The low-pressure turbine blades are susceptible to vibration issues due to their thin profiles and large aspect ratios. Blade vibration will significantly affect the evolution of the boundary layer and the flow state. This paper utilizes large eddy simulation to predict the development of the boundary layer on the suction side of low-pressure turbine blades at low Reynolds numbers (Re = 25,000). It introduces different vibration cases to elucidate the mechanisms by which blade vibrations influence boundary layer separation and transition. The study demonstrates that the introduction of vibration cases significantly reduces both the size of the overall spanwise vortices and their roll-up height. A staggered distribution of spanwise vortices, characterized by alternating high and low regions, is observed near the trailing edge of the vibrating blades. The shorter spanwise vortices develop rapidly, nearly traversing the process of hairpin vortices (Λ vortex) generation and development, and directly breaking down into smaller-scale vortices. This accelerates the transition process. Blade vibration primarily promotes turbulence reattachment by facilitating the transition process dominated by the K-H instability mechanism within the separating shear layer. Consequently, it effectively restricts the growth of the separation bubble on the suction side of the blades, significantly reducing aerodynamic losses. Moreover, increasing the vibration frequency within a certain range can amplify these effects, achieving up to a 23% reduction in total pressure loss compared to stationary blades.

中文翻译：

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基于大涡模拟的振动低压涡轮叶片过渡机理研究


低压涡轮叶片由于其薄型和大纵横比而容易受到振动问题的影响。叶片振动会显著影响边界层的演变和流动状态。本文利用大涡模拟来预测在低雷诺数 （Re = 25,000） 下低压涡轮叶片吸气侧边界层的发展。它介绍了不同的振动案例，以阐明叶片振动影响边界层分离和过渡的机制。研究表明，振动工况的引入显着减小了整个翼展涡流的大小及其卷起高度。在振动叶片的后缘附近观察到翼展涡流的交错分布，其特征是高低区域交替。较短的翼展涡旋发展迅速，几乎穿过发夹涡 （Λ 涡旋） 的产生和发展过程，并直接分解成较小尺度的涡旋。这加快了过渡过程。叶片振动主要通过促进分离剪切层内由 K-H 不稳定机制主导的过渡过程来促进湍流重新附着。因此，它有效地限制了叶片吸入侧分离气泡的生长，从而显著减少了空气动力学损失。此外，在一定范围内增加振动频率可以放大这些影响，与固定叶片相比，总压力损失最多可减少 23%。