In this work, consideration is given to a novel concept for aerofoil lift enhancement and delaying flow separation. Here, lift enhancement is attained by preventing the growth of the boundary layer through the elimination of the zero-slip condition between the wing surface and the air stream. The concept would simulate all the effects of a moving wall, leading to the appearance of a slip velocity at the gas–fluid interface, including the injection of momentum into the air boundary layer, but with one exception: here there is no moving wall but instead a ferrofluid thin film pumped parallel and attached to the wall by a magnetic field. Utilising a simplified physical model for the velocity profile of the ferrofluid film and based on ferrohydrodynamic stability considerations, an analytical expression for the interfacial velocity is derived. Finally, from the available experimental data on moving walls, the expected lift and angle-of-attack enhancement are found as well as the weight penalty per unit surface area of the wing is estimated. Additional research and development is required to explore the possibilities of using ferrofluid thin films.

中文翻译：

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用于机翼升力增强和延迟流动分离的铁磁流体薄膜

在这项工作中，考虑了一种用于提高翼型升力和延迟流动分离的新概念。在这里，通过消除机翼表面和气流之间的零滑移条件来防止边界层的生长，从而实现升力增强。该概念将模拟移动壁的所有影响，导致在气液界面出现滑移速度，包括将动量注入空气边界层，但有一个例外：这里没有移动壁，但取而代之的是一种平行泵送的铁磁流体薄膜，并通过磁场附着在壁上。利用铁磁流体薄膜的速度分布的简化物理模型，并基于铁流体动力学稳定性考虑，推导出界面速度的解析表达式。最后，从移动壁的可用实验数据中，发现了预期的升力和迎角增强，并估计了机翼单位表面积的重量损失。需要额外的研究和开发来探索使用铁磁流体薄膜的可能性。