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。     

GAP/ADN/nano–Al膏体推进剂的能量特性与激光点火特性

采用最小自由能原理方法计算了GAP(聚叠氮缩水甘油醚)/ADN(二硝酰胺铵)/nano–Al推进剂的能量特性,制备了一系列ADN质量分数为8%~38%的GAP/ADN/nano–Al膏体推进剂,采用CO2激光点火的方法研究了4种配方在不同激光功率密度作用下的激光点火特性。结果表明:GAP/ADN/nano–Al膏体推进剂的标准理论比冲(Isp)、特征速度(C*)、燃烧温度(Tc)均随ADN含量增加而依次增大,爆热(Qv)则主要随铝粉含量的增加而增大;GAP/ADN/nano–Al膏体推进剂的点火延迟时间和点火能量总体上随着激光功率密度增加呈现减小的趋势;配方中ADN含量较高时,GAP/ADN/nano–Al膏体推进剂具有较好的激光点火特性。     

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。     

硼颗粒在固冲环境中点火过程影响因素的数值模拟

采用修正的Williams 硼颗粒燃烧模型对固体推进剂燃烧环境条件下的硼颗粒点火进行了数值模拟,计算了环境温度、气相氧化剂种类和分压、颗粒初始半径及氧化层厚度对硼颗粒点火的影响.结果表明,环境温度升高可以缩短硼颗粒点火延迟时间和点火时间;环境中氧分压过大会延长点火延迟时间;水蒸气分压越大,点火时间越短;硼颗粒半径增大会导致氧化层厚度增大进而延长点火时间和点火延迟时间.     

四种混合不同碳材料的FOX-7粉末激光点火：点火延迟实验与简化计算（英文）

针对1,1-二胺-2,2-二硝基乙烯(FOX-7)因点火相对困难而限制其广泛应用的问题，利用CO₂激光器在一定的功率密度范围对4种混合不同碳材料的FOX-7粉末开展了点火实验，研究点火延迟时间的变化趋势。采用两种简化模型对点火延迟时间进行计算与分析，以探究点火机理和指导FOX-7的点火性能提升。结果表明，几种碳材料的添加会导致FOX-7粉末点火延迟时间发生不同程度的缩短。石墨烯和氧化石墨烯在缩短点火延迟方面表现出相对较强的促进作用，石墨的效果较为轻微。计算结果显示，模型1比模型2更适合预测FOX-7粉末的点火延迟时间。机理分析表明，石墨烯的添加能够有效提升FOX-7粉末对辐照能量的吸收且减小能量损失。研究表明FOX-7粉末样品的主要点火诱导过程受到激光辐照下传热性质的强烈影响。     

NC/Bu-NENA基推进剂性能研究(Ⅰ):推进剂能量及燃烧性能

为了研究丁基-硝氧乙基硝胺(Bu-NENA)对NC基推进剂能量及燃烧性能的影响,通过俄罗斯Real软件计算了Bu-NENA对推进剂的能量性能的影响;通过吸收-压延的方法制备了推进剂样品,测试了推进剂的密度、爆热、比容、点火延迟、燃速,计算了压强指数;通过燃烧波、火焰照片以及熄火表面探讨了Bu-NENA对推进剂燃烧性能影响的机理。结果表明,在NC基推进剂中Bu-NENA替代NG使能量下降,但是产气量增加,使推进剂的燃速大幅度下降,2MPa下燃速降幅75%以上,20MPa下燃速降幅64%以上;压强指数提升,NC/NG基推进剂用部分催化剂可能对NC/Bu-NENA基体系失效;推进剂的点火延迟时间增加;推进剂的燃速大幅度降低的原因可能是因为Bu-NENA在燃烧时挥发吸热以及燃温降低带来的热反馈降低。     

低强度冲击下炸药点火的数值模拟

为了研究炸药在低强度冲击下的反应特性,根据标准的Steven试验建立了数值计算模型,采用热力耦合模型和Arrhenius方程描述炸药的热反应,对不同速度弹头撞击炸药过程进行了数值模拟计算,获得了炸药点火的弹头阈值速度,分析了弹头形状对炸药反应的影响。计算结果表明,在弹头阈值速度下,炸药点火存在一定的延迟时间,随着弹头速度的增大,延迟时间缩短;弹头形状会影响炸药受力过程,使炸药点火特性发生变化。     

炸药激光起爆过程的准三维有限差分数值模拟

根据含锌材料的热起爆机理，建立了在激光作用下炸药点火过程的三维(二维轴对称)有限差分模型，运用此模型对RDX、PETN、HMX和改性B炸药在激光作用下的温度成长过程、温度场分布及点火延迟时间进行了数值模拟。结果表明，三维模型延迟时间计算结果与实验结果较为符合；药柱温度增长主要是在激光照射面上很薄一层药剂内发生；激光的光斑直径、脉宽和炸药的激光吸收系数对点火能量阈值有较大的影响。     

发射药的等离子体点火燃烧中止试验研究

用等离子体点火中止燃烧装置,研究了等离子体点火太根药、双基药、硝胺药及单基药的燃烧中止现象,借助所得回收样品的显微照片和中止压力-时间曲线分析了等离子体与发射药的相互作用规律.结果表明,由于等离子体的侵蚀和辐射作用,发射药的燃烧表面不规则;不同配方发射药的点火延迟时间不同,太根发射药等离子体点火的延迟时间最短,容易实现等离子体点火.发射药的理化性质,包括配方和添加剂成分、表面状况、热传导系数和光学吸收系数等对等离子体点火有着显著影响.     

铝镁贫氧推进剂的点火性能

为研究镁铝富燃料固体推进剂组分对点火性能的影响,采用改进的靶线法燃速测试系统对多种含镁铝富燃料固体推进剂在常压和加压下进行了通电金属丝点火性能的对比实验。被测试推进剂的镁铝合金含量为20%～40%,或者同时含镁铝合金及硼,氧化剂含量为30%～53%。实验表明,在固定外界输入热源的情况下,推进剂的点火性能主要与氧化剂含量和粒度有关;金属的含量和种类也有一定的影响;催化剂对点火延迟时间影响很小;压强对此种点火方式几乎无影响。该点火延迟测试方法简单易行,并具有一定的可靠度,适于配方调试。     

Experimental Investigation on Laser Ignition and Combustion Characteristics of NEPE Propellant

The ignition and combustion property of solid propellant is the main content in internal ballistic research, which has a great significance for propulsion application and combustion mechanism. In this study, the detailed gas‐phase reaction mechanism of Nitrate Ester Plasticized Polyether Propellant (NEPE) was developed. It is helpful to understand the intricate processes of solid‐propellant combustion. The factors which may have influences on ignition delay time and temperature distribution of propellant surface was analyzed by laser ignition experiment. Using high‐speed camera and an infrared thermometer, the ignition and combustion process and the surface temperature distribution of NEPE propellant under laser irradiation were measured. Laser heat flux, ambient pressure and initial temperature of NEPE propellant have an influence on the ignition delay time and the surface temperature. Results show that the ignition delay time decreases with the increase of laser heat flux, ambient pressure and initial temperature of NEPE propellant. At the same time, with the increase of laser heat flux, the influences of ambient pressure and initial temperature on the ignition delay time decrease. Besides, laser irradiation, ambient pressure and initial temperature have significant influences on the surface temperature distribution of the propellant.     

Study of solid propellant ignition by a hot gas stream

The process of fast ignition of double-base solid propellants (ignition time 0.6–40 msec) is studied in a model rocket chamber by means of fine thermocouples that are located on the surface being ignited and in the igniting gas stream under rapidly varying external conditions. The basic parameters of the process (propellant surface temperature, gas-propellant heat transfer coefficient, heat flux from the gas to the propellant, and the heat content and the heat release in the propellant) are obtained as functions of time. Three ignition regimes are found: fast, normal, and delayed. We discuss briefly the nature of the transition to steady-state combustion for the obtained regimes. The directions of future studies are noted.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 3, pp. 20–26, May–June, 1993.     

Numerical simulations of polymer pyrolysis rate: Effect of property variations

The mass loss rate (MLR) of poly(methyl methacrylate) (PMMA) exposed to known radiant fluxes is simulated with two recently developed numerical codes, the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) and the Federal Aviation Administration (FAA) ThermaKin. The influence of various material properties (thickness, thermal conductivity, specific heat, absorption of infrared radiation, heat of reaction) on mass loss history is assessed, via their effect on the ignition time, average MLR, peak MLR, and time to peak. The two codes predict the influence of material parameters on the MLR in the order of decreasing importance: heat of reaction, thickness, specific heat, absorption coefficient, thermal conductivity, and activation energy of the polymer decomposition. Changes in the material properties also influence the MLR curves by switching the sample from thermally thick to thermally thin. The two numerical codes are generally in very good agreement for their predictions of the MLR vs time curves, except when in‐depth absorption of radiation was important. Copyright © 2010 John Wiley & Sons, Ltd.     

Radiative Ignition of Fine‐Ammonium Perchlorate Composite Propellants

Radiative ignition of quasi‐homogeneous mixtures of ammonium perchlorate (AP) and hydroxyterminated polybutadiene (HTPB) binder has been investigated experimentally. Solid propellants consisting of fine AP (2 μm) and HTPB binder (~ 76/24% by mass) were ignited by CO₂ laser radiation. The lower boundary of a go/no‐go ignition map (minimum ignition time vs. heat flux) was obtained. Opacity was varied by adding carbon black up to 1% by mass. Ignition times ranged from 0.78 s to 0.076 s for incident fluxes ranging from 60 W/cm² to 400 W/cm². It was found that AP and HTPB are sufficiently strongly absorbing of 10.6 μm CO₂ laser radiation (absorption coefficient ≈250 cm⁻¹) so that the addition of carbon black in amounts typical of catalysts or opacitymodifying agents (up to 1%) would have only a small influence on radiative ignition times at 10.6 μm. A simple theoretical analysis indicated that the ignition time‐flux data are consistent with in‐depth absorption effects. Furthermore, this analysis showed that the assumption of surface absorption is not appropriate, even for this relatively opaque system. For broadband visible/near‐infrared radiation, such as from burning metal/oxide particle systems, the effects of in‐depth absorption would probably be even stronger.     

Ignition of pyrotechnic mixture by means of a laser diode. Part I: Numerical modelling

A numerical model of the heating and ignition of a reactive solid by a laser beam has been developed. A transient, two-dimensional heat equation was solved numerically using an explicit scheme. A nonlinear source term (Arrhenius equation) complicates the analytical resolution of this type of problem. Laser beam absorption is considered in a few micrometer depth. Influence of depth absorption coefficient is investigated. Influence of laser power density, lasering time and thermal diffusivity on ignition are examined by this model. The developed numerical model has been used to design a laser ignition system for explosive substances. It has been shown that ignition by a 0.6 W laser diode at a fiber optics output is feasible.     

固体火箭发动机的热安全性研究

采用带源项的热传导方程,对固体火箭发动机在外界热源作用下的加热过程进行了数值模拟,分析了固体发动机内推进剂在外界热源作用下的燃烧特点,并确定了发动机产生热危险性的临界温度和起始燃烧时间。研究结果表明,在热传导方程中加入化学反应源项,可以有效地模拟发动机在外界热源作用下的加热过程;推进剂产生热危险性的临界温度为520～525K;在外界火焰作用下,发动机内的推进剂将点火燃烧,随着外界火焰温度的上升,推进剂起始燃烧的延迟时间减少。     

基于图像传感器的推进剂发烟量测试方法

提出了一种基于图像传感器的推进剂发烟量测试方法。用平行光管代替传统测试装置中的卤素钨灯,用图像传感器代替传统测试装置中的光电二极管或光敏电阻,设计了一种表面有镂空条纹的遮光罩对光源信号进行调制,采取图像数据处理方法消除环境噪声对测试结果的影响。测量了SQ2推进剂、Al-CMDB推进剂和NEPE推进剂燃烧烟雾的发烟量。结果表明,SQ2推进剂和Al-CMDB推进剂的烟雾透过率曲线在点火后50s左右基本稳定;NEPE推进剂燃烧的烟雾光透过率曲线在点火50s后稳定,但有缓慢上升趋势;3种推进剂烟雾光透过率分别为84.1%、65.9%、22.3%,与传统测试方法一致。     

Plasma Ignition and Combustion

Electro‐thermal‐chemical (ETC) initiation and combustion offers the possibility to increase the performance of guns substantially as new propellant formulations and high loading densities (HLD) can be safely ignited and burnt in an augmented way. This paper reports investigations of burning phenomena in the low pressure region for JA2 and the effects of plasma interaction on ignition and study its influence on the burning rate. The comparison of transparent and opaque versions of the propellant is of special interest. Electrically produced plasma can strongly influence the ignition and combustion of solid propellants. Predominantly, plasma arcs influence strongly the burning of propellants by its radiation. The high intensity of the radiation initiates burning with short time delays in the µs‐range and high conversion during exposure also in the case of a stable burning. Radiation can penetrate into the propellant interior and partially fragment at absorbing structures which could be artificially introduced or be inherently present as in the case of a JA2 propellant. Simplified approaches based on the heat flow equation and radiation absorption can explain these effects at least on a qualitative scale. Dynamic effects are understood by more sophisticated models.