ISS: Collaborative Research: Thermally activated directional mobility of vapor bubbles in microgravity using microstructured surfaces

这项研究将使蒸汽气泡在没有重力驱动浮力的情况下从经历沸腾的表面迁移。研究小组将在国际空间站（ISS）上飞行一个稍微改进的飞行硬件包，称为孔隙形成和流动性调查（PFMI）炉。蒸气泡无法从表面分离，长期以来阻碍了电子元件在太空中实现有效的相变散热。研究小组的努力是基于一种新的不对称表面微观结构，这种结构可以在不使用外力的情况下产生蒸汽气泡的运动。纹理表面是具有30-60度面的重复毫米尺度不对称棘轮的形式。待测试的假设是，这种结构表面为电子产品在不利的地面方向和微重力环境下的热管理提供了沸腾蒸汽质量的流动性，从而减轻了过早烧毁。在可变重力环境中影响蒸汽气泡被动运动的潜力，以及在不利定向的加热表面可能具有深远的好处。长期目标是开发一种简单，被动，自我调节的微结构表面技术，用于消费电子产品和航空电子产品的散热器。国际空间站实验的设计、开发和实施将与CASIS实施合作伙伴TBE一起进行，利用航空航天承包商广泛的飞行实验专业知识。具体目标有三个方面：验证在国际空间站实验室微重力飞行实验中观察到的横向气泡运动，进行地面实验和分析以验证/完善分析模型，并探索地面应用。密封的方形横截面安瓿插入到PFMI将被重新配置，以适应一个平面加热棘轮表面。安瓿设计将在一个改良的开放式通道设施的地面实验指导下进行。国际空间站和地面环境中的高速可视化和传感器测量将作为项目的一部分产生。这些数据可以被传热界的计算专家用作沸腾数值模拟的验证案例。从国际空间站和地面实验获得的数据和视频图像将在NASA的物理科学信息学（PSI）数据库中传播，用于在国际空间站上进行的实验。除了为研究生提供指导之外，该项目还将通过UCD的麦克奈尔学者计划和奥本大学的阿拉巴马太空补助金计划，使代表性不足的本科生能够参与其中。

This study will enable the mobility of vapor bubbles in the absence of gravity-driven buoyancy from surfaces experiencing boiling. The research team will fly a slightly modified version of a flight hardware package called the Pore Formation and Mobility Investigation (PFMI) furnace aboard the International Space Station (ISS). The inability of vapor bubbles to detach from a surface has long impeded the implementation of efficient phase-change heat dissipation from electronics components in space. The research team's efforts are based on a novel asymmetric surface micro-structure that produces movement of vapor bubbles without the use of externally applied forces. The textured surfaces are in the form of repeating millimetric-scale asymmetric ratchets with 30-60 degree faces. The hypothesis to be tested is that such structured surfaces provide mobility to vapor mass in boiling for electronics thermal management under adverse terrestrial orientations and microgravity environments, thereby mitigating premature burnout. The potential to affect passive motion of vapor bubbles in variable gravity environments, as well as in adversely oriented heated surfaces could have far reaching benefits. The long-term goal is to develop a simple, passive, self-regulating micro-structured surface technology for heat sinks used in consumer electronics and aircraft electronics.The ISS experiment design, development, and implementation will be pursued in conjunction with CASIS implementation partner TBE, leveraging the aerospace contractor's extensive flight experiment expertise. The specific objectives are three-fold: to verify lateral bubble motion observed in microgravity flight experiments aboard the ISS lab, to perform ground-based experiments and analysis to validate/ refine an analytical model, and to explore terrestrial applications. Sealed square cross-sectioned ampoules inserted into the PFMI will be reconfigured to accommodate a planar heated ratcheted surface. The ampoule design will be guided by terrestrial experiments in a modified open-ended channel facility. High-speed visualization and sensor measurements in ISS and terrestrial environments will be generated as a part of the project. These data can be used by computational experts in the heat transfer community as validation cases for numerical simulations of boiling. The data and video images obtained from ISS and terrestrial experiments will be disseminated on NASA's Physical Science Informatics (PSI) data repository for experiments performed on the ISS. Apart from providing an avenue for graduate student mentoring, the project will enable the participation of under-represented undergraduate students through the McNair scholar program at UCD and the Alabama Space Grant program at Auburn.