以泄漏涡失稳和剪切层不稳定性为主导的复杂流动机理及其与旋转流动不稳定性的关联机制研究

Rotating instability (RI) is a unsteady flow phenomenon which occurs in the tip region of compressors. It is well accepted that RI is closely related to the emergence of pre-stall waves, a new type aeroelastic problem-blade nonsynchronous vibrations, and tip clearance noise. However, It is still unclear how it comes from due to the complex flow environment in the rotor tip region. In this project, we propose to investigate the complex turbulent flow mechanism in the rotor tip region from a new view angle of vorex and shear layer instibility and set up its linkage with RI. Therefore, systematic experimental and numerical investigations will be laid out in a high-loaded axial compressor rotor. The advanced instantaneous measurement techniques will be used to obtain the detailed experimental data which could shed light on the the complex flow mechanism in the rotor tip region and its linkage with RI, and provide a thorough validation for high-precision numerical methods. After fully validated by experimental data, simulation results will be analyzed in detail, and the complex flow mechanism in the rotor tip region and its linkage with RI will be uncovered. The fundamental investigation results will set up a inherent linkage between emergence of RI and design parameters of high loaded axial compressor rotor, and provide solid basis for the exploration of more effective methods for stall control, vibration reduction and noise suppression aiming to the design of advanced aeroengines.

旋转流动不稳定性（Rotaing instability, RI）是出现在压气机叶尖区的一种明显的非定常流动现象。它与高负荷压气机的气动稳定性、叶片新一类的振动问题-非同步振动，以及间隙流的噪音之间的关联已定性的成为共识，然而对其诱发机理的认识却处于很低的水平。以高负荷轴流压气机为载体，项目提出以泄漏涡失稳以及剪切层不稳定性为主线，采用先进的动态实验测试技术并结合高精度的数值模拟模拟方法，深入系统地开展叶尖区复杂湍流流动机理及其与RI的关联机制研究。项目开展的基础性研究将从机理上建立RI与高负荷压气机设计参数的内在关联，并从机理上探讨针对先进航空发动机有效的扩稳、减振及降噪技术，为我国先进航空发动机的自主研发提供理论依据和技术储备。

旋转流动不稳定性（Rotaing instability, RI）是出现在压气机叶尖区的一种明显的非定常流动现象。它与高负荷压气机的气动稳定性、叶片新一类的振动问题-非同步振动，以及间隙流的噪音之间的关联已定性的成为共识，然而对其诱发机理的认识却处于很低的水平。项目首先以高亚音轴流压气机转子为研究对象开展了叶尖动态压力的系统实验测量，结果表明：RI是其近失稳工况叶尖流场的主导流动特征。在此基础上，以实验测量的高亚音轴流压气机转子、平面叶栅和跨音轴流压气机转子为研究对象，系统的开展了其叶尖流场的高精度数值模拟。综合高亚音转子、平面叶栅、跨音转子的实验和数值研究结果可以看出：泄漏涡逆压梯度下传播导致的涡破碎以及其诱导出的旋涡结构对相邻叶片压力面近叶尖压力分布的影响是与转子/叶栅固结坐标系下流动由定常转变为非定常的流体动力学机制，这也是RI出现的先决条件；叶尖流动非定常性转变为RI的流体动力学机制是泄漏涡的螺旋破碎以及由其诱导的反流涡（Back Flow Vortex, BFV）能够诱发流动阻塞的周向传播.因此，压气机叶尖的设计负荷、激波强度、稠度和安装角是影响RI是否出现的主要因素。从压气机设计和流动控制的角度而言，以这四个主导因素为切入点来对压气机进行局部改型设计或有针对性地选择合适的调控方法可以抑制RI的出现，从而达到扩稳/减振/降噪的目的。