Study of Swirling Flow Pneumatic Conveying System

本文研究了水平管道和垂直管道的颗粒旋流气力输送系统。管道由内径为80 mm的管道组成，长度约为12 m。通过使用不同流动角的轴向导向叶片产生旋流，并且发现旋流的特征在于气体流动的旋流数。给出了一种预测长管内旋流特性的经验方法。聚乙烯、聚苯乙烯和聚氯乙烯粒料用于测试颗粒。研究了不同空气流量、颗粒负荷和入口旋流强度下的总压降（包括导叶损失、颗粒附加压降、颗粒流型、颗粒速度和颗粒浓度分布）。结果表明，在管道入口区域，该方法是有效的，与相同功率消耗的轴流气力输送相比，可以降低输送风速。在考虑颗粒碰撞的情况下，采用k-ε模型，对水平流中与实验条件相似的旋流气力输送进行了三维数值模拟。在源项中考虑了颗粒对气体方程的影响。对于稀相流，本文的模拟对于颗粒速度、颗粒浓度和平均风速分布是有效的。

A swirling flow pneumatic conveying system for granular particles is investigated both for horizontal and for vertical pipelines. The pipelines consist of 80mm inside diameter tubes and the length is about 12m. The swirling flow is generated by using axial guide vanes of different flow angle and is found to be characterized by a swirl number for gas flow. An empirical procedure is given to predict the characteristics of swirling flow in a long pipe. Polyethylene, polystyrene and polyvinyl chloride pellets were used for test particles. Total pressure drop including loss due to guide vanes, additional pressure drop due to the particles, flow pattern of particles, particle velocity and particle concentration profiles were examined for different air flow rates, particle loadings and intensities of inlet swirl. The is found out to be effective in the inlet region of pipeline, and is able to reduce transport air velocity as compared with the axial flow pneumatic conveying with the same power consumption. A three dimensional numerical simulation of swirling flow pneumatic conveying was carried out for similar flow conditions as experimental ones in horizontal flow by considering particle collision and using k-epsilon model. The effect of particles on gas equations was considered in the source term. For dilute flow, present simulation was found valid as for particle velocity, particle concentration and average air velocity profiles.