Hydrodynamic Study on the Separation of Inclusion from Liquid Metal

非金属夹杂物与液态金属的分离是获得清洁材料的重要手段。本研究的目的是为了了解夹杂物颗粒在液态金属中流体力学行为的基本知识。进行了以下两个模型实验。将直径为55 ~ 135mum的中空玻璃球注入垂直管道水流或甘油水溶液中，在管道出口处测量壁面颗粒的收集效率eta。得到以下结果：(1)在向上流动的情况下，eta值随管道长度的增加而增大，随液体速度、颗粒直径、液体粘度和管径的变化而变化。eta值在Re bbbb5000附近迅速减小，Re为管的雷诺数。(2)在向下流动时，在高雷诺数时，更多的物质倾向于离开管壁，分散均匀。(3)利用轨迹理论计算的各种升力理论的eta值与观测结果不一致。(4)对Rubinow和Keller关于均匀剪切流中旋转球体迁移速度的方程进行修正，并乘上修正因子β，计算出eta的值。比较了eta的计算值和观测值，确定了bata的值，并将其与粒子雷诺数和管雷诺数进行了关联。(5)利用这种相关性，估计了不同条件下钢液中氧化铝颗粒的eta值。在搅拌容器中测量了聚苯乙烯乳胶颗粒（PSL, 2.85mum）和氧化铝颗粒（1.8,4.85mum）在电解质水溶液中的湍流混凝率。得到以下结果：(1)快速混凝条件下PSL颗粒的混凝速率与前人混凝理论计算值一致。(2)测定不同pH值和电解质浓度下氧化铝颗粒的混凝率，寻找快速混凝条件。在pH=8， C(NaCl)>0.1mol/1的条件下，发现了这种情况。(3)氧化铝颗粒的混凝率（1.8mum）与前人理论计算值一致。对于较大的氧化铝颗粒（4.85mum），在凝固后期观察到团聚体的破碎和沉降。少

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 waterHollow 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 … More 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 vesselThe 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