AP和铝粉对AP-CMDB推进剂燃烧性能的影响

通过测定推进剂不同压强下的燃速和压强指数,研究了高氯酸铵(AP)和铝粉的粒度及含量对AP-CMDB推进剂燃烧性能的影响.结果表明,减小AP粒度和增大铝粉粒度均能有效提高AP-CDMB推进剂的燃速,推进剂在10～20 MPa压强范围内的燃速压强指数随AP和铝粉粒度的减小而明显增大;铝粉的质量分数低于14%时,调节不同比例的AP和铝粉含量对AP-CMDB推进剂的燃烧性能影响不明显,铝粉的质量分数高于14%时,由于铝粉燃烧不完全导致推进剂的燃速降低.     

微米铝粉在声场中的振荡燃烧特性

为了解声场中铝粉的燃烧特性,建立了甲烷平面燃烧器,利用外置喇叭产生振荡,进行了微米级铝粉的燃烧实验。研究了铝粉在不同振荡频率下的分布燃烧响应特性及粒径分别为10、20、30μm的3种铝粉颗粒的燃烧特性和产物的阻尼特性。结果表明,振荡频率不同时,铝粉燃烧对振荡压强的增益作用不同,粒径为20μm铝粉燃烧,在振荡频率200Hz和300Hz时增益作用明显。铝粉粒度越大,分布燃烧增益越大。粒径为10μm铝粉对燃烧器高频振荡阻尼最大。随着铝粉粒度增加,燃烧产物颗粒对高频压强振荡的阻尼减小。     

燃烧合成Y_3Al_5O_(12)过程中铝粉粒度与压块密度对燃烧速率的影响

采用自蔓延高温合成技术制备钇铝石榴石(Y3Al5O12,YAG)陶瓷,研究了铝粉粒度、压块密度对燃烧速率的影响.结果表明:铝粉的粒度小于10 μm时,铝粉的粒度越细小,燃烧速率越快;同时压块密度对燃烧波速的影响与反应剂各组分的粒度配合有较大关系.当铝粉粒度大于10 μm,压块密度在3.2～3.4 g/cm3范围内时,压块的燃烧波速存在一极低值.压块的显微形貌表明:压制压力、各组分粒度配合等因素影响压块内颗粒问的接触状况.实验结果表明:在空气中采用压块形式,可以燃烧合成出YAG陶瓷.     

铝含量和含氟有机化合物对丁羟推进剂燃烧性能的影响

为进一步提高HTPB推进剂的能量并抑制铝粉在燃烧过程中的团聚,制备了铝粉质量分数为16%~22%的端羟基聚丁二烯(HTPB)推进剂,并分别加入含氟有机化合物(OF)作为铝燃烧促进剂,研究了铝含量和OF对HTPB推进剂燃烧性能的影响;使用氧弹量热仪测定了推进剂在氩气氛围下(3 MPa)的爆热;收集在3 MPa下推进剂燃烧的凝聚相产物,采用激光粒度仪、X射线光电子能谱仪(XPS)及X射线衍射仪(XRD)等分别对其进行粒度分布、元素和物相分析;通过线扫描摄像机和高压燃烧室系统测定推进剂的燃速;利用高速摄影系统观察推进剂燃面上熔铝粒子的团聚过程。结果表明,HTPB推进剂在铝粉质量分数为20%时实测爆热最大,含氟有机物OF的引入使得爆热有所下降;随着HTPB推进剂中铝含量的提高,燃面上熔铝粒子的团聚愈加严重,凝聚相燃烧产物的尺寸和残留铝含量均逐渐增加;加入含氟有机物OF能够促使-Al2O3和AlF3的生成,有效抑制铝颗粒在燃烧过程中的团聚,使凝聚相燃烧产物的尺寸和残留铝含量显著降低,当铝粉质量分数为20%时,OF的加入使得残留铝的生成率降低了50%;较低的铝含量和OF的添加有利于HTPB推进剂燃速的提高。     

含铝固体推进剂燃烧过程中铝粉团聚现象研究进展

介绍了固体推进剂中铝的凝聚相燃烧产物种类及收集方法;分析了铝粉在燃烧表面区域的团聚物演化过程;综述了氧化剂粒径、燃烧压强、铝粉粒径和推进剂燃速对铝团聚的影响,并总结了各因素的作用原理;介绍了抑制铝粉团聚的方法。建议进一步开展铝团聚机理研究,深入揭示推进剂燃烧凝聚相及气相环境对铝团聚行为的影响,构建基于推进剂燃烧物理过程的铝团聚仿真模型,掌握满足高能量要求的铝团聚抑制技术。附参考文献74篇。     

超细铝粉燃烧性能研究

研究了四种粒度的铝粉在四组元（ＨＴＰＢ／ＨＭＸ／ＡＰ／Ａｌ）推进剂中的燃烧特性。实验结果表明，超细铝粉可减轻在燃面的凝聚程度，其燃烧性能明显优于粗铝粉。因此，在推进剂中合理使用超细铝粉，可以提高燃烧效率，对配方研制具有十分重要的意义     

含不同粒度铝粉的铝/冰燃料的燃烧特性

用微米铝粉逐级取代部分纳米铝粉制备铝/冰燃料,采用表面接触法和高速摄影技术研究了不同粒度铝粉改善铝/冰燃料燃烧特性的效果. 结果表明,随微米铝粉取代量增加,铝/冰燃料燃烧反应速率和剧烈程度均先提高后降低,微米铝粉取代量为30%(w)时,铝/冰燃料最高升温速率达6062.24℃/s,是纯纳米铝/冰燃料的3.8倍. 用微米铝粉取代部分纳米铝粉均不同程度提高铝/冰燃料的燃面传播速率,微米铝粉取代量约为20%(w)时燃烧性能最佳,燃面传播速率较纯纳米铝/冰燃料提高57.8%. 在分析实验结果的基础上,建立了铝/冰燃料的燃烧火焰模型.     

低铝含量NEPE推进剂燃烧性能研究

研究了铝粉含量为8％的NEPE推进剂。采用配浆浇铸法制备推进剂，并用恒压静态燃速仪测试了推进剂的燃烧性能。考察了NG／DEGDN的比例、AP粒度、HMX粒度对燃速及燃速压力指数的影响。发现增大NG／DEGDN的比例、减小AP粒径或增加细粒度AP含量，将提高NEPE推进剂的燃烧速度，压力指数升高；而HMX粒度降低，NEPE推进剂燃速降低，压力指数降低；不同来源的PbCO3对NEPE推进剂燃烧性能影响很大。     

KF对微米铝粉在水蒸气中着火燃烧特性的影响

为改善微米铝粉在水蒸气中的着火特性和燃烧效率，采用自行设计的管式炉实验平台研究了KF对30 ?m铝粉在1000℃水蒸气中着火燃烧特性的影响。用高速摄影系统记录了样品着火燃烧过程，并通过X射线衍射、扫描电镜技术和化学分析方法分析了产物组分、形貌和燃烧效率。结果表明，加入KF可显著降低30 ?m铝粉的点火延迟时间，与加入5wt% (0.003 g) KF相比，加入15wt% (0.009 g) KF后，样品的点火延迟时间减少了47.58 s；微米铝粉在1000℃水蒸气中不能着火，加入KF后能着火，这是因为KF与水蒸气反应生成KOH，KOH与Al2O3反应会破坏铝粉的氧化壳，加快铝与水蒸气的反应，促进铝粉着火。随KF加入量提高，样品的燃烧效率显著上升，最高为82.24%，比未添加KF样品的燃烧效率提升了38.75%。提高KF加入量，可产生更多的KOH，对氧化壳的破坏效果更显著，进一步促进铝与水蒸气反应，提高铝粉燃烧效率。     

低铝含量HTPB固体推进剂的燃烧特性

为研究低铝含量推进剂的燃烧特性，以铝粉质量分数5%的低铝含量HTPB推进剂为对象，以铝粉质量分数12%～18%的HTPB推进剂为参比，通过水下声发射、BSFΦ75及BSFΦ165标准试验发动机等测试方法研究了低铝含量推进剂的燃烧性能和能量性能。结果表明，同一固含量条件下，低铝含量推进剂燃速较高，压强指数没有明显变化；铝粉粒度越细，低铝含量推进剂燃速和燃速压强指数越大；经BSFΦ75发动机内弹道p(压力)—t(时间)曲线验证，8～10MPa内低铝含量推进剂燃烧稳定；经BSFΦ165发动机试车验证，7MPa下，低燃速低铝含量推进剂实际比冲2387N·s/kg,比冲效率达到97.3%,高燃速低铝含量推进剂实际比冲2465N·s/kg,比冲效率达到98.6%。低铝含量推进剂燃烧效率高，相近燃速下低铝含量推进剂与常规铝含量推进剂能量在同一水平。     

Effect of catalytic additives and aluminum particle size on the combustion of mixed compositions with a chlorine-free oxidizer

Experimental results on the stationary burning rate and solid content in the combustion products of mixed compositions with a chlorine-free oxidizer and an active fuel binder in the pressure range 0.025–6.0 MPa are presented. The effect of catalytic additives (silica and carbon black), the particle size of aluminum powder, and the method of preparing samples for combustion of the mixed compositions under consideration are analyzed.     

Microwave sintering of mullite–cordierite precursors prepared from solution combustion synthesis

Mullite–cordierite composite was synthesized using the solution combustion synthesis method and glycine as a fuel and aluminum nitrate, magnesium nitrate and colloidal silica as the reagents. The effect of fuel to oxidizer ratio on the combustion behavior, as well as chemical composition and morphology of the formed powders was investigated. All synthesized powders were amorphous with submicron particle size. It was found that the change of fuel to oxidizer ratio had no effect on synthesis of this composite without heat treatment. The smallest particle size of composite powder was obtained as 302 nm for ratio less than 1 (rich of fuel). Mullite, cordierite and spinel were detected after microwave heating at 1200 and 1400 °C. Mullite and cordierite were detected as the only crystalline phases when the stoichiometric ratio of fuel to oxidizer was chosen and this composite obtained the highest density of 2.61 g/cm³.     

Effect of ultrafine aluminum on the combustion of composite solid propellants at subatmospheric pressures

This paper presents the results of an experimental study of the combustion of composite solid propellants with a double oxidizer (ammonium perchlorate/HMX) at pressures of 0.03–0.1 MPa. Systems containing a micron-sized aluminum powder (ASD-4) and the Alex ultrafine aluminum powder were investigated. It was shown that the replacement of ASD-4 by Alex in propellant systems led to an increase in the burning rate. The aluminum particle size and the oxidizer excess coefficient were found to affect the exponent in the power-law burning-rate dependence. The range of the oxidizer excess coefficient was determined that corresponded to the effective replacement of micron-sized aluminum by ultrafine aluminum for which the exponent in the power-law burning rate dependence decreases. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 1, pp. 47–55, January–February, 2009.     

Influence of aluminum particle size on ignition and nonstationary combustion of heterogeneous condensed systems

The results of studies of the effect of particle size of aluminum powder in condensed systems on the ignition, nonstationary combustion, and acoustic conductivity of the burning surface are presented. Analysis of the experimental data shows that the ignition delay and the temperature of burning surface of the heterogeneous condensed systems under study decrease with increasing particle size of aluminum powder, and the nature of the dependence of the nonstationary burning rate on the time of depressurization of the combustion chamber for compositions containing micron or ultrafine aluminum powders is in qualitative agreement with the phenomenological theory of nonstationary combustion. Replacement of micron aluminum powder by ultrafine powder in a heterogeneous condensed system increases acoustic conductivity.     

不同气氛对铝粉点火燃烧特性的影响分析

为了研究流化气体对粉末推进剂点火燃烧性能的提高作用,采用CO_2激光点火器和光纤光谱仪相结合的实验方法,研究了不同气氛条件下Al粉的点火燃烧特性。采用光谱信号拟合测温法计算了Al粉在不同气氛环境中的点火温度。结果表明,常压环境下,粒径1μm的Al粉在N_2O和空气氛围下的点火延迟时间分别为10ms和359ms,从点火成功过渡到全面燃烧的时间分别为829ms和1 579ms,说明Al粉在N2O环境中点火阶段的表面异相反应速率与燃烧阶段的反应速率均快于在空气中;粉径1μm的Al粉在N2O和空气环境下的点火温度分别为1 550~1 650K和1 450~1 500K,两者相近,但都明显低于毫米级Al粉的点火温度(2 300K),说明Al粉的点火温度受粒径影响较大。     

Relationship between the dust flame propagation velocity and the combustion mode of fuel particles

A possibility of determining the regime of combustion of individual fuel particles on the basis of the dependence of the flame velocity on the fuel and oxidizer concentrations is considered by an example of a dust flame of microsized metal particles with diameters d ₁₀ < 15 μm and particle concentrations from ≈10¹⁰ to 10¹¹ m^?3 in oxygen-containing media at atmospheric pressure. The combustion mode (kinetic or diffusion) is responsible for the qualitative difference in the character of the normal velocity of the flame as a function of the basic parameters of the gas suspension. The analysis of such experimental dependences for fuel-rich mixtures shows that combustion of zirconium particles (d ₁₀ = 4 μm) in a laminar dust flame is controlled by oxidizer diffusion toward the particle surface, whereas combustion of iron particles of a similar size is controlled by kinetics of heterogeneous reactions. For aluminum particles with d ₁₀ = 5–15 μm, there are no clearly expressed features of either kinetic or diffusion mode of combustion. To obtain more information about the processes responsible for combustion of fine aluminum particles, the flame velocity is studied as a function of the particle size and initial temperature of the gas suspension. It is demonstrated that aluminum particles under the experimental conditions considered in this study burn in the transitional mode.     

Effects of Aluminum Particle Size on the Detonation Pressure of TNT/Al

To better understand the influence of the aluminum particle size on the detonation pressure of TNT/Al, electrical conductivity experiment and detonation pressure experiment were performed in this study. Four types of TNT/Al were considered, in which the particle size of aluminum was 50 nm, 100 nm, 1.50 μm, and 9.79 μm, respectively. The combustion process of Al in TNT/Al was detected by electrical conductivity experiment, and the detonation pressures of TNT/Al were measured by using the manganin pressure sensors. According to the experimental results, the Chapman Jouguet (CJ) pressure of the explosive containing nano‐sized aluminum is higher than the explosive containing micron‐sized aluminum powder because of the combustion of nano‐sized aluminum in the detonation reaction zone. In addition, a smaller aluminum particle size in TNT/Al is associated with a slower detonation pressure attenuation. This study gives a clearer picture of how aluminum particle size contributes to detonation pressure on timescales from 0 to 0.82 μs.     

高氯酸铵含量对高铝富燃料推进剂中重要组分高氯酸铵/铝 一次燃烧性能和铝粉团聚的影响

采用CO2激光点火装置联合高速摄影系统及扫描电子显微镜等凝聚相燃烧产物分析技术，研究了高氯酸铵(AP)含量对高Al富燃料推进剂中重要组分AP/Al一次燃烧过程中燃烧现象、引燃时间、燃烧扩散时间、燃尽时间、燃烧效率、颗粒团聚及凝聚相燃烧产物的表面形貌、粒径及其分布的影响。结果表明，各AP/Al混合粉体的燃烧过程均可分为表面引燃、燃烧扩散和火焰熄灭3个阶段，但各样品在不同燃烧阶段的燃烧现象存在明显差异。AP含量由10wt%增至30wt%，样品燃烧剧烈程度增强，燃烧过程中固相颗粒的溅射现象越加明显；在火焰熄灭阶段，各样品燃烧由以停留在样品燃面处的燃烧为主逐渐变为以溅射颗粒的燃烧为主，且随反应进行，燃面已燃固相颗粒最先熄灭，各样品表面引燃时间、燃烧扩散时间、燃烧持续时间均缩短，即燃烧反应速率逐渐加快。在AP/Al混合物中，铝粉的燃烧效率、凝聚相燃烧产物粒度及其团聚程度随AP含量增加而增加。