Abstract Riblets are a passive flow control method, which can be used for drag reduction, especially with small wind turbines that have a low Reynolds number. Riblet manufacturing, however, is a challenging task and the required production quality can cause extra barriers in terms of time and costs. If a relatively low-quality riblet structure could be successfully utilized in airfoils, it could enable wider adaptation of this particular flow control method. Public literature lacks studies that examine the applicability of non-ideally manufactured riblets on the ribleted airfoil. Therefore, in this study, Constant Temperature Anemometer and Particle Image Velocimetry are used to reveal the effect of non-ideal riblets on their performance and the flow field downstream of the airfoil. The measurements with a varying Reynolds number and incidence angle are conducted in the wind tunnel. The results indicate that, in the optimum conditions for the riblet design, the riblets reduce drag, thicken the boundary layer, reduce turbulence intensity, and weaken the mixing process. It is further demonstrated, that low-quality riblets have the potential to improve the performance of wind turbines, even when the riblet quality is lower than typically used.

中文翻译：

---

非理想制造的肋对翼型和风力涡轮机性能的影响

摘要 Riblets 是一种被动的流动控制方法，可用于减阻，尤其适用于低雷诺数的小型风力涡轮机。然而，Riblet 制造是一项具有挑战性的任务，所需的生产质量会在时间和成本方面造成额外的障碍。如果可以在翼型中成功使用质量相对较低的肋条结构，则可以更广泛地适应这种特定的流量控制方法。公共文献缺乏检查非理想制造的肋在带肋的翼型上的适用性的研究。因此，在本研究中，采用恒温风速计和粒子图像测速仪来揭示非理想肋对其性能和翼型下游流场的影响。在风洞中进行具有不同雷诺数和入射角的测量。结果表明，在肋条设计的最佳条件下，肋条减小了阻力，加厚了边界层，降低了湍流强度，减弱了混合过程。进一步证明，即使在肋条质量低于通常使用的质量时，低质量的肋条也有可能提高风力涡轮机的性能。