小型固体火箭发动机尾部点火设计与实验

根据固体火箭发动机点火器设计经验,选用赛璐珞为点火器盒体材料、黑火药为点火药,并以点火压强作为发动机装药可靠点燃的判据。采用头部点火设计经验公式对端面一侧面燃烧、尾部点火的小型固体火箭发动机点火药量进行了初步估算。为获得点火器的点火压强、点火延迟时间等性能参数,设计、加工了模拟发动机尾部点火空间的试验容器,研究了电点火头、电点火管点火方案在不同条件下的试验情况。结果表明,虽然点火药量相同,但两种点火方案的点火压强、点火延迟时间、喷管堵片的打开方式却存在较大差异,基于发动机可靠性、维修性考虑,将电发火管点火方案作为优选方案,并通过发动机点火试验的成功考核。     

美国海军新炸药的发展

过去15～20年间,美国海军炸药的发展集中到对PBX 的研究。这些PBX是一类可以铸装成型的配方。该配方是在柔软的聚合物粘结剂系统内加入了各种粉碎的固体粉末。这类PBX 的钝感性是由于配方的橡胶状物理性能产生的。对水下类炸药来说,是由于配方内使用了独立的燃料和氧化剂组分。这类钝感PBX 对冲击不敏感,在有约束的情况下,能缓慢燃烧且不易诱发从爆燃到爆轰的转交(DDT)。然而,这类PBX 仍易点火,燃料和氧化剂能稳定燃烧。它们是低强度材料,这类钝感PBX 异乎寻常的性能,引起了人们对小规模试验有效性的担心,并强调了在实际环境下,在通用器件中进行大规模试验。     

美国海军新炸药的发展

过去15～20年间,美国海军炸药的发展集中到对PBX的研究。这些PBX是一类可以铸装成型的配方。该配方是在柔软的聚合物粘结剂系统内加入了各种粉碎的固体粉末。这类PBX的钝感性是由于配方的橡胶状物理性能产生的。对水下类炸药来说,是由于配方内使用了独立的燃料和氧化剂组分。这类钝感PBX对冲击不敏感,在有约束的情况下,能缓慢燃烧且不易诱发从爆燃到爆轰的转变(DDT)。然而,这类PBX仍易点火,燃料和氧化剂能稳定燃烧。它们是低强度材料,这类钝感PBX异乎寻常的性能,引起了人们对小规模试验有效性的担心,并强调了在实际环境下,在通用器件中进行大规模试验。     

压装高能炸药的燃烧转爆轰实验研究

用电探针和压力传感器测定了质量分数为95%压装高能炸药(密度为1.86 g/cm~3)的燃烧转爆轰特性.研究了点火药量和约束条件对压装高能炸药燃烧转爆轰过程的影响.结果表明,压装高能炸药难以发生燃烧转爆轰,点火药药量从1.5 g增至3.0 g时,炸药的反应强度有所提高,但对燃烧转爆轰的影响较小.在强约束条件下,该压装炸药能基本实现燃烧转爆轰,爆轰诱导距离约为545 mm.     

PBX炸药细观结构冲击点火的二维数值模拟

为了研究冲击加载下非均质炸药的点火机理,对PBX炸药细观结构在冲击加载下的响应过程进行了二维数值模拟.首先对炸药颗粒的压制过程进行数值模拟,获得PBX炸药的细观结构模型.然后对炸药冲击点火进行数值模拟计算,考虑了热力耦合作用和炸药自热反应,分析了炸药颗粒尺寸、密度和黏结剂对炸药冲击点火的影响.结果表明,冲击作用下PBX...     

密度对压装B炸药燃烧转爆轰性能的影响

以常规武器中常用的B炸药为研究对象,采用电探针及压力传感器测量技术,在相同的实验条件下分别对3种不同密度固体压装B炸药（m（TNT）;m（RDX）=40：60）的燃烧转爆轰性能进行了实验研究。B炸药的密度范围为1．597～1．681g／cm^3。实验结果表明,在相同的约束条件下,炸药密度对其燃烧转爆轰（DDT）性能有较大影响。不同密度炸药的DDT性能不同。较低密度的炸药更容易发生DDT现象,固体压装B炸药存在一个燃烧转爆轰的临界密度值。在较强的约束条件下（45号钢管,内径20mm,外径64mm,长500mm）,密度为1．597g／cm^3的B炸药发生了DDT现象,诱导爆轰距离为295～310mm。     

四种典型炸药燃烧转爆轰试验研究

为了对常用组分构成的炸药燃烧转爆轰(DDT)过程进行预估,采用熔铸工艺制备了P1(40%TNT/60%RDX)、P2(40%DNTF/40%HMX/10%TATB/5%Al/5%添加剂)、P3(25%DNTF/40%AP/30%Al/5%添加剂)3种混合炸药,采用浇注工艺制备了P4(30%RDX/30%AP/30%Al/10%添加剂)炸药,用同轴电离探针测试技术对4种炸药进行了DDT试验,从DDT管的破碎状态、DDT过程中波阵面传播速度及爆轰转变距离分析了DDT响应特征。结果表明,炸药P1、P2、P3发生了DDT,爆轰转变距离范围分别为750~825mm、375~450mm、675~750mm,炸药P4未发生DDT;炸药P2的DDT管破裂最剧烈,炸药P3次之,炸药P1最小,表明DDT管的破碎程度与炸药的爆压正相关;炸药配方中含有热分解温度接近的组分,使热分解放热量快速叠加,促使燃烧状态失稳,提高燃烧向爆轰的转变;浇注成型工艺由于存在惰性添加剂对炸药组分的隔离包覆和吸热作用,降低了炸药由燃烧向爆轰转变的可能性。     

含预制缺陷PBX炸药的力学性能及破坏形式

为探索裂纹缺陷对炸药力学性能和破坏形式的影响,以压装HMX基PBX炸药为对象,采用改进后的圆弧巴西试验,研究了不同预制缺陷条件下炸药的破坏过程,并与无缺陷炸药的试验结果进行对比。结果表明,在所研究的范围内,压装PBX炸药的力学强度随缺陷的空间位置变化显著,最高降幅达75.3%;不同缺陷下炸药的破坏形式差异较大,缺陷与加载方向存在夹角时,炸药存在二次承载的现象,且裂纹从缺陷端部向炸药加载面扩展。     

炸药损伤及损伤炸药环境适应性的实验研究

为研究炸药损伤及损伤炸药的安全性,对有边界限定的压装PBX炸药,采用高、低温贮存、温度冲击的方法进行温度损伤实验;采用冲击、振动、跌落的方法进行冲击损伤实验,并利用CT扫描对炸药的损伤情况进行观察;同时通过冲击、振动、跌落实验,对损伤炸药的环境适应性进行了实验研究.结果表明,低温贮存、温度冲击、冲击实验都会使炸药产生裂纹损伤,温度冲击条件下更易引起炸药裂纹损伤.存在裂纹损伤的炸药经过环境适应性实验,未发生爆炸或燃烧现象.     

基于ABAQUS的PBX炸药烤燃试验数值计算

建立了炸药烤燃过程的三维计算模型,采用Frank-Kamenetskii模型描述炸药自热反应的放热过程,编写了ABAQUS有限元软件的用户子程序HETVAL,模拟计算了不同升温速率、装药尺寸和壳体厚度等条件下PBX炸药的烤燃过程,分析了点火位置的分布规律。计算结果表明,随升温速率的增加和装药长径比的减小,点火位置从PBX炸药内部移向边缘;随着升温速率的增加,炸药的点火时间显著缩短;装药尺寸和壳体厚度对PBX炸药点火时间和点火温度的影响较小。     

Continuous Wave Laser Irradiation of Explosives

Quantitative measurements of the levels of continuous wave (CW) laser light that can be safely applied to bare explosives during contact operations were obtained at 532 nm, 785 nm, and 1550 nm wavelengths. A thermal camera was used to record the temperature of explosive pressed pellets and single crystals while they were irradiated using a measured laser power and laser spot size. A visible light image of the sample surface was obtained before and after the laser irradiation. Laser irradiation thresholds were obtained for the onset of any visible change to the explosive sample and for the onset of any visible chemical reaction. Deflagration to detonation transitions were not observed using any of these CW laser wavelengths on single crystals or pressed pellets in the unconfined geometry tested. Except for the photochemistry of DAAF, TATB and PBX 9502, all reactions appeared to be thermal using a 532 nm wavelength laser. For a 1550 nm wavelength laser, no photochemistry was evident, but the laser power thresholds for thermal damage in some of the materials were significantly lower than for the 532 nm laser wavelength. No reactions were observed in any of the studied explosives using the available 300 mW laser at 785 nm wavelength. Tables of laser irradiance damage and reaction thresholds are presented for pressed pellets of PBX9501, PBX9502, Composition B, HMX, TATB, RDX, DAAF, PETN, and TNT and single crystals of RDX, HMX, and PETN for each of the laser wavelengths.     

PBX炸药剪切流动点火性能的实验研究

为了研究PBX炸药在完全约束加载和剪切流动加载下的点火性能,采用一级轻气炮对完全约束、剪切流动(不同开孔直径)的实验样弹进行加载,采用高速摄影记录了PBX炸药装药在冲击加载过程中的反应情况,并通过压力传感器测得了加载过程中的应力曲线。使用LS-DYNA软件对完全约束加载和剪切流动加载进行四分之一模型仿真计算,用完全约束下应力参数进行模型参数校核,使用校核的模型参数对剪切流动实验进行计算,获得了炸药在不同条件下的流动速率等参数。结果表明,炸药在剪切流动加载过程中相比于完全约束的装药更容易发生反应;剪切流动加载过程中,PBX炸药是否发生反应,不仅与剪切流动速率有关,而且还与单位时间流量有关,3 mm开孔直径单位时间流量比2 mm开孔直径增加62%。     

Effect of Temperature,Density and Confinement on Deflagration to Detonation Transition of an HMX‐Based Explosive

In order to obtain the characteristics of the deflagration‐to‐detonation transition (DDT) of PBX‐2 (an HMX‐based explosive) under different conditions, DDT tests were carried out as a function of charge density, temperature, and shell confinement. In these tests, the energetic materials were electrically ignited. The DDT response characteristics for PBX‐2 with 53 % and 99 % of theoretical maximum density (TMD) were evaluated by different shell thickness confinements at ambient temperature and at 85 °C. The test results with different densities, confinements and temperatures exhibited a wide range of reaction violence. Firstly, at both ambient temperature and at 85 °C under 10 and 20 mm shell thickness confinement, PBX‐2 did not undergo fully DDT at 99 % TMD, only a low velocity detonation (LVD) occurred. Secondly, PBX‐2 at 53 % TMD underwent DDT, and significant influence on the minimum run distance to detonation by the shell confinement thickness was observed. Strong confinement is favorable for the transition of DDT but the confinement does not influence reaction degree. Thirdly, the reaction degree of PBX‐2 at 85 °C was remarkably lower than that at ambient temperature. This insensitizing effect of temperature is induced by the melting and flowing of bonders which reduces the porosity and inhibits an important step of DDT, namely, high turbulent combustion.     

Shock Sensitivity of Pressed RDX‐Based Plastic Bonded Explosives under Short‐Duration and High‐Pressure Impact Tests

The shock sensitivities of plastic bonded explosives were studied with a thin flyer impact test by using two types of pressed RDX. The thin flyer, driven by an electrically exploding plasma, exerts a short‐duration, high‐pressure pulse to the samples to trigger a shock‐to‐detonation process. It was found that the duration and magnitude of the incident shock strongly influence the dominant mode of hot‐spot formation, promoting a fast pore collapsing mechanism while suppressing other slower shear or friction mechanisms, as proposed by Chakravarty et al. [1]. The pressed PBX based on reduced sensitivity RDX had higher shock threshold pressure, compared to the pressed PBX based on commercial RDX. The difference was observed even with a certain portion of external extragranular defects. It is postulated that the internal crystal defects are more efficient than the external porosity in terms of the rapid reaction of hot spots.     

基于气固两相反应流的温压炸药能量释放规律数值模拟及实验验证

为研究气体环境、铝粉含量、空间体积对温压炸药能量释放的影响,基于气固两相反应流模型,建立有限差分-物质点耦合算法,对温压炸药密闭容器内爆炸流场演化进行数值模拟及实验验证。结果表明,温压炸药在空气环境中爆炸释放的能量高于氮气中,壁面冲击波峰值压力和空间准静态压力的增幅分别在20%和80%以上,空间准静态压力随空间体积的增大呈先增大后减小的趋势;铝粉含量越高,冲击波在传播过程中衰减得越慢,空间准静态压力越高;铝粉燃烧反应度随空间体积的增加而下降,当比空间体积超过100m³/kg时,反应度下降到90%以下,且铅粉含量越高,其反应程度越低。     

JOB-9003炸药燃烧转爆轰现象研究

HMX颗粒炸药和JOB－9003炸药进行了燃烧转爆轰（DDT）实验，研究了炸药组分，装药密度以及约束条件对DDT过程的影响，分析了炸药DDT的机理，实验结果表明炸药DDT过程和炸药组分以及装药状态有很大关系。HMX颗粒炸药容量发生DDT现象，而以HMX为主要成分的JOHB－9003压装装药不容易发生DDT现象。     

The Development of a Confined Impact Test for Evaluating the Safety of Polymer‐Bonded Explosives During Warhead Penetration

During warhead penetration, which lasts several milliseconds, warheads undertake moderate pressures reaching hundreds of MPa. Previous methods have been unable to mimic such stimuli to evaluate the safety of ammunitions. Hence, new safety evaluation methods with moderate pressures and long durations to assess the stability of the explosive charges during actual penetrations are needed. Based on existing explosives safety estimation technologies and preliminary understanding of overload environments during penetration, a confined impact model was developed. The peak stimuli pressure is more than 0.3 GPa and the duration of the pressure is between 1 to 3 milliseconds. Various scales of a polymer‐bonded explosive (PBX‐9) were subjected to this confined impact test to study the response characteristics. The ignition mechanism of PBX‐9 was obtained by synthesizing results from X‐ray photoelectron spectroscopy (XPS), computed tomography (CT) scanning, differential scanning calorimetry (DSC) and thermalgravimetric analysis (TG). It was found that cracks formed on the surface during impact and the initial ignition of PBX‐9 is mainly due to the decomposition of Ammonium perchlorate (AP) and hydroxyl‐terminated polybutadiene (HTPB) on the interface at low temperature. Our study indicates that the designers of the PBX formulation should try to control the early decomposition of AP and HTPB in order to let the PBX survive the penetration.     

黏结剂对可燃传火管性能的影响

为研究黏结剂对可燃传火管性能的影响,分别采用惰性黏结剂、含能黏结剂、惰性/含能混合黏结剂和惰性黏结剂/RDX混合物,以卷制工艺制备了4种可燃传火管,测试了其力学性能和定容燃烧性能。结果表明,与制式可燃传火管相比,全部采用含能黏结剂可使可燃传火管的定容燃烧灰分降低69.0%,但拔断力、压缩力和耐压强度分别下降了52%、68%和60%;采用惰性黏结剂/RDX(质量比90∶10)混合物时,可燃传火管的力学性能基本不变,定容燃烧灰分降低12.2%;采用惰性/含能混合黏结剂(质量比为50∶50)时,可燃传火管的燃速和燃烧完全性得到改善,力学性能下降幅度较小。