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浇铸时未固化的复合固体推进剂的流动特性是十分重要的,因为它直接关系到发动机装药的完整性。增加推进剂的固体含量,可以提高能量特性,却导致药浆的流动性变坏。固体含量高的推进剂呈现非牛顿假塑性流动特性,即表观粘度依赖于剪切应力,以及随着未固化推进剂存放时间的增长,假塑性也增加。本文介绍了在 NASA 主办下进行浇铸研究的一些情况。对浇铸过程中剪切应力的三个明显不同区域和每一区域中推进剂的流动特性,进行了讨论。叙述了推进剂组分和工艺条件的变化对表观粘度的影响和浇铸过程中形成药柱缺陷的有关流变性能的实验结果。
The flow behavior of the uncured composite solid propellant during casting is important because it is directly related to the integrity of the engine charge. Increasing the solid content of the propellant can improve the energy characteristics but lead to deterioration of the fluidity of the syrup. The high solid content propellants exhibit non-Newtonian pseudoplastic flow characteristics, ie, the apparent viscosity is dependent on shear stress and the pseudoplastic increases as the uncured propellant storage time increases. This article describes some of the casting studies conducted under the auspices of NASA. The flow characteristics of propellants in three distinct regions of shear stress during casting and in each region are discussed. The effects of the change of propellant composition and process conditions on the apparent viscosity and the experimental results on the rheological behavior of forming column defects during casting are described.