Collaborative Research: Controlling Flow Separation via Traveling Wave Actuators

机翼或风扇叶片上的流动分离通常会导致升力、推力或功率的显著损失，阻力增加，燃料消耗增加等。因此，应通过设计或控制来防止这些表面上的流动分离。在这个项目中，为了控制流动分离，通过一种产生行波的新型轻型、高能效的致动器来触发不稳定性，为近地表的流动提供能量。该项目的主要目标是测试这种驱动比其他方法更有效的假设，并通过了解控制执行器与流体相互作用的关键参数来优化这种执行器的性能。这个项目将制作一系列教育视频，并通过我们机构成熟的项目让不同的本科生群体参与进来。这一方案的主要假设是行波激励器比其他产生驻波的激励器性能更好，因为：1)行波也注入动量(产生推力)，2)除了频率之外，还可以调节一个额外的参数(波长)来影响流动分离，初步结果表明。在典型翼型(NACA0018)上的流动将采用数值方法和实验方法。具有运动边界的大涡模拟(LES)将为行波致动器的初步设计提供可能的行波，并阐明流动再附着的机理。风洞实验将为验证模拟提供数据，并通过比较行波和驻波执行器来证实假设。S团队在通过压电致动器和风洞实验产生行波方面的协同能力，以及具有移动边界和流固耦合的大涡模拟技术，使我们能够应对这一挑战，完成本计划中提出的任务。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Flow separation over a wing or fan blade leads typically to a significant loss of lift, thrust, or power, an increase in drag, an increase in fuel consumption, etc. Consequently, flow separation over these surfaces should be prevented with design or controlled. To control flow separation in this project, the flow near the surface is energized through triggering instabilities by a new lightweight, energy-efficient actuator that generates traveling waves. The main goal of this project is to test the hypothesis that this actuation is more efficient than other means and to optimize the performance of this actuator by gaining an understanding of the key parameters that govern the interaction of the actuator with the flow. This project will create a series of educational videos and the engagement of a diverse group of undergraduate students through well-established programs at our institutions. The main hypothesis of this proposal is that traveling wave actuators perform better than other actuators that create standing waves because: 1) traveling waves also inject momentum (generate thrust), and 2) apart from frequency, an additional parameter (wavelength) can also be tuned to affect flow separation as demonstrated by the preliminary results. Numerical and experimental approaches will be used for flow on a typical airfoil (NACA0018). Large-eddy simulations (LES) with moving boundaries will provide possible traveling waves for the initial design of traveling wave actuators and elucidate the mechanisms of flow reattachment. The experiments in the wind tunnel will provide the data to validate the simulations and confirm the hypothesis by comparing the traveling against standing wave actuators. The team?s synergistic capabilities in generating traveling wave via piezoelectric actuators and the wind tunnel experiments as well as LES with moving boundaries and fluid-structure interaction uniquely position us to tackle this challenge and accomplish the tasks put forward in this proposal.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.