|Budget Amount *help
¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
In this research, a trial experimental apparatus for studying the working mechanism of the ram accelerator has been build. The apparatus is consists of a quick open valve type driver tube, a compression tube with a free piston, a launch tube with a dump tank and an accelerating tube. These tubes are manufactured and assembled. The test run was performed to demonstrate that the driver with the free psiton can accelerate a projectile to a speed larger than 600 m/s.
In a ram accelerator, a projectile, is accelerated by the high pressure generated by shock-induced combustion behind the body. To maintain the maximum thrust, detonations must be generated and stabilized at appropriate locations around projectile body. Therefore, successful development of such systems depends on understanding of the detonation structure on the projectile. In this study, a reactive flow around the projectile in the ram accelerator, which is ejected into the acceleration tube at a supersonic speed, is numerically
simulated to investigate an acceleration process by using detailed chemical reaction models. In formulating the problem, the following assumptions are made. At first, flow field is two dimensional and axisymmetric. Secondly, the flow is inviscid and non-heat-conducting, and the gas is thermally perfect. Thus, the specific heats for all chemical species vary with temperature. Chemical reaction rates of the gas mixture obeys Arrhenius'laws. The mixture through which the projectile is accelerating consists of H2, O2, N2.9 species (H2, O2, H2O,O,H,OH,HO2, H2O2 and N2) and 19 reactions are considered. Under these assumptions, governing equations are formulated as the Euler equation in general coordinates. Computer code used is semi-implicit predictor-corrector TVD scheme to solve the stiff chemistry. A configuration of the projectile is adopted as the RAMAC III benchmark test with its length 80 mm and its maximum radius 7.6 mm. The tube radius is 10 mm, which corresponds to RAMAC facility in Saitama University. Parameter is an initial velocity and an initial pressure in the tube, which contains a premixed of 2 H2+O2+3.76 N2 at 300K.Calculation region is 100 mm _x10 mm and includes grids 331_x 41 around the projectile, 71_x81 behind it. As a result, this computer code is available and captured the detonation structure in detail. And projectile is obtained constant acceleration for each pressure of acceleration tube. Less