中文摘要：

为了更全面细致地阐明工业建筑中生产过程运输物料时的产尘机理,本研究运用实验方法通过改变下落高度及出流口径,对颗粒流下落过程的轴心速度、颗粒流扩散规律进行了研究,利用高速摄像仪对下落过程进行拍摄,后处理软件PCC2.14对图片进行分析.结果表明：自由下落颗粒流由稳定段向过渡段转变时,轴心速度单调递增由过渡段向扩散段转变时,轴心速度先增后减;远离出流口处颗粒流扩散直径与高度之间呈线性规律变化;颗粒流核心直径与扩散直径比随着高度增大而减小,随着出流口径增大而增大,该比值可以定量的分析流态的变化.本研究成果为碰撞过程的研究提供初始条件,进而可预测并控制颗粒的扩散,对散装物料输送过程粉尘的治理及保护工作环境提高工作人员健康水平具有重要的意义.

英文摘要：

To illustrate the mechanism of dust emission during the industrial materials transfer process in industrial buildings, experimental investigation on the particle behavior of free falling particle stream collision process was conducted using a high speed camera. The software PCC2. 14 was used to analyze the images. Results indicate that the centerline velocity of the particle stream monotonically increased from stable regime to transitive regime, increasing first and then decreasing from the transitive regime to the dispersive regime. The dimensionless dispersive diameter of the stream has a linear relationship to the dimensionless falling height and the empirical equation is obtained. The ratio between particle stream core diameter and falling disperse diameter decreased as the drop height increased, and increased as the drop outlet increased. The ratio could be used to analyze the variation of flow regimes quantitatively. The research provided initial condition for the collide process study. Thus the particle disperse could be predicted and controlled. It is important for improving the working environment condition and managing the dust from the bulk material transport system.