Accurately predicting reactive flow is a challenge when characterizing an explosive under external shock stimuli as the shock initiation time is on the order of a microsecond. The present study constructs a new Ignition-Growth reaction rate model, which can describe the shock initiation processes of explosives with different initial densities, particle sizes and loading pressures by only one set of model parameters. Compared with the Lee-Tarver reaction rate model, the new Ignition-Growth reaction rate model describes better the shock initiation process of explosives and requires fewer model parameters. Moreover, the shock initiation of a 2, 4-Dinitroanisole (DNAN)-based melt-cast explosive RDA-2 (DNAN/HMX (octahydro- 1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazoncine)/aluminum) are investigated both experimentally and numerically. A series of shock initiation experiments is performed with manganin piezoresistive pressure gauges and corresponding numerical simulations are carried out with the new Ignition-Growth reaction rate model. The RDA-2 explosive is found to have higher critical initiation pressure and lower shock sensitivity than traditional explosives (such as the Comp. B explosive). The calibrated reaction rate model parameters of RDA-2 could provide numerical basis for its further application.

Investigations of the detonation characteristics of a new aluminized DNAN-based melt-cast explosive RMA-2X (containing 30 wt.% DNAN (2,4-dinitroanisole), 30 wt.% NTO (3-nitro-1,2,4-triazol-5-one), 10 wt.% HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) and 30 wt.% aluminum) were undertaken, as well as a lithium fluoride (LiF) substituted explosive RMF-2X (containing 30 wt.% DNAN, 30 wt.% NTO, 10 wt.% HMX and 30 wt.% LiF). The interfacial velocity experiment was carried out to measure the reaction zone parameters (including the CJ pressure, the pressure at the Von Neumann spike, and the reaction zone length) of RMA-2X. The cylinder test was also performed, and employing the test data, the detonation velocity, the Gurney energy, and the detonation energy of RMA-2X were calculated. Investigation results are analyzed and some conclusions are drawn. The role of aluminum in the detonation characteristics are also discussed. Finally, parameters of the Jones-Wilkins-Lee equation of state of the detonation products were confirmed.

为钝感高能炸药安全性设计和应用提供理论依据和物理基础,深入开展钝感熔铸含铝炸药冲击起爆特性实验研究.建立蓝宝石飞片平面撞击加载炸药一维拉格朗日分析组合式电磁粒子速度计实验测试系统,测量2,4-二硝基苯甲醚(DNAN)基熔铸含铝炸药冲击起爆爆轰成长过程中不同拉格朗日位置的粒子速度-时间变化曲线,获得飞片撞击速度和固相炸药颗粒度等变化对其冲击起爆爆轰成长的影响规律,并确定了该熔铸含铝炸药的冲击Hugoniot关系(D=2.439+2.137u,D为冲击波传播速度,u为粒子速度)和未反应炸药状态方程参数.结果表明:DNAN基熔铸含铝炸药冲击起爆爆轰成长过程的典型粒子速度曲线呈驼峰状,冲击波阵面波后粒子速度明显上升并加速追赶前导波阵面,冲击起爆过程整体表现为加速反应特征;在该装药颗粒度级配范围和加载压力下,加载压力越高或固相炸药颗粒度越小,炸药冲击起爆爆轰成长越快,越早转为爆轰.

A new shock initiation measuring system is developed with the reverse‑impact method， in which the explosive sample was driven by a gas gun and impacted the LiF window at a certain speed. The photonic Doppler velocimetry （PDV） was used to measure the interfacial particle velocity profile between the explosive sample and the LiF window. This measuring system has higher accuracy （3%）， higher time resolution （5 ns） and lower requirement of explosive samples than previous shock initiation measuring methods. Moreover， to explore the effect of aluminum powder， the shock initiation characteristics of three RDX‑based aluminized explosives （RDX/Al） with different contents of aluminum powder （0， 15% and 30%） were investigated by this measuring system. The experimental data indicates that with the same impacting speed， the shock initiation reaction growth becomes slower with a higher content of aluminum powder. The interfacial particle velocity of the RDX‑based aluminized explosive with 30% aluminum powder requires more time to arrive at a peak value， which is 47% longer than that of the RDX explosive. The aluminum powder makes the shock sensitivity significantly decrease and it plays a dilute role in explosive energy during the shock initiation process of aluminized explosives.

To investigate the detonation characteristics of a new aluminized DNAN-based melt-cast explosive RDA-2 (containing DNAN (2,4-dinitroanisole), HMX (cyclotetramethylene tetranitramine) and aluminum), a series of cylinder tests were conducted. The LiF (lithium fluoride) explosive of a similar formulation was also tested to study the influence of aluminum on the detonation characteristics of RDA-2. The cylinder wall expansion velocities were recorded by Photonic Doppler Velocimetry (PDV). From the experimental data, the detonation velocity, the Gurney energy, the detonation energy, and the CJ pressure of the explosives were calculated. Both the detonation velocity and CJ pressure results indicate that the aluminum seems to have no significant influence on the chemical reaction zone of RDA-2. The experimental data shows that a large amount of aluminum reacts behind the CJ point. Finally, the parameters of the Jones-Wilkins-Lee (JWL) equation of the state of the detonation products were determined.

为了探究钝感熔铸含铝炸药的冲击起爆特性,建立化学爆炸加载一维拉格朗日锰铜压阻测试系统,获得了不同加载压力下一典型2,4-二硝基苯甲醚(DNAN)基钝感熔铸含铝炸药的冲击起爆过程压力成长历史.利用熔铸含铝Duan-Zhang-Kim(DZK)细观反应速率模型,确定了该钝感含铝炸药的反应速率模型参数,并对其冲击起爆过程进行了数值模拟研究.结果表明在钝感熔铸含铝炸药的冲击起爆过程中,波阵面附近炸药的反应速率和反应程度均较低,而随着热点点火反应的进行以及化学反应的不断累积,炸药的波后化学反应速率不断增加,并在一段时间后到达峰值.当加载压力越高时,钝感熔铸含铝炸药内部的爆轰成长速率越快.同时,与粒子速度成长历史相比,压力成长历史包含更多的反应速率变化信息,更适用于反应速率模型的验证以及炸药反应流模型参数的确定.

为明确含铝炸药冲击起爆过程中爆轰产物状态方程参数的确定方法,采用2,4-二硝基苯甲醚(DNAN)基熔铸含铝炸药RA1(奥克托今(HMX)/DNAN/Al)和对应含氟化锂(LiF)炸药RF1(HMX/DNAN/LiF)开展φ50 mm标准圆筒试验.利用电探针测速法和光子多普勒速度测试技术获得RA1和RF1炸药的爆速和圆筒膨胀速度,并通过遗传算法和数值模拟技术分别确定两种炸药的爆轰产物状态方程参数.对比RA1与RF1炸药的圆筒速度变化曲线发现:在0～4.6μs时间内,两曲线重合度较高;在4.6μs以后,随着铝粉反应量的增加,两曲线出现明显分离.结果表明:铝粉在爆轰阶段反应量很少,反应主要发生在产物膨胀阶段,由此可得在含铝炸药冲击起爆过程中铝粉的反应量可近似忽略,冲击起爆数值模拟时含铝炸药爆轰产物的状态可由对应含LiF炸药的产物状态方程描述.

A melt-cast Duan-Zhang-Kim (DZK) mesoscopic reaction rate model is developed for the shock initiation of melt-cast explosives based on the pore collapse hot-spot ignition mechanism. A series of shock initiation experiments was performed for the Comp B melt-cast explosive to estimate effects of the loading pressure and the particle size of granular explosive component, and the mesoscopic model is validated against the experimental data. Further numerical simulations indicate that the initial density and formula proportion greatly affect the hot-spot ignition of melt-cast explosives.

An aluminized melt-cast Duan–Zhang–Kim mesoscopic reaction rate model based on the pore collapse hot-spot ignition mechanism is proposed to characterize the shock initiation behavior as well as size effects of explosive particles on the shock initiation of aluminized melt-cast explosives. For aluminized 2,4-dinitroanisole (DNAN)-based melt-cast R1 explosives [containing 60 wt. % HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazoncine), 30 wt. % DNAN, and 10 wt. % aluminium] with different particle sizes of HMX, both shock initiation experiments and corresponding numerical simulations were performed. The numerical results are found to be in good agreement with the experimental data, by which the mesoscopic reaction rate model is verified and the model parameters for the R1 explosive are determined. It is also found that the smaller the particle size of the granular explosive component, the faster the leading shock wave propagates, and the faster the detonation growth inside the aluminized melt-cast explosive.

To investigate the influence rule of quasi‑isentropic loading characteristics on the initiation response characteristics of polymer bonded explosive (PBX), the initiation response process of PBXC03 explosive under quasi-isentropic loadings with different loading pressures(8, 10, 12 GPa) and loading slopes was numerically simulated. The parameters of an elastic/viscoplastic double hollow spherical‑shell collapse reaction rate model (DZK) of PBXC03 explosive were determined by backside particle‑velocity history curves at 1, 1.5, 2, 3 mm and 4 mm obtained from the initiation response experiment of PBXC03 explosive under the quasi‑isentropic loading. The influence rule of peak pressures and loading slope on the initiation response characteristics of PBXC03 explosive under quasi‑isentropic loadings was obtained by the DZK model and the parameters. The results show that the two loading methods(different pressures and loading slopes) have a great influence on the initiation process of PBXC03 explosive. Under other conditions being equal, the higher the loading slope or peak pressure is, the faster the growth of peak pressure curve and the shock wave trace of shock wave front in the explosive, and the shorter the time‑detonation is.

A perforation model is developed to predict the attitude deflection in the oblique perforation of concrete targets by a rigid projectile,in which the inertial moment of the projectile is introduced,together with taking the attitude deflection during the shear plugging sub-stage into account,and the shape of the plug formed on the rear surface of target is also re-investigated.Moreover,a new classification of concrete targets is proposed based on the target thickness,with which the attitude deflections in different kinds of concrete targets are analyzed.It is found that the numerical results by using the new perforation model are in good agreement with the previous experimental data and simulated results.Furthermore,the variations of the attitude deflection with the initial conditions（the initial attitude angle and the initial impact velocity） are investigated.

A series of one-dimensional Lagrangian tests have been performed to examine model parameters in the mesoscopic reaction rate model for shock initiation of multi-component plastic bonded explosives (PBXs) for two multi-component plastic bonded explosives PBXC03 (87% HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazoncine), 7% TATB (triaminotrinitrobenzene), and 6% binder by weight) and PBXC10 (25% HMX, 70% TATB, and 5% binder by weight). As the numerical results are in good agreement with experimental data, the model parameters have been used to predict the effects of variations in mesoscopic properties (the particle size, initial density, binder strength, and content) on the shock initiation characteristics of PBXC03 and PBXC10. It is found that the time to detonation for PBXC03 increases with all these mesoscopic properties, while the time to detonation for PBXC10 is basically independent of its mesoscopic properties. Thus, PBXC03 is sensitive to mesoscopic properties, but PBXC10 is not. Moreover, it is also found that the pressure-history curves behind the initial shock wave in PBXC03 have different trends from PBXC10, which implies different chemical reaction mechanisms. Further analysis reveals that it arises from the different hot spot ignition processes due to their different threshold initiation pressures. The hot spots are ignited gradually and almost simultaneously in PBXC03 and PBXC10, respectively.

To study the influence of different quasi-isentropic loading modes on the ignition and the detonation growth processes of PBXs, a one-dimensional numerical model based on the DZK reaction rate model is presented, and then the parameters of DZK reaction rate model of PBXC03 can be experimental calibrated under the quasi-isentropic loadings. Moreover, the ignition and detonation growth processes of PBXC03 under different quasi-isentropic loading modes are simulated by using DYNA2D. It is found from the numerical results that both the increase of the peak pressure of shock front and the shock wave speed increase but the time to detonation decreases with the peak loading pressure, loading slope and curvature. It is also found that the explosive initiation process under the quasi-isentropic loadings can be divided into two stages: one is the initial stage that manifests mainly as the catch-up and convergence of the quasi-isentropic waves and the formation of shock waves; the other is the stage of shock initiation, in which a shock wave with a certain intensity is formed and grows gradually into a stable detonation wave. In addition, a necessary condition is proposed to discriminate the feasibility of an quasi-isentropic loading experimental calibration of the EOS parameters of a unreacted explosive, i. e., the sample's thickness must be smaller than the thickness of initial reaction.