A ram accelerator with a rectangular bore is working at Hiroshima University. The flowfield around a two-dimensional wedge-shaped projectile can be visualized by using this facility. In the present paper, a couple of inert gases are used in the test section (ram tube) instead of the combustible gas mixture to study the diffuser (consisted of projectile and tube wall) starting process. The projectile velocity and the pressure distribution along the tubes are measured by several magnetic detectors and pressure transducers. A schlieren system is employed through a pair of observation windows which are located on the side walls of the rectangular tube to take a photograph of the flowfield around a flying projectile. Experimental results show that the deffuser started has been obtained at inert gases in the pressure range around 0.3MPa. The photograph taken after a projectile ejected from the test section shows that the projectile retains its original shape.
Cylindrical shock waves have been generated by the impact of the flying disk on the metal plate. The flyer disk which is fixed several mm above the metal plate is accelerated downwards from its periphery by the high pressure after the detonation. The flyer disk acts as the piston running with the detonation speed. Although the high speed framing photograph showed the high implosion velocity of shocks, the expected temperature was not attained. This paradox was explained by the profile of imploding waves estimated by the numerical simulation and the feasibility of the flyer method was discussed.
By using of the optimal control theory, the optimal controls of the lift coefficient and the related flight paths of gliders are obtained to find the maximum flight range for given initial and final conditions. The results show that without ground effect the steady gliding flight at the maximum lift-to-drag ratio occupies a greater part of the flight path, but with the ground effect, the unsteady horizontal flight at the minimum allowable height takes the place of the steady gliding flight.
To restrain environmental pollution on the earth the energy supply from nuclear fusion using 3He is expected because of its cleanness. In this paper, the increase of CO2 emissions till A. D. 2040 is calculated using a energy consumption predict and based on the calculation result the energy to be supplied by a nuclear fusion system to stabilize CO2 emissions at the 1990 level is estimated. From this estimation, the feasibility study on the plant on the moon to produce 3He from the soil of lunar surface is presented.
The Engineering Test Satellite-VI (ETS-VI), which was launched on August 28, 1994 and named “Kiku-6, ” is a two-ton class three-axis stabilized satellite. The ETS-VI was injected to the elliptic orbit instead of planned geostational orbit unexpectedly. The ETS-VI has fixed satellite communication systems which was designed as geostationaly satellite service. We had to change the on-board program in Attitude Control Electronics to establish the communication link between the ETS-VI and ground stations. This paper shows an antenna pointing technique by way of adjusting the satellite attitude in accordance with its position in the orbit.
In the present study, the influence of the engine unit (air-intake, nacelle and nozzle) to the aerodynamic characteristics of the airframe was experimentally investigated at a free stream Mach number of 2.75. A series of wind tunnel tests was performed in NAL's M4 supersonic wind tunnel for the airbreathing engine unit/airframe integrated models of which the engine unit was installed on the bottom surface of the fuselage. These models were designed for Mach 3 flight. To identify the flow field (e. g., boundary layer and vortices) upstream of the engine unit, pitot pressure survey and flow visualizations by schlieren and oil-flow techniques were applied. The streamwise vortices due to down wash from upper side to lower side of forebody were observed at the low angle of attack, but these vortices could be suppressed by the modification of the forebody configuration. The diverter worked effectively so that the upstream boundary layer was removed. With the measurements of aerodynamic forces and schlieren visualization, it was found that the flow state, i. e., start, buzz or unstart condition, of air-intake affects the upstream flow field and the aerodynamic characteristics of the airframe. In the case that the shock spilled out from the air-intake, the aerodynamic force normal to the airframe axis decreased as the angle of attack increasing, because the force in the nozzle decreased due to higher loss of the total pressure in the engine unit.
In the preceding paper, the authors have shown by an experiment that the failure of a thin circular cylindrical shell under beam-like bending is attributed to the local bifurcation buckling at the extreme point on the compression side of the bending, rather than the collapse (the limit point buckling) due to the lack of the bending rigidity. The experiment was continued further to measure in detail the pre-buckling deformation of the cross section. The newly acquired results of the experiment are presented in this paper. It is shown that the bifurcation buckling occurs when the compressive stress at the extreme point approaches the classical buckling stress under axial compression for a cylindrical shell having a radius equal to the radius of curvature at that point of the deformed cross section of the cylindrical shell just before the buckling.
This paper presents an analysis of the nonlinear elastic deformation of elliptic cylindrical shells under the internal pressure. The papers published by the several authors treat this problem in small deformation theories. In this paper the curvatures in the circumference direction of the cylinder before and after deformed are expressed in power series of the distance along the circumference. The well agreement between the theoretical and experimental results are obtained.