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

在本研究中，考虑有限速率化学反应，通过准一维数值模拟分析了标度效应。数值模拟结果表明，为了在热堵塞工作模式下获得更大的工作范围，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。人们发现，设备越小，启动起来就越困难。为了更好地理解启动过程，进行了流动可视化实验。利用高速图像转换摄像机对先兆激波的行为进行了可视化。利用全息干涉术可视化了弹丸在撞锤加速管入口处撞击膜片周围的密度场，表明现有的膜片破裂模型在定量数值模拟中存在不足。通过改变混合料成分、填充压力、火药质量、弹型、破甲型和预加速段初始压力，进行了撞击加速度实验，获得了370 m/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.