Formation of carbon clusters in deflagration and detonation waves in gas mixtures

Numerical and experimental results of studying the formation of carbon clusters due to propagation of deflagration and detonation waves in enriched acetylene-oxygen and acetylene-air mixtures are described. Experiments are performed in tubes of different diameters (including tubes filled by a porous medium) with wide-range variations of the initial pressure and the fuel-to-oxidizer ratio. A large variety of carbon clusters formed in different regimes of burning of the mixture is found. A typical size of condensed carbon particles is 15–100 nm. In the case of detonation in a porous medium, the size of carbon particles is 15–45 nm; in some tests, large individual fullerene-type particles 150, 400, and 950 nm in size are formed. The fraction of condensed carbon in the total amount of carbon in the initial mixture is found to depend on the wave type; detonation is characterized by the minimum “yield” of condensed carbon. The amount of condensed carbon increases with increasing acetylene concentration in the mixture and initial pressure. The size of carbon particles in the case of deflagration is greater than that in the case of detonation. Cooling of reaction products decelerates condensation and interrupts the growth of carbon particles. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 3, pp. 81–94, May–June, 2008.     

Prediction of Caged Polyaza Polynitroamine (Tetracyclo-HMX) as Energetic Compound

By fusing four HMX rings into a cage, a powerful nitroamine explosive was predicted. The heat of formation (HOF) of hetero pentacyclo-icosane nitro compound of dodecanitrododecaza-pentacyclo[9.5.1.1^3,9. 1^5,15. 1^7,13]icosane (DNDAPI or, alternatively, tetracyclo-HMX) was obtained by using density functional theory B3LYP method with 6-31G? basis set. The isodesmic reactions designed for the evaluation of HOF keep most of the basic ring structures of the title compounds and thus ensure the credibility of the result. The value of HOF is 1394.59 kJ/mol. The predicted detonation velocity of the title compound is 10.6 km/s and detonation pressure is 56.8 GPa, even at 90% of its theoretical density. These values are much larger than those of the widely used 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), indicating that DNDAPI is a promising candidate of high energy material. The dissociation energy for the N-NO₂ bond in the cage skeleton of the title compound is 125.36 kJ/mol.     

Study of continuous velocity probe method for the determination of the detonation pressure of commercial explosives

ABSTRACT

A novel velocity probe, which permits recording the continuous velocities of detonations and shock waves, has been developed based on the transition of operation principle from ionization to pressure-conduction. Using the new probe and the impedance matching method, a series of measuring devices were set up to obtain the shock wave velocities in different inert materials, i.e., water, Plexiglas and paraffin wax. Two test types of powder ammonium nitrate/fuel oil (ANFO), exposed on the ground and tamped in the blast hole, were performed, from which we calculated their detonation pressures, with a density of approximately 0.86 g·cm^?3, ranged from 3.52 GPa to 3.65 GPa, and the adiabatic exponents from 2.24 to 2.30. The results show that the present velocity probe-based method can be used to determine the detonation pressure of commercial explosives conveniently and reliably, which is an important supplement for the testing techniques of explosive performance.     

电雷管导爆索爆压的测试及评价

简要叙述电雷管、导爆索爆压的试验原理,通过试验制定合理的输出压力检测指标,对电雷管的不同部位产生的爆压进行分析,解决人们在生产和实践中存在的一些问题。试验装置是在一个可以提供测试输出压力为1-15GPa的组合设备上进行的。经实验,雷管起爆索临界起爆压力(临界起爆点)为2.4GPa;导爆索起爆射孔弹临界起爆压力为1.6GPa,且同种导爆索条件下,雷管起爆导爆索的难度要远大于导爆索起爆射孔弹的难度;雷管轴向输出压力和雷管末端横向轴出压力对比试验说明,雷管的横向起爆性能优于轴向对接起爆性能;还有,雷管横向与导爆索连接的紧密程度会严重影响雷管的起爆性能。     

喷管对脉冲爆轰发动机爆轰噪声影响的实验研究

喷管不但可以增加脉冲爆轰发动机推力,而且对脉冲爆轰发动机噪声的形成与传播也具有重要作用。为探索脉冲爆轰发动机爆轰噪声形成机理及控制技术,搭建了脉冲爆轰发动机噪声测试实验系统,在不同位置不同角度对3种不同类型喷管的脉冲爆轰发动机爆轰噪声特性进行了研究。研究结果表明,收敛扩张喷管对于减小脉冲爆轰发动机爆轰噪声幅值作用最为明显,在0°方向3 000 mm处可以达到77.13%的降幅;对于收敛喷管,收敛角度越大指向性越明显,而扩张和收敛扩张喷管的喷管出口面积越大指向性越不明显;喉部直径48 mm的收敛扩张喷管与管口直径280 mm和320 mm的扩张喷管对参考半径影响最为显著,参考半径由1 600 mm减小至800 mm. 研究结果对于爆轰噪声机理研究以及脉冲爆轰发动机工程化应用具有重要参考意义。     

一种扫描式六象限激光探测系统弹目交会算法研究

针对某旋转式火箭弹定向战斗部定向探测与起爆控制系统,分析了扫描式六象限激光探测系统的构成和工作原理,提出了由激光束螺旋角计算弹体转速的方法,建立了弹体转速数学模型、弹目相对运动方程及相互间的迭代解耦算法,并编写Fortran程序进行仿真。仿真结果表明,建立的交会算法可以计算得到弹体转速、弹目相对运动速度、目标脱靶量、最佳起爆延迟时间、最佳起爆方位角等参量,且误差分析显示探测方位角误差满足定向战斗部的方位探测精度要求。     

ATBKW微机代码在爆轰参数计算中的应用

1986年版ATBKW微机代码可计算CHNO，CHNOB，CHNO－SiW，CHNOS，CHNOFB，CHNONa，CHNOFCl，CHNOFAl，CHNONa－Al，CHNOCl，CNO，HNO，CHNOClP，CHNF，CHNOAl，CHNOF和CHNOClAl等各种含能材料的爆轰性能。经本文改进和扩充后，可在IBM－PC－XT／AT及其兼容性微机上运行，同时还增加了国内用户要求的爆热和爆轰性能评价标准计算等功能。     

一种新型爆焊粉状乳化炸药的研制

研制了一种新型爆焊用药,以粉状乳化炸药为主体,配以相应量的惰性添加剂A和疏松可燃剂B满足了双金属爆炸复合焊接用药的要求。该混合炸药具有性能稳定、成本低、储存期长的优点。     

Application of pulse detonation technology for boiler slag removal

Pulse detonation technology for removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. This technology offers a potentially convenient, inexpensive, yet efficient way for on-line slag removal. This paper presents a feasibility study that includes both Computational Fluid Dynamics (CFD) simulations and laboratory experiments. CFD simulations provided visual and quantitative data to study the potential mechanisms for removal of slag. Mechanisms included direct impact, flow scrubbing, wave reflection and negative velocity impact on the back side of the tubes. Several experiments were carried out to verify the potential of the pulse detonation technology. Experiments were done using a pulse detonation engine and heat exchanger tubes with different types of slag placed in different orientations on the tubes. Tubes were placed at various distances from the detonation tube and in different configurations. The results present a strong case for the application of this technology for online slag removal. It is especially effective for removal of slag on the back sides of the tubes where other traditional methods are not very successful. A preliminary cost analysis indicated that the technology can be paid for within the first year itself and provide substantial savings in the subsequent years.     

极近距离煤层群下层煤工作面巷道合理布置位置数值模拟

澄合百良旭升煤矿开采的两层煤间距很近,下煤层开采巷道布置受上煤层开采影响大。应用FLAC 3D数值软件模拟分析了极近距离煤层群下煤层工作面巷道采用内错、重叠和外错布置形式时巷道的塑性破坏、顶板垂直应力和下沉位移特征。根据模拟结果分析,采用内错布置方式时巷道的破坏范围、巷道顶板应力变化和变形量均相对较小。通过进一步的数值模拟研究,巷道的塑性破坏大小、顶板垂直应力值和下沉位移量在内错8 m内变化不大,而随着内错距离的增大,塑性破坏范围和垂直应力值等也逐渐增大。结合压力传递影响角理论,经计算应力集中在下煤层中的影响范围为4 m。得出了下煤层开采巷道合理布置应采取内错的方式,具体位置参数为内错4~8 m。