RDX对含硼富燃料推进剂一次燃烧产物组分影响的计算研究

为了研究黑索今(RDX)对含硼富燃料推进剂一次燃烧产物组分的影响,用吉布斯最小自由能法计算了5种推进剂配方的一次燃烧产物组分,并通过测试燃烧产物中的总硼含量对热力学计算结果进行了验证。结果表明,采用最小自由能法计算含硼富燃料推进剂的一次燃烧产物组分,其结果准确、可靠;当含硼富燃料推进剂中RDX含量增加时,一次燃烧产物中B_4C和B_2O_3含量减少、C和BN含量增加,且一次燃烧温度也升高;提高一次燃烧压强可提高硼的氧化率、降低B_4C的生成量,有效提高一次燃烧温度,因此提高一次燃烧压强有助于提高含硼富燃料推进剂的二次燃烧效率。     

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。     

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.     

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。     

含团聚硼粉富燃料推进剂一次燃烧模型的建立

为研究团聚硼粉对富燃料推进剂燃烧过程中能量释放和燃速特性的影响,结合实验分析建立了基于BDP模型的含团聚硼粉富燃料推进剂一次燃烧的物理和数学模型.该物理模型中,燃烧表面由团聚硼粉、AP和黏合剂的聚集区两部分组成,气相区形成了AP火焰和FF(终焰)聚集区,团聚硼粉中团聚剂参与了PF(初焰)和FF.在假设团聚硼粉为惰性物质基础上,建立了该推进剂的数学燃烧模型.通过AP/HTPB体系、团聚硼粉/AP/HTPB体系的简化与计算,推导出燃速公式中SAP/S的表达式.该模型充分考虑了团聚硼粉体积分数ζ1对推进剂燃面的影响,将硼粉的体积因素引入含硼富燃料推进剂的数学燃烧模型公式,该模型合理解释了这种推进剂的主要燃烧特性.     

铝/有机氟化物复合物对含铝HTPB推进剂燃烧性能的影响

为研究有机氟化物(OF)对含铝HTPB固体推进剂燃烧性能的影响,采用球磨法制备了纳米和微米铝/有机氟化物复合物(nmAl/OF和μmAl/OF),将其作为复合添加剂替代微米铝粉加入HTPB推进剂中,并考察其对推进剂燃烧性能的影响。采用SEM、TEM、粒度分析等对nmAl/OF和μmAl/OF复合物及推进剂凝聚相燃烧产物进行了表征。结果表明,nmAl/OF和μmAl/OF复合物有不同的结合状态;添加OF、nmAl/OF和μmAl/OF后,推进剂的爆热值下降约2%;添加nmAl/OF的推进剂配方燃速最低,在3MPa时仅为6.28mm/s,添加OF和μmAl/OF体系的推进剂燃速压强指数相比于原配方降低约20%;添加nmAl/OF的推进剂配方凝聚相燃烧产物粒度(D_(50))比原配方降低约47%。     

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。     

含团聚硼富燃料推进剂的能量特性及燃烧性能

用最小自由能计算程序计算了含硼富燃料推进剂的能量性能,探讨了不同压力时硼粉的质量分数对富燃料推进剂能量性能的影响,采用靶线法和化学滴定法研究了富燃料推进剂的燃烧特性和燃烧残渣中硼粉的燃烧效率。结果表明,随着硼粉含量的增加,推进剂的能量增大;大粒径的团聚硼对富燃料推进剂的燃速和压强指数影响较大,随着团聚硼含量的增加,推进剂的燃速提高;含硼富燃料推进剂中的硼粉燃烧后单质硼和硼化物的摩尔比发生了明显的变化,无定形硼粉经团聚后燃烧效率明显提高。     

组分对高能HTPB推进剂燃烧性能和力学性能的影响

通过调整氧化剂AP粒径与含量、键合剂及R值，研究了固体质量分数为90％的HTPB推进剂的燃烧性能和力学性能。结果表明，在HTPB推进剂能量性能得到提高的同时，推进剂的燃烧性能和力学性能也得到了较好的保证。高固体含量下HTPB推进剂的燃烧和力学性能随配方调节呈现出较为明显的规律。推进剂的燃烧性能稳定，燃速和压力指数可调，压力指数控制在0．30～0．40；分别测定了高温（60℃）、常温（20℃）和低温（-40℃）力学性能，高温、低温和常温下的拉伸强度一般均大于1．0MPa，低温延伸率最高可达74．7％。     

团聚硼对富燃料推进剂燃速的影响

通过调节黏合剂种类和团聚工艺,采用于法硼团聚工艺制取球形度良好、粒径为0．105～0．19mm的团聚硼粒子,并制得硼质量分数32％、热值约32MJ／kg、工艺性能良好的含硼富燃料推进剂;采用靶线法测试含硼富燃推进剂的燃速及压强指数,并测试不同AP粒度级配、镁铝合金粒径以及团聚硼粒径对富燃推进剂燃速的影响。结果表明,减小AP粒度及团聚硼粒径、增加超细AP含量和固体组分含量,可大大改善含硼富燃推进剂的燃烧性能。而镁铝合金粒径对推进剂的燃烧性能基本没有影响。     

Effect of acceleration on agglomeration of aluminum particles during combustion of composite solid propellants

The effect of the normal acceleration (g-load) on formation of agglomerates and their distribution function is examined within the framework of the statistical model of aluminum agglomeration. A parametric study of aluminum agglomeration with different values of normal g-loads is performed. The theory developed predicts a new effect, namely, a nonmonotonic dependence of the mean-mass size of agglomerates leaving the burning surface on the magnitude of normal g-loads: with increasing g-load, the mean-mass size of agglomerates can increase if the g-loads are low or moderate and decrease if the g-loads are high; in the latter case, the size distribution of agglomerates becomes less spread and more stable. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 40–50, November–December, 2007.     

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.     

Condensed combustion products of aluminized propellants. IV. Effect of the nature of nitramines on aluminum agglomeration and combustion efficiency

The condensed combustion products of two model propellants consisting of ammonium perchlorate, aluminum, nitramine, and an energetic binder were studied by a sampling method. One of the propellants contained HMX with a particle size D ₁₀ ≈ 490 μm, and the other RDX with a particle size _{D 10} ≈ 380 μm. The particle-size distribution and the content of metallic aluminum in particles of condensed combustion products with a particle size of 1.2 μm to the maximum particle size in the pressure range of 0.1–6.5 MPa were determined with variation in the particle quenching distance from the burning surface to 100 mm. For agglomerates, dependences of the incompleteness of aluminum combustion on the residence time in the propellant flame were obtained. The RDX-based propellant is characterized by more severe agglomeration than the HMX-based propellant — the agglomerate size and mass are larger and the aluminum burnout proceeds more slowly. The ratio of the mass of the oxide accumulated on the agglomerates to the total mass of the oxide formed is determined. The agglomerate size is shown to be the main physical factor that governs the accumulation of the oxide on the burning agglomerate. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 78–92, July–August, 2006.     

超细高氯酸铵的制备及其在固体推进剂中的应用

总结了超细高氯酸铵的制备方法,主要包括超临界流体法、机械研磨法、气流粉碎法、喷雾干燥法、冷冻干燥法、反溶剂重结晶法等,并结合国内外主要生产厂家的实例,介绍了其在固体推进剂中的应用.     

Mg2NiH4储氢材料的制备及对高氯酸铵热分解的催化作用

采用置换-扩散法制备得到Mg₂NiH₄,用SEM、XRD和DSC等对其结构和性能进行了表征。Mg₂NiH₄纯度较高,含氢量为3.6％,放氢温度为292.4℃。用DSC法研究了Mg₂NiH₄对高氯酸铵（AP）热分解的催化性能。结果表明：加入含量为10％的Mg₂NiH₄可使AP高温放热峰温降低108.2℃,使表观分解热增加217.0％,Mg₂NiH₄对高氯酸铵热分解具有良好的催化作用。Mg₂NiH₄含量增加,对高氯酸铵热分解的催化作用增强。初步探讨了Mg₂NiH₄催化高氯酸铵热分解的作用机理。     

Ignition,combustion, and agglomeration of encapsulated aluminum particles in a composite solid propellant. II. Experimental studies of agglomeration

The combustion characteristics of propellants containing AP, HMX, an energetic binder, and aluminum particles with various polymer coatings are studied at pressures of 0.15 and 4.6 MPa. It is found that the coatings influence the burning rate, the particle size distribution of condensed combustion products, and the completeness of aluminum combustion. It is shown that the agglomeration can be reduced by using aluminum with fluorine-containing coatings. The application of some coatings results in a reduction in the mass of the agglomerates with an insignificant increase in their size. The greatest effect was achieved when using aluminum coated with (CH₂=CH-CH₂-O)₂Si[OCH₂(CF₂-CF₂)₂H]₂ [bis(allyloxy)-bis(2,2,3,3,4,4,5,5-octafluoropentyloxy)silane]. For this coating, a size reduction is also observed for micron-size oxide particles. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 3, pp. 83–97, May–June, 2007.     

Fe2O3/CNTs纳米粒子的制备及其对高氯酸铵燃速的催化作用

采用液相沉淀法制备沉积于碳纳米管（CNTs）表面的Fe2O3复合纳米催化剂,用透射电子显微镜（TEM）和光电子能谱（XPS）对制备的Fe2O3／CNTs复合纳米催化剂进行表征,研究了Fe2O3／CNTs复合纳米催化剂对高氯酸铵（AP）燃烧的催化性能。结果表明,纳米级Fe2O3颗粒均匀包覆在CNTs表面,Fe2O3／CNTs复合纳米催化剂能明显降低AP的分解温度,提高AP单元推进剂的燃速;Fe2O3／CNTs复合纳米催化剂对AP的催化活性明显优于纳米Fe2O3、纳米Fe2O3和CNTs的简单混合催化剂。     

Effects of moisture content and heating condition on pyrolysis and combustion properties of structural fuels

The objective of this research was to measure the pyrolysis and combustion properties of selected structural fuels as a function of fuel moisture content (MC) levels under various external heating conditions. The pyrolysis properties were measured by using the thermogravimetric analysis technique at 3 MC levels (5%, 10%, and 15%) and 3 heating rates (5, 15, and 25K/min.). The combustion properties were measured by using a cone calorimeter at the same MC levels and 3 heat flux levels (20, 30, and 50 kW/m²). In addition, density and thermal conductivity as a function of MC levels were also measured. Statistical analysis was performed over the experimental data by using a 95% confidence interval. Most materials had significant increase in density when the MC levels increased, while the increase was more significant for natural woods than engineered woods. No statistically significant changes in thermal conductivity were observed for most materials. The pyrolysis properties were affected by both the MC and heating rate levels. Both MC and heat flux levels affected the combustion properties.     

Effects of operational parameters on emission performance and combustion efficiency in small-scale CFBCs

A well-designed CFBC can burn coal with high efficiency and within acceptable levels of gaseous emissions. In this theoretical study effects of operational parameters on combustion efficiency and the pollutants emitted have been estimated using a developed dynamic 2D (two-dimensional) model for CFBCs. Model simulations have been carried out to examine the effect of different operational parameters such as excess air and gas inlet pressure and coal particle size on bed temperature, the overall CO, NO_x and SO₂ emissions and combustion efficiency from a small-scale CFBC. It has been observed that increasing excess air ratio causes fluidized bed temperature decrease and CO emission increase. Coal particle size has more significant effect on CO emissions than the gas inlet pressure at the entrance to fluidized bed. Increasing excess air ratio leads to decreasing SO₂ and NO_x emissions. The gas inlet pressure at the entrance to fluidized bed has a more significant effect on NO_x emission than the coal particle size. Increasing excess air causes decreasing combustion efficiency. The gas inlet pressure has more pronounced effect on combustion efficiency than the coal particle size, particularly at higher excess air ratios. The developed model is also validated in terms of combustion efficiency with experimental literature data obtained from 300 kW laboratory scale test unit. The present theoretical study also confirms that CFB combustion allows clean and efficient combustion of coal.