| Summary: | 碩士 === 中正理工學院 === 兵器系統工程研究所 === 88 === Abstract
Due to the advancement of electronic techniques, renovation of the experimental methods, the out flow field of two-phase flow was propelled by employing photography techniques and fast data acquisitions in the internal flow. These results not only offer to figure out the problems in theoretical calculation and numerical simulation but also contribute in application and development of industry. Thus, the present work, which is in accordance with two different fields of two-phase flow by employing data acquisition and micro-photographic techniques, investigates two subjects systematically.
The first subject of the study is “Experimental Study on Top Venting of Water Solutions with Neutral Polymer of PVP during Emergency Relief.” In this study the transient behavior of venting from a vessel was visualized by employing a photography technique and experimental measurement. The fluids used in this study were pure water and water solutions made by adding a neutral polymer of PVP (polyvinyl-pyrrolidone) to water with 10 weight percent of the concentrations of the additive in the water. The fluids were pure water, water solution with 40000 g/mol molecular weight PVP and water solution with 360000 g/mol molecular weight PVP, respectively. The pressure and temperature of liquid inside the vessel that was used to simulate a reactor were acquired by using a fast data acquisition system. Some windows were set on the wall of the vessel to allow the flow visualization. The fluid before venting was heated by using heating tubes which were inserted in the wall of vessel and the temperature and pressure of fluid were measured by a k-type thermocouple and a pressure transmitter, respectively. The venting was initiated by relieving the solenoid valve that was connected to the exit pipe of the vessel and controlled by a controller. The major parameters were the fluid properties of the liquid and the orifice of the exit pipe of the vessel. The results show that the flow pattern of pure water can be classified as churn-turbulent mode; in contrast, the flow pattern of PVP40000 solution as bubbly flow and PVP360000 solution behaviors a characteristic between pure water and PVP40000. The vented volume can not be only related to viscosity, on the contrary it should be related to the flow pattern of working fluid. The fact is that the vented volume of the bubbly flow is larger than that of the churn-turbulent flow. The results provided quantitative evidence about the effect of fluid properties, such as viscosity and surface tension, and flow pattern, such as bubbly and churn turbulent flow, on the venting. The present study may contribute a better understanding of the dynamic behavior and the mechanism of flashing flow.
The second topic of the study is “ The Study and Fabrication of the Visualized Injector.” The present work is to design the size of the simple nozzle which is made of the acrylic material, observe the condition of cavitation of the working fluid in the nozzle hole and check the availability of the methodology by employing the micro-photographic techniques. The results show that the observed cavitation in the internal flow actually affects the mechanism of atomization of the outer flow. The present study may contribute a better understanding in making the nozzle for the relative researches and the results of this analysis can be helpful in the relative industrial applications.
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