Turbulent multiphase flow with interfacial mass and heat transfer: linking microscopic physics to macroscopic mixing

CBET-1705246PI：Ni，Rui许多自然发生的和工业过程涉及包含颗粒的湍流，例如分散在流体中的气泡或液滴。在这些情况下，分散相可以与周围的流体交换质量和热量，其方式取决于湍流的细节。该奖项将支持实验，以了解质量和热量传输在湍流大尺度统计中的作用。挑战在于将单个气泡或液滴尺度上的微观传质与宏观混合和传质联系起来。垂直水洞将被用来研究气泡，这些气泡可以保持静止并成像，以确定在气泡和周围流体之间交换的示踪剂的浓度场。质量交换速率将与描述湍流强度和分散相特性的参数相关联。LED照明系统将用于量化湍流中的温度分布，从而提供对蒸汽气泡大规模混合效率的洞察。该系统还将用于研究各种形状的颗粒浓度，以分析湍流中的混合。这些研究的结果将广泛应用于蒸发喷雾、云中的雨滴、发酵反应器中的气泡和多相化学反应器。研究小组将为参加宾夕法尼亚州立大学和宾夕法尼亚中部艺术节项目的K-12学生团体准备多相流演示。将使用垂直隧道设施来研究含有颗粒的湍流中的质量传递。相反的平均流平衡了颗粒的浮力驱动上升或沉降，从而使颗粒保持在成像的视野中。该装置允许分别调整平均流量和湍流雷诺数。成像方法的结合将被用来测量分散颗粒的三维拉格朗日轨迹、周围流动的统计以及通过界面转移在两相之间交换的质量浓度场。将进行实验以确定具有界面传递的湍流多相流的相关参数。将对含有气泡和其他惯性颗粒的流动进行检查，以确定惯性颗粒是否增强了传质和混合。将研究界面动量传递和质量传递之间双向耦合的可能性。将确定界面传质在气泡破碎和合并中的作用。

CBET - 1705246PI: Ni, RuiMany naturally occurring and industrial processes involve turbulent flows that contain particles such as bubbles or drops dispersed in a fluid. In these cases, the dispersed phase can exchange mass and heat with the surrounding fluid in a way that depends on details of the turbulent flow. This award will support experiments to understand the role of mass and heat transfer on large-scale statistics of turbulent flows. The challenge is to relate microscopic mass transfer on the scale of individual bubbles or drops to macroscopic mixing and mass transport. A vertical water tunnel will be used to study bubbles that can be held stationary and imaged to determine the concentration field of tracers that are exchanged between the bubbles and surrounding fluid. The rate of mass exchange will be correlated with parameters that describe the turbulence intensity and characteristics of the dispersed phase. An LED illumination system will be used to quantify temperature profiles in turbulent flow, which provides insight into large-scale mixing efficient of vapor bubbles. This system will also be used to study the concentrations of particles of various shapes to analyze mixing in turbulent flow. The results of these studies will be broadly relevant to such applications as evaporating sprays, rain droplets in clouds, air bubbles in fermentation reactors, and multiphase chemical reactors. The research team will prepare demonstrations of multiphase flows for K-12 student groups participating in programs at Penn State and for the Central Pennsylvania Festival of the Arts.A vertical tunnel facility will be used to study mass transfer in particle-laden turbulent flows. An opposing mean flow balances the buoyancy drive rise or settling of particles, which allows the particles to remain in a field of view for imaging. The facility allows the mean flow and the turbulence Reynolds number to be adjusted independently. A combination of imaging methods will be used to measure the three-dimensional Lagrangian trajectories of dispersed particles, statistics of the surrounding flow, and the concentration field of mass exchanged between the two phases by interfacial transfer. Experiments will be conducted to identify the relevant parameters for turbulent multiphase flow with interfacial transfer. Flows containing bubbles and other particles with inertia will be examined to determine if inertial particles enhance mass transfer and mixing. The possibility of two-way couplings between interfacial momentum transfer and mass transfer will be investigated. The role of interfacial mass transfer on breakup and coalescence of bubbles will be determined.