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Vortex Evolution in Unsteady Aerodynamics

非定常空气动力学中的涡演化

基本信息

批准号：
248352504
负责人：
Professor Dr.-Ing. Cameron Tropea
金额：
--
依托单位：
Fachgebiet Strömungslehre und Aerodynamik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/248352504?language=en
关键词：
Vortex Evolution Unsteady Aerodynamics

项目摘要

The proposed project addresses basic mechanisms of vortex growth and detachment under unsteady conditions, in particular when lifting surfaces are moving. Such conditions exist not only in nature (flapping flight), but also in the aerodynamics of helicopters or wind turbines, the latter occurring during gusty conditions. Motivation for this study arises from the well-known influence of leading-edge vortices on lift hysteresis, also known as dynamic stall, which can be used advantageously if properly controlled, but otherwise can be detrimental in many respects through fluctuating aerodynamic loads (fatigue) and due to acoustic excitations. The overriding goal of the project is to secure a deeper understanding of the flow physics and dependencies of leading-edge vortex dynamics and to use these in formulating concepts for modeling and influencing these flows.The study proposes an experimental investigation of the above phenomena, capturing the flow field using time-resolved Particle Image Velocimetry simultaneous to direct force measurements, from which the inception, growth and detachment of the leading and trailing-edge vortex can be visualized topologically and quantified in terms of circulation. The experimental facility is designed to offer a unique parameter space, allowing single governing parameters (Reynolds number, Strouhal number and reduced frequency) to be varied, while other parameters are kept constant. Kinematically, pure pitch, pure plunge and other periodic motions are achievable. The experiments are conducted on the basis of working hypotheses derived from preliminary work and from open literature and which postulate the changing role of viscosity, depending on Reynolds number. Having identified the main mechanisms involved in the leading-edge vortex evolution, specific concepts for influencing the duration and strength of this vortex will be tested.

拟议的项目解决了在非定常条件下，特别是当升力面移动时，涡旋增长和脱离的基本机制。这种情况不仅存在于自然界中(扑翼飞行)，也存在于直升机或风力涡轮机的空气动力学中，后者发生在阵风条件下。这项研究的动机来自于众所周知的前缘涡对升力滞后的影响，也称为动态失速，如果控制得当，这种影响可以得到有利的利用，但如果控制得当，通过波动的空气动力载荷(疲劳)和声学激励，在许多方面可能是有害的。该项目的首要目标是更深入地了解流动物理和前缘旋涡动力学的相关性，并利用这些概念来建立建模和影响这些流动的概念。该研究提出了对上述现象的实验研究，在直接测力的同时使用时间分辨粒子图像测速仪捕捉流场，由此可以可视化地显示前缘和后缘旋涡的开始、发展和脱离，并从环流的角度进行量化。该实验装置提供了一个独特的参数空间，允许单一调节参数(雷诺数、斯特鲁哈尔数和折合频率)变化，而其他参数保持不变。在运动学上，可以实现纯俯仰、纯俯冲和其他周期性运动。这些实验是在从前期工作和公开文献中得出的工作假设的基础上进行的，这些假设假设粘度的作用取决于雷诺数。在确定了前缘涡旋演变的主要机制后，将测试影响该涡旋持续时间和强度的具体概念。