T字形エルボにおけるキャビテーションの流動特性に関する研究

概要

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Water is more liable to evaporate than oils since its saturated vapor pressure is higher than the ones of oils. Therefore it is important to prevent erosion due to cavity in hydraulic devices using water. In our previous study, we reported that erosion at elbow of pipeline can be reduced by using T-shape elbow. However its mechanism has not been clarified yet. In the present study, we observed cavitating flows in T-shape elbows with different shapes using a digital and high-speed video cameras. The amount of cavity was evaluated from taking images. As a result we confirmed that (1) circulating flow is steadily formed when the length of cavity-trapping region L ≥ 22.5 mm. If L ≤ 15 mm, circulating flow is formed intermittently, or it is not formed, (2) The amount of cavity in cavity-trapping region increases with L, and (3)there are two uses (a) T-shape elbows can be used to guide cavity into the region, in which circulating flow is formed, for defending the downstream of pipeline, and (b) Then the elbows can also be used to guide bubbles to the downstream so as to prevent erosion at the elbows.
神戸市立工業高等専門学校の論文