In-hole velocity of detonation(VOD) measurements as a framework for the selection type of explosive

Velocity of detonation （VOD） is one of the most important properties of explosives and indicates perfor- mances of explosives in real time. With the development of blast monitoring systems, continuous VOD monitoring systems are recently available. The VOD measurement in holes helps in comparing and eval- uating relative performances of explosives. The purpose of this paper is a framework for selecting the type of explosives. This paper analyses the results of VOD measurements, carried out at the limestone quarry （Zrnotiti （~~rni kal）, Slovenia. Experiments were conducted to measure VOD in blast holes which were loaded with ANFO, heavy ANFO and emulsion explosives. The explosives are produced at the point of use with mobile equipment. In this study, resistance wire continuous VOD measurement system MicroTrap, VODSYS-4 from MREL was used and framework for selection the type of explosives has been suggested.

Velocity of detonation measurement and fragmentation analysis to evaluate blasting efficacy

In holes, the measurement of the velocity of detonation（VOD） helps in comparing and evaluating relative performance of explosives. In this paper a blast performance assessment was conducted based on the results obtained from the steady state VOD measurement of emulsion explosives HEF100 and degree of blast fragmentation conducted on an open pit blast. The aim of this study was to compare the steady state VOD measured in the field and the published VOD of HEF100 under ideal laboratory conditions and ascertain its efficacy. In the trial, a resistance wire continuous VOD measurement system connected to a SpeedVOD was employed to measure and record the steady state VOD values from five different blast holes. Furthermore, a post fragmentation analysis was conducted using the existing fragmentation models and an image processing software. The steady state VOD values recorded from the field ranged between 4981 m/s to 5387 m/s consistent with the published VOD subjected to ideal laboratory conditions and the analyzed fragmentation size distribution indicates that 90% of the blasted muck pile was within the allowable and optimal 700 mm passing size.

Study on detonation velocity deficits of bending flexible detonation fuses

In order to study the detonation velocity deficits of bending flexible detonating fuses,a physical model and a theoretical mathematical equation of detonation velocity deficits for bending flexible detonation fuses were established based on the detonation wave＇s corner effects and delay time phenomenon by using non-dimensional analysis method.Besides,a semi-empirical formula of detonation velocity deficit for bending fuses in the same charge size was obtained through experiment and curve fitting.The result shows that an exponential relationship between the detonation velocity deficits and reciprocal of curvature radius.

Thermal Behavior,Sensitivity,Detonation Velocity and Pressure of a Nitrogen-Rich Compound

The nitrogen content of tetrazolo triazines is 68.9%.In this paper,tetrazolotriazines was synthetized.The TG-DSC test indicated its decomposition process in detail.The non-isothermal kinetic parameters were speculated by Kissinger and Ozawa methods.It revealed the mechanism function of thermal decomposition.The impact and friction sensitivity were tested.The detonation pressure and velocity were calculated.It has a wide range of potential applications as a kind of energetic material.

Numerical simulation of flow field characteristics and the improvement of pressure oscillation of rotating detonation engine

Due to the inherent working mode of rotating detonation engine(RDE),the detonation flow field has the characteristics of pressure oscillation and axial kinetic energy loss,which makes it difficult to design nozzle and improve propulsion performance.Therefore,in order to improve the characteristics of detonation flow field,the three-dimensional numerical simulation of annular chamber and hollow chamber is carried out with premixed hydrogen/air as fuel in this paper,and then tries to combine the two chambers to weaken the oscillation characteristics of detonation flow field through the interaction of detonation flow field,which is a new method to regulate the detonation flow field.The results show that there are four states of velocity vectors at the outlet of annular chamber and hollow chamber,which makes RDE be affected by rolling moment and results in the loss of axial kinetic energy.In the external flow field of combined chamber,the phenomenon of cyclic reflection of expansion wave and compression wave on the free boundary is observed,which results in Mach disk structure.Moreover,the pressure monitoring points are set at the external flow field.The pressure signal shows that the high-frequency pressure oscillation at the external flow field of the combined chamber has been greatly weakened.Compared to the annular chamber,the relative standard deviation(RSD) has been reduced from 14.6% to5.6%.The results thus demonstrate that this method is feasible to adjust the pressure oscillation characteristics of the detonation flow field,and is of great significance to promote the potential of RDE and nozzle design.

Microstructure, mechanical and oxidation characteristics of detonation gun and HVOF sprayed MCrAlYX coatings

Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.

Detonation Propagation Characteristics of Superposition Explosive Materials

In order to investigate detonation propagation characteristics of different charge patterns,the detonation velocities of superposition strip shaped charges made up of a detonating cord and explosives were measured by a detonation velocity measuring instrument under conditions of different ignition.The experimental results and theoretical analysis show that the maximum detonation propagation velocity depends on the explosive materials with the maximum velocity among all the explosive materials.Using detonating cord in a superposition charge can shorten detonation propagation time and improve the efficiency of explosive energy.The measurement method of detonation propagation velocity and experimental results are presented and investigated.

Experimental study on detonation parameters and cellular structures of fuel cloud

In this paper, detonation parameters of fuel cloud, such as propylene oxide （PO）, isopropyl nitrate （IPN）, hex- ane, 90# oil and decane were measured in a self-designed and constructed vertical shock tube. Results show that the deto- nation pressure and velocity of PO increase to a peak value and then decrease smoothly with increasing equivalence ra- tio. Several nitrate sensitizers were added into PO to make fuel mixtures, and test results indicated that the additives can efficiently enhance detonation velocity and pressure of fuel cloud and one type of additive n-propyl nitrate （NPN） played the best in the improvement. The critical initiation energy that directly initiated detonation of all the test liquid fuel clouds showed a U-shape curve relationship with equiva- lence ratios. The optimum concentration lies on the rich-fuel side （;b 〉 1）. The critical initiation energy is closely related to molecular structure and volatility of fuels. IPN and PO have similar critical values while that of alkanes are larger. Detonation cell sizes of PO were respectively investigated at 25;C, 35;C and 50;C with smoked foil technique. The cell width shows a U-shape curve relationship with equivalence ratios at all temperatures. The minimal cell width also lies on the rich-fuel side （;b 〉 1）. The cell width of PO vapor is slightly larger than that of PO cloud. Therefore, the deto- nation reaction of PO at normal temperature is controlled by gas phase reaction.

Study on detonation characteristic of low energy detonating fuse in bending conditions

Detonation of low energy detonating fuse was studied in numerical simulation and experiments in bending conditions using LS_DYNA3D. The results show that pressure of the explosion and detonation velocity decrease in the same section areas after bending. In bending conditions, detonation wave was similar to small angle comer diffraction. So the detonation velocity was lower than normal velocity.

环境温度对TATB/RDX传爆药起爆及驱动性能的影响

为了获得环境温度对TATB/RDX传爆药起传爆性能及驱动性能的影响特性,采用激光多普勒测速技术及瞬态太赫兹波多普勒干涉测速技术,对TATB/RDX传爆药在隔层起爆条件下的起爆、传播及驱动性能开展实验研究,获取了-45~70℃温度环境中TATB/RDX传爆药的到爆轰距离、爆轰反应区时间宽度、爆轰传播速度及驱动飞片的飞行速度曲线。结果表明:TATB/RDX传爆药的到爆轰距离及爆轰反应区时间宽度随环境温度的降低均近乎呈线性增长趋势;爆轰传播速度随环境温度的降低而逐渐提高;驱动飞片的速度随环境温度的变化特性在飞片主体-层裂层融合前后存在明显不同。

单相发汗冷却对脉冲爆震燃烧传播的影响

作为一种先进推进系统,脉冲爆震发动机热端部件的热载荷随着工作频率和飞行马赫数的提高而大幅增加。发汗冷却具有很高的冷却效率和更低的冷却剂消耗,使其成为脉冲爆震发动机燃烧室壁面冷却的理想方案。开展发汗冷却与爆震燃烧耦合研究,是爆震发动机发汗冷却设计的理论基础。为了探索发汗冷却的固体和流体结构对爆震燃烧的影响规律,本文采用实验方法,研究了不同多孔介质结构和单相发汗冷却对充分发展爆震燃烧传播过程的影响。结果表明,爆震波在多孔介质壁面上传播时发生减速,但不会引起爆震波解耦。单相发汗冷却引发爆震燃烧失效的主要原因是冷却剂的稀释作用使得局部当量比低于燃料的可爆极限。当冷却剂注入率超过12.5%时,爆震燃烧解耦。

弹间干扰对聚能射流成型及射孔穿深的影响规律

射孔是油气开采过程中的重要一环,射孔间距是影响射流成型效果和穿深的主要参数之一,相邻两射孔弹之间会产生弹间干扰,进而影响射流质量和穿深。为探究弹间距对弹间干扰的影响规律,利用LS-DYNA软件,结合ALE(Arbitrary Lagrange-Euler)算法进行算子分离,实现了单元边界的质量、内能和动量的穿透,并以某油田井下射孔为例,建立了射孔弹—射孔枪—套管—水泥环三维模型,分析了弹间干扰对射流成型和射孔穿深的影响规律。研究结果表明:①弹间干扰降低了射孔弹总能量转化为射流能量的效率:弹间距为5.0 mm时,临近射孔弹射流能量转化率减少0.31%,射流轴向速度减小39 m/s,径向速度增大20 m/s;弹间距为3.5 mm时,临近射孔弹射流能量转化率减少2.21%,射流轴向速度减小130 m/s,径向速度增大111 m/s。②弹间干扰减小了对穿深有效的轴向速度,增加了无效的径向速度,径向速度的增大影响射流质量,使得射流趋向发散,降低射孔穿深。③数值模拟结果揭示,随着相位角的减小,射流线之间的距离减小,弹间干扰加强,有效能量转化降低,射孔穿深降低。结论认为,该规律认识给出了弹间干扰对射流成型和射孔穿深的量化影响,可为合理优化射孔孔密和提高射孔弹穿深提供理论依据。

添加复合稀释剂的低爆速乳化炸药的制备及性能

以玻璃微球和滑石粉共同作为稀释剂制备一种低爆速乳化炸药。观察不同质量分数的玻璃微球和滑石粉对乳化炸药形貌的影响,并对乳化炸药的爆速、猛度、空中爆炸冲击波压力及储存稳定性进行测试。实验结果表明,随着滑石粉质量分数的增加,乳化炸药的形貌由乳胶状逐渐向颗粒状转化,爆速呈线性下降,对玻璃微球质量分数为5%、10%、15%的乳化炸药,测得最低爆速分别为3440、2740、2188 m/s。而随着滑石粉质量分数的增加,猛度、空中爆炸冲击波峰值超压均呈非线性下降,当滑石粉控制在一定量时,冲击波正压作用时间变化不大,乳化炸药储存稳定性较好。这种低爆速乳化炸药成本低廉、爆轰性能可调、储存稳定性好,具有较好的实用性。

圆环形燃烧室两相混气旋转爆震波传播过程实验研究

为分析不同燃烧室结构和来流工况对两相混气旋转爆震波传播过程的影响,在圆环形燃烧室内进行了实验研究。获得了不同来流总温T、燃烧室出口堵塞比β以及混气当量比φ对旋转爆震波传播特性的影响,并对典型工况下圆环形燃烧室内旋转爆震波传播频率和切向热声耦合燃烧固有频率进行了计算。结果表明,燃烧室出口堵塞比变小时有利于旋转爆震波的稳定;旋转爆震波传播速度随来流总温和当量比的提高而增加;在两相混气中获得了一种传播速度大幅低于C-J理论值的低速爆震波。

JHX-1不敏感传爆药的起爆与传爆特性研究

聚黑烯-1(JHX-1)是一种新型的不敏感传爆药。采用水悬浮工艺制备了JHX-1,通过模压成型工艺制备了不同尺寸的炸药药柱,利用电测法测试了JHX-1的爆速、临界爆轰直径以及爆轰增长距离。结果表明:JHX-1具有较低的机械感度,摩擦感度最高为8%,撞击感度最高为4%;97%理论最大密度时的爆速为(8432±25)m/s;临界爆轰直径小于5 mm,在临界起爆压力下,爆轰增长距离不大于18 mm。JHX-1在保持不敏感性的同时,具备了良好的起、传爆稳定性。

大质量弹体冲击下带壳装药起爆特性数值分析

为探讨新型抗导弹防护结构,采用非线性动力学软件LS-DYNA,建立典型形状大质量弹体对圆柱形带壳装药结构的冲击起爆数值分析模型,计算分析了不同质量、形状与倾斜角的钨合金块体低速撞击下带壳B装药冲击起爆特性,获得了临界冲击速度,冲击起爆过程及压力变化。结果表明:弹体质量越大,装药内部形成的透射压力波影响范围越广,持续时间越长;质量在0.1~30 kg范围内,弹体冲击起爆带壳装药的性能与弹体的初始动能有关,端盖厚度为20、40、60 mm的B装药发生冲击起爆的弹体临界动能分别为250、930、1 600 kJ;弹体的临界起爆速度随倾斜角φ变化的规律受弹体形状影响,φ≤15°时,圆柱形弹体临界起爆速度最低,φ>15°时,球形弹体临界起爆速度最低。

环氧丙烷/O2/固态氧化剂复合促进甲烷爆轰

为缓解水力压裂的淡水损耗与污染,原位甲烷燃爆压裂技术应运而生.其首要挑战是如何设计助燃剂配方,诱导甲烷产生剧烈爆轰以劈裂页岩.采用点火(环氧丙烷与氧气)及燃烧改进剂(Ba(NO3)2、KMnO4、NaClO3或NaClO4)混合的方案,解决了甲烷爆轰的形成与维系,并初步提升了爆炸特性.在一套502.4L管道爆炸装置中,探究了添加物对甲烷爆轰的贡献,确定了最优配方.发现点火改进剂可提升甲烷爆炸能量并加快燃烧,诱导爆燃转爆轰,而燃烧改进剂可进一步增强爆轰波冲击与传播性能.研究结果获得了效果最佳的NaClO4,最终将甲烷爆轰的超压与速度分别提升了281.4%和117.2%.

以废弃煤矸石为惰性剂的低爆速乳化炸药性能研究

为了研制低成本、低爆速乳化炸药,并将大量废弃的煤矸石进行废物利用以减小环境污染,将3种不同粒径的煤矸石粉末作为惰性剂,添加入乳化炸药中进行了爆速测试、空中爆炸冲击波超压试验和TG-DSC同步热分析。试验表明,随煤矸石粉末质量分数由0%升至40%,爆速呈降低趋势,其中含较小粒径粉末的炸药爆速要较低,当3#煤矸的质量分数达40%时爆速降至2 755 m/s,空中爆炸冲击波超压峰值由48.53 kPa降至22.23 kPa,正压时间从343.15μs升至426.10μs,压力上升速率由2.210 9 kPa/μs降至0.369 1 kPa/μs,正相冲量减少25.44%。可见煤矸石可有效降低乳化炸药的爆速和爆轰冲击载荷。热分析结果表明,煤矸石粉末未显著改变乳化炸药热分解结果,仅使热分解温度下降29~34℃,仍处于乳化炸药合理的热分解温度范围。

含攻角动能块撞击带壳B炸药冲击起爆阈值研究

为研究动能块攻角对带壳B炸药冲击起爆阈值速度的影响规律,使用LS-DYNA仿真软件和Lee-Tarver点火与增长模型,对钨合金动能块撞击带壳B炸药进行数值模拟,得到了攻角0°~90°条件下撞击不同盖板厚度(6、10、14 mm)装药的冲击起爆阈值速度;在Jacobs-Roslund冲击起爆判据模型中引入攻角修正项,所得到的冲击起爆判据模型与数值模拟结果吻合较好。结果表明:壳体厚度在6~14 mm范围内,随着攻角的增大,冲击起爆阈值速度先增大后减小。

硝酸铵细度对铵胺炸药性能的影响

为研究硝酸铵细度对铵胺炸药性能的影响,以六亚甲基四胺作为可燃剂制备了一种胶状炸药—铵胺炸药;对多孔粒状硝酸铵进行破碎,分别过20、40、60、80目筛区分不同的细度,对混合各细度硝酸铵颗粒铵胺炸药基质的黏度、炸药的爆速和猛度进行了测试,对炸药进行了储存稳定性实验。结果表明,当硝酸铵细度由0~20目增至80目以上时,铵胺炸药基质的混合均匀性增加,基质的初始黏度由92828mPa·s增至148637mPa·s,基质黏度随着剪切时间增加而逐渐降低,铵胺炸药基质属于触变性流体;炸药的爆速由3569m/s增至4316m/s,猛度由26.00mm增至30.50mm,能量释放更集中,对周围介质的的冲击力提升;分别储存2d和120d的铵胺炸药,爆速降幅均小于5%;说明硝酸铵细度的增加可以提高铵胺炸药的爆轰性能和储存稳定性。