【作者】 刘圣照；

【导师】 王奎升；

【作者基本信息】 北京化工大学 ， 化工过程机械， 2007， 硕士

【摘要】 涡流式空气分级机是干法分级的重要设备。采用激光多普勒测速仪（LDV），研究了涡流式空气分级机内转笼和环形区的流场特性，并用重质CaCO₃物料试验，验证了蜗壳结构改变对分级指标的影响，为进一步改进分级机结构，获得更佳的分级指标，提供了依据。涡流式空气分级机转笼内的流场测试表明：转笼旋转，位于叶片间的气流与转笼一起运动，受到转笼叶片与出风口负压的作用，气流切向速度分布不同于转笼刚性旋转；转笼低速旋转，随着测点半径的减小，切向速度呈减小趋势；转笼高速旋转，随着测点半径的减小，切向速度呈增大趋势。在转笼叶片间存在旋涡，其位置与转笼的转速有关；由于出风口负压及转笼旋转的影响，转笼内存在不可忽略的轴向速度，其数值的大小与进口风速、转笼转速及在转笼中的位置有关。旋转的转笼影响环形区流场特性，用系数F表示转笼旋转对环形区气流切向速度的影响程度，在低速时F值较大，随转速的增加而迅速减小。流场测试结果表明：在蜗壳内加装水平隔板，能够有效的减小环形区气流轴向速度，使流场变得稳定；在转笼叶片间加装水平隔板，可以有效地减小转笼内轴向速度的数值。通过物料试验又进一步证明：转笼低速旋转时环形区是主要的分级区，转笼高速旋转时，环形区主要起分散和辅助分级作用。更多还原

【Abstract】 The turbo air classifier is very important dry-state classification equipment. By using Laser Doppler Velocimeter (LDV) the flow field characteristics of the annular region and the rotor in a turbo air classifier is measured. Classification experiment of raw materials is carried out to test the effect of the structure of classifier rotor and classifier volute on classification performance. This result should increase the depth of understanding of optimizing the structure of the turbo air classifier.Velocity measurement of air flow in the classification region of the rotor in a turbo air classifier is performed by Laser Doppler Velocimeter (LDV). The results indicated that the tangential velocity of air flow is not agreement with tangential velocity of the rotary rotor blade. In the low rotary speeds of the rotor the tangential velocity of air flow decreases with the decreasing radius of the measurement point; in the high rotary speeds of the rotor the tangential velocity of air flow increases with the decreasing radius of the measurement point. Vortex is present in the revolving flow field, and position of vortex is in relation to the rotary speeds of the rotor. The axial velocity is in evidence because of the rotation of the rotor and the present of negative pressure. The axial velocity distribution is not uniform in the classification region of rotor blades and the value is in relation to the inlet air velocity and the rotary speed of the rotor. The effect of rotary speed on the flow field characteristics of the annular region was studied. The influence coefficient of rotary speed on the flow field characteristics of the annular region is defined as F. F decrease with the increase of rotary speed.The results indicate that the axial velocity of the annular region is decreased and flow field is optimized when horizontal boards are installed in the classifier volute. Horizontal boards are installed in the blades so that the axial velocity decreases in a certain extent. Experiments of the material classification are carried out. The results show that as low rotary speeds are employed the annular region is considered as the main classification region, and in high rotary speeds the annular region works as the function of dispersion and secondary classification.更多还原