21世纪先进发射药(2):低敏感高能发射药--新配方、装药、点火和理论模拟技术

研究开发低敏感高能发射药必将成为2l世纪发射药及其装药发展的趋势。讨论和分析了低敏感高能发射药的新配方、装药及点火设计、理论模拟等方面的最新研究进展和成果，展现了新一代先进发射药的优异性能。     

少烟HTPB/AP/RDX/Al推进剂比冲效率分析

对少烟HTPB／AP／RDX／A1推进剂能量性能进行了理论计算，通过BSFφ165和φ315试验发动机试验，考察了试验发动机类型，工作压力对经冲效率的影响，而且与高铅含量HTPB／AP／RDX／A1推进剂的比冲效率进行了比较，结果表明，铅含量对推进剂的比冲效率有显著的影响，低铝配方的比冲效率比高铝配方的比冲效率相对要高些；对于推进剂组分确定的配方，合适选择发动机的工作压力，可以不同程度地提高比冲效率，对于同一类型推进剂配方，通过计算理论比冲，结合比冲效率水平，可以对实际比冲进行有效的预估。     

Efficient Tate pairing computation using double-base chains

Pairing-based cryptosystems have developed very fast in the last few years. The efficiencies of these cryptosystems depend on the computation of the bilinear pairings, In this paper, a new efficient algorithm based on double-base chains for computing the Tate pairing is proposed for odd characteristic p 〉 3. The inherent sparseness of double-base number system reduces the computational cost for computing the Tate pairing evidently. The new algorithm is 9% faster than the previous fastest method for the embedding degree k = 6.     

A coaxial pulsed plasma thruster using chemical propellants

Pulsed plasma thrusters (PPTs) have the advantages of mechanical simplicity and robustness compared to other electric propulsion systems. However the thrust power ratio of PPTs is lower than that of other electric propulsion systems. To enhance the thrust performance of the PPT, we propose to use several combustible solid chemicals as coaxial PPT propellants to replace Teflon^® (Polytetrafluoroethylene: PTFE). With the design, the force obtained thermodynamically is expected to augment the PPT thrust power ratio with the help of the chemical energy contained in the propellants. As a result, the thrust power ratio is increased using hydroxyl-terminated polybutadiene-ammonium perchlorate (HTPB-AP)-based propellants compared to the case of ordinary Teflon. The discharge current and voltage waveform does not change even when the propellant is changed. These findings could indicate that the impulse bits by gasdynamic contribution are lager in the case of chemical solid propellants than in the case of Teflon.     

Experimental investigation on no-vent fill process using tetrafluoromethane (CF4)

This paper investigates the transfer of liquid cryogens using a no-vent fill (NVF) process experimentally to identify the dominant NVF parameters. The experimental apparatus has been fabricated with extensive instrumentations to precisely study the effects of each NVF parameter. Liquid tetrafluoromethane (CF₄) is selected as the working fluid due to its similar molecular structures and similar normal boiling point and triple point with liquid methane which has been considered as an attractive future cryogenic propellant. The experimental results show that the initial receiver tank wall temperature and the incoming liquid temperature are the primary factors that characterize the (non-equilibrium) thermodynamic state at the start of a NVF transfer. The supply pressure is also critical as it indicates the ability to condense vapor in the receiver tank. A non-dimensional map based on energy balance is proposed to find acceptable initial conditions of the filling volume at the desired final tank pressure. The non-dimensional map shows good agreement with the NVF data not only in this paper but also in the previous research.     

Estimation of the Ballistic Effectiveness of3,4-and3,5-Dinitro-1-(trinitromethyl)-1H-Pyrazoles as Oxidizers for Composite Solid Propellants

The experimental values of the enthalpy of formation of two isomeric 3,4-and 3,5-dinitro-1-(trinitromethyl)-1H-pyrazoles have been obtained(261.5±5.0and 246.4±6.7kJ/mol for crystalline 3,4-and 3,5-dinitro-1-(trinitromethyl)-1H-pyrazoles,respectively).The ballistic effectiveness of these potential oxidizers in composite solid propellants was studied.It is shown that these two oxidizers may be successfully applied in metal-free compositions or with a small content of metal.For the bottom stage 3,4-dinitro-1-(trinitromethyl)-1H-pyrazole is a bit better than 3,5-dinitro-1-(trinitromethyl)-1H-pyrazole,for the upper stage the both oxidizers show the equal ballistic parameters.These oxidizers allow to create metal-free solid composite propellants with the binder percentage not lower than 19%(volume fraction),with I3spequal to 256.5-257.0sat density equal to 1.72-1.74g/cm~3.     

提高低燃速丁羟推进剂力学特性研究

大量粗粒度AP和降速剂的添加很难实现低燃速丁羟推进剂高强度的技术要求。研究以静态燃速不高于5.1 mm/s(20℃,6.0 MPa)低燃速丁羟推进剂作为基础配方,通过优选HTPB规格、键合剂组合和添加新型扩链剂的方法提高推进剂力学特性。结果表明,采用新型扩链剂SX,使70℃推进剂的抗拉强度高于1.0 MPa,伸长率大于10%。     

火炸药多组分气体现场测量装置动态校准技术研究

利用自研的火炸药专用自动配气系统和实验室校准装置,通过混合气体校准以及"预估-校准-逼近"的方法,对火炸药气体现场测量装置进行了动态校准。结果表明,多组分气体动态校准技术实现了火炸药配方燃烧爆轰过程产生气体的准确测量。混合气体校准相对标准偏差RSD≤0.3%,保证了动态测量数值的有效统一和量值传递。     

Determination of Viscoelastic Poisson’s Ratio of Solid Propellants using an Accuracy‐enhanced 2D Digital Image Correlation Technique

Poisson’s ratio plays a significant role in the structural response of solid propellants, which is, in essence, a nearly incompressible viscoelastic material. Numerical models that assume a constant Poisson’s ratio generally cannot achieve good results, thus requiring an accurate knowledge of time‐dependent viscoelastic Poisson’s ratio of solid propellants. In this work, accurate determination of tensile strains and viscoelastic Poisson’s ratio of solid propellants using an accuracy‐enhanced 2D digital image correlation (DIC) technique is described. To achieve high‐accuracy measurement, great improvements were made to regular 2D‐DIC technique to maximally eliminate the errors caused by non‐ideal loading conditions, specimen deformation and lens distortion. Rigid body translation tests with zero strain state are first performed to verify the accuracy of the proposed DIC technique. Then application of the proposed technique for determining the time‐varying viscoelastic Poisson’s ratios of solid propellants in stress relaxation tests are demonstrated. The results reveal that, by adequately eliminating the measurement errors associated with the unavoidable out‐of‐plane displacements and lens distortion, the present DIC technique can be used for precise determination of viscoelastic Poisson’s ratio of solid propellants, which is found to be increasing nonlinearly to the incompressible value of 0.50 as time increases.     

2,4-二羟基苯甲酸铋对双基推进剂燃烧的催化作用

为了考察2,4-二羟基苯甲酸铋对双基推进剂燃烧的催化效果以及探索其催化作用机理,用螺压工艺制备了含2,4-二羟基苯甲酸铋的推进剂样品,研究了2,4-二羟基苯甲酸铋对双基推进剂燃烧的催化性能。结果表明,2,4-二羟基苯甲酸铋对双基系推进剂的燃烧具有良好的催化作用,能显著提高推进剂的燃速,并大大降低压力指数,与少量碳黑复合后,对提高推进剂的燃速效果更明显,铋盐、铜盐与碳黑三元复合后,催化效果更优。用快速热裂解固相原位池／傅里叶变换红外光谱（RSFT-IR）联用装置研究了2,4-二羟基苯甲酸铋的热分解机理,发现2,4-二羟基苯甲酸铋在催化推进剂燃烧过程中的活性组分为Bi2O3。