Interaction Effects in Tandem Configurations of Airfoils with Pitch/Plunging Motion

在自然界中，无论是游泳还是飞行，都经常遇到气动涡流干扰，其性质和影响由雷诺数（Re）和约化频率（k）表征。尽管昆虫飞行的区域（低Re和高k）已被广泛地研究并应用于微型飞行器（MAV），但鸟类飞行和鱼类游泳遇到的Re和k的中间范围受到的关注要少得多，特别是在实验上。在这个项目中，达姆施塔特工业大学的低速风洞已经提出了这样一个串列机翼-机翼装置，它将允许研究大范围的干扰效应。通过使用具有俯仰/倾伏运动的翼型，问题已被简化为二维情况，这对于使用时间分辨粒子图像测速技术（PIV）的实验可视化和使用大涡模拟（LES）的拟议数值模拟都是有利的。。该项目的目的是提供洞察力的潜在增加升力或推力使用涡干扰效应和相关的效率这个相当技术性的目标被认为是解释自然界中气动涡流相互作用发生的一个基本的初步步骤。然而，也将研究从流中提取能量是可行的条件。最初的资金集中在实验设施和数字代码的建设和资格认证上。初步的实验方案已被概述，并提出了进一步研究的可能扩展。特别是，在第二个供资期，将强调对生物学上有意义的结构的研究。

Aerodynamic vortex interaction is encountered frequently in nature, either in swimming or flying and is characterized in its nature and effect by the Reynolds number (Re) and the reduced frequency (k). Whereas the region of insect flight (low Re and high k) has been extensively investigated with application to Micro Air Vehicles (MAV), the intermediate range of Re and k encountered with bird flight and fish swimming has received much less attention, especially experimentally. In this project such a tandem wing-wing facility for the low-speed wind tunnel at the TU Darmstadt has been proposed, which will allow investigation of a wide range of interference effects. By using airfoils with pitch/plunge motion the problem has been simplified to the two-dimensional case, which is advantageous both for the experimental visualization using the time-resolved particle image velocimetry technique (PIV) and for the proposed numerical simulations using Large Eddy Simulations (LES).The aim of the project is to provide insight into the potential augmentation of lift or thrust using vortex interference effects and the associated efficiency. This rather technically orientated goal is felt to be an essential preliminary step in interpreting occurrences of aerodynamic vortex interaction in nature. However also the conditions under which energy extraction from the flow is feasible will be investigated. The initial funding period concentrates on construction and qualification of the experimental facility and numerical code. An initial experimental program has been outlined and possible extensions for further studies have been proposed. In particular the investigation of biologically interesting configurations will be emphasized in the second funding period.