Predictive formulation of high solids content suspensions through understanding the statistics of flow-induced jamming

通过了解流动引起的干扰的统计数据来预测高固体含量悬浮液的配方

• 批准号: 1859217
• 金额: --
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1859217
• 关键词: Predictive; formulation; solids; content; suspensions

When suspensions of solid particles in a fluid are transported at high particle concentration major problems often occur, such as catastrophic thickening or 'jamming' and highly erratic and apparently uncontrollable flow. In industries ranging from ceramics and paint manufacture to drilling muds in oil extraction, these problems mean unreliable product quality and unpredictable process failure. Recent work has shown that despite this apparent unpredictability, such erratic jamming flows do follow meaningful statistical 'rules' which could be used to design better processes and formulate better products. Improved understanding of the statistics of jamming is thus the focus of this PhD project, using novel experimental apparatus and theoretical analysis. The candidate will explore the fundamentals of how erratic flow and stress-driven transient jamming occur in high solids content particulate suspension flow, and thus how to develop engineering methods to improve flow reliability. The project will impact a very wide range of fields and processes, including powder flows and slurries in chemical processes, formulation and manufacture of particle-based products such as foods and ceramics, the stability of soils and sediments in geology, and even the flow of blood cells in arteries and pedestrians in crowded environments. Such systems present many common puzzles and challenges, such as jamming followed by catastrophic collapse (e.g., earthquakes, eruptions, landslides), erratic fluctuations (e.g., blood clots and strokes) and pattern formation (e.g., stratified sediments, segregation in powders). The project thus crosses many engineering and manufacturing sectors and academic disciplines.The research will determine when 'solid' particle configurations appear, how this depends on flow geometry, on formulation (concentration, flow rate, particle interactions, fluid viscosity/viscoelasticity, etc) and how we can develop statistical analyses to interpret apparently unpredictable fluctuations and develop reliable predictive control methods and strategies. Experiment: Using suspensions with controllable particle and fluid properties, statistical data on local stress fluctuations will be obtained via novel shear and pipe flow cells, varying particle interactions, size distributions, etc. Stress data will be linked to structural fluctuations through optical microscopy using high speed video. Analysis: A key advance will be to analyse the statistics of the measured stress fluctuations to arrive at predictive methods based on jamming probabilities, which will allow optimisation of flow control, product formulation and process reliability for given processes and products. Underlying fundamentals: The analysis will also allow us to draw analogies with related systems and phenomena such as earthquake magnitude distributions and pedestrian crowd safety design (for example how to design buildings to minimise probability of jamming during evacuations). Results already obtained show clear similarities, but also significant differences, across these different jamming scenarios, and this project promises a significant advance in our wider fundamental understanding of the role of fluctuations in 'crowded' interacting systems.Engineering and design: Informed by the experimental and analysis results, we will go on to investigate how to manipulate geometry and product formulation, to reliably control jamming-prone flows in shear and channel flows, leading to novel ideas for design of such flows in applications.Results will both maximise our understanding of the fundamentals, vital for future innovative engineering, and help identify potential strategies to improve efficiency and controllability of real processes involving suspensions.

当固体颗粒在流体中的悬浮液以高颗粒浓度输送时，经常会出现重大问题，如灾难性的增稠或堵塞，以及高度不稳定和明显无法控制的流动。在从陶瓷和涂料制造到石油开采钻探泥浆的各种行业中，这些问题意味着产品质量不可靠，工艺失败不可预测。最近的研究表明，尽管存在这种明显的不可预测性，但这种不稳定的干扰流确实遵循有意义的统计‘规则’，这些规则可以用来设计更好的工艺和制造更好的产品。因此，使用新的实验设备和理论分析，改善对干扰统计的理解是本博士项目的重点。应聘者将探索在高固体含量颗粒悬浮流中如何发生不稳定流动和应力驱动的瞬变堵塞的基本原理，以及如何开发工程方法来提高流动可靠性。该项目将影响非常广泛的领域和过程，包括化学过程中的粉末流动和浆体，食品和陶瓷等以颗粒为基础的产品的配方和制造，地质学中的土壤和沉积物的稳定性，甚至拥挤环境中动脉和行人中的血细胞流动。这类系统提出了许多常见的难题和挑战，例如，堵塞之后是灾难性的坍塌(例如地震、喷发、山体滑坡)、不稳定的波动(例如血栓和中风)和图案形成(例如分层沉积、粉末分离)。因此，该项目跨越了许多工程和制造部门以及学术学科。研究将确定“固体”颗粒形态何时出现，这如何取决于流动几何形状、配方(浓度、流速、颗粒相互作用、流体粘度/粘弹性等)，以及我们如何开发统计分析来解释明显不可预测的波动，并开发可靠的预测控制方法和策略。实验：使用颗粒和流体性质可控的悬浮液，将通过新型剪切和管流单元、不同的颗粒相互作用、尺寸分布等获得局部应力波动的统计数据。应力数据将通过使用高速视频的光学显微镜与结构波动联系起来。分析：一个关键的进步将是分析测量的应力波动的统计数据，以得出基于堵塞概率的预测方法，这将允许对给定工艺和产品的流量控制、产品配方和工艺可靠性进行优化。基本原理：分析还将使我们能够与相关系统和现象进行类比，例如地震震级分布和行人人群安全设计(例如，如何设计建筑物以将疏散期间发生拥堵的可能性降至最低)。已经获得的结果显示，这些不同的干扰场景既有明显的相似之处，也有显著的差异，这个项目有望在我们更广泛的基础上理解波动在‘拥挤’交互系统中的作用。工程和设计：受实验和分析结果的启发，我们将继续研究如何操纵几何形状和产品配方，可靠地控制剪切流和槽流中的易堵塞流，从而为应用中此类流的设计带来新的想法。结果将使我们最大限度地理解对未来创新工程至关重要的基本原理，并帮助确定潜在的策略，以提高涉及悬浮的实际过程的效率和可控性。