Processing effects on ballistic response of composite solid propellant grains
Processing effects on ballistic response of composite solid propellant grains
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加工对复合固体推进剂颗粒弹道响应的影响
DOI：
10.2514/6.1995-2585
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
O. Suys
中科院分区：
文献类型：
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作者：
G. Uhrig;D. Ribereau;A. Hiss;C. Brauner;G. Namah;O. Suys
综述了SNPE和大学合作伙伴为研究工艺对复合推进剂药柱弹道响应的影响而开展的工作。它的总体指导方针如下：已进行了一项实验工作，以研究浇注工艺的影响，并用子尺度(圆柱形和细长圆柱形)关联在不同颗粒形状内测得的燃速分布。重点观察了发射药在浇注过程中的流动情况，分析了条纹的形成机理，确定了条纹对燃速的影响。一个恒定的cKort被支持用来识别并从观察到的燃速异常中去除，而不是产生“驼峰”的加工效应(颗粒形成、腐蚀性燃烧、压降等)。发展和验证了改进的弹道分析和预测方法，其中发动机的每个部件都有自己的燃速分布。在一些CASC中，这允许比使用全局燃速异常系数(BRAF)的传统方法更好地反馈预测经验。使用了推进剂流动模拟程序，并对其进行了修改，以产生条纹的图形表示。首先，与在小尺度颗粒内观察到的条纹相比，结果是非常有希望的。这种对条纹的描述可以用于与波尔多大学合作开发的数值模式，该模式模拟了二维燃烧锋面在给定条纹介质中的运动，该介质包含非常标准的推进剂层和薄的结合富铬层。THC联合方法(推进剂流动模拟和条形介质燃烧)的验证程序正在进行中。利用条纹的一些基本构型，将测量的燃速与计算的燃速进行了比较，证明了条纹假设的一致性和THC模型模拟燃烧速率异常因子的能力。这些不同工作的最终目标是建立一个完整的模型来预测与给定电机和铸造工艺相关的BRAF。技术背景制造过程在未固化的复合推进剂中产生各种应力：流经管道、裂缝板和气孔(在注射的情况下)，沿芯棒和壁面流动，主要产生边界层型剪应力。自由膏流的下落倾向于在滴落区附近产生高的速度梯度和推进剂内部的剪切。落下区域周围堆积的推进剂的扩散导致移动的FRCC表面的“粘合”。浇注后的下沉会再次引起剪切应力，并使推进剂结构完全重组。现在人们普遍承认，这些不同的结构导致固体颗粒的分离和/或推进剂成分的变化，这反过来又导致燃速作为火药中的位置和火焰锋面与碎片线或表面之间的相对入射角的函数而变化。在简单几何结构的情况下(即圆柱形中心穿孔颗粒)，这一效应得到了很好的表征。对于已就位浇注芯棒的颗粒，其燃烧速率总是在腹板上呈现低-高的变化。这种变化有不同的BCCN，有时还被称为：驼峰cffcct，彩虹效应，燃速异常因素，...一些半螺旋模型已经被提出，并且仍然有效。通过对试件(铸坯)的燃速测试，证实了铸模几何形状(孔口、缝隙)以及铸模位置对烧损率的影响，并与电机壳体和芯棒进行了比较，并进行了定性分析。对于更复杂的几何形状(开槽、开槽)，也观察到了燃速随腹板分数的变化。相应的燃速异常因子BRAF(燃速异常因子)通常具有不同的形状，与全粒烧分析得到的剖面形状不同。这个
A synthcsis of works carried out by SNPE and university partners to investigatc processing effects on ballistic response of composite propellant grains is prcsented. It has been organizcd with the following general guidelines : An experimcntal work has been done to investigate the effects of casting processes and correlate burning rate profiles measured inside various grain shapes using subscales (cylindrical and finocyl). A particular attention has been paid to observe propellant flow during casting, analyze striations formation mechanism and determine their influence on burning rate. A constant cKort has bcen supported to identify and remove from observed burning rate anomalies, causes other than processing effects giving "Hump" (Grain dcformation, erosive burning, pressure drops,...). Improved ballistic analysis and prediction methods have been dcveloped and validatcd, whcrc each part of the motor has its own burning rate profile. This allows, in some cascs, a bctter feedback of experience on predictions than traditional methods using a global Burning Rate Anomaly Factor (BRAF). Propellant flow simulation codes have been used and adapted to produce a graphical reprcscntaton of striations. First results are vcry promising when compared to striations observcd inside snbscale grains. This represcntation of striations can bc used by a numerical model, still undcr developmcnt in cooperation with University of BORDEAUX, which simulates a 2D burning front moving in a given striatcd medium containing altcrnativcly standard propellant laycrs and thin bindcr rich layers. A validation program of thc combincd approach (propcllant flow simulation and combustion in a striatcd medium) is in progress. Comparisons betwccn measured and calculated burning rates, using somc basic configurations of striations, dcmonstratc the consistency of the striation hypothesis and thc ability of thc model to simulatc thc Burning Ratc Anomaly Factor observcd. The final aim of these different works is to build a complete model to predict a BRAF related to a given motor and casting process. Introduction Technical Background Manufacturing processes generate various stresses into uncured composite propellants : Flow through pipes, slit plates and blowholes (in the case of injection), along mandrels and walls, induces mainly boundary layer type shear stresses. Fall of free paste streams tends to create high vclocity gradients and shearing inside propellant mass in the vicinity of dropping zones. Spreading of propellant accumulated around dropping zones leads to "bonding" of moving frcc surfaces. Plunging after casting can induce again shear stresses and a complete reorganization of propellant structures. I t is now widely admitted that these different strcsses indncc separation of the solid particles and/or changes in propellant composition4 which in turn leads to burning rate variations as a function of location in the grain and relative angle of incidence between flame front and shcarcd lines or surfaces?. In the case of simple geometries (i.e. cylindrical central perforatcd grains) this effcct has bcen quite well characterized. For grains cast mandrel in place it is always rclated to a low-highlow burning rate variation through web. This variation has bccn differently, and sometimes poctically, named : Hump cffcct, Rainbow effect, Burning Rate Anomaly Factor, ... Somc semicmpirical modcls have been proposed and are still efficient. Burning rate measurements on samples (strand burncr) havc confirmed the burnin rate influencc of casting tools geometry (ports, slit plate ) and of thcir location compared to thc motor case and mandrel havc been observed and qualitatively analysedl. For more complcx geomctries (Slotted, Finocyl) burning rate variations as a hnction of web fraction havc been also observed3. Thc corresponding BRAF (Burning Rate Anomaly Factor) features generally a different shape comparcd profile derived from full grain firing analysis 3 5 3 . The