Bio-inspired unsteady load control to enhance power output and fatigue life of wind and tidal turbines

该项目旨在为风力和潮汐涡轮机开发一种新的叶片概念，使用多孔叶片来被动缓解非定常负载。它建立在对多孔性和灵活性用于被动飞行控制优势的自然启发研究的基础上。风力和潮汐涡轮机上的非稳定流体负载会导致疲劳和功率波动，增加统一能源成本(LCOE)。以前对被动变形叶片的研究表明，它们可以完全缓解载荷波动。然而，对于弹性和可靠的叶片，灵活性可能被限制在后缘，从而限制了缓解效果。为了获得额外的载荷缓解，后缘可以是多孔的，其孔隙度可以被动地控制，并与其变形同步。由于增加的流体载荷使后缘偏转，后缘顶面和底面上的交错孔可能会对齐。这种低惯性、被动控制的后缘可以对高频波动做出反应，从而将主动、低Interia控制面的有效性与减少被动控制的维护结合在一起。此外，与依赖结构耦合的现有被动控制方法不同，尾缘可以沿整个叶片跨度量身定做，从根本上减轻非稳定载荷，以减少流动分离和能量损失，并为下游涡轮机创造更清洁的尾流--这对大型紧凑型农场至关重要。该项目利用最近结束的关于蒲公英果实飞行的Leverhulme Trust(RPG-2015-255)项目，该项目演示了如何通过孔隙度控制涡流结构和多孔表面上的力，从而使流动浸没物体后面的尾流稳定，从而产生否则将过于不稳定的新流动结构。事实上，这就是蒲公英果实在数百公里内无动力地飞行的机制。我们假设，类似的原理也被鸟类利用，它们的翅膀既灵活又疏松，以减轻阵风的影响。世界领先的研究小组，如加州大学洛杉矶分校的Spedding，目前正在研究航空应用的多孔翼的空气动力学。该项目将结合最近关于孔隙率和柔性叶片影响的研究结果，为风力和潮汐涡轮机开发一种新的叶片概念。

This project aims to develop a new blade concept for wind and tidal turbines using porous blades to passively mitigate unsteady loads. It builds on nature-inspired research on the advantages of porosity and flexibility for passive flight control.Unsteady fluid loads on wind and tidal turbines cause fatigue and power fluctuations, increasing the levelised cost of energy (LCOE). Previous work on passive morphing blades shows that they can completely mitigate load fluctuations. However, for resilience and reliable blade, flexibility may be restricted to the trailing edge, limiting mitigation efficacy. To gain additional load mitigation, the trailing edge can be porous, with its porosity controlled passively and in tandem with its deformation. Staggered holes in the top and bottom surfaces of the trailing edge may be brought into alignment as the trailing edge is deflected by increased fluid load. This low inertia, passively controlled trailing edge could react to high frequency fluctuations thereby combining the efficacy of active, low interia control surfaces with the reduced maintenance of passive control. Additionally, unlike existing passive control methods that rely on structural couplings, the trailing edge could be tailored along the full blade span, mitigating unsteady loads down to the root to reduce flow separation and energy losses and create a cleaner wake for downstream turbines - critical for large, compacted farms.This project capitalises on the recently concluded Leverhulme Trust (RPG-2015-255) project on the flight of the dandelion fruit, which demonstrated how the vortical flow structures and the forces on a porous surface can be controlled by porosity, making it possible to stabilise the wake behind a flow immersed body to generate new flow structures that would otherwise be too unstable to exist. This is, in fact, the mechanisms exploited by the dandelion fruit to fly, unpowered for hundreds of kilometres. We hypothesise that a similar principle is also exploited by birds, whose wings are both flexible and porous, to mitigate the effect of gusts. World-leading research groups, such as Spedding at UCLA, are currently investigating the aerodynamics of porous wings for aeronautical applications. This project will combine recent findings on the effects of porosity and flexible blades to develop a new blade concept for wind and tidal turbines.