STUDY ON THE COMBUSTION IN RAM ACCELERATOR

冲压式加速器是近年来开始研究的一种不需要助推火箭发动机就能以很高的速度发射的新型航天器，有望成为一种经济的航天器发射装置。它也有望成为研究超声速燃烧的基础实验装置。考虑到目前对冲压加速器的认识水平还不足以满足实际应用的需要，本课题研制了一台小型冲压加速器，通过光学手段对冲压加速器的燃烧流场进行观测，以获得其基础数据。我们一直试图使它作为冲压加速器工作，当弹丸的初速度不是那么高，当初始压力不是那么高，在世界上其他冲压加速器。为了与实验结果进行比较，为冲压加速器的发展提供参考，我们还开发了一个计算程序，对弹丸周围的燃烧流场进行了数值模拟 ...更多信息 冲压加速器由轻气枪启动，以使弹丸具有足够的初速度。我们研制的轻气炮是由气体爆轰驱动的，容易获得高压。我们研制的冲压加速器的下一个部件是破坏弹托和从管中排出驱动气体的装置。作为这些发展的结果，射弹可以满足启动条件而行进。结果表明，要获得稳定的燃烧，起动条件的范围很窄。初始速度有一个下限，这取决于混合气体的压力和成分以及要点燃的弹托的尺寸。由于冲压加速器的运行参数众多，目前还不能完全确定其启动条件的范围。数值模拟有助于我们在这些起动条件下进行试验。求解相互独立运动的弹丸和点火托周围的燃烧高速气体流动，模拟初始非稳态起动过程。采用自适应多层网格加密方法和移动边界技术，得到了与实验定性一致的数值解。少

Ram acceletator is recently begun to study expecting the possibility to use as the economic launcher of space vehicles, for the projectile can be launched with very high speed without booster rocket motor. It is also expected as the fundamental experimental apparatus to study on the supersonic combustion. In the present reserch project we made a small ram accelerator, which allowa us optically to observe the burning flow fields in order to get its fundamental data, for we considered as the understanding level on the ram accelerator is not ready for its practical use. We have been tried to make it work as a ram accelerator, when initial velocity of the projectile is not so high and when initial pressure is not so high as other ram accelerators in the world. We have also developed a computer program to simulate numerically the burning flow field around the projectile in order to help our development of the ram accelerator by comparing with our experimental results.The development of our … More ram accelerator is started by that of a light gas gun to give the projectile enough initial speed. The light gas gun we developed is driven by gaseous detonation, which is easy to get high pressure. The next parts of the ram accelerator we developed are the apparatus to break a sabot and to evacuat the driver gas from the tube. As a result of these developments, the projectile can travel satisfying the conditions to start. It is cleared that the range of starting conditions is very narrow to get stable combustion. There is a lower limit of initial speed, which depends on the pressure and the composition of the gas mixture as well as the size of the sabot to ignite. As there are so many parameters to run the ram accelerator, we could not complete to decide the range of its starting conditions up to now. The numerical simulatios help us to do experiments on these starting conditions. We have to solve the burning high speed gas flow around the projectile and the sabot to ignite, which move independently each other, to simulate the initial unsteady starting processes. We got the numerical solutions in qualitative agreement with the experiments, using the solution adaptive multilevel grid refinement method and the moving boundary technique. Less