水平に置かれた平行電極板間を誘導帯電して飛昇するアルミナ粒子の上昇速度 [in Japanese] Lifting Velocity of an Induction-Charged Alumina Particle in Horizontally Set Parallel Plate Electrodes [in Japanese]
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水平に置かれた平行2平板の電極間において, 誘導帯電して飛昇する粉体粒子の上昇速度を理論的に求め, また実験によってこれを裏付けた.<BR>理論的には単一粒子の運動方程式 (一次元常微分方程式) を4次のRunge-Kutta法で解いて速度の非定常過程を解き, また粒子の位置を得るために速度を時間積分する方法をとった.<BR>実験ではアルミナ粉を用いて水平・平行の電極間を飛昇させ上電極中央に開けた穴から噴き上がる高さを計測し, 上電極を通過する速度に換算した.得られた値は, 概略理論計算の結果と一致した.数値解より, 粒子基準のレイノルズ数, 外力, 位置の無次元数の3者の関係を整理し回帰式を求めた.粒子径が小さい時, 流体からの粘性抵抗によって, または大きい時は重力によって上昇速度が低くなる事を明かにした.
The lifting velocity of an induction-charged particle in horizontally set parallel plate electrodes was studied by both theoretical and experimental approaches.<BR>In the theoretical analysis, a momentum conservation equation of a particle, the first order ordinary differential equation in a lagrangian frame work, was solved to obtain the velocity field of particles by using a method of the fourth order Runge-Kutta. Thereafter, a numerical integration of the velocity field was performed to define locations of particles.<BR>For the experiment, by using alumina powders with A 4 paper-sized electrodes, the maximum lifting height of a particle above the upper electrode was measured to estimate the lifting velocity of a particle in the first few seconds after high voltage was supplied, and a laser doppler velocity meter was used to measure the velocity fields of particles in the subsequent period when particles were circulating between the two electrodes.<BR>The particle velocities obtained by the theoretical and the experimental approaches were approximately identical. A simple formula for the prediction of particle's velocity field was derived by using a curve to fit the results of the numerical simulations. This could make relations between both the Reynolds number on the basis of a particle and other dimensionless numbers consisting of both external forces and locations. The predictions with the formula showed that in the case of a small-sized particle, the velocity of particles increases with the increase in particle diameter, because of viscous force dominating and that in the case of a large-sized particle, the velocity decreased with the increase of the particle diameter because of gravity force dominating.
- Chemical engineering
Chemical engineering 22(5), 1222-1229, 1996-09-10
The Society of Chemical Engineers, Japan