Rotary drums equipped with longitudinal flights are mainly used to dry granular solids and handle high throughputs. The design of the flights is a crucial task because they decisively influence the distribution of the particles over the dryer cross section. In a previous work, the authors derived a mathematical model for the particle flow in rotary drums with rectangular flights. In this model, the final discharge angle was underpredicted resulting in errors when calculating the contact area of the particles in the air-borne phase. Therefore, a new model was developed in this study to predict the final discharge angle based on a forces balance approach on a single particle. This approach includes the Coriolis force acting on the last discharging particles sliding down the inclined flight sheet. The model was solved by using the vector analysis method. Experiments were performed at rotary drums with 0.5 m and 1.0 m in diameter, respectively, and 0.15/0.3 m in length using glass beads and quartz sand as bed materials. Each drum was equipped with 12 flights around the shell. The model validation was performed by varying the bed material, drum diameter, flight length ratio, and the rotating speed. The model predictions have shown that as the flight length ratio and the Froude number increased, the final discharge angle attained higher values. The model predictions agree well with the measurements.

Graphic abstract

中文翻译：

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模拟飞行旋转滚筒中的最终排放角度

配备纵向螺纹的转鼓主要用于干燥粒状固体和处理高吞吐量。叶片的设计是一项至关重要的任务，因为它们决定性地影响颗粒在干燥器横截面上的分布。在之前的工作中，作者推导出了具有矩形飞行的旋转滚筒中的粒子流的数学模型。在该模型中，最终排放角度被低估，导致在计算气载相中颗粒的接触面积时出现错误。因此，本研究开发了一种新模型，以基于单个粒子的力平衡方法来预测最终放电角。这种方法包括科里奥利力作用在沿倾斜飞行板滑下的最后排放颗粒上。该模型采用矢量分析法求解。实验在直径分别为 0.5 m 和 1.0 m、长度为 0.15/0.3 m 的转鼓上进行，使用玻璃珠和石英砂作为床材料。每个鼓配备有 12 个围绕外壳的飞行器。通过改变床材料、滚筒直径、飞行长度比和旋转速度来进行模型验证。模型预测表明，随着飞行长度比和弗劳德数的增加，最终排放角达到更高的值。模型预测与测量结果非常吻合。通过改变床材料、滚筒直径、飞行长度比和旋转速度来进行模型验证。模型预测表明，随着飞行长度比和弗劳德数的增加，最终排放角达到更高的值。模型预测与测量结果非常吻合。通过改变床材料、滚筒直径、飞行长度比和旋转速度来进行模型验证。模型预测表明，随着飞行长度比和弗劳德数的增加，最终排放角达到更高的值。模型预测与测量结果非常吻合。

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