Chi-Ho Yoon

Experimental Studies on Hydraulic Lifting of Solid-liquid Two-phase Flow

Experimental studies with 4.3m and enlarged 30m in height have been conducted to investigate the flow characteristics of solid-liquid mixture in a lifting pipe and to acquire the design data for sea tests that will be performed in the future. From the results, it was observed that the more the discharged volume fraction and the solid diameter increase, the more the hydraulic gradient increases. Also, the more the diameter of the lifting pipe increases, the smaller the friction loss, and consequently, the less pressure drop and hydraulic gradient. From the enlarged hydraulic pumping experiments, it was shown that the results of the experiments were matched with those of the numerical model previously developed. On the bases of these studies, we plan to conduct further experiments and validate the hydraulic pumping model.

The Effects of Pipe Curvature on the Flow Characteristics of Solid-liquid Two-phase Mixture in an Experimental Flexible Hose System

ABSTRACT The flexible hose system, which smoothly connects the buffer system and the miner in the deep sea lifting system, maximizes the action radius of the miner and prevents the lifting pipe from being twisted or broken. In order to predict and prevent accidents such as pipe clogging and to minimize the required power through the system, it is important to understand the flowing characteristics of manganese nodules and seawater in a flexible hose system. In this study a lab-scale flexible hose apparatus has been designed and manufactured to analyze the effects of pipe curvature on the flow characteristics of solid-liquid two-phase mixture in a flexible hose. The experiments for solid-liquid two-phase flow in a flexible hose has been performed by changing experimental factors, such as particle size, particle injection rate, hose shape and two-phase mixture velocity. The experimental results show that the increase of discharged volume fraction and diameter of the solid particles causes the pressure drop in the hose and the increase of the minimum velocity to transport the solid particles in the identical flexible hose. In the case of the solid-liquid two-phase mixture velocity more than 1.5 m/sec, the more the shape of the flexible hose becomes curved, the more the pressure drop in the hose increases. When it is lower than 1.5 m/sec, it was confirmed that the more the shape of the flexible hose becomes linear, the stronger the accumulation phenomenon becomes and the more the pressure drop in the hose increases.