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저밀도 입자의 액상 자유부상특성

Free Rising Characteristics of Low Density Particle in Liquid Phase

김동석 박영식 최윤찬 송승구

Kim DS Park YS Choi YC Song SK

HWAHAK KONGHAK, August 1994, 32(4), 566-571(6), NONE

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Abstract

평균직경이 0.0765-0.454cm이고 평균밀도는 0.13-0.63g/㎤인 11종류의 styrofoam입자를 이용하여 입자의 액상 자유상승속도를 측정하였다. Re_t>200에서 자유상승입자의 항력계수, C_D는 입자직경과 입자밀도에 관계없이 0.9 정도로 거의 일정하게 나타났으며, 자유침강입자의 항력계수에 비해 높게 나타났다. 입자의 Galileo number와 terminal Reynolds number와의 관계는 Ga=18Re_t+2.2Re_t^1.8, 표준항력곡선은 C_D=(24/Re_t)+2.93Re_t^-0.2로 나타났다.

Eleven styrofoam particles, with diameter ranges of 0.0765-0.454cm and density ranges of 0.13-0.63g/㎤, were used to measure free-rising velocity of particles. At Re_t>200, drag coefficient, C_D of free rising particle was independent of its diameter and density. The drag coefficient was calculated as a constant value of 0.9 which showed higher value than that of free settling particle. The correlation between Galileo number and terminal Reynolds number was given to Ga=18Re_t+2.2Re_t^1.8 and standard drag curve was found as C_D=(24Re_t)+2.93Re_t^-0.2.

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