Freely-Falling Granular Powder Streams as Sensitive Probes of Interparticle Forces

自由落体颗粒粉末流作为颗粒间力的敏感探针

• 批准号: 0933242
• 负责人: Heinrich Jaeger
• 金额: $ 30.67万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0933242&HistoricalAwards=false
• 关键词: Freely; Falling; Granular; Powder; Streams

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0933242JaegerA better understanding of the behavior of powders is becoming increasingly important as industrial processes require smaller and smaller particle sizes. In addition, there is a growing realization that the existence of fines even in nominally larger sized powders critically affects their flowability. What makes dense granular powder flows particularly challenging is the multitude of interparticle forces that are at work simultaneously and the range of size scales involved, down to nanoscale particle surface roughness. In this regard, freely falling streams of powder offer special opportunities to investigate particle particle as well as particle-gas interactions because they make it possible to observe very small interparticle forces directly.Intellectual Merit. Changes in the free falling stream profile and, in particular, the break up of the stream into particle clusters can serve as macroscopic signatures and sensitive diagnostics of microscopic, grain-scale interactions. The research involves a unique experimental facility designed to track the evolution of dense granular powder streams over two meters of free fall, using a high speed video camera falling alongside the particulate material. The combination of imaging in the co-moving frame with extensive computer modeling and with characterization of grain surfaces by atomic force microscopy and scanning electron microscopy is used to establish a quantitative connection between the overall stream properties and their dependence on various types of cohesive particle-particle interactions, including capillary, van der Waals and electrostatic forces.Broader Impact: In addition to the industrial and economic value associated with the proper control of particulate matter, the study of granular materials provides insights into fundamental, crosscutting scientific issues across a wide range of science and engineering disciplines. The research will train graduate students in key aspects of particulate matter and multi phase flow research, and it includes the active participation of a large and diverse group of undergraduates as well as a close collaboration with an industrial partner. The research will be integrated with a multi faceted set of education and outreach activities, including activities with the nearby Chicago Museum of Science and Industry.

该奖项是根据2009年的《美国复苏与再投资法》（Pribag）（公共法第111-5）进行资助的。0933242JAEGERA更好地理解粉末行为的情况变得越来越重要，因为工业过程需要越来越小的颗粒大小。此外，人们越来越认识到，即使在名义上更大的粉末中，罚款的存在也会影响其流动性。使密集的颗粒粉流特别具有挑战性的是，同时工作的众多颗粒室内力以及涉及的尺寸尺度范围，降低到纳米级粒子表面粗糙度。在这方面，自由掉落的粉末流提供了研究颗粒粒子以及粒子气相互作用的特殊机会，因为它们可以直接观察到非常小的颗粒室内力。自由下落的流曲线的变化，尤其是，溪流分为粒子簇的变化可以用作宏观特征和微观晶级相互作用的敏感诊断。这项研究涉及一个独特的实验设施，旨在使用掉在颗粒物材料旁边的高速摄像机，在两米的自由跌落上跟踪密集的颗粒粉流的演变。使用原子力显微镜和扫描电子显微镜在共同移动框架中的成像与广泛的计算机模型与粒度表面的表征相结合，以建立依赖整体粒子粒子相互作用的整体粒子相互作用之间的定量连接，包括毛细管，范围和电位的界面。颗粒状材料的研究提供了有关广泛的科学和工程学科的基本，跨越科学问题的见解。这项研究将培训研究生的颗粒物和多相流研究的关键方面，其中包括大量多样化的本科生组的积极参与以及与工业合作伙伴的密切合作。这项研究将与多个方面的教育和外展活动集成，包括与附近的芝加哥科学与工业博物馆的活动。