Theoretical Investigation of Pyridine Derivatives as High Energy Materials

In this work, properties of polynitro-bridged pyridine derivatives were systemically studied at the B3LYP/6-31G(d) level. Gas-phase heats of formation (HOFs) for the designed compounds were calculated using isodesmic reactions, and their solid-phase HOFs were estimated using the Politzer approach. All designed compounds possess large solid-phase HOFs, larger than 700 kJ/mol. Based on the predicted crystal densities, solid-phase HOFs, and chemical energies, detonation properties were evaluated by means of Kamlet-Jacobs empirical equations. The results show that detonation velocities and pressures of all of the designed compounds are above 9.30 km/s and 40.00 GPa, respectively. In addition, bond dissociation energy (BDE) was employed to investigate their thermal stability. Considering solid-phase HOFs, detonation performance, and thermal stability, most of the designed compounds meet the requirements of high energy density materials (HEDMs).     

Microstructure effects on the detonation velocity of a heterogeneous high-explosive

ABSTRACT

Although numerous methods exist for the theoretical calculation of detonation parameters of explosives, few thermodynamic-hydrodynamic-based theoretical codes take into account particle size. The basis for their computational analysis is primarily focused on the equation of state of the detonation products, heat of formation, and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing cyclotrimethylene-trinitrmaine (RDX). The principal characteristics examined were the average particle size of RDX, amount of HMX impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. % solids and 27 wt. % polyurethane binder. An equation is developed that accurately predicts detonation velocity based on average particle size, density, and manufacturing process for RDX. The model underscores the significance of the relationship between the average particle size and detonation velocity. Compositions containing smaller average particle sizes of RDX generate higher detonation velocities. A 100 micron increase in the average particle size was shown to decrease detonation velocity by 161 m/s for the monomodal polyurethane compositions used in this study. The relevance of using statistical models for selecting characteristics that result in optimum explosive performance is addressed.     

爆炸喷涂WC-Co涂层研究及在螺杆钻具中的应用

对爆炸喷涂WC- Co涂层的工艺研究表明: 采用还原性气氛, 即C2H2 /O2 值为1∶1 13~1∶1 25范围内, 可获得最佳质量涂层。对WC -Co涂层和MoCr铬镀层的摩擦学性能研究表明: 在水润滑条件下, WC Co涂层的耐磨性是MoCr铬镀层的10倍以上。爆炸喷涂WC -Co在螺杆钻具表面涂层的应用表明: 对于形状复杂的螺杆型面, 采用喷枪对称布置喷涂的方法可获得理想厚度的均匀涂层, 喷涂后的螺杆表面仅经过珩磨抛光, 不需要磨削加工即可满足工程应用。     

脉冲爆震发动机模型机爆震室壁温分布试验研究

利用TVS2000-MKⅡ热成像仪,在脉冲爆震发动机原理性试验模型上,对爆震燃烧室在多循环工作状态下的外壁面温度分布进行了实验研究。发现爆震室外壁面温度分布呈现从前到后逐渐升高的趋势,距推力壁近的区域上升斜率大,距推力壁远的区域上升斜率趋缓,并在爆燃转变为爆震后的区域内温度梯度较小,壁温分布热平衡时间随爆震频率的升高而减小,且基本上呈线性关系。同一轴向位置处,壁温随爆震频率的升高而升高,并呈线性关系,同一爆震频率下,不同轴向位置处,壁温随时间的变化规律基本相同。     

Experimental investigation on two-phase pulse detonation engine

This paper presents some results of experimental investigation on a two-phase pulse detonation engine (PDE) model. Proof-of-principle experiments of this model with liquid C₈H₁₆/air mixture were successfully conducted. Efforts were focused on initiation and propagation of detonation waves by means of one-step detonation initiation method, low-energy ignition system (total stored energy of 50 mJ), and effective Schelkin spiral. Three PDE models with different sizes were tested: 30 mm-I.D. by 2 m-length; 56 mm-I.D. by 2 m-length and 50 mm by 1 m, which were operated over a repetition frequency range from 1 Hz to 36 Hz. One-way valves were used to adaptively control intermittent supplies of air and fuel flows. The results of detonation velocity, over-pressure and impulse measurements were presented. The measured pressure ratio of detonation wave was close to that of C-J detonation. The effects of equivalence ratio, PDE diameter, length, and detonation frequency on its performance were experimentally investigated. The obtained results have demonstrated that the averaged thrust of PDE is approximately proportional to the volume of detonation chamber and detonation frequency. For liquid C₈H₁₆/air mixture, the PDE operation with as short a length as 1000 mm and detonation frequency up to 36 Hz was successfully realized, which made an important step to practical PDE.     

单次爆震波的实验研究

本文对单次爆震进行了实验研究，找出形成爆震波的条件、机理及其规律，为多次脉冲爆震试验及脉冲爆震发动机的设计奠定基础。     

炸药可燃气安全度试验中爆炸压力的测试

在炸药可燃气安全度试验中,爆炸巷道是一个半封闭式的压力容器,内部压力分布情况十分复杂,本文通过理论分析和实际测量,阐明了爆炸巷道内部压力大小,内部压力与内壁压力的比例关系,为进一步开展科学研究奠定了理论和实践基础。     

岩溶发育区微差爆破孔间殉爆引起拒爆的分析

在岩溶发育区进行深孔台阶微差爆破,溶洞和裂缝可能贯通相邻炮孔,先爆孔产生的冲击波,容易通过裂缝殉爆后爆孔的装药,从而破坏起爆网络,产生拒爆.本文通过某石灰石矿爆破实例,分析了在岩溶发育区采用电雷管--导爆索起爆网路进行深孔台阶微差爆破时,岩溶裂隙引起相邻孔装药殉爆,进而产生拒爆的原因,并提出了克服此类拒爆事故的有效措施.     

AP和Al含量对DNTF基炸药燃烧转爆轰的影响

为了研究配方组分对二硝基呋咱基氧化呋咱(DNTF)基复合炸药燃烧转爆轰性能的影响,设计了AP和Al粉摩尔比分别为0.306、0.414、0.574的三种配方。采用同轴电离探针测试技术,对这三种DNTF基复合炸药配方进行了燃烧转爆轰性能试验。从燃烧转爆轰过程中波阵面传播速度及诱导爆轰距离的变化分析了AP和Al粉摩尔比对炸药燃烧转爆轰的影响。结果表明,随着炸药配方中AP和Al摩尔比从0.306增大到0.574,炸药初始燃烧持续时间从1065μs增大1395μs,燃烧速度从141 m·s~(-1)减小到108 m·s~(-1),但对流燃烧段和爆燃段持续时间快速减小,对流燃烧速度从500 m·s~(-1)增加到1668 m·s~(-1),爆燃速度从3000 m·s~(-1)增加到4800 m·s~(-1),发生燃烧转爆轰的诱导爆轰距离从675 mm左右减小到425 mm左右。     

利用支持向量回归对燃爆单元宽度进行预测的方法研究

燃爆单元宽度λ是衡量可燃气体燃爆风险的一项重要参数,通常认为其与特征化学反应区宽度δ的比值是无量纲活化能和无量纲温度的函数。在以上述两个无量纲量为自变量、以λ/δ的对数为因变量对实验数据进行回归的基础上,更进一步引入无量纲压力作为第3个自变量进行回归。另外,针对传统参数回归方法的不足,采用基于机器学习的支持向量回归方法进行数据拟合。比较回归结果发现,与采用二变量模型及参数回归方法相比,采用三变量模型及支持向量回归方法的计算结果与实验数据的拟合度更好,并能更为准确地预测不同初始条件下可燃爆气体的特征单元宽度。