SGER: Hydrophobic Surface Effects on Sheet Cavitation

建议没有。项目描述：这是一个探索性的研究项目，旨在利用最近的非定常部分空化流的研究经验。这项工作已经确定了表面性质和水质对这些流动动力学的重要和意想不到的影响。以前认为表面性质和水质只影响空化起始物理。与此同时，人们对使用疏水表面来减少阻力也很感兴趣。还提出了混合减阻方案，包括微泡注入与疏水表面的结合。pi将探索使用疏水表面来控制或最小化部分空化状态下不必要的振动和不稳定操作的可能性。在开始一项涉及结构疏水表面开发的重大研究计划之前，有限的探索性努力将确定这一概念进一步发展的潜力。三种表面将被评估，如阳极氧化铝（亲水性），特氟龙（疏水性）和高度抛光不锈钢（疏水性）。接触角将被测量，在可行的接触角范围内，pi将根据他们之前的实验和他们的数值模型来预测空腔长度的变化和估计升力动力学的变化。然后，他们将设计和建造三个相同横截面的水翼。第一个分子有亲水性表面；第二个疏水的和第三个在一半的张成空间中有一个疏水的表面而在另一半的张成空间中有一个亲水的表面。对非定常升力进行对比测量。高速视频将被分析以确定完全浸湿的时间。这项研究具有重要的技术和广泛的影响。在部分空化状态下的操作已经被考虑用于水翼，并且在广泛的涡轮机械应用中变得越来越普遍。这开辟了一系列新的考虑，包括控制这些流动的可能性，以消除或尽量减少不必要的振动和不稳定的操作。这项研究的结果将表明使用疏水表面来控制空化引起的振动和失稳是否可行。

PROPOSAL NO.: CTS-0649572PRINCIPAL INVESTIGATORS: R. ARNDTINSTITUTION: UNIVERSITY OF MINNESOTASGER: Hydrophobic Surface Effects on Sheet CavitationThis is an exploratory research project aimed at capitalizing on recent research experience with unsteady partially cavitating flows. This work has identified the significant and unexpected effect of surface properties and water quality on the dynamics of these flows. Previously it was thought that surface properties and water quality only affected cavitation inception physics. At the same time there has been significant interest in the use of hydrophobic surfaces for drag reduction. Hybrid drag reduction drag reduction schemes involving a combination of microbubble injection coupled with the use of hydrophobic surfaces have also been proposed. The PIs will explore the possibility of using hydrophobic surfaces to control or minimize unwanted vibration and unstable operation in the partially cavitating regime. Before embarking on a significant research program that would involve the development of structured hydrophobic surfaces a limited exploratory effort will identify the potential for further development of this concept. Three surfaces will be evaluated, such as anodized aluminum (hydrophilic), Teflon (hydrophobic), and highly polished stainless steel (hydrophobic). Contact angle will be measured and based on the range of contact angle that is feasible, the PIs will predict the change in cavity length and estimate the change in lift dynamics on the basis of their previous experiments and with the help of their numerical model. They will then design and build three hydrofoils of identical cross section. The first will have a hydrophilic surface; the second hydrophobic and the third will have a hydrophobic surface for one half of the span and a hydrophilic surface for the other half of the span. Comparative measurements of unsteady lift will be made. High-speed video will be analyzed to determine fully wetted time. This research has important technological broader impacts. Operation into a regime of partial cavitation has been considered for hydrofoils and is becoming common in a wide range of turbomachinery applications. This opens up a wide range of new considerations including the possibility of control of these flows to eliminate or minimize unwanted vibration and unstable operation. The results of this will research will indicate whether the use of hydrophobic surfaces for control of cavitation induced vibration and unsteadiness is feasible.