The purpose of this experimental investigation is to understand the physical processes involved near the hollow cathode of a conventional MPD arcjet. A newly developed Divided-Cathode Method was successfully applied to the measurements of current distribution on a hollow cathode of usual size. Most of the measurements were conducted under the quasi-steady operation of an MPD arcjet, although some measurements were conducted under the elongated-duration operation in order to examine the influence of the change of cathode surface temperature. Some characteristic behaviors of current distribution on the hollow cathode were observed with the changes of discharge current, propellant mass flow rate, or applied magnetic field. In this report, the results of plasma diagnostics in the discharge region of the MPD arcjet are also involved.
In a wall-attachment fluid amplifier, there are cases which the internal flow becomes unstable and the jet is not stably attached to the one of walls. The case of the large scale model is reported previously, this unstable phenomenon is an oscillation with almost constant periods. And those periods are longer than those of other types of fluidic oscillators previously reported. For a small scale amplifier model that is onefifth of the previous large scale model, geometrical shapes in the fluid amplifier occuring the oscillation are measured and relations between the velocity of the main jet at the nozzle exit and frequencies are examined. By use of the theory of the attached jet and the analysis of the switching mechanism, the oscillation process is modeled by dividing into three processes, geometrical shapes occuring the oscillation and frequencies are calculated and compared with experimental ones. Geometrical shapes occuring the oscillation in the small scale model is different from those in the large scale model reported before. Oscillating frequencies in the small scale model are higher than those in the large scale model and they are same order as those of the load-type fluidic oscillator. It is found that the frequency is easy to vary by changing the velocity of the main jet.
An ideal lattice arrangement of the Vortexlattice method for rectangular wings is obtained by applying STARKS'S quadrature formula for a CAUCHY integral to the integral equation of the lifting-surface theory. The relation between the circulation of a lattice vortex and the corresponding local lift is thereby clearly defined, and the spanwise distribution of the induced drag is shown to be calculated accurately.
Analysis by use of finite element method and experiments are performed in order to study the compressive buckling strengths of CFRP laminated panels. An inconsistent assumed stress hybrid model, which can satisfy even mechanical boundary conditions, is derived as an analysis tool. The numerical results show that the inconsistent assumed stress hybrid model is very useful to analyze the states of deformation and stress accurately in geometrical nonlinear problems. The snap through phenomena observed in experiments can be explained very well by numerical results as stability problems. From the results of experiments about four kinds of CFRP laminated panels containing 0° plies, 90°Plies and ±45° plies, it is observed that, different from the results of Part 1, the fracture of laminated panels is caused by the delamination near the free edge in inplane condition. Therefore, numerical solutions of the free edge effects on the interlaminar stresses are obtained using a finite element procedure. The failure stresses of uniderectional CFRP, whose resin is 3130 epoxy, are estimated from experimental results and numerical results in the present paper, taking experimental results of Part 1 also into consideration. It can be concluded that a 0°+90°laminated panel among the test specimens has the highest compressive buckling strength.