Humpback whales possess bumpy tubercles on the leading edge of their flippers. Due to these leading edge tubercles, whales are able to produce high degree of maneuverability. Inspired by the flippers, this paper applies sinusoidal-like tubercles to the leading edge of blades in an annular compressor cascade, and presents a numerical investigation to explore the effects of tubercles with the aim of controlling the corner separation and reducing losses. Steady 3D RANS simulations are performed to investigate the aerodynamic performance and behavior of the corner separation in compressor cascades with and without leading edge tubercles. A crucial geometry parameter of the tubercles, wavelength, is varied to obtain different configurations. Results show that a smaller wavelength (more wave number) corresponds to a larger loss reduction and the maximum loss reduction reaches to 46.0%. Also, it is found that leading edge tubercles result in a stall delay and the maximum stall angle improvement reaches to 28.1%. Flow visualizations show that leading edge tubercles could induce the formation of counter-rotating streamwise vortices. The interaction between the streamwise vortices and corner separation is thought to be the primary flow mechanism generated by leading edge tubercles in an annular compressor cascade.

中文翻译：

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环形压气机叶栅中不同波长的前缘结节的研究

座头鲸在鳍状肢的前缘有颠簸的结节。由于这些前缘结节，鲸鱼能够产生高度的可操纵性。受到鳍状肢的启发，本文将正弦形结节应用于环形压缩机级联中的叶片前缘，并进行了数值研究以探讨结节的影响，目的是控制角部分离并减少损失。进行了稳定的3D RANS仿真，以研究具有和不具有前缘结节的压缩机级联中的空气动力学性能和转角分离行为。改变结节的关键几何参数波长，以获得不同的构型。结果表明，较小的波长（更多的波数）对应更大的损耗减少，最大损耗减少达到46.0％。另外，发现前缘结节导致失速延迟，并且最大失速角改善达到28.1％。流动可视化显示，前缘结节可能诱导反向旋转的流向涡流的形成。流向涡旋和转角分离之间的相互作用被认为是环形压缩机级联中的前缘结节产生的主要流动机制。