The separation of bubbles in the water/oil was tried using a hydrophobic PTFE/hydrophilic PVA membrane modules. The PTFE membrane was effective to recover the bubbles flowing the outside the fiber in the water into the fiber when inside of fiber was evacuated. The recovery rate, i. e. the gas permeation rate, depended on the gas flow rate, the length of fiber and the degree of vacuum. The recovery ratio which was defined by the recovery rate/the gas flow rate had a good correlation with the gas hold up. On the other hand, the bubbles in the oil were flowing up outside the fiber without any contact to the fiber, and only the oil containing no bubbles was recovered inside the fiber for PTFE membranes. From the results mentioned above this recovery method of bubbles would be available in the nongravitational field such as space station.
Fundamental solutions of a point source and a point vortex in a two-dimensional stratified shear flow are presented. The flow has the velocity increasing exponentially with y and the density decreasing exponentially with y. The Euler equations are linearlized for small disturbances to the flow, and the method of Fourier transform is used to derive the solutions. Two types of solutions are obtained according to the magnitude of buoyancy effect; one is wavy form solution for large buoyancy and the other is non-wavy one for small buoyancy. For appropriate combination of source and vortex in a large buoyancy, the solution shows streamlines like lee waves.
An educational computer aided aircraft design (ECAAD) system is developed using microcomputers. The constitutive details of the program is presented with some examples. The convergence rate and accuracy of the four different optimization methods are compared and the simplex method is found to have superior characteristics to the other three ones. The effect of introducing a relaxation factor in optimization of the structural initial design is also discussed.
The static pitch stability of small ACVs fitted with finger-type skirts is investigated. A simple method which predicts the static stability and the cushion stiffness is proposed. It yields rough approximations of quantities needed for the initial design. Numerical results of the analysis are presented. We consider two different operating conditions. In one case the skirt is in contact with the ground. In another case the contact does not occur. In both cases the pitch stability decreases with increasing distance of the center of gravity from the skirt hem line and with increasing hover height. However variation of the skirt inclination angle affects the pitch stability in opposite way in two different operating conditions.