Purpose

The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers.

Design/methodology/approach

In this paper, an experimental study on fluid-structure interaction of flexible membrane wings was presented at Reynolds numbers of 2.5 × 10⁴, 5 × 10⁴ and 7.5 × 10⁴. In the experimental studies, flow visualization, velocity and deformation measurements for flexible membrane wings were performed by the smoke-wire technique, multichannel constant temperature anemometer and digital image correlation system, respectively. All experimental results were combined and fluid-structure interaction was discussed.

Findings

In the flexible wings with the higher aspect ratio, higher vibration modes were noticed because the leading-edge separation was dominant at lower angles of attack. As both Reynolds number and the aspect ratio increased, the maximum membrane deformations increased and the vibrations became visible, secondary vibration modes were observed with growing the leading-edge vortices at moderate angles of attack. Moreover, in the graphs of the spectral analysis of the membrane displacement and the velocity; the dominant frequencies coincided because of the interaction of the flow over the wings and the membrane deformations.

Originality/value

Unlike available literature, obtained results were presented comparatively using the sketches of the smoke-wire photographs with deformation measurement or turbulence statistics from the velocity measurements. In this study, fluid-structure interaction and leading-edge vortices of membrane wings were investigated in detail with increasing both Reynolds number and the aspect ratio.

中文翻译：

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低雷诺数流动下柔性翼流固耦合实验分析

目的

这项详尽的实验研究的目的是研究柔性膜翼在各种雷诺数的攻角范围内的流固耦合。

设计/方法/方法

在本文中，提出了雷诺数为 2.5 × 10 ⁴、5 × 10 ⁴和 7.5 × 10 ⁴时柔性膜翼流固耦合的实验研究。在实验研究中，分别通过烟线技术、多通道恒温风速计和数字图像相关系统对柔性膜翼进行了流动可视化、速度和变形测量。结合所有实验结果并讨论流固耦合。

发现

在具有更高展弦比的柔性机翼中，注意到更高的振动模式，因为前缘分离在较低的迎角下占主导地位。随着雷诺数和纵横比的增加，最大膜变形增加并且振动变得可见，观察到次级振动模式，前缘涡在中等迎角下增加。此外，在膜位移和速度的谱分析图中；由于机翼上的流动和膜变形的相互作用，主要频率重合。

原创性/价值

与现有文献不同，获得的结果是使用烟线照片的草图与来自速度测量的变形测量​​或湍流统计进行比较呈现的。在这项研究中，随着雷诺数和纵横比的增加，膜翼的流固耦合和前缘涡流进行了详细研究。