High Flow Rate Ratio Research Articles

212 付着噴流の制御に関する研究

A numerical study is performed on control of jet attachment by parallel controlling jet. The analysis of this study was carried out for the several combination models in the width of controlling jet nozzle over a wide range of the flow rate ratio between main jet and controlling jet. The k-ε turbulence model was chosen to calculate the velocity. The results obtained were as follows; the attachment distance of jet was increase with increasing flow ratio and flow direction changed discontinuously, and attachment distance decreased in high flow rate ratio region with increasing flow ratio. These numerical results gave fairly good agreement with the experimental results.

Kinetics of epitaxial Si1−xGex growth using SiH2Cl2–GeH4–H2 mixture in reduced-pressure chemical vapor deposition

The dependences of the Ge/Si ratio in epitaxial Si1−xGex layers grown using a SiH2Cl2–GeH4–H2 mixture by reduced-pressure chemical vapor deposition on the flow rate ratio of GeH4/SiH2Cl2 and on the total flow rate have been examined in the temperature range from 480 to 600 °C. As previously reported, the Ge/Si ratio does not increase linearly with the flow rate ratio; instead, the rate of increase decreases at high flow rate ratios. Additionally, it increases with increasing total flow rate when the ratio of GeH4/SiH2Cl2 is fixed. It is found that these flow rate dependences are well accounted for by assuming that the reaction order for SiH2Cl2 adsorption is twice as large as that for GeH4 adsorption.

Flow Patterns of Air-Water Two-Phase Flow in Vertical Twisted-Tape-Inserted Tubes.

Experiments were performed to investigate the flow patterns which occur in upward air-water two-phase flow in vertical twisted-tape-inserted and circular empty tubes. Three basic flow patterns, i. e., bubbly, intermittent and annular flow, were defined based on the observations in the present experiments. At high water flow rate and small twist ratio, the bubbly-intermittent transition occurred at a lower air flow rate in the twisted-tape-inserted tubes than in the empty tube due to the centrifugal force of swirl flow which concentrated bubbles at the center of tube. The effect of centrifugal force was successfully modeled to obtain the criterion equation of the bubbly-intermittent transition. The intermittent-annular transition could be predicted well by the existing criterion equation developed for empty tube.

Extraction of L-Lysine from Its Dilute Aqueous Solutions by Rotating Film Pertraction

Removal and concentration of L-lysine in a three liquid phase pertraction system was studied using a laboratory three stage rotating disk pertractor. A 5% (vol) solution of Di-2-ethyl hexyl phosphoric acid (D2EHPA) in normal paraffins was used as an intermediate membrane liquid. The amino acid was extracted from its dilute aqueous solution (feed F) and concentrated in the stripping liquid R—a 1N solution of HCl in water. D2EHPA dissolved in the membrane liquid played the role of a ion exchange carrier. It was found that the most important parameters controlling the efficiency of this continuous pertraction process are the speed of disk rotation and the feed solution flowrate. The counter-current flow arrangement in the apparatus and the high flowrate ratio chosen provided nearly complete removal of solute from the feed as well as a concentrated solution of L-lysine.

Process Studies on Indirect Electrosynthesis of 1,4‐Naphthoquinone

A bench‐scale investigation was carried out on the indirect electrolytic oxidation of l‐naphthol to 1,4‐naphthoquinone by ceric ions. Chemical reaction of the naphthol (dissolved in methylene chloride) with ceric sulfate (dissolved in aqueous sulfuric acid) took place in a continuous flow static mixer. The immiscible liquids were separated, and the aqueous phase was recycled through a continuous flow electrolytic cell which regenerated the spent cerous ions. Measurements were made of chemical rate constant, liquid‐liquid phase equilibria, mass‐transfer coefficient, and reaction stoichiometry. Mathematical models of the process units were developed from fundamental principles of transport and chemical reaction phenomena, thermodynamics of ionic equilibria, and hydrodynamics of two‐phase dispersions. The models were combined to simulate the overall process flow sheet. Predictions agreed with experimental observations that conversion was highest for high flow rate and low phase ratio. It was recognized that the two‐phase chemical reactor was of central importance since its behavior influenced both product yield and electrochemical cell design.

プラズマＣＶＤ法により形成したａ‐ＳｉＣ：Ｈ膜の基板温度依存性

Substrate temperature dependence of a-SiC:H films prepared by r.f. glow discharge decomposition of a methanesilane gas mixture diluted with helium has been investigated. A phenomenon which shows a peak accompanying a negative temperature coefficient in the measurement of temperature dependence on dark d.c. conductivity has been observed. This phenomenon appears for the films prepared at low substrate temperatures (100°C), with high methane gas flow rate ratios (CH4/SiH410/1) and with high r.f. powers (160W). The conductivity peak associated with the negative coefficient appears at about 170°C, which is independent of the deposition conditions. The hydrogen concentration in these films is found to be different from the estimated value. The correlation between the hydrogen concentration and optical properties of the films suggests that this phenomenon correlates with the film morphology. The results indicate that this phenomenon is related to the relaxation process of the films; the annealing attributed to the conductivity measurement is likely to relax the disorder caused by the deposition described above.

Ultrastructural changes in the endothelial surface of the canine carotid artery induced by wall shear stress load.

To study the morphological changes in the endothelial surface of the artery induced by wall shear stress load, an arterio-venous shunt was constructed between the common carotid artery and the external jugular vein in 21 dogs. The ultrastructural changes in the endothelial surface were observed by scanning electron microscopy after the measurement of the hemodynamic parameters. In acute experiments (3 days or 1 week postoperative), the clear ultrastructural changes, such as the disturbance of the smooth folds, the find transverse wrinkles, the small spindle swellings, the splitting of the intercellular junction of the endothelial cells and occasionally the desquamation of the endothelial cells, were significantly observed as proportional to the elevated flow rate ratio (fs/fc, fs: flow rate of the shunted artery, fc: flow rate of the control artery). In subacute experiments (2 or 4 weeks postoperative), the small spindle swellings were observed in the shunted artery with high flow rate ratio. In chronic experiments (5 or 6 months postoperative), these changes were less proportional to the flow rate ratio. These morphological changes were significant in the disturbance of the endothelial barrier in acute experiments and they were significant in adaptive regulatory change in the chronic experiments. These support our previous observation (Am. J. Physiol. 239, H14-21, 1980). The possibility of the wall shear stress for atherogenesis was discussed.