An experimental and theoretical investigation into ice ribbing instabilities

冰肋不稳定性的实验和理论研究

• 批准号: 2281451
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2281451
• 关键词: experimental; theoretical; investigation; into; ice

Ice formations on aircraft wings or wind turbines both reduce performance and present significant hazard. In typical UK conditions, where temperatures rarely go much below freezing, ice usually forms as hard, smooth glaze ice with water present in sheets sheared by the airflow over the wing or blade. On a wind turbine the freezing of the radial water flow can form shards some metres long at the tips, which represent lethal projectiles when dislodged. The change in geometric presentation due to the glaze ice can also cause aerodynamic instabilities. On an aerofoil, the sheared water film can itself be unstable and freeze as ribs that change the surface roughness and performance. However, the mechanics of icing in these transitional regimes is not well studied, and without this understanding it remains challenging to develop effective anti- and de-icing strategies for structures to safeguard performance and safety.This project seeks to develop that understanding of the complex interplay between the fluid mechanic and thermodynamic processes in freezing water sheets with geometries relevant to wind turbine blades and aerofoils. Through this understanding we can identify interventions that could delay the formation of ice ribs, or remove the possibility of turbine tip formations through e.g. smart coatings.The project will first explore the stability of water films accelerated on a spinning disk, mimicking the sheared boundary layer over an aerofoil or wind turbine blade, using linear stability analysis of the governing equations and verified though laboratory experiments. In the second phase, freezing through a glaze ice boundary condition will be incorporated into the stability analysis to gain insight into the origin of frozen ribs, and their growth into three-dimensional ice formations. The laboratory experiment will be developed alongside this theory, to verify the predictions under tightly controlled fluid mechanic and thermodynamic boundary conditions.

飞机机翼或风力涡轮机上的冰层均降低性能并呈现出明显的危害。在典型的英国条件下，温度很少在冰点以下，冰通常像翼或刀片上空的气流剪切的床单一样坚硬，光滑的釉面形成。在风力涡轮机上，径向水流的冷冻可能会在尖端上形成一些米长的碎片，这在移位时代表致命的弹丸。由于釉料冰而导致的几何表现变化也可能导致空气动力学不稳定性。在钢制上，剪切的水膜本身可能不稳定并冻结，因为肋骨会改变表面粗糙度和性能。但是，在这些过渡制度中结冰的机制尚未得到很好的研究，如果没有这种理解，就可以制定有效的反冰和去冰策略来保护绩效和安全性。流体机械师和热力学过程之间的相互作用，与风力涡轮机叶片和架翼相关的几何形状。通过这种理解，我们可以确定可能延迟冰肋形成的干预措施，或者消除通过例如智能涂料。该项目将首先探索在旋转磁盘上加速的水膜的稳定性，使用控制方程的线性稳定性分析，模仿钢丝或风力涡轮机刀片上的剪切边界层，并通过实验室实验进行了验证。在第二阶段，将通过釉面冰边界条件进行冷冻融合到稳定性分析中，以深入了解冷冻肋骨的起源，并将其生长成三维冰层。实验室实验将与该理论一起开发，以验证紧密控制的流体机械和热力学边界条件下的预测。