Development of a small-sized ram accelerator for improving the muzzle velocity

在本研究中，通过考虑有限速率化学反应的准一维数值模拟，分析了结垢效应。数值模拟结果表明，在热阻工况下，为了获得较宽的运行区域，小型装置是有利的。在此基础上，搭建了小型冲压加速器，并进行了运行试验。结果发现，仪器越小，启动就越困难。为了更好地了解启动过程，进行了流动可视化实验。利用高速图像转换相机对前兆冲击波的行为进行了可视化。利用全息干涉法对冲压加速管入口处弹丸撞击横隔板周围的密度场进行了可视化，得出了现有横隔板破裂模型在定量数值模拟中的不足。通过改变混合气组成、充填压力、药剂质量、弹丸构型、弹托构型和预加速度段的初始压力，进行了冲压加速实验，获得了370m/S的速度增益。

In this study, the scaling effects were analyzed by conducting quasi-one-dimensional numerical simulation with finite-rate chemical reactions being taken into account. From the numerical simulation, it was concluded that in order to obtain a wide operation regime in the thermally-choked operation mode, small-sized apparatus was favorable. Based on this, a small sized ram accelerator was constructed and its operation tests were conducted. It was found that the smaller the apparatus the more difficult its starting became. In order to better understand the starting process, flow visualization experiments were conducted. The behavior of a precursory shock wave was visualized by using a high-speed image converter camera. Density field around a projectile impinging the diaphragm at the ram acceleration tube entrance was visualized by holographic interferometry, concluding that the existing diaphragm rupture model was inadequate in quantitative numerical simulation. By varying mixture components, fill pressure, powder mass, projectile configuration, sabot configuration and the initial pressure in the pre-acceleration section, ram acceleration experiments were done, obtaining a velocity gain of 370 m/s.