Collaborative Research: ISS: Revealing interfacial stability, thermal transport and transient effects in film evaporation in microgravity

合作研究：ISS：揭示微重力下薄膜蒸发的界面稳定性、热传输和瞬态效应

• 批准号: 2224417
• 负责人: James Hermanson
• 金额: $ 33.28万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2224417&HistoricalAwards=false
• 关键词: Collaborative; Research; ISS; Revealing; interfacial

Evaporation at the surface of a liquid film is critical to many industrial processes including coatings, semiconductor crystal growth, surface texturing in magnetic storage devices, surface finish during paper production, polymer processing, and electrode manufacturing for fuel cells. These applications depend on volatility-induced evaporation (no applied heat). Many other evaporation applications involve heating a solid substrate such as cooling, drying, fuel vaporization, food processing, chemical manufacturing and pharmaceuticals. Evaporation is also used for self-assembly of particles and morphological control of porous structures. Many space-based thermal management systems also depend on evaporation. Despite this ubiquity, the current understanding of film-evaporation processes is incomplete. The unsteady motion at the film surface and the motion of the liquid within the films drastically affect evaporation rates and heat transfer, particularly during transient, or unsteady, evaporation. The overarching goal of this research is to probe the fundamental mechanisms of these complex phenomena by conducting detailed experiments and numerical analysis of evaporating films in both normal- and microgravity conditions. The improved understanding of evaporation processes resulting from this effort may have broad impact in numerous practical applications. This project will use the unique capabilities of the ISS for long-duration microgravity testing to develop a more complete understanding of the behavior of evaporating films by revealing physical mechanisms normally masked under terrestrial conditions. Specific scientific objectives include determining: (i) the transitions between long-wave and short-wave surface instabilities in evaporating films, (ii) the evolution of the convective structures from the onset of evaporation to steady-state, and (iii) the corresponding impacts on thermal transport. Evaporation rates will be controlled using a combination of external heat addition and impulsively changing the system pressure. Diagnostic techniques include ultrasonic film thickness measurements, optical imaging, and thermal and pressure measurements. The stability of evaporating films will be examined by linear stability analysis and Recurrence Quantification Analysis. The latter is a relatively new diagnostic technique that provides metrics such as the rates and trapping-times that measure the recurrence of interfacial film states and their duration. The extraction of these quantitative signatures of film events can serve as triggers for “early warning systems” to predict and control emergent film behavior. The new, detailed information resulting from this investigation will be transformative in that it will lead to fundamental understanding of the origins and nature of the complex mechanisms that impact the liquid film behavior and the rate of heat transfer in evaporating films.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

液膜表面的蒸发对于许多工业过程至关重要，包括涂层、半导体晶体生长、磁存储设备中的表面纹理、造纸过程中的表面光洁度、聚合物加工和燃料电池的电极制造。许多其他蒸发应用涉及加热固体基质，例如冷却、干燥、燃料汽化、食品加工、化学制造和制药，蒸发也用于颗粒的自组装和形态控制。许多太空热管理系统也依赖于蒸发，但目前对薄膜蒸发过程的理解并不完整，薄膜表面的不稳定运动和薄膜内液体的运动会极大地影响蒸发速率。和传热，特别是在瞬态或不稳定蒸发过程中，这项研究的首要目标是通过对正常和非稳态蒸发膜进行详细的实验和数值分析来探讨这些复杂现象的基本机制。这项工作提高了对蒸发过程的了解，可能会对许多实际应用产生广泛影响。该项目将利用国际空间站的独特功能进行长期微重力测试，以更全面地了解蒸发薄膜的行为。通过揭示通常在陆地条件下掩盖的物理机制，具体的科学目标包括确定：（i）蒸发膜中长波和短波表面不稳定性之间的转变，（ii）蒸发膜的演化。从蒸发开始到稳态的对流结构，以及（iii）对热传输的相应影响将通过外部热量添加和脉冲改变系统压力的组合来控制，包括超声波膜厚度测量，光学成像、热和压力测量将通过线性稳定性分析和重现定量分析来检查，后者是一种相对较新的诊断方法，可提供速率和捕获时间技术等指标。测量界面膜状态的重现及其持续时间，提取膜事件的定量特征可以作为“预警系统”的触发因素，以预测和控制紧急膜行为，这项研究产生的新的详细信息将具有变革性。因为它将导致对影响液膜行为和蒸发膜传热速率的复杂机制的起源和性质的基本理解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值以及更广泛的影响审查标准。