随着能源效率需求的不断提升，汽轮机叶片的设计在不同应用场景中展现出显著的多样性。大展弦比叶片因端壁损失较低、流动效率较高，广泛用于传统燃气轮机和工业汽轮机。然而，在空间受限或特殊工况下，例如航空发动机的高负荷小型化设计、船舶推进系中的高压级和调节级的应用场景，小展弦比叶片因其紧凑设计成为首选。尽管如此，小展弦比叶片在性能上仍存在明显短板。端壁二次流和混合损失等问题显著增加了能量损失，严重影响整体性能。本文基于跨音速条件下的极小展弦比汽轮机叶片，采用延迟脱体涡模拟（DDES）方法，深入研究了小展弦比叶片的流动特性，重点分析了涡流结构、激波与边界层干扰引发的流动分离及其对性能的影响。研究发现，小展弦比叶片虽然具有结构紧凑的优势，但其能量损失主要集中在尾缘区域，且尾迹涡、端壁涡与激波的相互作用是损失增加的关键因素。结果表明，DDES方法在捕捉小展弦比叶片中小尺度涡流和瞬时现象方面表现出显著优势，能够更准确地反映激波的平均扰动效应及涡流对整体性能的影响。此外，本文还提出了针对极小展弦比叶片性能优化的未来方向，包括优化尾缘形状、调整端壁区域设计、减少激波干扰以及控制边界层分离等略。本研究为小展弦比叶片的性能优化提供了理论支持，同时展示了DDES方法在复杂流动模拟中的巨大优势。未来研究将进一步验证这些优化方案的可行性，以有效降低能量损失并提升汽轮机的整体效率。

With the increasing demand for energy efficiency, turbine blade design has shown significant diversity across different application scenarios. Large aspect ratio blades, known for their low end-wall losses and high flow efficiency, are widely used in traditional gas turbines and industrial turbines. However, in space-constrained or special working conditions, such as high-load miniaturized designs in aero engines and high-pressure stages and control stages in marine propulsion systems, small aspect ratio blades have become the preferred choice due to their compact design. Despite these advantages, small aspect ratio blades still exhibit notable performance drawbacks. Issues such as end-wall secondary flow and mixing losses significantly increase energy losses and adversely affect overall performance.This study focuses on the flow characteristics of ultra-small aspect ratio turbine blades under transonic conditions, employing the Delayed Detached Eddy Simulation (DDES) method. It investigates the flow structures, shockwave-boundary layer interactions, and flow separation phenomena that impact performance. The results reveal that while small aspect ratio blades have the advantage of compact design, energy losses are primarily concentrated in the trailing edge region. The interaction between wake vortices, end-wall vortices, and shockwaves is identified as a key contributor to the increased losses.The findings demonstrate that the DDES method shows significant advantages in capturing small-scale vortex flows and transient phenomena in small aspect ratio blades, providing a more accurate representation of the average disturbance effects of shockwaves and the impact of vortex flows on overall performance. Furthermore, this study proposes future directions for optimizing the performance of ultra-small aspect ratio blades, including refining trailing edge shapes, adjusting end-wall designs, reducing shockwave interference, and controlling boundary layer separation.This research provides theoretical support for the performance optimization of small aspect ratio blades and highlights the great potential of the DDES method in simulating complex flows. Future work will further validate the feasibility of these optimization strategies, aiming to effectively reduce energy losses and improve the overall efficiency of turbines.

国家自然科学基金面上项目（No. 52276031），国家科技重大专项（No. J2019-II-0008-0028）