Dynamics and Destabilisation of Helical Vortices

螺旋涡旋的动力学和失稳

• 批准号: 469304061
• 负责人: Dr.-Ing. Thorsten Lutz
• 金额: --
• 依托单位: Institut für Aerodynamik und Gasdynamik (IAG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/469304061?language=en
• 关键词: Dynamics; Destabilisation; Helical; Vortices

Wind turbine wake effects can significantly reduce the global power production of wind parks. In order to achieve a quicker recovery of the wake velocity deficit, exciting the wake in order to induce earlier wake breakdown has been proposed as an attractive possibility to reduce these effects. For the efficient development of such wake control techniques, understanding instabilities and their driving parameters is necessary. The UBeRT Project aims to investigate the fundamental physics of helical wake breakdown. This shall be achieved by establishing a unique and novel experimental and numerical testbed for investigating instabilities. Response to wake excitation measures shall be explored using three turbine models: i) An experimental turbine (UBeRT), ii) a kinematically scaled numerical twin of the UBeRT (NumBeRT), that shall operate in air instead of water, and, iii) a generic full-scale 15 MW turbine numerical model (IEA 15MW). The UBeRT rotor shall be operated in the large towing tank at VWS (TU Berlin) in order to achieve higher Reynolds number than in a conventional wind tunnel. Simulations of the numerical twin NumBeRT shall serve to evaluate transferability of the experimental results in the air. Simulations of the IEA 15MW wind turbine shall provide information about possible scaling effects and address the effects of broadband inflow turbulence on wake stability. Fundamental investigation of modal and frequency content of helical wakes under excitation of long- and short-wave instabilities is required to understand the fundamental physics of helical wake breakdown. Long-wave instabilities shall be introduced numerically and experimentally via a periodic variation of the relative inflow velocity. Short-wave instabilities shall be introduced experimentally via a secondary vortex emerging from the blade tip section, which through interaction with the tip vortex shall give raise to a short-wave instability. Numerically, it shall be introduced via an added vorticity at the blade tip which shall create an elliptic instability in the vortex core. The proposed project aims further at identifying unstable modes excited through turbulent inflow and which interaction mechanisms occur between inflow turbulence and the helical vortex. Modal analysis of the wake development shall reveal the perturbation scales that lead to the quickest instability growth. Highly-resolved velocity fields of the wake development and breakdown downstream of the UBeRT rotor will be collected by means of stereo Particle Image Velocimetry. High-fidelity scale-resolving simulations of the NumBeRT rotor and the IEA15MW turbine will be performed with the flow solver FLOWer. Both data sets will be publicly available for code comparisons and validation of lower order wake models while complementing existing turbine databases, which do not explicitly focus on wake breakdown phenomena.

风力涡轮机唤醒效应可以显着减少风公园的全球电力生产。为了更快地恢复尾流速度的赤字，令人兴奋的唤醒以诱发早期的唤醒分解是减少这些影响的一种有吸引力的可能性。为了有效地开发此类尾流控制技术，必须了解不稳定性及其驾驶参数。 UBERT项目旨在调查螺旋尾流崩溃的基本物理。这是通过建立独特的，新颖的实验和数值测试床以研究不稳定性来实现的。应使用三种涡轮机模型对尾流激发措施的响应进行探索：i）实验性涡轮机（UBERT），ii）一个运动尺度的Ubert（数字）的数值双胞胎（数字），该数值应在空气中而不是水，而III）是一个通用的全尺度全尺度15 MW 15 MW涡轮机型号（IEA 15MW）。 Ubert Rotor应在VWS（TU柏林）的大型牵引箱中操作，以便获得比传统风洞更高的雷诺数。数值双胞胎数字的模拟应用于评估空气中实验结果的可转移性。 IEA 15MW风力涡轮机的模拟应提供有关可能缩放效应的信息，并解决宽带流入湍流对尾流稳定性的影响。需要对长波和短波不稳定性激发螺旋唤醒的模态和频率含量的基本调查，以了解螺旋尾流分解的基本物理。长波不稳定性应通过相对流入速度的周期性变化在数值和实验上引入。短波不稳定性应通过从刀片尖端部分出现的次级涡流进行实验引入，通过与尖端涡流的相互作用，该涡流应加重短波不稳定。从数值上讲，应通过刀片尖端的附加涡度引入，该涡旋应在涡旋芯中产生椭圆的不稳定性。拟议的项目进一步旨在确定通过湍流流入激发的不稳定模式，以及在流入湍流与螺旋涡流之间发生哪些相互作用机制。尾流开发的模态分析应揭示导致不稳定性增长最快的扰动量表。将通过立体粒子图像速度计收集尾流式发育的高度分辨速度场和Ubert rotor的崩溃。数字转子和IEA15MW涡轮机的高保真尺度解析模拟将使用流量求解器进行。这两个数据集将公开用于代码比较和验证较低的唤醒模型，同时补充现有的涡轮机数据库，这些数据库并未明确关注唤醒崩溃现象。