碳氢混合燃料（C5~C6）气云爆轰胞格结构实验研究

 改进烟迹技术之后，在初始为常温常压的条件下，进行了碳氢混合燃料（C₅~C₆）的气云爆轰胞格结构实验研究，得到了清晰的胞格烟迹记录，同时讨论了燃料气云的当量比和起爆能对胞格结构的影响。实验表明：C₅~C₆混合燃料的爆轰波胞格宽度和胞格长度均随当量比的增加而线性增大；随着起爆能的不断增大，混合燃料的胞格宽度和胞格长度均是先增大后减小，且当起爆能足够高时，在胞格结构内可观察到精细结构的存在。     

气-液-固三相体系云雾爆轰特性的实验研究

在内径为0.2m、高5.4m的大型立式激波管内,同时对液体燃料和黑索金(RDX)粉末进行抛撒,采用底部直接起爆,得到了RDX-液体燃料-空气三相体系的爆压和爆速,利用烟熏技术得到了爆轰波的胞格结构、尺寸及长宽比。结果表明:90#溶剂油-空气两相体系的平均爆压为5~6 MPa,可以将其作为燃料-空气炸药的主燃料;向该燃料中添加硝酸异丙酯(IPN)可以降低其临界起爆能,添加RDX能够提高体系的爆速和爆压。此外,通过理论分析结合实验验证得出,多相爆轰的临界起爆能和爆轰胞格尺寸之间存在与气相爆轰类似的关系。     

均匀炸药冲击起爆和起爆后的行为

 介绍并分析了Campbell等人研究均匀炸药冲击起爆和起爆后行为所获得的实验结果,但不涉及其冲击起爆条件。Campbell等人的实验表明,足够强的冲击波进入硝基甲烷后,经过若干微秒的感应时间,爆轰发生在隔板与炸药间的界面处。这就是说,在均匀炸药中,足够强的冲击虽非瞬时但直接（指不经过其它过程,如爆燃）引发了爆轰。重新处理后的实验数据表明：硝基甲烷起爆后,爆轰波的净爆速小于正常爆速;当进入硝基甲烷的初始冲击波的有效压力p_eff由8.82 GPa升至12.14 GPa时,感应时间t_ind的实验值由3.06 μs降至0.705 μs。以两相的排平（A,m）物态方程描述爆轰产物,较为严格地重新推导了基于热起爆理论的估算感应时间t_ind的公式。在上述p_eff的变化范围内,t_ind的理论值则由248 μs降至0.99 μs,明显地高于实验值。这表明,热起爆理论不适于描述硝基甲烷的冲击起爆行为。从本质上讲,热起爆理论对均匀炸药的冲击起爆行为的描述,不符合物质运动的微观图像,因此,它不适于描述均匀炸药的上述行为。     

BaCO3和TiO2粉末混合物冲击压缩性和BaTiO3冲击合成的实验研究

 利用高能炸药爆轰驱动冲击波、狭缝扫描闪光隙高速照相技术和阻抗匹配解原理，在10~100 GPa压力范围内，测量了BaCO₃和TiO₂粉末混合物的冲击绝热数据。同时，利用轴对称柱面和平面爆轰装置，进行了该混合物样品的冲击后回收实验和回收样品的X射线衍射分析，考察BaTiO₃的冲击合成。测量出的冲击绝热数据，以冲击波压力和比容平面上的结果为例，在约30和45 GPa两个压力值时，比容发生明显跃变。冲击绝热数据与回收样品X射线衍射分析结果相结合，判断出，这两个跃变分别对应于TiO₂从锐钛矿相转变到高压β-TiO₂相，BaCO₃与TiO₂开始急剧化学反应合成出BaTiO₃并放出CO₂。此外，在压力为10 GPa左右作回收实验，其回收样品的X射线衍射分析表明TiO₂由锐钛矿相完全转变为金红石相。     

氢气-空气混合物中瞬态爆轰过程的二维数值模拟

 对高温火团引发的氢气-空气混合气的瞬态爆轰过程进行了二维数值模拟,考虑了H₂-O₂-N₂的详细化学反应动力学机理,该机理包含了19个基元反应和9种组分。采用分裂格式处理带化学反应的Euler方程,其中使用全耦合的TVD格式求解流场,使用基于Gear算法的微分方程解法器求解化学反应过程。计算结果表明：在H₂∶O₂∶N₂＝0.4∶0.4∶0.2（摩尔比）的混合气中,高温气团初始温度为T/T₀=5.3时可诱导爆轰,爆轰波以2 300 m/s的速度传播,同时爆轰波阵面在管壁会形成反射波。还对计算的爆轰波后组分的浓度和温度进行了讨论,为理解爆轰波后结构提供信息。     

爆轰法制备纳米MnFe2O4粉体的实验研究

 采用硝酸铁、硝酸锰作为主要氧化剂，油相作为可燃剂研制成两种不同氧平衡的乳化炸药，均成功地爆轰合成了纳米MnFe₂O₄粉体。用XRD表征粉末的物相结构，并比较了此两种不同氧平衡炸药所得产物成分的区别。根据DSC和XRD结果，分别在200 ℃（1 h）、260 ℃（1 h）、280 ℃（1 h）、360 ℃（40 min）和500 ℃（1 h）下对产物进行热处理，在280 ℃时得到了纯净的纳米MnFe₂O₄颗粒，并用TEM对其形貌进行了观察。实验结果表明，负氧平衡炸药的爆轰产物成分比零氧平衡炸药的爆轰产物相对纯净，280 ℃是一个合适的热处理温度。爆轰法具有合成方便快捷、后期热处理简单的优点。     

环形通道内爆轰波的起爆机制

旋转爆轰发动机环形燃烧室和预爆轰管的设计是影响发动机点火性能的关键因素。为了获得环形燃烧室中的起爆机制，使用多帧短时开快门摄像法，研究了不同含量氩气稀释的乙炔-氧气爆轰波经直管道沿切向进入环形通道中的传播过程和模式，重点关注爆轰波的失效和重新起爆机制。通过分析胞格模式发现环形通道内爆轰波的传播模式可以分为亚临界、临界和超临界3种状态。环形通道内爆轰波在顺时针和逆时针方向同时传播，根据初始压力和环形管道宽度的不同，会出现完全熄爆模式、熄爆-重新起爆模式和完全不熄爆模式，对应亚临界、临界和超临界3种状态。3种状态在顺时针和逆时针方向出现的顺序并不一致，相比较而言逆时针方向更易熄爆。研究同时也发现重新起爆通过两种方式实现：一种是通过解耦爆轰波与内壁面的反射以及其后的横向爆轰波，另外一种是通过燃烧转爆轰。通过分析直管的临界管径发现，随着环形通道宽度的增大，对于高浓度或低浓度氩气稀释的乙炔-氧气爆轰波，其临界管径均趋近于经典衍射问题中不稳定爆轰波的临界管径。实验研究结论将为旋转爆轰发动机燃烧室和预爆轰管的结构设计提供技术支持。     

基于基元反应模型的H2-O2-N2爆轰数值模拟

 采用12组分、23个化学反应的基元化学反应模型,用5阶加权本质无震荡格式（WENO）、3阶TVD Runge-Kutta格式,对H₂-O₂-N₂混合气体胞格爆轰进行了数值模拟。研究了一维ZND爆轰、自维持爆轰的详细结构以及三波点附近的流动结构。计算结果表明：由横波的压力可以显著促进二维爆轰波波阵面的形成;横波的运动生成三波点,三波点造成了爆轰的自维持传播。     

立方氮化硅及其冲击波合成

 立方氮化硅是高温高压研究近期合成得到的一种新物相，与已经在工业上普遍使用的氮化硅的两种六方物相（α相和β相）相比，新物相的密度增加了26%，预期是一种新型功能材料。简要综述了立方氮化硅的研究进展和存在的问题，讨论了立方氮化硅的人工合成和相关物性研究、Ⅳ(A)族氮化物（Ge₃N₄、Sn₃N₄、C₃N₄）的高密度物相研究，以及后尖晶石相氮化物的实验和理论探索等问题。介绍了作者最近利用炸药爆轰加载技术开展的冲击波合成实验结果，以α相氮化硅为冲击压缩前驱体，实现了在单次冲击波压缩实验中合成出了克量级立方氮化硅粉体，为进一步开展立方氮化硅的性能研究奠定了基础。     

PZT95/5粉体的冲击合成反应机理初探

 采用柱面冲击波回收装置，通过炸药爆轰产生的冲击波作用于Pb₄O₃、ZrO₂和TiO₂混合物粉体以合成PZT95/5粉体。通过对回收粉体进行的X射线衍射（XRD）分析，并结合冲击波理论，从实验和理论两个方面探讨了PZT粉体的合成机理和过程。结果表明，PZT的合成反应与Pb₃O₄的分解反应几乎同时进行，由于冲击波的特殊性，系统的温度和压力能同时满足Pb₃O₄分解和PZT合成的反应热力学条件，由Pb₃O₄分解的PbO一旦形成，就立刻与ZrO₂、TiO₂等氧化物反应生成PZT；冲击波合成PZT粉体属于特殊的固相反应，物质的扩散速度和反应速度大大提高。     

涡轮导向器对旋转爆轰波传播特性影响的实验研究

为了研究涡轮导向器对旋转爆轰波传播特性的影响,以氢气为燃料,空气为氧化剂,在不同当量比下开展了实验研究.基于高频压力传感器及静态压力传感器的信号,详细分析了带涡轮导向器的旋转爆轰燃烧室的工作模式以及涡轮导向器对非均匀不稳定爆轰产物的影响.实验结果表明:在当量比较低时,爆轰燃烧室以快速爆燃模式工作;逐渐增大当量比,爆轰燃烧室开始以不稳定旋转爆轰模式工作;继续增大当量比,爆轰燃烧室以稳定旋转爆轰模式工作,且旋转爆轰波的传播速度和稳定性均随当量比的增大逐渐提高.爆轰波下游的斜激波与涡轮导向器相互作用,涡轮导向器对压力振荡的幅值具有明显的抑制作用,但对压力振荡频率的影响较小.随着当量比的增大,涡轮导向器上下游的静压均同时增大,经过涡轮导向器的作用,涡轮下游静压明显降低.     

A scaling analysis of the critical conditions for a deflagration-to-detonations transition

In this paper an intuitive criterion for the deflagration-to-detonations transition (DDT) by turbulent mixing was deduced. An analysis was first carried out to determine the critical conditions for detonation initiation within a reactive mixture, which is non-uniformly heated. It was demonstrated that the critical conditions depend on both the size and the characteristic heating time of the energy source. If the characteristic heating time is larger than a critical value, no detonation initiation can be expected, no matter how large the total energy of the heat source is. The critical parameters obtained were then applied to determine the critical conditions for detonation initiation via turbulent mixing. It was found that the DDT depends on both the mixing time and length scales. According to the Damkohler number, there are two regimes. (a) When the Damkohler number is smaller than unity, the critical integral length scale for DDT decreases as the inverse of the turbulent velocity. (b) When the Damkohler number is larger than unity, the critical integral length scale increases according to the cube of the turbulent velocity. These critical conditions were explained in a turbulent phase diagram of Borghi.(Some figures in this article appear in colour in the electronic version; see www.iop.org)     

破片对带铝壳炸药的冲击起爆数值模拟研究

 采用AUTODYN-2D数值模拟软件，应用冲击起爆Lee-Tarver模型，对钢破片撞击带铝壳Octol炸药的起爆问题进行了数值模拟，分析了冲击起爆机理及破片形状、着速、铝壳厚度等因素对炸药起爆特性的影响规律，利用“升-降”法得到了破片对Octol炸药的临界冲击起爆速度。研究结果对反导战斗部破片杀伤元素的设计具有指导意义。     

Direct blast initiation of spherical gaseous detonations in highly argon diluted mixtures

In this study, direct initiation of spherical detonations in highly argon diluted mixtures is investigated. Direct initiation is achieved via a high voltage capacitor spark discharge and the critical energy is estimated from the analysis of the current output. Stoichiometric acetylene–oxygen mixtures highly diluted with 70% argon is used in the experiment. Previous investigations have suggested that detonations in mixtures that are highly diluted with argon have been shown to be “stable” in that the reaction zone is at least piecewise laminar described by the ZND model and cellular instabilities play a minor role on the detonation propagation. For the acetylene–oxygen mixture that is highly diluted with argon, the experimental results show that the critical energy where the detonation is “stable” is in good agreement with the Zel’dovich criterion of the cubic dependence on the ZND reaction length, which can be readily determined using the chemical kinetic data of the reaction. The experimental results are also compared with those estimated using Lee’s surface energy model where empirical data on detonation cell sizes are required. Good agreement is found between the experimental measurement and theoretical model prediction, where the breakdown of the 13λ relationship for critical tube diameter – and hence a different propagation and initiation mechanism – is elucidated in highly argon diluted mixtures and this appears to indicate that cellular instabilities do not have a prominent effect on the initiation process of a stable detonation.     

Experimental study of detonation in a cryogenic two-phase H2–O2 flow

Direct initiation and propagation of detonation through a cryogenic two-phase flow constituted by liquid oxygen droplets in gaseous hydrogen at 100 K are experimentally investigated. The influence of droplet size distribution is characterized in a cryogenic gaseous helium and liquid oxygen two-phase flow. Droplet sizing and detonation experiments are conducted by varying different parameters: distance from the injector, helium and hydrogen mass flow rates, global equivalence ratio and addition of gaseous nitrogen. Droplet size distributions reveal quick vaporization of the smallest droplets of the cryogenic jet. Results in terms of wave velocity, pressure, and detonation cells show that a detonation wave can be directly initiated, with a propagation wave velocity of 20% higher than the Chapman–Jouguet value. Cell size measurements show that the mixture sensitivity is not affected by the presence of droplets. Addition of gaseous nitrogen reduces only slightly the peak pressure, but the detonation velocity is reduced by about 30%.     

半开口管道中的氢/空气火焰加速和压力发展过程

本文研究了氢／空气预混火焰在半开口管道中的火焰加速现象和压力发展过程．结果表明,重复布置的障碍物对火焰速度和压力提升产生显著的影响．火焰传播状态随着氢气当量比的变化而发生改变,在氢气当量比约为０．３４时,火焰速度出现第一次跃变;随着氢气当量比进一步提高,火焰速度发生第二次跃变,即由爆燃转为爆轰．发生爆轰时氢气当量比的范围随着阻塞比的不同而发生变化．     

Direct detonation initiation with thermal deposition due to pore collapse in energetic materials – towards the coupling between micro- and macroscale

In this work we investigate the initiation of detonations in energetic materials through thermal power deposition due to pore collapse. We solve the reactive Euler equations, with the energy equation augmented by a power deposition term. The deposition term is partially based on previous results of simulations of pore collapse at the microscale, modelled at the macroscale as hotspots. It is found that a critical size of the hotspots exists. If the hotspots exceed the critical size, direct initiation of detonation can be achieved even with a low power input, in contrast to the common assumption that a sufficient power is necessary to initiate detonation. We show that sufficient power is necessary only when the size of the hotspots is below the critical size. In this scenario, the so-called ‘explosion in the explosion’, the initial ignition does not lead to a detonation directly, but detonation occurs later as a result of shock-to-detonation transition in the region processed by the shock wave generated by the initial ignition.     

Effect of ozone addition and ozonolysis reaction on the detonation properties of C2H4/O2/Ar mixtures

Ozone is one of the strongest oxidizers and can be used to enhance detonation. Detonation enhancement by ozone addition is usually attributed to the ozone decomposition reaction which produces reactive atomic oxygen and thereby accelerates the chain branching reaction. Recently, ozonolysis reaction has been found to be another mechanism to enhance combustion for unsaturated hydrocarbons at low temperatures. In this study, the effects of ozone addition and ozonolysis reaction on steady detonation structure and transient detonation initiation and propagation processes in C₂H₄/O₂/O₃/Ar mixtures are examined through simulations considering detailed chemistry. Specifically, the homogeneous ignition process, the ZND detonation structure, the transient direct detonation initiation, and pulsating instability of one-dimensional detonation propagation are investigated. It is found that the homogenous ignition process consists of two stages and the first stage is caused by ozonolysis reactions which consume O₃ and produces CH₂O as well as H and OH radicals. The ozonolysis reaction and ozone decomposition reaction can both reduce the induction length though they have little influence on the Chapman–Jouguet (CJ) detonation speed. The supercritical, critical and subcritical regimes for direct detonation initiation are identified by continuously decreasing the initiation energy or changing the amount of ozone addition. It is found that direct detonation initiation becomes easier at larger amount of ozone addition and/or larger reaction progress variable. This is interpreted based on the change of the induction length of the ZND detonation structure. Furthermore, it is demonstrated that the ozonolysis reaction can reduce pulsating instability and make the one-dimensional detonation propagation more stable. This is mainly due to the reduction in activation energy caused by ozone addition and/or ozonolysis reaction. This work shows that both ozone decomposition reaction and ozonolysis reaction can enhance detonation for unsaturated hydrocarbon fuels.     

隔板深度对激波聚焦起爆影响的数值模拟研究

考虑几何结构参数对激波聚焦触发爆轰波的复杂影响,对H2/Air预混气的环形射流激波聚焦起爆现象开展了数值模拟研究,详细分析了不同隔板深度条件下的激波聚焦过程、流场演化特征以及爆轰波参数变化规律。研究结果表明,凹腔内激波聚焦诱导的局部爆炸以及隔板前缘处射流形成"卷吸涡"是引起爆轰波触发的两个重要机制,而隔板深度是影响环形射流激波聚焦起爆性能的关键因素。随着隔板深度的增加,凹腔内激波聚焦的强度逐步增强,回传的能量损失有所减小,进而导致爆燃转爆轰的距离与时间显著缩短。此外,当隔板深度由1 mm逐渐增加至3 mm时,爆轰波自持传播稳定性呈现出先降低后升高的变化趋势,产生这一现象的主要原因是爆轰波强度与三波点运动的相互作用。