【作者】 黄旭东；

【导师】 符松；

【作者基本信息】 清华大学 ， 力学， 2010， 博士

【摘要】 压气机是航空发动机的核心部件之一,其性能对航空发动机的整体性能具有决定性的影响。现代航空发动机的发展对压气机的单级压比提出了越来越高的要求,需要对旋转失速等制约压气机性能、并严重影响发动机安全的问题有更加深入的了解。机匣处理作为一种简单、有效的被动流动控制方式在提高压气机的失速裕度方面已经得到了较为广泛的应用。但对其作用机理的认识还比较匮乏,使得相关设计主要还依赖于大量的实验,并且通常以降低压气机的绝热效率为代价。本文采用先进的数值方法对跨音速压气机和机匣处理内的流动结构进行了较为系统的研究。通过讨论不同工况下跨音速轴流压气机中叶尖附近关键流动结构的变化和发展,发现叶片前缘顶隙泄漏涡的破裂和叶片尾缘的分离分别是大、小两种顶隙高度下导致压气机失速的直接原因,而这两种流动现象都与主要受顶隙泄漏涡轨迹影响的前缘顶隙泄漏流的二次泄漏相关,揭示了目前得到广泛认可的失速判据背后的物理机理。在此基础上,本文对环向沟机匣处理在跨音速轴流压气机中的应用进行了数值研究。讨论了轴向位置和深度对环向沟机匣处理效果的影响;并从越过顶隙的质量和动量输运的角度分析了环向沟机匣处理的作用机理。相关结果与压气机的失速机理是一致的。由此提出的设计准则在ND-TAC实验压气机上得到了验证。此外,本文还研究了自循环式机匣处理在跨音速离心压气机中的应用。分析了自循环式机匣处理在堵塞端和失速端提高压气机失速裕度的不同机理和引起压气机效率损失的机理;提出了按扩压器设计机匣处理通道的指导原则;讨论了机匣处理通道的开口位置、宽度和扩张度对机匣处理效果的影响;得到了使压气机绝热效率取得明显改善的机匣处理新构型,并得到了相关实验结果的支持。更多还原

【Abstract】 Compressor is one of the core components of aero-engine. Its performance has a decisive influence to the overall performance of an aero-engine. Modern development of aero-engine requires a compressor with higher and higher total pressure ratio per stage. It challenges our understanding on the phenomena like rotating stall et al, which restrict the performance of compressor and threaten the safety of aero-engine. Casing treatment as a simple but effective passive flow control method has been widely used to extend the compressor stall margin. But the lack of good knowledge on the mechanism of casing treatment makes the design largely depend on ad hoc experiments and usually be accompanied with efficiency penalty.The flow structures in the transonic compressor and casing treatment are investigated in detail via an advanced numerical simulation. Based on the discussion on the change and development of the critical flow structures at tip region at different operation points, the blade trailing edge separation and the breakdown of the leading edge tip leakage vortex is considered to be the direct reason for the triggering of stall respectively for configurations with small and large tip clearance width. These two phenomena are both related to the second leakage of the leading edge tip leakage flow which is greatly influenced by the trajectory of the leading edge tip leakage vortex. The results reveal the physical mechanism behind the widely accepted stall criteria.On the basis of the discussion on the stall process, a numerical investigation on the application of Circumferential Groove Casing Treatment (CGCT) on the transonic axial compressor is performed. The influence of the axial location and depth of the grooves is studied. The mechanism of CGCT is also discussed via an analysis on the mass and momentum transport across the blade tip. The result is accordance with the stall process of the compressor. Some design suggestions are presented, and validated by the application in ND-TAC test compressor.Besides, the application of a self recirculation casing treatment on the transonic centrifugal compressor is numerically studied. The mechanisms for the stall margin improvement and efficiency loss are analyzed. Designing the casing treatment channel like a diffuser is suggested as a design rule. Following this rule, the influence of the location, width and diffusion level is investigated. A new casing treatment configuration which leads to significantly improved compressor efficiency (compare with datum casing treatment design) is achieved. The result is supported by experiments.更多还原