When a solar array in Low Earth Orbit has a high voltage of 100V or higher, an arc occurs. It causes surface degradation, electromagnetic interference and other undesired side-effects. Considering a large space platform of 1MW power in future, solar array which can operate at a voltage of 300V or higher is required. We report the results of experiments where we test the following three mitigation techniques to suppress the arcing; (1) Because an arcing is due to the charging of the coverglass by positive ions, we place PET (polyethyleneterephthalate) film in front of the coverglass to physically prevent the charging by ions. (2) We place conductive wire in front of the interconnector to narrow the plasma sheath region around the interconnector. (3) We use conductive ITO (Indium Tin Oxide) coating coverglass to reducing the charging on coverglass. The effect of each mitigation method is compared based on the tests in a vacuum chamber which simulates the plasma conditions in Low Earth Orbit.
This paper describes an experimental comparison of three passive approaches for controlling the shock interaction with a turbulent boundary layer. The first is the application of passive cavity (PC) by use of the slots. The effects of the slot were studied by varying the number of slots from n=2 to 8. The second is to use the vortex generators (VG). The shape of VG is a low profile triangular plow type arranged in four different types. The last method is a combination of the preceding two methods. The experiments were conducted in a 10×8 cm2 supersonic blow down wind tunnel at a free stream Mach number of 2.0. The measurements made were wall static pressures, pitot profiles, and Schlieren visualizations of the flow field. It was found that in the case of PC the pressure rises in two steps and weaken the shock strength, especially for n=8 case. For the VG arranged in coarse, the velocity profile downstream of the shock is fuller than the solid wall case. Furthermore with an appropriate combination of PC and VG, the combined method is effective in reducing the wave drag and also in suppressing the growth of the boundary layer.
The application of ceramic components in gas turbine engines enables the improvement of the power output and the efficiency of gas turbines by increasing the turbine inlet temperature. The high temperature properties of the ceramic materials offer the potential of higher turbine operating temperatures with no cooling techniques and therefore the ceramic components with higher temperature limits are becoming more attractive. In this study, the ceramic turbine wheel is applied in the aircraft gas turbine engine and the engine testing is demonstrated under full load operating conditions. The successful testing of the ceramic turbine components in the aircraft gas turbine engine has been accomplished. The test results indicate that the ceramic turbine wheel is capable of operating under the high thermal shock condition of fast starting to full speed. Furthermore, the adoption of some new ceramic turbine design concepts is proposed in actual use for aircraft ceramic turbine engines.
Experimental verification of identification of location and force history of a point impact on rectangular composite laminated plates is made in order to establish the identification method proposed previously. In experiments, a point impact on a rectangular composite laminated plate supported at one side was produced by an impulse hammer and the acceleration at points on the surface of the plate was measured by small accelerometers attached on the plate. It is found that by choosing appropriately the number of vibration modes in the identification method, the identification results of the location and force history of the point impact are in good agreement with the exact ones. This may imply that the possibilities of the practical application of the identification method can be expected.
This paper proposes a gain scheduled flight controller design method satisfying various design requirements, including gain and phase margins. The problem to satisfy stability margin requirement can be converted to an Integral Quadratic Constraints (IQC) stability condition. This IQC condition can be considered as a kind of mixed sensitivity H∞ problem with complex constant weights. Linear Matrix Inequality (LMI) theory is used to solve the derived mixed sensitivity problem. The effectiveness of the proposed method is verified by designing a lateral-directional flight controller for the Automatic Landing Flight Experiment (ALFLEX).
Structure of premixed laminar edge-flame in counterflow field with a strain rate gradient was investigated by numerical simulation. Two-dimensional incompressible Navier-Stokes equations with full chemistry of CH4/air were solved in curvilinear coordinates. When the strain rate gradient was produced by inclining an axis of the burner, the edge-flame was observed at the side of higher strain rate. On the other hand, the structure of twin flames in the side of lower strain rate was similar to that of normal counterflow premixed flame with no strain rate gradient, and therefore temperature and mole fractions of species were almost constant along the flame surface. The local strain rates at the edge were constant for an equivalence ratio as same as the extinction strain rates for the normal counterflow flames were.