| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Separation of nonmetallic inclusion from liquid metal is very important for getting clean materials which is desired in recent years. The purpose of this study is to get fundamental knowledge on the hydrodynamic behavior of inclusion particles in liquid metal. The following two model experiments have been made.
1. Lateral migration of hollow glass spheres in vertical pipe flows of water
Hollow glass spheres, 55-135mum in diameter, were injected in a vertical pipe flow of water or aqueous glycerol solution, and the collection efficiencies of particles on the wall, eta, was measured at the exit of the pipe. The following results were obtained;
(1) In the case of the upward flows, the value of eta increased with increasing the length of the pipe, and it changed with the liquid velocity, the particle diameter, the viscosity of liquid and the pipe diameter. The value of eta decreased rapidly in the region of Re>5000, Where Re is the tube Reynolds number.
(2) In the case of the downward flows, p
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articles tended to depart from the pipe wall and dispersed homogeneously at the high Reynolds numbers.
(3) The values of eta calculated from various lift force theories by using the trajectory theory did not agree with the observed results.
(4) Rubinow and Keller's equation on migration velocity of a rotating sphere in a uniform shear flow was modified by multiplying a correction factor, beta, and then values of eta were calculated. Comparing the calculated and observed values of eta, the values of bata were determined and correlated with the particle Reynolds number and the tube Reynolds number.
(5) By using this correlation, values of eta of alumina particles in liquid steel were estimated for various conditions.
2. Coagulation rate of fine particles in a stirred vessel
The turbulent coagulation rates of polystyrene-latex particles (PSL, 2.85mum) and alumina particles (1.8, 4.85mum) in aqueous electrolyte solutions were measured in a stirred vessel. The following results were obtained;
(1) The coagulation rates of the PSL particles in the rapid coagulation condition were consistent with the calculated values by the previous coagulation theory.
(2) The coagulation rates of alumina particles were measured at various pH values and electrolyte concentrations to find a rapid coagulation condition. This condition was found to be at pH=8 and C(NaCl)>0.1mol/1.
(3) The coagulation rates of alumina particles (1.8mum) agreed with the calculated values by the previous theory. For larger alumina particles (4.85mum), breakup and sedimentation of agglomerates were observed in the later stage of coagulation. Less
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