Collaborative Research: Flow Instabilities in Gas-solid Flows

合作研究：气固流中的流动不稳定性

• 批准号: 1236157
• 负责人: Christine Hrenya
• 金额: $ 20.19万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236157&HistoricalAwards=false
• 关键词: Collaborative; Research; Flow; Instabilities; Gas

1236157/1236490PI: Hrenya/YinGas-solid flows are ubiquitous in both nature (landslides, avalanches, planetary rings, etc.) and industry (pharmaceuticals, food products, chemical and petroleum industries). High-velocity gas-solids flows that are found in a wide range of applications (circulating fluidized beds, pneumatic transport lines, sand flow modeling, erosion prevention, planetary rings, etc.), in particular, often develop instabilities that are referred to as ?clusters?, which are known to have a large impact on system performance. Accurate prediction of onset and evolution of the clusters is critical to the design, scale-up, and optimization of related systems. It is shown that inelastic inter-particle collisions and gas-solid drag can both independently lead to instabilities; in real systems, however, they always cooperate and their relative importance has not been examined. The objective of this research is twofold: (i) to elucidate the relative importance of the various origins of the instabilities in high-velocity, gas-solid flows, and (ii) to critically assess the ability of a new kinetic-theory (continuum) model to predict the quantitative nature of such instabilities. This research will begin with a simplistic, time-dependent cooling system where kinetic energy input is absent, and then move to more complex and practically relevant fluidization systems with and without solid boundaries to investigate time-independent statistics. Four different computational methods will be used. Lattice Boltzmann simulations that solve the detailed flow around particles will be used to provide first-principle-based data sets needed to assess the relative importance of collisions and gas phase effects as well as cluster formation and evolution. On the continuum level, linear stability analyses based on two-fluid kinetic theories will first be used to predict the stability boundary; Euler-Lagrangian method where only gas phase is treated as a continuum and particles are discrete, and Euler-Euler models where both gas and particle phases are treated as continua, will then be used to simulate the evolution of the clusters. These results will be compared to the lattice Boltzmann data for a critical assessment of the predicative ability of the various continuum models. This research will generate first-principle-based simulation data on cluster formation and evolution for high-velocity gas-solid flows, and these data will be used to establish an accurate theory able to predict both onset and evolution of the clustering instability on the continuum level.The simultaneous flow of gas and solid particles occurs in windstorms, landslides, reactors used for energy production, and mixing units used by the pharmaceutical industry, to mention just a few. The complex physical interactions occurring in these systems make them difficult to predict from past experiments alone. In this project, mathematical models with no fitting parameters will be developed and used to predict flow phenomenon unique to these systems. The availability of such a modeling tool is expected to reduce to improved design of reactors in shorter turn-around times and at smaller costs than is currently possible. The model will be made available to researchers worldwide via an existing open-source code, and thus is expected to find future use in numerous sectors, including pharmaceuticals, chemical process industries, energy production, geology, and astrophysics.

1236157/1236490PI：Hrenya/Yingas-Solid流在自然界（滑坡，雪崩，行星环等）和工业（制药，食品，化学和石油工业）中无处不在。在广泛的应用中发现的高速气体固体流量（循环流化床，气动传输线，砂流型建模，预防侵蚀，行星环等），特别是通常会发展为“插图”的不稳定性？ 簇的发作和演变的准确预测对于相关系统的设计，扩展和优化至关重要。结果表明，非弹性粒子间碰撞和气体固定阻力都可以独立导致不稳定性。但是，在实际系统中，它们始终合作，并且尚未研究其相对重要性。这项研究的目的是双重的：（i）阐明不稳定性在高速度，气体固体流和（ii）批判性评估新动力学理论（Continuum）模型的能力以预测这种不稳定性的定量性质的能力。这项研究将从不存在动能输入的简单，时间依赖性的冷却系统开始，然后转向具有和没有固体边界的更复杂且实际相关的流化系统，以研究与时间无关的统计数据。将使用四种不同的计算方法。解决粒子周围详细流的晶格玻尔兹曼模拟将用于提供基于第一原则的数据集，以评估碰撞和气相效应的相对重要性以及群集形成和进化。在连续水平上，基于两流体动力学理论的线性稳定性分析将首先用于预测稳定性边界。 Euler-Lagrangian方法只有气相被视为连续性和颗粒是离散的，而欧拉 - 欧拉（Euler-Euler）模型将使用气体和粒子相被视为连续性，然后将使用来模拟簇的演变。这些结果将与晶格Boltzmann数据进行比较，以评估各种连续模型的谓语能力。 This research will generate first-principle-based simulation data on cluster formation and evolution for high-velocity gas-solid flows, and these data will be used to establish an accurate theory able to predict both onset and evolution of the clustering instability on the continuum level.The simultaneous flow of gas and solid particles occurs in windstorms, landslides, reactors used for energy production, and mixing units used by the pharmaceutical industry, to mention just一些。 这些系统中发生的复杂的物理相互作用使它们很难仅仅从过去的实验中进行预测。 在这个项目中，将开发无拟合参数的数学模型，并用于预测这些系统独有的流动现象。 这种建模工具的可用性有望减少，以改善转弯时间的反应堆设计，并且成本较小。 该模型将通过现有的开源代码在全球研究人员提供，因此有望在包括药品，化学过程行业，能源生产，地质和天体物理学在内的众多领域找到未来的用途。