Masao Taga

On the Polymer Thickener for Viscosity-Stabilized Solar Pond

The optimal physical properties of an ionized polyacrylamide solution, selected as the most suitable thickener for the insulating layer of a viscosity-stabilized solar pond, are described. Light transmittance, viscosity and viscosity degradation were obtained for a range of thicknesses from 1 cm to 15 cm (1–15 cm), weight concentrations of 0.1–0.5% (0.1–0.5 wt%) and temperatures of the polymer of 20–80°C. Onset of co nvection was also measured for a given thickness of the polymer solution. An exposure test was carried out to prevent degradation of the polymer using an antioxidant. It was confirmed that the viscosity was not decreased and, on the contrary, increased slightly after 100 days. It was shown experimentally that the critical Rayleigh number coincided with the theoretical values reported by Tien et al.. [Int. J. Heat Mass Transf. 12 (1969) 1173]. Transmittances of the polymeric gel for the case of vessels greater than 5 cm in thicknesses were better than those of the SPR402 solution (0.5 wt%).

Measurement of displacement on facial bone by real-time holographic interferometry

The displacement of human dried facial bone was measured and considered under static loads by real time holographic interferometry. Materials were dried human skulls. Various loads were applied to the zygomatic, maxillary and other facial bones by means of a loading apparatus. As the experimental result obtained from the load to the neighborhood of the fronto-malar suture on the zygomatic bone, density of interference fringes increased on the zygomatic bone more than on the other facial bones and parallel interference fringes were observed on the zygomatic bone. Densities of orbital maxillary and zygomatic bones were greater, when the load was applied to the center of infraorbital margin than when it was applied to the other facial bones. When the neighborhood of the front-malar suture on the frontal bone was loaded, coarse interference fringes occurred on the zygomatic, maxillary and orbital bones, while fine interference fringes appeared on the frontal bone. When the maxillary bone near infraorbital margin was loaded, concentric circular fringes were observed. The result shows that the displacement depends on the loading point. When the load applied to the zygomatic bone, parallel fringes appeared on the bone. This means that the bone deformed almost as a body.

Physics of a Porous Solar Pond

A solar pond is a useful system for storing solar energy only if convection is strictly prevented. The temperature difference of 50°C between the bottom and the top is obtained with a pond of 1 m depth in one week (radiative heating time), if conduction loss to the ground is neglected. It takes two and a half months (conduction time), however, for the pond to settle in a quasi-stationary state. Then, 90% of the solar energy flux can be utilized. The variation principle is generalized to prove that length scales of thermal conduction and viscous forces acting in a porous pond are reduced so much that the Rayleigh number may be lowered below the critical value for the onset of convection. Piles of coarse sheets of transparent artificial lawn or vertical strings or rods, one in each 4-mm-square area, will be sufficient to prevent convection. The conduction equation is solved, giving the daily variation of temperature as less than 1°C at the bottom and negligible at the top.

Visualization of Flow Pattern of Self Oscillated Turbulent Jet in Enclosed Room

A new method based on the Coanda effect for self oscillation of a circular jet bounded by rectangular enclosure is suggested. The flow pattern is observed by an experiment for water flow by using a light sheet and a domestic movie camera. And the experiments in both air and water reveal regions of stable oscillation wherein relationships are obtained between geometrical dimensions of the enclosure.

A Fundamental Study on Flow Characteristics in Boiler Furnaces : 2nd Report, A Quantitative Evaluation on Mixing Characteristics in Furnaces

In the first report the experimental results of the flow patterns and the concentration distribution of tracer fluid in a two-dimensional model in which perforated plates were installed instead of a tube bundle were reported. In the present report, in order to evaluate these characteristics quantitatively, numerical calculations of the flow pattern and the transient concentration distribution based on the turbulence energy model (one equation model) have been conducted. The effects of the magnitude of flow resistance of the tube bundle on the flow pattern and the mixing performance were clarified quantitatively referring the comparisons with the experimental results.