Fundamental and Applicational Investigation of Ram Accelerator

研制了一套冲压发动机加速器系统。测试段的内径为25毫米，长度为6米。它的预加速器是粉枪，能够在30克无烟粉末的情况下，将40克有效载荷发射到1.2公里/S。混合气供应系统由质量流量控制器和背压调节器组成，操作方便，使用的钢瓶压力最高可达1 Mpa，高于充填压力。弹丸速度的测量是通过使用自制的拾取线圈感应磁感应来测量的。该多路复用器系统能够记录一个通道中多个点的压力数据。在甲烷-氧气-氮气(或Ar)混合物中进行了60次冲压加速实验。弹托分离只能通过混合气中的非定常气体动力学来实现。冲压加速的启动条件强烈依赖于无量纲热释放、入射速度和弹托设计，在现有冲压加速器Hugoniot理论的基础上，开发了推力性能数值计算程序。此外，通过考虑有限速率化学对该理论进行了扩展。利用扩展的理论，不仅可以分析热堵塞模式的性能，而且可以分析跨爆轰模式的性能。通过这一研究项目，重要的是证明用这种小口径装置加速冲压是可能的，从而加深对冲压加速器的尺度效应的了解。该技术在日本的空间技术、材料技术等领域具有广阔的应用前景。

A ram accelerator system has been developed. The test section has a 25 mm bore and a 6m length. Its preaccelerator, a powder gun, is capable of launching a 40-gram payload to 1.2km/s with smokeless powder of 30 grams. The mixture supply system, composed of mass flow controllers and backpressure regulators, is easy to handle and utilizes cylinder pases up to a pressure about 1MPa higher than the fill pressure. Projectile velocity is measured by sensing magnetic induction using home made pick-up coils. The multiplexer system is capable of recording pressure data at plural points in one channel.Sixty ram acceleration experiments were made with methane-oxygen-nitrogen (or argon) mixtures. Sabot separation was made only by unsteady gas dynamics made in the mixture. Starting condition for ram acceleration strongly depended on non-dimensional heat release, entry speed and sabot design.A numerical code which can calculate the thrust performance based on the existing ram accelerator Hugoniot theory has been developed. Moreover, the theory was extended by taking finite-rate chemistry into account. With the extended theory, performances not only of the thermally choked mode but also of the transdetonative mode can be analyzed.It is important through this research project to show that ram acceleration is possible with this small bore apparatus, thereby enhancing understandings of scaling effects of ram accellerators. This technology is promising in being applied to space technology, material technology etc. in Japan.