Investigation of the lift and virtual mass force in gas-liquid flows with particle-resolved direct numerical simulation

通过粒子分辨直接数值模拟研究气液流中的升力和虚拟质量力

• 批准号: 1438143
• 负责人: Alberto Passalacqua
• 金额: $ 33.85万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1438143&HistoricalAwards=false
• 关键词: Investigation; lift; virtual; mass; force

CBET 1438143Many chemical manufacturing processes are carried out in bubble column reactors in which gas bubbles are dispersed throughout a liquid to perform chemical reactions. These reactors are designed to contain a large number of small bubbles to increase the contact area between the gas and liquid phases. The dynamics of gas-liquid flow inside these reactors and in similar multiphase processes is often described using mathematical models called two-fluid models. This project focuses on improving two-fluid models by explicitly taking into account the effects of interactions among the bubbles on certain terms in the models. The investigators will evaluate these critical terms by using computational simulations of bubble motions that account for interactions among bubbles and the development of bubble assemblies in flow. The improved two-fluid model will then be used in computational fluid dynamic simulations to compare with experimental data and help validate the model. The results of the project will be useful to design and optimize a broad array of manufacturing processes such as fermentation, wastewater treatment, algae growth, and antibiotic production.The accuracy of volume averaged two-fluid models for gas-liquid flow depends on terms that estimate momentum transfer between gas and liquid phases. These terms include several forces such as drag, lift and virtual mass forces. These forces are usually evaluated for the case of an isolated bubble in the flow. This project will study the effects of assemblies of interacting bubbles in the flow on the lift and virtual mass forces, and will use the results to develop improved momentum exchange terms for two-fluid models. The forces will be determined by conducting particle-resolved direct numerical simulations of spherical buoyant particles, which are a surrogate for bubbles in the limit where bubble deformation can be neglected. The simulations will be used to develop expressions for the lift and virtual mass forces for use in the two-fluid equations. The improved two-fluid models will then be used in computational fluid dynamics simulations over a wide range of operating conditions for which experimental data are available to validate the newly developed terms.

CBET 1438143许多化学制造过程都是在鼓泡塔反应器中进行的，在鼓泡塔反应器中，气泡分散在整个液体中进行化学反应。这些反应器被设计成包含大量的小气泡，以增加气相和液体之间的接触面积。在这些反应器内和类似的多相过程中，气液两相流动的动力学通常用称为双流体模型的数学模型来描述。该项目致力于通过明确考虑气泡之间的相互作用对模型中某些项的影响来改进双流体模型。研究人员将通过使用气泡运动的计算机模拟来评估这些关键术语，这些模拟解释了气泡之间的相互作用和流动中气泡组件的发展。然后将改进的双流体模型用于计算流体动力学模拟，以与实验数据进行比较，并帮助验证该模型。该项目的结果将有助于设计和优化广泛的制造过程，如发酵、废水处理、藻类生长和抗生素生产。气液两相流动体积平均双流体模型的准确性取决于估计气液两相之间动量传递的项。这些术语包括几种力，如阻力、升力和虚拟质量力。这些力通常是在流动中有孤立气泡的情况下评估的。这个项目将研究流动中相互作用的气泡集合对升力和虚拟质量力的影响，并将利用结果来开发改进的双流体模型的动量交换项。作用力将通过对球形浮力粒子进行粒子分辨的直接数值模拟来确定，在可以忽略气泡变形的极限情况下，球形浮力粒子是气泡的替代品。这些模拟将被用来开发用于双流体方程的升力和虚拟质量力的表达式。然后，改进的双流体模型将用于在各种操作条件下的计算流体力学模拟，这些操作条件下的实验数据可用于验证新开发的条件。