Study on High Lift and Thrust Mechanisms of Unsteady Airfoil and Its Effective Application

非定常翼型高升力推力机构研究及其有效应用

• 批准号: 15360098
• 负责人: TANAKA Kazuhiro
• 金额: $ 9.73万
• 依托单位: Kyusyu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360098/
• 关键词: Unsteady flow; Separation; Airfoil; Pitching motion; Heaving motion; Vortex; Lift; Thrust; 非定常運動; Unsteady flow (非定常流れ); Separation (はく離); Airfoil (翼); Piching motion (ピッチング運動); Heaving motion (ヒービング運動); Vortex (渦); Lift (揚力); Thrust (推進力)

It is well known that a flow field around a moving airfoil, which is a typical unsteady flow, is extremely complicated since there are a number of parameters and dynamic behaviors of vortices that characterize such a flow. A number of studies on unsteady flow around a moving airfoil have been carried out with numerical and experimental approaches. Most of them, however, focused high Reynolds number regions over Re=10^6. Recently, a few studies on unsteady flows in low Reynolds number regions have been attracting attentions since the Micro-Electro-Mechanical-Systems has been improved with the aim of flow control and development of Micro-Air-Vehicle and micro flight robot. This flow field has also attracted significant attentions in biohydrodynamics as there is a high need to understand the propulsion mechanisms of aquatic animals, birds and insects. However, the detailed vortex flow structure behind moving airfoils and the relationship between the characteristics of dynamic forces actin … More g on them and the vortex flow structure at low Reynolds number region have not been clarified sufficiently.In this study, the authors have measured the detailed vortex flow behind a pitching airfoil and a heaving airfoil, at low Reynolds number region by PIV measurement. Moreover, the authors have performed dynamic thrust measurement acting on them by a six-axes sensor in a water tunnel. The result clarified not only the detailed vortex structure, such as vortex flow pattern, vorticity distribution and jet characteristics, but also the relationship between the characteristics of dynamic thrust and detailed vortex flow structure.The re-circulation region was formed by a few discrete vortices. The scale of discrete vortex shed from the leading edge was about one fourth of the chord length and it did not depend on the airfoil configuration. The length of the re-circulation region to the chord length determined the number of discrete vortex consisting there. The dynamic behavior of discrete vortex depended on the airfoil configuration, however the vortex shedding frequency of the discrete vortices did not depend on the airfoil configuration. Moreover, the dynamic behavior of discrete vortex influenced much on the dynamic lift.At the high non-dimensional trailing edge velocity and the non-dimensional heaving velocity, the thrust producing vortex street is formed clearly. Moreover, it has been founded that not only the distance between vortices becomes narrow but also vorticity increases as the non-dimensional trailing edge velocity and the non-dimensional heaving velocity increase. As a result, the jet velocity induced by the strong vorticity turns out to be high.The averaged dynamic thrust acting on a pitching airfoil and a heaving airfoil increases as the non-dimensional trailing edge velocity and the non-dimensional heaving velocity increase. The hysteresis loops of dynamic thrust acting on a pitching airfoil and a heaving airfoil show reentrant and convexity shapes characteristics. The dynamic behavior of dynamic thrust acting on a heaving airfoil is different from that on a pitching airfoil.The thrust efficiency of a pitching airfoil increased up to V_p=0.7 rapidly and maximum thrust efficiency was 0.34. The thrust efficiency of a heaving airfoil increased up to V_p=0.5 rapidly and the maximum thrust efficiency was 0.20. In both airfoils, the thrust efficiency decreases with increase of the non-dimensional velocity because not only thrust but also moment acting on a pitching airfoil and lift acting on a heaving airfoil increases rapidly. Less

众所周知，运动翼型周围的流场是一种典型的非定常流，由于存在许多表征这种流动的参数和涡动态行为，因此其非常复杂。然而，大多数研究都集中在Re=10^6以上的高雷诺数区域，近年来，一些关于低雷诺数区域的非定常流动的研究引起了人们的关注。微机电系统以流动控制和微型飞行器和微型飞行机器人的发展为目标得到了改进，这种流场也引起了生物流体动力学的广泛关注，因为非常需要了解推进机制。然而，运动翼型背后的详细涡流结构以及其上的动力作用力特征与低雷诺数区域涡流结构之间的关系已经得到了证实。在这项研究中，作者通过PIV测量在低雷诺数区域测量了俯仰翼型和垂荡翼型后面的详细涡流，此外，作者还通过六轴对其进行了动态推力测量。结果不仅阐明了涡流流型、涡度分布和射流特性等详细涡流结构，而且还阐明了动态推力特性与详细涡流流之间的关系。再循环区域由几个离散涡流形成，从前缘流出的离散涡流规模约为弦长的四分之一，并且不依赖于翼型的再循环长度。区域与弦长的关系决定了其中存在的离散涡的数量。离散涡的动态行为取决于翼型，但离散涡的涡脱落频率并不依赖于翼型。而且，离散涡的动态行为对动态升力影响很大。在高无量纲后缘速度和无量纲升沉速度时，产生推力的涡街明显形成，涡之间的距离变窄，涡量也增加。随着无量纲后缘速度和无量纲垂荡速度的增加，强涡引起的射流速度变高。平均动态。作用于俯仰翼型和垂荡翼型的推力随着无量纲后缘速度和无量纲垂荡速度的增大而增大，作用于俯仰翼型和垂荡翼型的动态推力的滞回线表现出凹凸形状特征。作用在垂荡翼型上的动推力的动态行为与作用在俯仰翼型上的动态行为不同。俯仰翼型的推力效率增加到V_p=0.7，最大推力效率为0.34，升沉翼型的推力效率迅速增加到V_p=0.5，最大推力效率为0.20，因为无量纲速度的增加，推力效率降低。不仅推力而且作用在俯仰翼型上的力矩和作用在起伏翼型上的升力也迅速增加。

项目成果

ヒービング運動翼に働く非定常流体力

作用在升沉运动翼上的非定常流体力

• 发表时间: 2005
• 作者: 梁昌照; 田中和博; 渕脇正樹
• 通讯作者: 渕脇正樹

ピッチング/ヒービング運動翼後流の渦構造と非定常推進力特性

俯仰/垂荡桨叶尾流的涡结构与非定常推进特性

• 发表时间: 2004
• 作者: 渕脇正樹; 田中和博
• 通讯作者: 田中和博

ヒービング運動翼の後流構造と非定常推進力

垂荡运动翼尾流结构与非定常推进力

• 发表时间: 2004
• 作者: 渕脇正樹; 小田智恵; 田中和博
• 通讯作者: 田中和博

Detailed Vortex Structure on the Wake of Unsteady Airfoils

不稳定翼型尾迹的详细涡流结构

• 发表时间: 2004
• 作者: Masaki Fuchiwaki; Kazuhiro Tanaka
• 通讯作者: Kazuhiro Tanaka

Unsteady Separation and Vortex around Moving Airfoil

运动翼型周围的不稳定分离和涡流

• 发表时间: 2003
• 作者: Masaki Fuchiwaki; Chang Jo Yang; Kazuhiro Tanaka
• 通讯作者: Kazuhiro Tanaka