压气机尖区非定常流动与叶片振动耦合机理的实验研究

Non-synchronous vibration is a novel Fluid-Structure Interaction which often happens in a high-load aircraft engine, resulting in blade fractures and injuring the engine’s reliability. The corresponding mechanism is still unclear. Therefore, there is an urgent need to perform the experimental research. Currently, the research on non-synchronous vibrations has just started, mainly focused on the unsteady flow structure in the tip region through numerical simulation and lacked detailed experimental measurements. In this investigation, the experimental study,which use various dynamic measurement techniques, will be conducted on the non-oscillating cascade, controllable oscillating cascade and free oscillating cascade, at the conditions of different incidence and different tip clearances.The measurements will be focused on the three-dimensional unsteady flow structures, such as the tip leakage flow, tip leakage vortex, corner flow and separation flow.The unsteady aerodynamic excitation characteristics will also be discussed. Effects of blade vibrations at various amplitudes and frequencies on the unsteady tip flows will be studied to know the one-way fluid-structure interaction mechanism, comparing test results in the non-oscillating cascade with those in the controllable oscillating cascade. Similarly, the two-way fluid-structure interaction mechanism between unsteady tip flows and blade vibrations will be investigated. In additon, the experimental study using various dynamic measurement techniques, will be conducted on the single-rotor compressor as well. The measurements will be focused on the three-dimensional unsteady tip flow structures and the unsteady aerodynamic excitation characteristics. This study aims to establish relationship between the information measured on the cascade and the information measured on the compressor. Finally, an experimental database systematically reflecting the fluid-structure interaction mechanism between the unsteady tip flow and the blade vibrations will be obtained, which can provide a scientific basis to study deeply the non-synchronous vibration mechanism in a compressor.

非整阶振动是高负荷航空压气机新发现的一种新型流固耦合现象，造成叶片高周疲劳断裂，严重影响航空发动机的可靠性，急需开展实验研究。国内外针对非整阶振动诱发机理的研究刚起步，主要通过数值模拟进行，缺少振动条件下叶栅尖区三维非定常流场实验数据验证。本项目基于压气机无振动叶栅、可控振动叶栅、自由振动叶栅，利用多种先进动态测试技术详细测量叶栅通道内的非定常流动结构和叶片的振动响应，研究非定常流动与叶片振动的单向与双向耦合机制；基于压气机单转子模型试验台，测量旋转条件下尖区的非定常流动结构与叶片的振动响应，把平面叶栅上测得的丰富的流动与振动信息与压气机旋转条件下的流动与振动信息进行关联，贴合工程实际，深度揭示压气机叶片非整阶振动的气动激励特性以及其与叶片振动的耦合机理。获得一套验证计算程序急需的、系统反映尖区非定常流及其与叶片振动耦合的高质量实验数据库，为认清压气机叶片非整阶振动机理提供科学依据。

本项目搭建了压气机无振动叶栅、可控振动叶栅、自由振动叶栅试验台，采用动态压力传感器、SPIV、热线等多种动态测试技术详细测量了不同叶栅在不同条件下通道内的非定常流动，澄清了攻角、叶尖间隙对无振动叶栅尖区非定常流场的影响。对比分析各叶栅尖区的非定常流动结构，可以发现，叶片振动导致泄漏涡与泄漏流产生了更强烈的摆动，叶片振动引起的泄漏涡/流摆动相对于叶片振动自身之间存在相位差，泄漏涡/流摆动落后于叶片振动；叶片自由振动会使叶片实际进气角随振动周期性变化，叶背附面层分离点随之周期性变化，叶背附面层分离流动的非定常性提高，泄漏涡非定常性也随之周期性变化，揭示了叶栅非定常流动与叶片振动的单向与双向耦合机制。.基于单转子、双级低速压气机试验台，采用动态压力探针、动态压力传感器、SPIV、热线等多种动态测试技术，详细测量了不同条件下转子尖区非定常流动，压气机尖区非定常流动形成的凸包、宽频的流场特征，与平面叶栅实验中大攻角下叶背分离涡与尖区泄漏涡掺混造成的流场的凸包宽频特征相对应；进一步分析压气机尖区非定常流动与叶片振动响应数据，揭示了压气机叶片非整阶振动的气动激励特性及其与叶片振动的耦合机理。.本项目获得一套验证计算程序急需的、系统反映尖区非定常流及其与叶片振动耦合的高质量实验数据库，为认清压气机叶片非整阶振动机理提供了基础实验数据。