Solid Propellant Extinction by Laser Pulse

The possibility to generate a combustion transient of a composite AP.HTPB/86.14 propellant, burning under steady state conditions, was experimentally demonstrated by using a CO₂ laser energy pulse. The experimental results point out that the burning propellant behavior can be defined by the curves separating, for every operating pressure, the continuous burning from the extinction solutions. In this paper, a simplified theoretical approach gives a phenomenological explanation of the energy pulse effect on the combustion process and the consequent burning propellant response after the deradiation transient. In the framework of this study the extinction condition is formulated in terms of the minimum temperature that causes the burning propellant to quench at the Pressure Deflagration Limit. The proposed theoretical work is aimed, first of all, to determine the critical radiant flux values, for different operating pressures, below which the burning propellant extinction is never achieved even if the laser pulse duration tends to infinity. Then, the extinction boundaries are defined choosing two different approximate approaches that take into account the ratio between the condensed phase relaxation time and the radiant energy pulse duration. Two limit cases, defined as slow/fast interaction of the radiant energy with the combustion process, can be used to describe the burning propellant extinction phenomena, and the results of this work indicate that the general trend of the computed boundary limits reproduces the experimental data.     

丁羟复合推进剂的辐射点火

采用CO2激光点火装置,对丁羟复合推进剂的点火过程进行了实验研究,利用描述固体推进剂物化现象的一维传热模型对复合推进剂的辐射点火特性进行了理论分析。通过最小二乘法拟合实验数据得到了丁羟复合推进剂的点火准则。结果表明,丁羟复合推进剂的点火过程主要包括惰性加热及气相点火过程,惰性加热时间和点火延迟时间随热流密度的增大而减小,且随着热流密度的增大,热流密度的影响逐渐降低。固相传热数学模型能够比较准确地描述复合推进剂的辐射点火特性。     

Low Pressure Combustion of Composite Propellant

The combustion behaviour of two batches of a new type of composite propellant was investigated in the pressure range between 5 kPa and 915 kPa absolute. A newly developed technique to determine simultaneously the burning rate, combustion efficiency, and the propellant's sensitivity for combustion instability is described together with a specially developed data reduction code. Notwithstanding the low pressure during the experiments no lower deflagration limit could be traced but a Vieille type burning rate law appeared to be applicable for the whole pressure range of interest. A large difference found in the combustion behaviour could be attributed to the fact that the two batches had been manufactured with AP from different suppliers. Combustion efficiency was poor while combustion instability occurred in the whole pressure range.     

HTPB/AP复合推进剂冲击波点火实验研究

根据增效射孔器的实际作用,以AP-丁羟（HTPB/AP）复合推进剂为研究对象,利用隔板试验研究了冲击波对AP-丁羟复合推进剂的点火性能,结果表明,合理控制冲击波强度能够使AP-丁羟复合推进剂可靠点燃,并为其它推进剂的点火提供了一种新方法.     

超低分压下CO2在NaOH和Na2CO3水溶液中的溶解度

在10℃、25℃、35℃下分别测定了超低分压下CO2在NaOH和Na2CO3水溶液中的溶解度,并建立了该过程基于化学平衡和相平衡的数学模型。建立了一套CO2在碱性水溶液中吸收的相平衡实验装置,并进行了实验测试和结果分析。     

HTPB/AP复合推进剂装药直径对冲击波点火的影响

为研究HTPB／AP复合推进剂装药直径对冲击波点火的影响作用,用隔板实验测试了不同装药直径对冲击波点火临界燃烧厚度及峰值压力的影响。确定了最佳药柱直径,并对其点火可靠性及药柱受冲击波点火后密度变化进行测试。结果表明,药柱直径与临界燃烧隔板厚度及冲击波强度有着密切的关系。密度为1．563g／cm^3时,HTPB／AP复合推进剂的最佳冲击波点火推进剂装药直径为40mm,且冲击波点火可靠性良好,药柱受冲击波作用后,密度发生一定变化。     

环境气体氧含量对NEPE推进剂激光点火过程的影响

为研究环境气体氧含量对硝酸酯增塑聚醚(NEPE)推进剂激光点火过程的影响,采用CO2激光辐射点火并利用高速摄影仪记录NEPE推进剂的点火过程,讨论了环境气体氧含量对NEPE推进剂初焰位置与点火延迟时间的影响。结果表明,当环境气体氧含量小于NEPE推进剂热解产物中氧化性气体含量时,NEPE推进剂点火的气相反应发生在推进剂热解产物的分散区,初焰紧靠NEPE推进剂表面,环境气体氧含量变化不影响NEPE推进剂的点火延迟时间;当环境气体氧含量大于NEPE推进剂热解产物中氧化性气体含量时,NEPE推进剂点火的气相反应发生在推进剂热解产物与环境气体的扩散区,初焰远离NEPE推进剂表面,此时由于扩散区氧含量高于NEPE推进剂热解产物分散区氧含量,NEPE推进剂的点火延迟时间减小。     

LOVA发射药点火燃烧性能

制备了含有两种不同黏结剂的低易损性发射药(即LOVA发射药),并应用点火燃烧模拟装置与密闭爆发器对其点火燃烧性能进行了研究。结果表明,LOVA发射药难点火,但在点火药中添加高氯酸铵后可有效改善LOVA发射药的点火性能。LOVA发射药燃烧具有燃速系数低、燃速压力指数高等特点。     

无烟交联改性双基推进剂的高、低压燃烧特性

分析了无烟交联改性双基推进剂样品的火焰结构、燃烧波温度分布和熄火表面成分,初步研究了无烟交联改性双基推进剂在高、低压力下的燃烧特性。结果表明,压力升高,无烟交联改性双基推进剂的燃烧模式由双基推进剂的燃烧模式转变为与复合推进剂类似的燃烧模式。     

Ignition of Propellant by Metallic Vapour Deposition for an ETC Gun System

The Defence Evaluation and Research Agency are exploring the potential of electrothermal‐chemical (ETC) gun technology. An important area is that of plasma ignition of solid propellant gun charges. An understanding of the energy transfer mechanisms from the metallic plasma to the propellant grain is central for optimisation of an ETC ignition system. This paper explores, both theoretically and experimentally, the energy transfer mechanisms involved in plasma–propellant interactions during plasma ignition of a conventional charge system, with a view to minimising the electrical energy requirements of an ETC gun system. A mechanism of energy transfer due to the condensation of metallic vapour onto the propellant grain is advanced and experimentation provides some evidence for this. In principle, it should be possible with vapour deposition to initiate self‐sustaining combustion using very small quantities of electrical energy, provided the power transfer is greater than that required to accomplish self‐sustained combustion processes. A ‘vapour generator’ may be required rather than a plasma generator for ETC ignition.     

Mathematical Modeling of Ignition and Extinction of Surface Exothermic Reactions

A mathematical model is developed for unsteady ignition of a reaction at the catalyst surface in a well-stirred reactor. Ignition and extinction of carbon monoxide oxidation at the platinum catalyst surface are studied.     

一种低易损固体发射药的等离子体点火及燃烧特性

采用密闭爆发器实验对低易损性(LOVA)发射药等离子体点火和燃烧性能进行了实验研究,通过分析P-t曲线和dP／dt-P／P-曲线的变化规律,探讨了等离子体对该种火药作用机理,以便进一步研究它用于电热化学炮发射试验中的装药结构和增强燃烧的机理。     

燃气动力补贴加固器用复合火药的应用研究

研制了一种地下油水井损伤套管补贴加固器用低燃速复合火药.通过实验确定了该复合火药的两种配方,并在复合火药中加入惰性辅助增塑剂降低推进剂的燃速和燃温,测试了复合火药的燃速、感度、耐热性及热安定性.抽样实验和现场试验结果验证了该复合火药性能的适用性,计算出解卡锚定力与最小火药量的对应关系.结果表明,研制的复合火药完全满足加固器的性能要求.     

射频激光对氧化铝陶瓷基片划片的研究

分析了射频CO2激光陶瓷基板划片的机理及工艺参数选择的原则,通过数值模拟和实验,分析了脉冲频率、脉冲宽度、划片速度、辅助气压大小、离焦量等工艺参数对激光划片质量的影响。     

CdS/C-TiO2复合光催化剂光催化还原CO2性能研究

采用沉淀-水热法制备了CdS/C-TiO2系列复合光催化剂,通过XRD、UV-Vis、FESEM、XPS等分析手段对催化剂晶体结构、形貌及光电性能进行了表征,考察了柠檬酸(CA)/TiO2质量比R对CdS/C-TiO2复合光催化剂光催化性能的影响。实验结果表明,碳掺杂影响催化剂的晶体结构及其微观形貌,掺杂后光催化活性显著提高。在紫外光照射下进行光催化还原CO2反应,当CA/TiO2质量比R=3/1时,催化活性最高,还原产物HCOOH和HCHO总收率达到533μmol/(g.h)。     

Flamespreading during Base Ignition of Propellant Charge: Theoretical and experimental studies

In the paper theoretical modeling of flamespreading through granular propellant charge during base ignition is given. The theoretical model includes the balance equations for the gas and solid phase, as well as necessary constitutive laws. The stable convergent numerical procedure for solution of the system of equations is developed. This procedure is included in computational program FSPC (Flame-spreading through Propellant Charge). The program FSPC enables investigations of influence of ignition material, physical and chemical characteristics of propellant and propellant charge loading density on the flamespreading process. The experimental investigations by an especially designed apparatus are performed. The verification of the theoretical-numerical access through the comparison with the experimental data (pressure vs. time and locations, flamespreading velocity, propellant grains displacements) is carried out. The entire access makes possible more successful solutions of many interior ballistics problems.     

Effect of Gas Mixture Pressure on the Ignition,Combustion, and Spontaneous Extinction of Chars of Coals of Different Polymorphisms

Combustion, Explosion, and Shock Waves - The dependence of the diameter of a porous carbon particle on stationary temperature at various gas mixture pressures is analyzed. The cases of particle...     

射频CO2激光陶瓷基板划片机

介绍了RF CO2激光器及其陶瓷基板划片的特点;分析了RF CO2激光陶瓷基板划片的机理,给出了整机总体设计方案。对导光系统的激光束进行了模拟,给出了导光系统的光路图及聚焦镜焦平面处的光斑尺寸及能量分布图,整机性能指标达到国外进口机的水平。