Cavitation on MicroElectro Mechanical Systems

微机电系统中的空化

• 批准号: 0520604
• 负责人: Yoav Peles
• 金额: --
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0520604&HistoricalAwards=false
• 关键词: Cavitation; MicroElectro; Mechanical; Systems

ABSTRACT - 0520604Rensselaer Polytechnic InstituteThe proposed research will greatly advance the exceedingly limited fundamental knowledge ofcavitation in microsystems through a meticulous study of cavitating flows in rudimentary micro scale configurations such as orifices and venturis. Establishing a micro-scale cavitation knowledge base will ameliorate the design of numerous innovative microfluidic systems, such as micro-rockets, micro-coolers, micro-refrigerators, micro mixers, drug delivery systems, micro power systems including launch vehicles and high density power sources, electronic chip cooling systems, chemical micro-reactors, DNA synthesis assays and bio-MEMS systems. The current state-of-the-art technology in MEMS has enabled the integration and assembly of assorted independent micro components such as pump, valves, and nozzles into complex high-speed microfluidic machines. These neoteric systems posses geometrical dimensions in the range of 1-1000 microns, which are 103-104 times less than conventional machines, and operate at liquid flow speeds up to 300 m/s. Recent studies performed by our group on cavitation in Microsystems have yielded unexpected results and major deviations from conventional scale behavior. Therefore, an extensive scientific investigation of cavitation in microfluidic systems is exigent and imperative for the pragmatic realization of numerous novel micro machines.Cavitation, the formation of vapor pockets in liquid when the pressure falls below the vapor pressure, has long been a concern in the engineering of fluid machines. The deleterious effects of cavitation on conventional fluid machinery are well documented and have been aggressively researched in the last century. Cavitation in hydraulic machinery can limit performance, lower efficiency, modify the hydrodynamics of the flow, introduce severe structural vibration, generate acoustic noise, choke flow and cause catastrophic damage. Research on cavitation has contributed immensely towards improving the design of macro-scale hydraulic machinery. In the current scenario, it is indeed tempting to scale down the available information on cavitation in macro-scale machinery and employ it in the design of microscale devices. Although concomitant scaling effects of cavitation have been investigated, they are at best applicable for scaling between prototypes and real-world paragons at the macro-scale. Thus, the objectives of this research are to establish quantitative and qualitative understanding of nuclei effects on cavitation in microsystems, to assess the applicability of conventional scale models to predict cavitation inception in micro devices, and to study cavitating flow mechanisms pertinent to microfluidic systems under various conditions. To accomplish these objectives, a comprehensive experimental investigation is proposed. The proposed work will involve microfabrication and subsequent experiments on micro venturis and microorifices with various surface (topography and chemistry) and flow (stream nuclei) conditions, over a range of hydraulic diameters, surface geometries and dimensions, flow rates, pressures, and power levels. Two commonly encountered working fluids (ethanol and water) will be employed in this study. Highspeed, microscopic flow visualization studies will be undertaken to complement the quantitative measurements. Both cavitation inception and developed cavitation for various surfaces and flow conditions will be studied and flow patterns will be mapped under various flow conditions. The results will then be compared against models developed for conventional scale systems. All these tasks will provide means to enhance the understanding and unveil the mechanism of cavitation in microsystems.The Intellectual merit of the proposed research will be to establish pioneering engineeringknowledge quantifying the effects of surface topography and chemistry and stream nuclei on cavitation in microsystems. The derived engineering information will greatly clarify the role played by surface and stream nuclei in cavitation inside microsystems, and provide guidelines to properly design micro power devices. Additionally, this research work will stimulate research on cavitation in microsystems.The Broader impact of this research will be to provide vital scientific information to the MEMS and cavitation community and highlight the pernicious effects of cavitation in microsystems via seminars and presentations at national and scientific forums. Additionally, the proposed work will educate one minority female graduate student (from the University of Puerto Rico-Mayaguez) in the emerging field of MEMS technology, especially high-speed microfluidics. The results from the proposed research endeavor will be disseminated in archival journal and conference publications, and will also be incorporated into the undergraduate and graduate courses taught by the PI.

摘要 - 0520604伦斯勒理工学院拟议的研究将通过对孔口和文丘里管等基本微尺度结构中的空化流的细致研究，极大地推进微系统中极其有限的空化基础知识。建立微尺度空化知识库将改善众多创新微流控系统的设计，例如微火箭、微冷却器、微冰箱、微混合器、药物输送系统、微动力系统（包括运载火箭和高密度电源） 、电子芯片冷却系统、化学微反应器、DNA 合成分析和生物 MEMS 系统。目前最先进的 MEMS 技术已经能够将泵、阀门和喷嘴等各种独立的微型部件集成和组装到复杂的高速微流体机器中。这些新型系统的几何尺寸在 1-1000 微米范围内，比传统机器小 103-104 倍，并且在高达 300 m/s 的液体流速下运行。我们小组最近对微系统中的空化现象进行的研究产生了意想不到的结果，并且与传统的尺度行为存在重大偏差。因此，对微流体系统中的空化现象进行广泛的科学研究对于实用地实现许多新型微型机器来说是迫切和必要的。空化现象，即当压力低于蒸气压时在液体中形成的蒸气穴，长期以来一直是人们关注的问题。流体机械工程。空化对传统流体机械的有害影响已有充分记录，并在上个世纪得到了积极的研究。液压机械中的气蚀会限制性能、降低效率、改变流体的流体动力学、引入严重的结构振动、产生噪音、阻塞流体并造成灾难性损坏。空化研究对于改进宏观液压机械的设计做出了巨大贡献。在当前情况下，确实很容易缩小宏观机械中空化的可用信息，并将其用于微型设备的设计。尽管已经研究了空化的伴随缩放效应，但它们最多适用于宏观尺度上原型和现实世界典范之间的缩放。因此，本研究的目的是建立对微系统中核对空化影响的定量和定性理解，评估传统尺度模型在预测微装置中空化起始的适用性，并研究与微流体系统相关的空化流动机制。状况。为了实现这些目标，建议进行全面的实验研究。拟议的工作将涉及对具有各种表面（地形和化学）和流动（流核）条件的微文氏管和微孔进行微加工和后续实验，范围包括水力直径、表面几何形状和尺寸、流速、压力和功率水平。本研究将使用两种常见的工作流体（乙醇和水）。将进行高速微观流动可视化研究以补充定量测量。将研究各种表面和流动条件下的空化起始和发展的空化，并绘制各种流动条件下的流动模式。然后将结果与为传统秤系统开发的模型进行比较。所有这些任务都将提供增强对微系统空化机制的理解并揭示其机制的方法。拟议研究的智力价值将是建立开创性的工程知识，量化表面形貌、化学以及流核对微系统空化的影响。导出的工程信息将极大地阐明表面和流核在微系统内部空化中所起的作用，并为正确设计微功率器件提供指导。此外，这项研究工作将促进微系统中空化的研究。这项研究的更广泛影响将是向 MEMS 和空化界提供重要的科学信息，并通过在国家和科学论坛上的研讨会和演讲强调微系统中空化的有害影响。此外，拟议的工作还将在新兴的 MEMS 技术领域，特别是高速微流体领域，对一名少数族裔女研究生（来自波多黎各马亚圭斯大学）进行教育。拟议研究工作的结果将在档案期刊和会议出版物中传播，并将纳入 PI 教授的本科生和研究生课程中。