高负荷低压涡轮内部非定常流动机理及其控制策略研究进展

Research Progress on Unsteady Flow Mechanism and Control Strategies of High-Lift Low Pressure Turbine

关键词:  低压涡轮  高负荷  流动机理  损失机制  流动控制

Key words:  Low pressure turbine  High-lift  Flow mechanism  Loss mechanism  Flow control

摘要:

低压涡轮湍流问题是制约高性能航空发动机研制的难点之一。为了理清低压涡轮内部湍流流动机理，并掌握相应的控制策略，获得计及非定常流动特征的高负荷低压涡轮气动设计方法，基于课题组长期从事高负荷低压涡轮的研究基础之上，结合国内外低压涡轮大量研究工作，系统地介绍了尾迹扫掠下低压涡轮叶片吸力面附面层发展演化过程、端区二次流非定常特征变化以及相应的流动损失机制及其抑制方法。优化叶片载荷分布在一定程度上能够减小叶型损失和二次流损失；尾迹扫掠能够诱导吸力面附面层发生转捩从而减小叶型损失，同时也有助于抑制端区二次流的发展，但在不同雷诺数下，尾迹的作用效果可能不同；对于高/超高负荷低压涡轮，特别是在低雷诺数条件下，需要借助有效的流动控制手段来抑制分离。

Abstract:

The turbulence issue in high-lift low pressure turbines is one of the most important factors for the aero-engine performance. For understanding the physical mechanisms of turbulence flow in high-lift low pressure turbines， and mastering flow control strategy， research on the unsteady flow in high-lift low pressure turbine blade is necessary to get the aerodynamic design methodology of low pressure turbine considering unsteady flow characteristics. Based on the large amount of research for high lift low pressure turbine from domestic and foreign researchers， together with the efforts current authors had been done， this paper systematically introduces the evolution process of boundary layer behaviors， the unsteady characteristic change of endwall secondary flow， the loss mechanism and the control strategies of low pressure turbines under periodically unsteady incoming flow conditions. To optimize blade-loading distribution can decrease profile losses and secondary losses to some extent. Upstream wakes can induce the transition of blade suction side boundary layer to decrease profile losses and also contribute to suppress the development of endwall secondary flow， but the effect of wake is double-edged at different Reynolds numbers. The effective flow control strategies are necessary to suppress flow separation for high/ultra-high lift low pressure turbine， especially at low Reynolds number.