Experimental study of oblique impact between dry spheres and liquid layers.
Experimental study of oblique impact between dry spheres and liquid layers.
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DOI：
10.1103/physreve.88.033018
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发表时间：
2013-09
期刊：
影响因子：
--
通讯作者：
Jiliang Ma;Daoyin Liu;Xiaoping Chen
中科院分区：
文献类型：
--
作者：
Jiliang Ma;Daoyin Liu;Xiaoping Chen
液体添加在工业流化过程中很常见。详细了解颗粒与液体层的碰撞力学有助于优化这些过程。对液体的正常撞击进行了广泛的研究；然而，关于液体斜冲击的研究却很少。在这项工作中，进行了实验，以追踪Al_{2}O_{3}球体斜撞击被液体层覆盖的表面，其中自由落体球体最初受到水平气流的干扰。斜碰撞由于发生强烈的旋转而表现出不同于正常碰撞的回弹行为。分析了液桥的法向恢复系数e_{n}和切向恢复系数e_{t}以及液桥破裂时间t_{rup}。随着液层厚度和粘度的增加，e_{n}和e_{t}减小，t_{rup}增大。随着切向速度的增加，e_{t}先减小后增大，e_{n}基本保持不变，t_{rup}不断减小。为了进一步探讨恢复系数与冲击参数之间的关系，提出了修正的Stokes数。最后，对能量耗散的分析表明，接触变形和液相是总能量耗散的两个主要来源。出乎意料的是，液相引起的耗散能与切向速度无关。
Liquid addition is common in industrial fluidization-based processes. A detailed understanding of collision mechanics of particles with liquid layers is helpful to optimize these processes. The normal impact with liquid has been studied extensively; however, the studies on oblique impact with liquid are scarce. In this work, experiments are conducted to trace Al_{2}O_{3} spheres obliquely impacting on a surface covered by liquid layers, in which the free-fall spheres are disturbed initially by a horizontal gas flow. The oblique impact exhibits different rebound behaviors from normal collision due to the occurrence of strong rotation. The normal and tangential restitution coefficients (e_{n} and e_{t}) and liquid bridge rupture time (t_{rup}) are analyzed. With increase in liquid layer thickness and viscosity, e_{n} and e_{t} decline, and t_{rup} increases. With increase in tangential velocity, e_{t} decreases first and then increases, whereas e_{n} remains nearly unchanged, and t_{rup} decreases constantly. A modified Stokes number is proposed to further explore the relation between restitution coefficients and the impact parameters. Finally, an analysis of energy dissipation shows that the contact deformation and liquid phase are the two main sources of total energy dissipation. Unexpectedly, the dissipative energy caused by the liquid phase is independent of tangential velocity.