Microscale Heat Transfer Enhancement through Fluid Structure Interaction in the Slip Flow Regime

通过滑流流态中的流体结构相互作用增强微尺度传热

• 批准号: 0933574
• 负责人: Timothy Ameel
• 金额: $ 29.12万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0933574&HistoricalAwards=false
• 关键词: Microscale; Heat; Transfer; Enhancement; through

0933574AmeelA novel heat transfer enhancement technology is proposed for gas convection electronic cooling applications. Use of heat sinks with surface arrays of microscale flexible pin fins, oscillating at their fundamental frequency in response to unsteady flow, is expected to significantly increase heat dissipation rates. The small size of the proposed flexible pin fins will result in slip flow occurring on the fin surface. Non-continuum effects of slip flow and temperature jump at the surface, coupled with fluid structure interaction (FSI), produces a unique and challenging computational problem that has not been investigated before. An existing methodology that combines a computational fluid dynamics algorithm (ICE) with the material point method (MPM) for solids modeling will be modified to account for the momentum and energy exchange between a rarified gas and a deformable surface. The resulting FSI algorithm will be validated using four representative cases of slip flow for which analytical and/or numerical data are available. The proposed work will naturally lead to other slip flow FSI studies, such as associated with atomic force microscope probes, microscale diaphragm pumps and valves, and micro air vehicle wings and control flaps. Following the implementation and validation of slip flow and temperature jump conditions into the MPM-ICE methodology, a systematic study will be conducted to gain physical understanding into the FSI behavior and heat transfer enhancement of microscale flexible pin fins, individually, in pairs, and in arrays. Single microscale flexible pin fin studies will a) confirm the existence of unsteady flow at Reynolds numbers Re 47 in the continuum regime and b) produce data for the flow and heat transfer characteristics in the slip flow regime as functions of Re, Knudsen number Kn, fin aspect ratio, and material properties. The thermal fluid interaction of two microscale flexible pin fins, aligned with the principal flow direction, will be examined to determine optimal spacing. An array of microscale flexible pin fins will be studied to ascertain optimal configurations for maximum overall heat transfer rates, taking into account the previously mentioned parameters. Intellectual Merit: Computational modeling of fluid structure interaction in the slip flow regime has not been reported in the literature. Thus, the proposed project is expected to be transformative, resulting in an enabling technology for the design and analysis of a number of novel micro- and nano-fluidic systems, including the proposed microscale flexible pin fin concept for enhancement of air-side heat transfer. Data from continuum flow rigid pin fins and microscale flexible pin fin studies will increase the understanding of mechanisms related to drag and heat transfer enhancement in this complex FSI system. In addition, for the first time, data will also be produced for a system with FSI in the slip flow regime with concurrent momentum and thermal transport.Broader Impacts: The algorithm will enable modeling of systems in which fluid structure interaction takes place in the slip flow regime. Many other microscale systems, such as particulate flows, two-phase flows, and microactuators could be modeled with the modified MPM-ICE methodology. The optimized design of microscale flexible pin fin arrays could be extensively applied to a wide variety of electronic packages to enhance heat dissipation in applications limited to air cooling. Local impact will occur through the introduction of project results into two existing undergraduate/graduate course within the College of Engineering. Project results will be conveyed to the scientific community through refereed archival journal publications and by presentations at multidisciplinary meetings, providing opportunities for cross-fertilization of ideas. Graduate students involved in the project will be actively recruited from underrepresented groups in engineering. Research outcomes will be converted into engaging video presentations for outreach and recruitment activities. Underrepresented groups in engineering will be the focus of outreach, utilizing existing College of Engineering activities. Examples of these programs include Utah's Engineers: A Statewide Initiative for Growth, an NSF-funded initiative to increase engineering graduation rates, and Hi-GEAR Girls Summer Camp which is a residence summer program for high school females.

0933574Ameel提出了一种用于气体对流电子冷却的新型强化换热技术。使用带有微尺度柔性针翅片表面阵列的散热器，根据非定常流动以其基频振荡，预计将显著提高散热率。建议的柔性销钉尺寸较小，将导致翅片表面发生滑移流动。滑移流动和表面温度跃变的非连续效应，再加上流体结构相互作用，产生了一个以前从未研究过的独特而具有挑战性的计算问题。现有的结合计算流体力学算法(ICE)和物质点方法(MPM)的固体建模方法将被修改，以考虑稀薄气体和可变形表面之间的动量和能量交换。所得到的FSI算法将使用四个有分析和/或数值数据的滑移流的典型情况进行验证。拟议的工作自然将导致其他滑流FSI研究，例如与原子力显微镜探头、微型隔膜泵和阀以及微型飞行器机翼和控制襟翼相关的研究。在将滑移流动和温度跳跃条件应用到MPM-ICE方法并进行验证之后，将进行系统的研究，以获得对微尺度柔性销钉的FSI行为和强化换热的物理理解，包括单独、成对和成阵列。单个微尺度柔性销钉翅片的研究将a)证实在连续流区雷诺数Re为47的非定常流动的存在，b)产生关于滑移流区流动和换热特性的数据，这些数据是Re、Knudsen数Kn、翅片长径比和材料特性的函数。将研究两个微尺度柔性销钉的热流体相互作用，使其与主流动方向一致，以确定最佳间距。将研究微尺度柔性针翅片阵列，以确定最大总传热率的最佳配置，并考虑上述参数。智能优点：滑移流区流体结构相互作用的计算模型在文献中尚未报道。因此，拟议的项目预计将具有变革性，产生一种能够设计和分析若干新型微纳流体系统的技术，包括拟议的微尺度柔性针状翅片概念，用于加强空气侧的换热。来自连续流刚性销钉和微尺度柔性销钉的研究数据将增加对这一复杂FSI系统中阻力和换热强化机理的理解。此外，还将首次产生具有FSI的系统的数据，该系统处于同时存在动量和热传输的滑移流状态。广泛影响：该算法将能够对在滑移流状态下发生流固耦合的系统进行建模。许多其他微尺度系统，如颗粒流、两相流和微执行器，都可以用改进的MPM-ICE方法建模。微尺度柔性针翅阵列的优化设计可广泛应用于各种电子封装中，以增强空气冷却应用中的散热。通过将项目成果引入工程学院现有的两个本科生/研究生课程，将对当地产生影响。项目成果将通过参考的档案期刊出版物和在多学科会议上的陈述向科学界传达，为思想的交流提供机会。参与该项目的研究生将从工程学中代表性不足的群体中积极招聘。研究成果将转化为宣传和招聘活动的精彩视频。工程学中任职人数不足的群体将成为外联的重点，利用工程学院现有的活动。这些计划的例子包括犹他州的工程师：全州范围的增长计划，一个由NSF资助的提高工程学毕业率的计划，以及Hi-Gear女孩夏令营，这是一个针对高中女性的住宿暑期计划。