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。     

爆轰和燃烧法合成SrAl2O4：Eu2+，Dy3+纳米发光粉

 在低温条件下分别用爆轰法和燃烧法制备出了SrAl₂O₄：Eu²⁺，Dy³⁺ 纳米发光粉。从合成条件、热处理温度等方面详细对比了爆轰法和燃烧法对所制备的SrAl₂O₄：Eu²⁺，Dy³⁺纳米发光粉的晶体生长行为、粒子形貌和光学性质等的影响。研究表明，随着热处理温度的升高，爆轰法制备的纳米发光粉的平均粒径逐渐增大，而燃烧法制备的纳米发光粉的平均粒径先减小后增大，在600 ℃时平均粒径存在一个极小值。在同样热处理温度下，爆轰法制备的纳米发光粉的平均粒径增长明显高于燃烧法合成的纳米发光粉的平均粒径。最后讨论了长余辉的发光机理，并给出了如何改进合成方法的建议。     

制备Al2O3/Cu复合材料中CuO-Al体系的化学反应

 对CuO-Al粉末预制块经不同温度下反应，测试其温度随时间的变化曲线，利用X射线衍射仪对其反应后的试样进行物相分析，得出产生热爆的反应温度及不同温度下的反应产物。 结果表明，CuO-Al体系反应随介质温度升高，可分为3个不同阶段，温度小于1 200 K，不发生化学反应；温度为1 200~1 473 K时CuO-Al体系发生部分化学反应，其产物为Cu₂O、CuAlO₂ 及Al₂O₃；温度高于1 473 K，CuO-Al体系发生化学反应，其产物为Cu和Al₂O₃，此阶段易出现热爆现象。     

高岭石的高温高压相图及其地学意义

 用阻抗匹配法和PZT压电探针技术,在100 GPa的冲击压力范围内测量了初始密度分别为1.375 g/cm³和2.001 g/cm³两种孔隙度叙永石样品的Hugoniot状态方程。根据其p_H-ρ_H线所给出的高温高压相变点,用Grüneisen状态方程计算其相变点压力所对应的温度,并结合常压下受热相变的温度值,建立了“高岭石/Al₂O₃+SiO₂+H₂O”的温度-压力相平衡图。通过该相图与线性地热线的交点推断：高岭石至少可在上地幔50 km深处作为一种含水（OH^-）矿物而稳定存在;或在俯冲板块中至少于133 km深处作为一种含水（OH^-）泥质沉积物的过渡相而存在。     

CH4-O2-N2预混气体爆炸二维数值模拟

 利用CFD软件,基于ISAT算法和简化的甲烷氧化基元反应模型,建立了CH₄-O₂-N₂预混气体的二维湍流爆炸模型。数值计算结果表明,该模型较好地模拟了CH₄-O₂-N₂预混气体在高温气团作用下的点火、燃烧和爆炸过程。计算中,考察了高温点火气团的初始温度和混合气体初始组分对CH₄-O₂-N₂预混气体燃烧和爆炸过程的影响。结果表明：高温气团的初始温度对CH₄-O₂-N₂预混气体的点火延迟时间和燃烧初始阶段有重要影响,但对CJ爆燃没有影响;惰性气体N₂的加入,降低了混合气体的反应活性,导致点火延迟时间增大,燃烧反应速度、爆炸超压和重要自由基浓度都随之减小。相同条件下爆炸超压峰值的计算结果与实验测量结果符合较好。     

感应读出式自猝灭流光计数器

本文介绍了自猝灭流光计数器的新技术——具有阻性阴极的感应读出式自猝灭流光计数器的特点及初步实验结果. 用不同比例的Ar/C₄H₁₀、Ar/CH₄或Ar/CO₂作为基本工作气体, 研究了阳极丝直径、电子学死时间等对计数率坪曲线的影响; 研究了几种不同的猝灭剂(H₂C(OCH₃)₂、C₂H₅OH、C₆H₆、C₇H₁₂)含量与坪曲线的关系; 也测量了该计数器的探测效率和死时间.     

利用分子轨道法计算黑索金的生成热和分子结构

 利用分子轨道方法MNDO、AM1、PM3等计算了高能炸药RDX（C₃H₆N₆O₆）及其中间产物C₃H₆N₅O₄ 、C₃H₆N₄O₂ 、(H₂C)(N—CH₂)(N—CH₂)NN、CH₂＝N—NO₂的分子结构与热力学性质。用PM3方法给出了可与实验直接比较的生成热。     

凝聚炸药中超压爆轰的实验研究

 采用飞片碰撞技术，在TNT/RDX（40/60）炸药中获得了2.5倍于正常爆轰的最大超压值，得到了超压爆轰下爆轰产物物态方程p=Aρ^{k+A₁(p-p_J)}（p－爆压，单位GPa，ρ－密度，单位kg/m³，A=ρ_J/ρ^k_J，p_J=27.06 GPa，ρ_J=2.3×10³ kg/m³，k=2.77，A₁=2.7×10^-3 GPa^-1，下表J代表正常爆轰状态）。该方程还可以较好地描述超压爆轰产物的二次冲击状态。     

液态甲烷的高温密度物态方程理论研究

 采用热力学统计理论研究了液态甲烷在高温高压下分子分解反应特点及该体系的物态方程。着重讨论了体系中CH₄-H₂分子间有效势对体系化学反应平衡及物态方程的影响,并根据实验Hugoniot点(p_H, V)优化确定出其exp-6势函数中的参数值。该势函数的排斥部分值比理想混合条件下Lorentz-Berthelot规则给出的势函数值低约50%,预示着高压下CH₄和H₂之间存在着某种亲合性。用该势函数计算得到的p-T线与现有的两个实验点符合很好。还讨论了CH₄-H₂之间的有效作用势参数对CH₄分子冲击离解度（x）的影响。     

爆轰产物物态方程及CHBr3相变的理论研究

 由吉布斯自由能最小计算处于化学平衡状态的气体和固体混合系统的平衡组分。以BKW和VLW作为爆轰产物的物态方程对几种炸药爆轰参数作了预言，计算结果与实验值吻合得非常好。另外，还对CHBr₃的冲击压缩分解作了化学平衡计算，给出了冲击压缩曲线，对文献[6]中提出的CHBr₃在55~60 GPa存在相变的看法提出了质疑。     

Supercritical fluid thermodynamics from equations of state

Supercritical multicomponent fluid thermodynamics are often built from equations of state. We investigate mathematically such a construction of a Gibbsian thermodynamics compatible at low density with that of ideal gas mixtures starting from a pressure law. We further study the structure of chemical production rates obtained from nonequilibrium statistical thermodynamics. As a typical application, we consider the Soave-Redlich-Kwong cubic equation of state and investigate mathematically the corresponding thermodynamics. This thermodynamics is then used to study the stability of H₂-O₂-N₂ mixtures at high pressure and low temperature as well as to illustrate the role of nonidealities in a transcritical H₂-O₂-N₂ flame.     

一维爆轰波不稳定性的数值模拟

 对当量比为1的乙烷与空气的混合气体的一维爆轰不稳定问题进行数值模拟，得到了不同大小的网格对爆轰不稳定问题数值模拟结果的影响。网格大小Δx由从ZND模型分析得到的导引长度L_in确定，网格大小从0.2L_in变到0.002 5L_in。随着网格变细，没有得到振幅趋于一致的解，每一种网格尺寸得到的解的振幅都互不相同。当网格大小为Δx=0.01L_in、0.005L_in时，得到有规则的爆轰激波阵面压力的振荡，振荡的模式是峰值一大一小的振荡。网格更细时，爆轰波的振荡在计算范围内由一些有规则的振荡和一些较不规则的振荡组成。但爆轰激波阵面压力振荡的波长最后趋于一致，为91~93 mm，与实验得到的胞格长度88 mm很接近。     

Influence of Small Xe Additives on the Detonation Threshold for O<Subscript>2</Subscript>−H<Subscript>2</Subscript>−He Mixtures

The effect of a small Xe additive on the conditions of detonation initiation in incident shock waves of various intensities is studied. The experiments are carried out on a shock tube facility with 10% H₂ + 5% O₂ + 85% He, 10% H₂ + 5% O₂ + 84.75% He + 0.25% Xe, and 10% H₂ + 5% O₂ + 84.5% He + 0.5% Xe mixtures. The addition of Xe led to a shift in the detonation threshold toward weaker shock waves. This effect is probably due to a significant increase in the frequency of high-energy collisions between O₂ and Xe molecules in the shock wave front in comparison with that characteristic of the equilibrium behind the wave, a factor that significantly accelerates the chemical reaction between O₂ and H₂ behind the front. The effect is a consequence of the formation of a specific translational nonequilibrium in the wave front. A previously performed numerical study of the distributions of pairs of O₂ and Xe molecules in the shock wave front shows that this effect can be enhanced by decreasing the Xe concentration from 0.5 to 0.25%. The experiment performed indirectly confirms this conclusion. It turns out that, for the mixture with 0.25% Xe, the detonation threshold shifts more strongly to the region of weaker shock waves than for the mixture with 0.5% Xe. This result gives additional arguments in favor of the assumption that this effect is due to the specifics of the translational nonequilibrium in the wave front.     

On the mechanism of the deflagration-to-detonation transition in a hydrogen-oxygen mixture

The flame acceleration and the physical mechanism underlying the deflagration-to-detonation transition (DDT) have been studied experimentally, theoretically, and using a two-dimensional gasdynamic model for a hydrogen-oxygen gas mixture by taking into account the chain chemical reaction kinetics for eight components. A flame accelerating in a tube is shown to generate shock waves that are formed directly at the flame front just before DDT occurred, producing a layer of compressed gas adjacent to the flame front. A mixture with a density higher than that of the initial gas enters the flame front, is heated, and enters into reaction. As a result, a high-amplitude pressure peak is formed at the flame front. An increase in pressure and density at the leading edge of the flame front accelerates the chemical reaction, causing amplification of the compression wave and an exponentially rapid growth of the pressure peak, which “drags” the flame behind. A high-amplitude compression wave produces a strong shock immediately ahead of the reaction zone, generating a detonation wave. The theory and numerical simulations of the flame acceleration and the new physical mechanism of DDT are in complete agreement with the experimentally observed flame acceleration, shock formation, and DDT in a hydrogen-oxygen gas mixture.     

Formation of a detonation wave in the thermal decomposition of acetylene

The formation of a condensation detonation wave has been experimentally observed in the shock-induced thermal decomposition of acetylene. The stable detonation wave in the 20% C₂H₂ + 80% Ar mixture has been obtained at an initial pressure behind the shock wave of no less than 30 atm. The main kinetic characteristics of the pyrolysis of acetylene—the period of the induction of condensation and the growth rate constant of condensed particles—have been determined. The correlation of various stages of the process with the heat release in the condensation has been analyzed. It has been shown that the period of the particle growth induction is not accompanied by noticeable heat release. The subsequent condensation stages characterized by significant heat release occur very rapidly (faster than 10⁻⁵ s) in the so-called explosive condensation. The analysis of the results indicates that the reactions leading to the growth of large polyhydrocarbon molecules, which precede the formation of condensed carbon particles, constitute the limiting stage of the process, which determines the possibility of the formation of the condensation detonation wave in acetylene. An increase in the pressure is accompanied by the sharp narrowing of the induction region and the transition of the process to the condensation detonation wave.     

Spontaneous initiation and development of hydrogen–oxygen detonation with ozone sensitization

This work studies numerically the spontaneous initiation and sustenance of a detonation wave from a hot spot with a nonuniform initial temperature embedded within an H₂O₂ mixture with and without O₃ addition. For the case with either no or just a small amount of O₃ addition, a weak reaction wave is auto-ignited at the hot spot, accelerates and then transitions to a pulsating detonation, which propagates along the temperature gradient and quenches as it runs into the cold fresh mixture. However, with increasing O₃ addition, the possibility of sustenance of a developing detonation within the gradient is significantly enhanced as it enters the cold mixture. Furthermore, the reduced induction time by O₃ addition leads to earlier appearance of the spontaneous reaction wave and detonation formation in the cold mixture, demonstrating that quenching of the detonation is largely related to the instability property of the mixture because the shortened induction time reduces substantially the instability. It is also noted that, for 5%O₃ addition, a low-temperature flame produced by the O₃ reactions is present in front of the spontaneous reaction wave, inducing a local pressure wave, which facilitates spontaneous initiation and sustains the detonation entering the cold mixture. Moreover, O₃ addition renders the critical temperature to induce the minimum spontaneous wave speed higher than the crossover temperature, while they are very close for the case without O₃.     

空气中激光支持爆轰波实验及理论分析

为了研究激光击穿空气产生的等离子体爆轰波形成机制和传播规律,利用高能量CO2激光器产生强激光,进行了空气中产生激光支持等离子体爆轰波实验。实验中:设置了诱导靶板,用于诱发和定位空气中的激光支持爆轰波;以激光器升压过程球隙放电产生的光信号作为触发源,触发高时间分辨率(纳秒级)的高速相机,记录了激光支持爆轰波的成长和传播全过程。分析了激光支持爆轰波的形成机理和传播规律。采用C-J爆轰理论,计算了激光支持爆轰波的压力和温度。研究结果表明:激光支持等离子体爆轰波形成初期,等离子体爆轰波发光体为球形;随着时间增加,等离子体爆轰波发光体的形状类似流星,且头部为等离子体前沿吸收层,亮度较高,而尾部等离子体温度较低,亮度较弱。等离子体爆轰波高速向激光源的方向移动,爆轰波速度高达18 km/s,温度约为107K。随着激光强度的减弱,爆轰波速度迅速按指数规律衰减,当爆轰波吸收的激光能量不能有效支持爆轰波传播时,爆轰波转变为冲击波。     

液态水、苯和壬基乳化剂混合物冲击压缩特性的实验研究

 利用二级轻气炮在3.75~57.87 GPa 压力范围内，对体积比为10∶10∶1的液态水-苯-壬基酚聚氧乙烯醚混合体系进行了动高压加载实验，获得了10个Hugoniot数据。拟合结果表明，该混合体系的D-u关系可近似用直线方程D=1.407+1.503u_p描述，拟合精度约为0.102。混合体系H₂O-C₆H₆-C₃₅H₆₄O₁₁的冲击压缩实验结果基本符合体积相加原理，而在给定的实验压力区间内，冲击绝热曲线发生多次拐折的事实意味着该系统可能在6 GPa、10 GPa和30 GPa压力点附近发生了多次结构性相变。另外，还讨论了Lawrence-Berthlot混合规则中修正因子对高密度条件下指数-6型相互作用势排斥部分的影响。     

Numerical prediction of oblique detonation wave structures using detailed and reduced reaction mechanisms

Modelling of the structure and the limiting flow turning angles of an oblique detonation wave, established by a two-dimensional wedge, requires the implementation of detailed chemical kinetic models involving a large number of chemical species. In this paper, a method of reducing the computational effort involved in simulating such high-speed reacting flows by implementing a systematically reduced reaction mechanism is presented. For a hydrogen - air mixture, starting with an elementary mechanism having eight species in 12 reactions, three alternate four-step reduced reaction mechanisms are developed by introducing the steady-state approximation for the reaction intermediates HO2, O and OH, respectively. Additional reduction of the computational effort is achieved by introducing simplifications to the thermochemical data evaluations. The influence of the numerical grid used in predicting the induction process behind the shock is also investigated. Comparisons of the induction zone predicted by two-dimensional oblique detonation wave calculations with that of a static reactor model (with initial conditions of the gas mixture specified by those behind the nonreactive oblique shock wave) are also presented. The reasonably good agreement between the three four-step reduced mechanism predictions and the starting mechanism predictions indicates that further reduction to a two-step mechanism is feasible for the physical flow time scales (corresponding to inflow Mach numbers of 8 - 10) considered here, and needs to be pursued in the future.