U.S.-Netherlands Cooperative Research on the Structure of a Turbulent Boundary Layer with Suction

该奖项支持格鲁吉亚理工学院助理教授Minami Yoda与F.T.M.教授合作进行机械工程研究。荷兰德尔夫特理工大学空气动力学和流体动力学实验室的Nieuwstadt博士说。 使用粒子成像测速技术，他们将在几个直径为局部边界层厚度10%的孔附近进行有和无抽吸的湍流边界层研究。 荷兰实验室拥有优秀的实验设施进行这项研究，并与他们的设置将获得美国PI的经验将提供基础，决定是否和如何建立类似的设施在格鲁吉亚技术。 这两个实验室带来的研究工作互补的专业知识，在两个流体动力学系统和专业仪器：德尔夫特在有界流和粒子成像测速和格鲁吉亚技术的应用在自由剪切流控制和激光诱导荧光。 湍流增加了运动表面（如机翼）的阻力（和运行成本）。 吸力可以使紊流附面层再层化和延迟分离，但吸力太大实际上会增加分离。 通过大的孔或槽的抽吸已经被广泛研究;较小的孔效果更好，但是已经发现实施的成本不值得阻力的节省。 虽然新技术现在允许经济地生产微小的穿孔表面，但关于吸力对附面层结构上的这种小孔的影响，人们知之甚少。 这项工作将有助于澄清这种吸力如何影响附面层中的相干结构，并增加对“空气动力学粗糙度”的理解，在这种粗糙度中，强吸力实际上会引起分离。

This award supports Assistant Professor Minami Yoda of Georgia Institute of Technology to collaborate in mechanical engineering research with Professor F.T.M. Nieuwstadt of the Laboratory of Aeroand Hydrodynamics of the Delft University of Technology, The Netherlands. Using particle imaging velocimetry, they will carry out a study of a turbulent boundary layer with and without suction in the vicinity of a few holes of a diameter of ten percent of the local boundary layer thickness. The Dutch laboratory has excellent experimental facilities for this research, and the experience with their set-up to be gained by the US PI will provide the basis for deciding whether and how to establish similar facilities at Georgia Tech. The two laboratories bring to the research effort complementary expertise in both hydrodynamic systems and specialized instrumentation: Delft in bounded flows and the application of particle imaging velocimetry and Georgia Tech in free shear flow control and laser-induced fluorescence. Turbulence increases drag (and operating cost) on moving surfaces such as airplane wings. Suction is known to re- laminarize and delay the separation of turbulent boundary layers, but too much suction can actually increase the separation. Suction through large holes or slots has been widely studied; smaller holes work better, but the cost of implementing has been found not to be worth the savings in drag. While new technology now permits economical production of minutely perforated surfaces, relatively little is known about the effect of suction on such small holes on the boundary layer structure. This work will help to clarify how such suction affects the coherent structures in the boundary layers, and increase understanding of `aerodynamic roughness`, where strong suction levels actually cause separation.