STUDY ON ACCURATE-HIGH SPEED POWDER CLASSIFICATION SYSTEM CONSIDERING PARTICLE CHARACTERISTICS

提出了一种新的湿式离心分级系统，该系统可以采用稳定的轴对称几乎刚性旋转流。该分级系统的特点是可以任意设定作用在颗粒上的离心力与流体阻力的比值，并可以通过数值模拟从颗粒的运动轨迹出发对分级机理进行理论研究。我们之前研究了不同通流速率和转速下的分类性能结果，明确了真比重接近1的1微米到亚微米范围内球形颗粒的锐度指数和切割尺寸与ekman数和rosby数的关系。但是，吞吐量对于系统来说很小。工业需求还要求对各种形状和真实比重大于2的颗粒材料进行更准确的分类。因此，为了使该系统切实可行，我们必须将该系统扩展到更有效的系统。本研究的目的是将分类系统发展为一种满足工业需要的分类系统新技术。我们得到了以下结果：1。为了阐明重力的标度规律，我们定义了离心效应参数Ce、重力效应参数Ge和粒子雷诺数Re，并研究了这些参数与主要分级流场斯特沃森层中流体和粒子速度差的关系。通过数值模拟计算了粒子的运动轨迹和粒子的概率密度分布。并从ekman层和stewartson层探讨了分类机制。我们将新系统作为一个简单的形状，如圆盘-圆柱形状，并通过数值模拟来评估其分类性能。

WE PROPOSE A NEW WET TYPE CENTRIFUGAL CLASSIFICATION SYSTEM TO WHICH A STABLE AND AXISYMMETRIC ALMOST RIGIDLY ROTATING FLOW CAN BE APPLIED. THE CLASSIFICATION SYSTEM HAS DISTINCTIVE FEATURES IN THAT WE CAN ARBITRARY SET THE RATIO OF THE CENTRIFUGAL FORCE TO THE FLUID DRAG ACTING ON PARTICLES AND CAN THEORETICALLY INVESTIGATE THE CLASSIFICATION MECHANISM FROM THE PARTICLE TRAJECTORIES BY NUMERICAL SIMULATION. WE PREVIOUSLY INVESTIGATED RESULTS OF THE CLASSIFICATION PERFORMANCE FOR VARIOUS THROUGH FLOW RATE AND ROTATION RATE, AND CLARIFIED THE DEPENDENCE OF THE SHARPNESS INDEX AND CUT SIZE ON EKMAN AND ROSSBY NUMBERS FOR THE SPHERICAL PARTICLES FROM ONE-MICRON TO SUB MICRON REGIME HAVING TRUE SPECIFIC GRAVITY NEAR ONE. HOWEVER, THE THROUGHPUT IS SMALL FOR THE SYSTEM. INDUSTRIAL NEEDS ALSO DEMAND MORE ACCURATE CLASSIFICATION OF PARTICULATE MATERIALS HAVING VARIOUS SHAPES AND TRUE SPECIFIC GRAVITY MORE THAN TWO. HENCE IN ORDER TO MAKE THIS SYSTEM PRACTICABLE, WE HAVE TO EXTEND THE SYSTEM TO MORE EFFICIENT ONES.THE OBJECTIVE OF THE PRESENT STUDY IS TO DEVELOP THE CLASSIFICATION SYSTEM TO A NEW TECHNIQUE ON THE CLASSIFICATION SYSTEM SATISFYING INDUSTRIAL NEEDS. WE HAVE OBTAINED THE FOLLOWING RESULTS:1. IN ORDER TO CLARIFY A SCALING LAW ON THE GRAVITY FORCE, WE DEFINE CENTRIFUGAL EFFECT PARAMETER Ce, GRAVITATIONAL EFFECT PARAMETER Ge AND PARTICLE REYNOLDS NUMBER Re. AND WE INVESTIGATE THE RELATION BETWEEN THESE PARAMETERS AND THE DIFFERENCE OF FLUID AND PARTICLE VELOCITIES IN THE STEWARTSON LAYER WHICH IS THE MAIN CLASSIFICATION FLOW FIELD.2. WE CALCULATED THE PARTICLE TRAJECTORIES AND THE PROBABILITY DENSITY DISTRIBUTION OF THE PARTICLES BY THE NUMERICAL SIMULATION. AND WE INVESTIGATE THE CLASSIFICATION MECHANISM IN THE EKMAN AND STEWARTSON LAYERS.3. WE TREAT NEW SYSTEM WITH A SIMPLE SHAPE LIKE A DISK-CYLINDER SHAPE AND EVALUATE ITS CLASSIFICATION PERFORMANCE BY NUMERICAL SIMULATION.