固体火箭推进剂——西欧发展情况

详细介绍西欧各国研制固体火箭推进剂的情况及其进展.对双基推进剂,包括浇注双基推进剂、压伸双基推进剂、复合改性浇注双基推进剂和复合推进剂,以及一些粘合剂的特性和发展分别作了叙述.探讨在固体推进剂中加入硼粉后性能的改进以及所带来的问题.今后固体推进剂发展的重点将是:提高总固体含量,进一步提高燃速,改进药柱的力学性能,降低温度敏感系数,以及降低推进剂成本.     

NEPE型推进剂述评

一、前言随着战略及战术武器的发展,对固体推进剂的要求越来越高,不仅要求能量高(大于250秒)、力学性能好,而且使用温度范围要宽、安全贮存性能要好。要满足以上要求,单纯地在复合推进剂和改性双基推进剂的原有基础上改进是比较困难的。目前固体推进剂发展的主要趋势是:发挥复合推进剂和改性双基推进剂各自的优点,突破这两类推进剂的界限而发展成为高能交联推进剂。从美国 K.Klager 提出的固体推进剂发展历程(表1)中可以清楚地看到这种趋势。     

固体推进剂爆轰感度影响因素研究

卡片试验是考察固体推进剂爆轰感度的重要试验项目。首先对卡片试验的输入冲击波压力进行了标定,然后开展了不同种类固体推进剂的爆轰感度试验,考察了固体推进剂种类、固体含量、Al含量和RDX含量对其爆轰感度的影响。结果表明,卡片试验的输入冲击波压力为7 GPa;固体推进剂的种类及配方组成是影响爆轰感度的主要因素;丁羟三组元推进剂、富燃料推进剂和燃气发生剂不具有爆轰感度;在HTPB四组元固体推进剂中,固体含量和Al含量对爆轰感度影响不大,RDX是影响爆轰感度的主要因素,RDX含量越高,爆轰感度越低,临界RDX含量为11.5%。     

固体推进剂的最新进展—NEPE推进剂

什么是NEPE推进剂NEPE是硝酸酯增塑聚醚的英文缩写,全称是Nitrate Ester Plasti cized Polyether。NEPE推进剂是美国为满足MX洲际导弹的需要,赫克力斯公司于70年代末研制成功,80年代初开始使用的一种新型固体推进剂。对于MX导弹的高能量、高性能的要求,目前的复合固体推进剂和改性双基推进剂都不能满足。但复合固体和改性双基各有所长,突破两者的界限,充分发挥双基中硝酸酯增塑剂的能量高、复合固体中高分子主链低温力学性能好的优点,再加入高性炸药HMX,就组成了NEPE推进剂。它不仅能量高、低温性能好、不脆变,而且其它性能也满足要求。除在MX第     

浇铸法生产的复合双基固体推进剂系统

本文叙述通过改变推进剂基本组份可改变复合双基固体推进剂的性能。无论变化怎样,都可使用相同的生产工艺和相同的加工设备。通过高燃速复合双基推进剂,以及排气中无氯化氢的复合双基推进剂和气体发生器所用的复合双基推进剂三个例子说明了这些推进剂系统的性能。     

美国固体推进剂的检验与鉴定规程

美国建立了测定固体推进剂的化学、物理和界面等各项性能的标准检验规程。对推进剂来说,所产生的整套数据,必须是充分的,而且足以确保其安全、工艺参数,并满足质量鉴定指标。固体推进剂的安全、化学、物理、力学等各项性能的检验,是与特定的发动机指标相联系的。测试项目的选择取决于推进剂的类型(如单基或双基,复合或复合改性双基),发动机使用条件(如密闭或不密闭的发动机壳体、相对应的溫度及高度的点火条件),以及要求的贮存寿命。目前,美国对推进剂的检验和鉴定大约进行六十种测试。本文提出了检验与鉴定准则的概要,讨论了各项或各类测试的细节与目的。     

验证板反射冲击波对固体推进剂冲击起爆影响的实验研究

根据隔板实验确定固体推进剂临界爆轰压力时,往往假定被测推进剂药柱是在隔板界面附近起爆,忽视了验证板界面会反射强冲击波的特性,这些假定并没有实验进行验证和事实依据。因此,文中对隔板实验中验证板反射的冲击波对冲击起爆影响进行了实验研究,设计了对比验证实验,对比实验结果清楚地消除了验证板反射冲击波影响的不确定性,为以隔板界面入射冲击波压力作为被测推进剂药柱临界爆轰压力提供了可靠依据。     

固体推进剂粘合剂HTPE研究及其分子设计思想概述

为探究固体推进剂粘合剂分子改性的发展需求和发展思路,总结了国外HTPE固体推进剂粘合剂的研究应用状况,分析了这种粘合剂所处的高分子化学发展环境及所涉及的一些前沿问题,重点评述了HTPE粘合剂推进剂适应高压强工作环境、满足钝感要求的应用特点和所采用的嵌段共聚分子设计技术的研究意义,以此提出固体推进剂粘合剂的一种发展途径.在总结HTPE粘合剂发展思路的同时,为了进一步说明这种嵌段改性发展思路的可行性,也佐证了国外在其他粘合剂分子改性的努力,如HTPB、GAP等.     

固体推进剂空隙含量的体积模量测定

本研究采用体积压缩系数测量来确定固体推进剂中因气体逸出而导致的内部空隙含量(空隙区)的变化。而且测定了复合改性双基(CMDB)、交联双基(XLDB)和硝酸酯增塑聚醚(NEPE)三种推进剂体内空隙形成的速率。发现在400mm立方体内空隙含量和体积压缩系数,同用X—射线的检查结果具有良好的一致性。在这三种推进剂中,采用70和80℃下的高温贮存来加速空隙的形成。其中CMDB推进剂显示出最高的空隙形成速率。最后,探讨了断裂力学在空隙形成研究中应用的最新进展。     

含CL-20固体推进剂研究现状

综述了含CL-20(六硝基六氮杂异伍兹烷)固体推进剂,包括改性双基推进剂、高能低特征信号推进剂、NEPE推进剂以及其他类型固体推进剂的研究现状;主要涉及引入CL-20后固体推进剂的热分解特性、能量特性、燃烧性能、力学性能及安全性能等方面的内容;最后,总结了目前CL-20及含CL-20固体推进剂在实际的工程化应用过程中依然存在的一些尚未解决的难题,并指出了CL-20及含CL-20固体推进剂今后的研究方向及重点。     

A numerical study of the charge diameter effect on unsteady detonation

A numerical study for the unsteady detonation of an unconfined tetryl charge of small diameter, which is assumed to be homogeneous, was performed by using the two-dimensional Lagrangian hydrodynamic computer code, 2 DL, with the first order Arrhenius equation of reaction rate. Becker-Kistiakowsky-Wilson (BKW) and Kihara-Hikita (KH) equations of state have been applied to the detonation products.In the case of BKW, it is shown that the rarefaction waves propagating inward from the lateral surface make the reaction rate slow and give a curvature to the front. Then after an induction time, a strong initiation occurs in the reaction zone near the lateral surface and higher pressure zone moves to the axis. This higher pressure accelerates the detonation propagation near the lateral surface and the curvature of detonation front is reduced. Then, the reaction at the lateral surface again begins to decay by the rarefaction waves. Such a sequence of process is repeated periodically.The possibility of the occurrence of the strong initiation depends on the pressure and temperature in the shocked zone near the surface. In a small diameter charge, the delayed explosion becomes weaker near the surface, while its frequency increases. No shock interaction occurs because the direction of the particle flow is always divergent.In the case of KH equation of state, the temperature of detonation is higher than that obtained by BKW and the behaviour of instability becomes rather different from the previous result, i.e. in the axis the pressure oscillates repeating the overdriven and underdriven detonation similar with the case of BKW.     

Initiation of spherical detonation in hydrocarbon/air mixtures

Spherical detonations have been initiated by solid explosive (Tetryl) charges in well-mixed stoicheiometric air mixtures with each of the hydrocarbons, ethane, propane, n-butane, isobutane and ethylene at atmospheric pressure. Prior to initiation, the gases were contained in plastic bags; total gas volume and available path length were up to 1.6 m³ and 2 m, respectively. The detonations were shown to be self-sustained by continuous measurement of detonation velocity using X-band microwave interferometry. Measured detonation velocities were in all cases close to calculated C-J values.In a few experiments close to the limits of detonability, velocity and blast pressure/time records indicated that the propagating wave system is sometimes irregular. The irregularity that occurs just after initiation is characterised by a reaction front velocity very much lower than the constant detonation velocity, but subsequently attaining the latter by an acceleration process. These observations indicate the existence of a dissociated phase in which shock and reaction fronts may no longer be coupled.Because similar experimental conditions were used throughout, it was possible to establish the relative susceptibilities of the various fuel gases to detonation. Comparison is made with the Zeldovich criterion and a detonation kernel theory of Lee.     

Cylindrical heterogeneous detonation waves

Further experimental studies of blast wave initiated cylindrical heterogeneous (liquid fuel drops, gas oxidizer) detonation waves are described. A pie-shaped shock tube, used for these studies, was altered in certain ways so as to improve the modeling of cylindrical waves. These modifications, along with some operational aspects, are briefly discussed. The breech of the facility, where the blast wave is generated by an explosive, became distorted with usage. Results are presented which show that lower detonation velocities are realized with the damaged breech (other conditions being the same). A photographic and pressure switch wave time of arrival study was made to ascertain the wave shape. Photographs are shown which show that the waves, blast as well as detonation, are close to cylindrical. However, in some cases there is appreciable distortion of the wave front by debris ahead of the wave. Presumably this debris comes from the blasting cap used to ignite the condensed explosive. A series of experiments was conducted using kerosene drops of 388 μm diameter dispersed in air through use of a large number of hypodermic needles. Radial fuel void regions were established by cutting off the fuel flow to a number of needles. Preliminary results relating to the effect of the size of the cloud gap on detonation velocity, quenching, and the initiator energy levels required for detonation are discussed.     

Pulse detonation engines: Technical approaches

The paper contains analysis of the problems preventing from wide use of pulse detonation engines (PDE), and provides suggestions to overcome those problems. In particular, the results of theoretical investigations of basic operating cycle in PDE—deflagration-to-detonation transition (DDT) processes in combustible gaseous mixtures and transmission of detonation into large chambers—are presented. The paper investigates the effect of implosion shock waves on the onset of detonation in gases, and suggests the scheme of detonation transmission from a narrow gap into a wide chamber, which makes it possible to reduce the predetonation length thus shortening the necessary length of the engine.     

偶氮四唑胍对含催化剂的RDX-CMDB推进剂燃烧性能的影响研究

采用浇注工艺制备了GZT部分取代RDX的系列含催化剂的RDX-CMDB推进剂样品。研究了GZT对含催化剂的RDX-CMDB推进剂的燃速、压强指数及燃烧火焰结构等燃烧性能的影响,对比分析了GZT对含催化剂和不含催化剂的RDX-CMDB推进剂燃烧行为影响不同的原因,并采用DSC实验初步研究了含GZT和催化剂的RDX-CMDB推进剂的热行为。结果发现,GZT对推进剂的火焰温度、火焰的暗区厚度、燃面上的亮点数目、燃烧表面对凝聚相的温度梯度等都呈现一定规律性的影响;在1～10 MPa内,GZT使含催化剂的RDX-CMDB推进剂燃速降低,压强指数升高;热行为研究表明,含催化剂的GZT-RDX-CMDB推进剂的DSC曲线上出现了GZT单独分解峰,且DSC的第一分解峰温随GZT的加入而减小。     

Shock sensitivity of nitromethane with well defined hot spots distribution

The behavior of nitromethane under the action of a plane shock wave presenting local overpressures is experimentally analysed. The role of hot spots and the successive activation of new reaction sites are clearly evidenced. The optical observations made during the build-up to detonation and the measured shock sensitivities support a model of initiation for heterogeneous explosives.     

H2／O2燃烧的超声速非平衡流动的数值模拟

本文从包含组分方程的完全ＮＳ方程出发，采用ＮＮＤ格式和Ｈ２／Ｏ２燃烧模型，通过求解ＮＳ方程，模拟了具有压缩拐角的二维管道和球头两类激波点火、燃烧流动。计算清楚地给出了流场中的激波，爆震波以及各种物理量的分布，并分析了激波、爆震波及其相互之间的合。在此基础上，讨论了稀释剂添加情况对流场的影响。计算中为了解决耦合方程组的刚性，提高计算的稳定时间步长，对化学生成源项，妥善地采用了隐式处理技术。     

Characterizing high-energy-density propellants for space propulsion applications

A technique for computationally determining the thermophysical properties of high-energy-density matter (HEDM) propellants is presented. HEDM compounds are of interest in the liquid rocket engine industry due to their high density and high energy content relative to existing industry-standard propellants. In order to accurately model rocket engine performance, cost and weight in a conceptual design environment, several thermodynamic and physical properties are required over a range of temperatures and pressures. The approach presented here combines quantum mechanical and molecular dynamic (MD) calculations and group additivity methods. A method for improving the force field model coefficients used in the MD is included. This approach is used to determine thermophysical properties for two HEDM compounds of interest: quadricyclane and 2-azido-N,N-dimethylethanamine (DMAZ). The modified force field approach provides results that more accurately match experimental data than the unmodified approach. Launch vehicle and Lunar lander case studies are presented to quantify the system level impact of employing quadricyclane and DMAZ rather than industry standard propellants. In both cases, the use of HEDM propellants provides reductions in vehicle mass compared to industry standard propellants. The results demonstrate that HEDM propellants can be an attractive technology for future launch vehicle and Lunar lander applications.     

Detonation in two-layer systems

Detonation in heterogeneous systems involving parallel layers of two different substances was investigated. It was assumed that the denser medium can undergo fast chemical reaction without mixing with the other medium, and the detonation propagates along the two layers. The process of initiation is associated with a shock wave advancing through the medium of lesser density. An idealized gasdynamic model of the phenomenon is proposed in order to evaluate detonation parameters of the two-layer system on the basis of the characteristic features of its constituents. As calculation shows, in the absence of mixing between the two layers, the detonation is capable of propagating at a higher velocity than in the case when the constituents forming the layers are mixed.     

爆震波点火器在氢氧塞式喷管的工程应用

建立了氢氧爆震波点火器试验系统,并根据试验塞式喷管发动机工作状态要求设计了爆震波点火器。在高空条件下(0.005￣0.002MPa),爆震波点火器供气压力0.3MPa、混合比3左右,对爆震波点火器的点火性能进行了试验,成功实现了高空条件下爆震波点火火炬。在同样高空条件下对爆震波点火器点燃单元塞式喷管试验发动机成功进行了点火试验。试验结果表明,氢氧爆震波点火器能以较低的供气压力实现可靠点火。爆震波点火器在气氢气氧单元塞式喷管试验发动机点火的成功应用,为下一阶段应用于多管塞式喷管发动机的实际点火试验提供了技术基础。