The present study has been the first to examine the electrokinetic principle as the basis for a new class of microscale actuator arrays for active sublayer control on full scale aeronautical and hydronautical vehicles under realistic operating conditions. The Helmholtz-Smoluchowski scalings that govern such electrokinetic actuator arrays show significant performance advantages from their miniaturization to the microscale. The electrokinetic microactuator arrays that are the subject of this study seek to interrupt the bursting process associated with naturally-occurring streamwise sublayer vortices in the turbulent boundary layer. Specific performance requirements for microactuator spacing, flow rate, and frequency response for active sublayer control have been determined from fundamental scaling laws for the streamwise vortical structures in the sublayer of turbulent boundary layers.; In view of the inherently local nature of the sublayer dynamics, a general system architecture for microactuator arrays appropriate for active sublayer control has been developed based on the concept of relatively small and independent “unit cells”, each with their own sensing, processing, and actuation capability, that greatly simplifies the sensing and processing requirements needed to achieve practical sublayer control.; A fundamental three-layer design has been developed for such electrokinetic microactuator arrays, in which electrokinetic flow is induced by an impulsively applied electric field across a center layer, with a bottom layer containing an electrolyte reservoir and a common electrode, and a top layer that containing individual electrodes and lead-outs for each microactuator in the unit cell.; Microfabrication techniques have been developed that permit mass production of large numbers of individual electrokinetic microactuators in unit cells on comparatively large-area tiles. Several generations of such electrokinetic microactuator arrays have been built leading to the MEKA-5 full-scale hydronautical array, composed of 25,600 individual electrokinetic microactuators with 350 μm center-to-center spacings, arranged in a 40 x 40 pattern of unit cells, each composed of a 4 x 4 matrix of actuators. MEMS design and fabrication processes were used to produce a top layer for the MEKA-5 hydronautical-scale array. Stereo-PIV measurements successfully demonstrated lateral displacement of synthetically-generated streamwise vortical structures by volumetric pumping from a wall actuator in a set of large-scale wind tunnel tests.
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机译：本研究是第一个研究电动原理作为新型微型执行器阵列的基础，该阵列用于在实际操作条件下对航空和水上飞行器进行有源子层控制。控制此类电动执行器阵列的Helmholtz-Smoluchowski缩放比例从其小型化到微米级显示出显着的性能优势。电动微致动器阵列是本研究的主题，旨在中断与湍流边界层中自然产生的沿流子层涡旋相关的爆发过程。对于有源子层控制，微致动器间距，流速和频率响应的特定性能要求已从湍流边界层子层中流向旋涡结构的基本比例定律确定。考虑到子层动力学的固有局部性质，基于相对较小和独立的“单位单元”的概念，开发了适用于有源子层控制的微执行器阵列的通用系统架构，每个单元都有自己的感应，处理和驱动能力，极大地简化了实现实际子层控制所需的感测和处理要求。已经为这种电动微致动器阵列开发了一种基本的三层设计，其中电动流是由跨过中心层的脉冲施加电场引起的，其底层包含电解质储存器和公共电极，顶层包含单个电极和单位单元中每个微执行器的引出线。已经开发了微制造技术，其允许在相对大面积的瓷砖上的晶胞中大量生产大量的单个电动微致动器。已经建立了几代这样的电动微致动器阵列，形成了MEKA-5完整水力航海阵列，该阵列由25,600个独立的电动微致动器组成，它们之间的中心距为350μm，以40 x 40的单位晶格排列由4 x 4的执行器矩阵组成。 MEMS设计和制造工艺用于生产MEKA-5水上规模阵列的顶层。立体PIV测量成功地证明了在一系列大型风洞测试中，通过从墙壁执行器进行体积泵送，对合成产生的气流涡旋结构进行了侧向位移。
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