Developmental study of a new technique to classify submicron particles

点击翻译按钮获取中文摘要

We have studied a new classifier using the almost rigidly rotating through-flow between rigidly totating housing and rotor, and have obtained the following results.1. Theoretical results(1) In the interior region, the axial velocity depends on slopes and curvatures of the housing and rotor walls, while the azimuthal velocity depends only on the slopes.(2) The ratio of the Ekman transport on the housing to that on the rotor is determinated by the ratio of the function of housing's slope to that of the rotor's.2. Experimental results(1) The condition of occurrence of a steady axisymmetric regime of the flow is epsilon(〕SY.ltorsim.〔)1.6E^<0.46>, Where epsilon and E are Rossby and Ekman numbers.(2) Velocity distributions of the interior region agree with the theoretical results.(3) The Stewartson layr constitutes of the inner layr with a strong axial flow and the outer layr with a weak reverse flow.(4) We got excellent classification efficiency (sharpness index * 1.5) for the case where the feed is supplied only within the Ekman layr on the rotor.3. Computational analysis(1) A computational code to simulate the almost rigidly rotating through-flow between the coaxially rotating rotor and housing and a computational code to analyze motion of particles in the flow are constructed.(2) In the analysis of the almost rigidly rotating through-flow between the rotating disk and cylindrical tank, we have numerically considered the mechanism of the present classification technique.(3) Theoretical and experimental results are confirmed by the computational analysis.(4) Almost all particles at the inlet go to Stewartson layr through Ekman layr.(5) Coarse particles go to rigidly rotating region by the effect of centrifugal force at Stewartson layr.(6) Particle classification efficiency are specified by a parameter Dp/^<0Eepsilon>0 (Dp ; diameter of particles, E ; Ekman number, epsilon ; Rossby number).