Hydrokinetic flapping foil turbines in swing-arm mode have gained considerable interest in recent years because of their enhanced capability to extract power, and improved efficiency compared to foils in simple mode. The performance of foil turbines is closely linked to the development and separation of the Leading-Edge Vortex (LEV). To accurately model the formation and the separation of the LEV on flapping foils, a purpose-built 2D numerical model was developed. The model is based on the weighted residual Finite Element Method (FEM); this is combined with an interface capturing technique, Level-Set Method (LSM), which was used to create a reliable and high-quality numerical solver suitable for hydrodynamic investigations. The solver was validated against well-known static and dynamic benchmark problems. The effect of the mesh density was analyzed and discussed. This paper further covers an initial investigation of the hydrodynamics of flapping foil in swing-arm mode, by studying the structure of the vortex around a NACA0012 foil. The presented method helps to provide a better understanding of the relation between the Leading-Edge Vortex creation, growth, and separation over the flapping foil in swing-arm mode and the extracted power from a hydrokinetic turbine.
翻译:近些年来,由于肥皂涡轮的发电能力得到加强,而且与简单模式的肥料相比,效率有所提高,因此对摇篮式的风扇涡轮机产生了相当大的兴趣。Foil涡轮机的性能与Gead-Edge Vortex(LEV)的开发和分离密切相关。为了精确地建模LEV的形成和分离在摇篮式风扇上的形成和分离,开发了一个目的建造的2D数字模型。模型以加权残留的精致元素蛋白法(FEM)为基础;结合了一种界面捕捉技术,即Delage-Set 方法(LSM),用于建立一个可靠和高质量的数字求解器,适合水动力学调查。对于众所周知的静态和动态基准问题,对溶液涡轮密度的影响进行了验证。本文还进一步介绍了对摇篮式风扇的动力学的初步调查,研究了在NACA0012 Foil周围的涡轮结构。所提出的方法有助于更好地了解在冲动动力式、从冲压式变压式变压式变压式变压式变压式的形成中和压式变压式变压式变压式变压式变压机之间的关系。</s>