Flow Analysis on Solid-Liquid Two-Phase Flows by Using the Image Processing

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1. Objective : In designing a hydraulic transport system of solid particles through pipelines, the pump capacity is generally determined, based on the pressure loss for slurries. The pressure loss is closely related to the particle behavior in pipelines. Therefore, this research objective is to obtain a large quantity of data on the particle behavior by using the image processing, and to stochastically investigate the particle behavior.2. Approach : in order to approach the above mentioned objective, the following phases were organized. (1) Measurement and estimation of solid concentration profiles by the shutoff method and by the image processing technique. (2) Lagrangian analysis on the behavior of tracer particles by the image processing technique. (3) Measurement of the pressure loss for air-solid-liquid three phase flows.3. Results : (1) The threshold values to conduct the thresholding were determined by analyzing the video image of O-12 overlapping particles. The solid concentration profiles were estimated by the image processing technique using the above threshold values, and were compared with the experimental results. It was confirmed that the agreement was satisfactory. (2) It was found that the Probability Density Function (PDF) of saltation length and height had two peaks, and these were corresponded to the behavior of rolling・sliding and saltation of particles. The modelling of the motion of saltating particles was conducted, and the simulation on particle behavior was performed. The simulated PDF of the saltation length and height approximately agreed with the experimental ones. (3) The pressure loss reduction for air-solid-liquid three phase flows was observed in the vicinity of the critical velocity, and it was confirmed that the pressure loss was predicted by the two-layer model.