束缚前驱波的非正规折射、带双Mach反射的非正规折射、带λ波结构的非正规折射.