Improving aerodynamic control strategies for low Reynolds number airfoils

改进低雷诺数翼型的气动控制策略

• 批准号: RGPIN-2022-03071
• 负责人: Sullivan, Pierre
• 金额: $ 2.84万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=759701
• 关键词: Improving; aerodynamic; control; strategies; low

Standard airfoil profiles are designed for optimal aerodynamic performance at high speed based on the Reynolds number, a ratio of flow inertia and fluid viscosity. For example, a Boeing 747 operates at a Reynolds number of approximately 80 million while an insect might have a Reynolds number of roughly 1000. Operating airfoils at low Reynolds number (below one million) is of interest in many engineering applications including low-speed unmanned aerial vehicles, wind turbines, and low-speed/high-altitude aircraft; however, airfoil performance is significantly reduced. For wind turbine installation in most of Ontario, this is a concern as there are limited locations with high enough wind speeds to produce power. Flow separation on airfoils, the detachment of the boundary layer from a surface into a wake, is particularly prevalent at low Reynolds numbers due to the interaction of the laminar boundary layer on the suction surface where flow pressure increases in the flow direction (an adverse pressure gradient). The momentum contained in the boundary layer is often unable to withstand the forces imposed by the adverse pressure gradient, which causes the flow to separate. The use of periodic excitation, i.e., active flow control, applied locally at the surface to mitigate flow separation and restore the aerodynamic performance of stalled airfoils is a technique that has been applied with varying degrees of success for several years. Because these devices are flat to the airfoil surface, no geometric drag is introduced. Since 2005, our lab has been studying the synthetic jet actuator (SJA) as a candidate control method. The SJA has a vibrating diaphragm mounted in a cavity with an orifice/slot leading to the surface where control is desired. Deformation of the diaphragm causes the working fluid to be alternately ingested and expelled by the cavity, thereby adding momentum (but not mass) to the flow. The main difficulties faced with this technology and, particularly the approach proposed here, is that despite the relat

标准的机翼轮廓设计为基于雷诺数，流量惯性和流体粘度的比例，可在高速下以高速空气动力性能。例如，波音747的雷诺数量约为8000万，而昆虫的雷诺数可能大约为1000。在低雷诺数下的操作机翼数量（低于100万）（低于100万）是在许多工程应用中感兴趣的，包括低速无人驾驶汽车，无人机/高速/高速涡轮，高速涡轮和高空飞行器，但是，机翼性能大大降低。对于安大略省大部分地区的风力涡轮机安装，这是一个令人担忧的问题，因为在有限的位置有足够高的风速以产生动力。在机翼上的流动分离，边界层从表面向唤醒的脱离，在雷诺数低的雷诺数下尤为普遍，因为吸气表面上的层层边界层相互作用，其中流动压力在流动方向上增加（不良压力梯度）。边界层中包含的动量通常无法承受不利压力梯度施加的力，这会导致流动分离。使用周期性激发，即主动流控制，在局部在表面上应用，以减轻流动分离并恢复失速机翼的空气动力学性能，是一种已在多年成功的程度上应用的技术。由于这些设备平坦至机翼表面，因此没有引入几何阻力。自2005年以来，我们的实验室一直在研究合成射流执行器（SJA）作为候选控制方法。 SJA的振动膜片安装在腔体中，孔/槽通向需要控制的表面。隔膜的变形导致工作流体交替地被腔摄入和排出，从而在流动中增加动量（但不质量）。 这项技术面临的主要困难，尤其是这里提出的方法是，尽管有关系