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-0520604RensSelaer理工学院提出的研究将通过对基本微型构型（例如OrifieS and Venturis）中的cavit缩流的精心研究，从而极大地推动微型系统中极为有限的基本知识。建立微尺度的空化知识基础将改善许多创新的微流体系统的设计，例如微孔，微冷器，微冷器，微型冰箱，微型混合器，微型混合器，药物输送系统，微电力系统，包括发射车辆和高密度电源电源，高密度冷却源，化学微型微型技术，化学微连接器，DNA Synsiss，DNA Synsiss和Bio-bio-sysess sysise，dna synsiss。 MEMS中的当前最新技术使各种独立的微型组件（例如泵，阀门和喷嘴）的集成和组装成复杂的高速微流体机器。这些Neoteric系统的几何尺寸在1-1000微米的范围内，比传统机器少103-104倍，并且在液态流速最高300 m/s的情况下运行。我们小组对微系统的空化进行的最新研究产生了意外的结果和与常规规模行为的重大偏差。因此，对微流体系统中空化的广泛科学研究是对众多新型微型机器的实用实现的紧急和必要的，当压力降至蒸气压力以下时，液体中的蒸气口袋的形成一直是流体机工程的关注点。空化对传统流体机械的有害影响已得到充分记录，并在上个世纪进行了积极的研究。液压机械中的空化可以限制性能，降低效率，改变流动的流体动力学，引入严重的结构振动，产生声音噪声，cho绕流动并引起灾难性损害。空化研究为改善宏观液压机械的设计做出了巨大贡献。在当前情况下，确实很容易缩小有关宏观机械空穴的可用信息，并将其用于显微镜设备的设计。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的原型和现实世界中的缩放。因此，这项研究的目标是对核对微生系统中空化的影响建立定量和定性的理解，以评估常规量表模型在各种条件下与微流体系统有关的库流动机制的适用性。为了实现这些目标，提出了全面的实验研究。所提出的工作将涉及微生物和随后的微型文库和微型实验，以及各种表面（地形和化学）和流动条件（流核）条件，在一系列液压直径，表面几何形状和尺寸，流速，压力，压力和功率水平上。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。对于各种表面的空化开始和开发的空化，将研究流动条件，流动模式将在各种流动条件下进行映射。然后将将结果与为传统规模系统开发的模型进行比较。所有这些任务都将提供手段，以增强微系统中空化机制的理解和揭示。拟议的研究的智力优点是建立开拓性的工程知识，量化了表面形貌，化学和流核对微生系统气腔的影响。派生的工程信息将大大阐明表面和流核在微系统内部空化中所扮演的角色，并为正确设计微功率设备提供指南。此外，这项研究工作将刺激微型系统中的空化研究。这项研究的更广泛影响是向MEMS和空化社区提供重要的科学信息，并通过在国家和科学论坛上通过研讨会和演示来强调微型系统对空化的有害影响。此外，拟议的工作将在新兴的MEMS技术领域，尤其是高速微流体学领域，教育一名少数族裔女研究生（来自波多黎各大学）。拟议的研究努力的结果将在档案期刊和会议出版物中传播，还将纳入PI教授的本科和研究生课程中。