The hydrocode simulations were conducted to verify the JEM Pressurized Module shield and structural performance for the orbital debris impacts to complement the HVI test capabilities. The first part reports the design evaluation for the strikes of debris smaller than 1 cm in diameter. The simulation results are correlated with the HVI test results and agreed well in the middle-velocity range of 3 to 6km/sec. However, the simulation results in the high-velocity range of 8 to 14km/sec where the HVI test data is not available show lower ballistic performance than the empirical ballistic limit curve given by Christiansen. Next, we report the results of hydrocode simulation results for large (5 and 10 cm in diameter) debris impacts with a velocity of 14km/sec. The simulations were conducted to estimate the module wall penetration hole size to be used for the follow-on structural safety assessments.
A microwave neutralizer was developed in Institute of Space and Astronautical Science. Plasma properties in the discharge chamber of the neutralizer were measured using Langmuir probe and a microwave connector called bias-T. A dense plasma over the cut off density of 2.2×1011cm-3 was observed at the electron extraction orifice. To investigate the endurance problem, an erosion rate was measured using three types of microwave neutralizer, changing the magnetic field strength and chamber length as parameters.
The structure of supersonic mixing flow field in ram/scramjet combustor was investigated numerically and experimentally. One type of parallel injection method with a ramp injector was selected and the effects of oblique shock impingement on the mixing layer generated from the ramp had been studied. The wedge angle of the shock-generator and the distance from the injection plane to the leading edge of it were varied parametrically. The pattern of shock waves and the flow pattern on the wall surface were visualized in the experiments. The numerical results of those flow pattern images had a good agreement with the results. Also, comparisons of static pressure on the wall surface showed good agreement qualitatively. Numerical results captured the structures of vortical flow field clearly. It was shown that the impingement of oblique shocks made streamwise vorticies strongly and the wedge angle of the shock-generator was more effective to enhance vorticity of the streamwise vorticies.
Visualizations of flowfield around the X-33 test vehicle have been performed utilizing the electric discharge method. The electric discharge method has been invented and developed by the authors and others for visualizing three dimensional hypersonic flowfield phenomena. In this experiment the objectives of visualization are three dimensional shock shapes, temperature distributions, and flow patterns near the model surface. It is considered that these visualized results are useful for verifying the theoretical and numerical results of the flowfield around the model. These visualizations are carried out using the hypersonic gun tunnel whose main characteristics are that the Mach number is 10 and the duration is 10ms.
Dynamic response of a jumping balloon was focused in the present paper. Differential equations of motion for the balloon-pilot system were derived as for two degrees of freedom. Numerical simulation was performed to figure out the characteristics of vertical movement of the balloon-pilot system, and it was found that the system was stabilized and controlled by attaching an extending rope to the pilot as for balance. Effects of spring constants and balancing rope density upon the dynamic behavior of the system were identified. The jumping balloon is significantly improved by the present simple technique and is expected as one af new sky-sports.
We have made a new type of anemometer for monitoring a wind tunnel velocity using a small electrically heated thermistor bead. Although this is the same principle as the constant temperature hot-wire anemometer, it is a main characteristic that this operates either as an anemometer or as a thermometer by changing a current through the one thermistor bead. This anemometer changes to the thermometer at regular intervals, then it continues to monitor the variation in air temperature for that period. If the temperature of heated thermistor could be changed immediately by a computer as air temperature varies, the difference in temperature between a hot-thermistor and an ambient air flow would be kept constant. Thus, the reading of anemometer will always be compensated for changes in air temperature. This paper describes a new correction method for drift in air temperature and the result examined some characteristics of this anemometer.