某型轴流发动机气动不稳定试验

Experimental investigation on aerodynamic instability of axial flow engine

关键词:  轴流式压气机  失速  喘振  不稳定性

Key words:  Axial flow compessor  Stalling  Surge  Instability

摘要:

对某轴流式涡喷发动机节流过程中的气动不稳定现象进行了试验研究。通过定性分析和数据处理, 揭示了节流过程中发动机气动失稳的过程和机理, 压气机第1级静子机匣壁面静压脉动分量的形式和强度变化与上游转子端壁流动分离的程度密切相关, 且静压脉动的概率密度函数分布可以反映这种变化。提出了一种检测失速征兆的新思路, 即检测压气机第1级的流动分离, 而不是直接检测出现在级负荷和轮毂比较高的压气机级中、导致压气机整机失速的模态扰动和(或) 短周期扰动, 来判断发动机工作点接近不稳定工作边界的程度。应用这种思路,预期可以提高失速征兆检测的时效性。

Abstract:

Experiments were performed to investigate the aerodynamic instability of axial flow aeroengine during throttling operation. The aerodynamic destabilization route and mechanism were revealed through qualitative analysis and data processing. It was observed that the variation of form and intensity of pulsating components of stator casing wall static pressure signal of the first compressor stage was closely related to the degree of end wall flow separation of upstream rotor. Further data analysis manifested that the variation of compressor stator casing wall static pressure fluctuations could be represented by probability density analysis. A new method of identifying the stall precursors by means of sensing the degree of flow separation in the first compressor stage, rather than to detect modal and/or spiky disturbances inducing compressor rotating stall directly, is suggested, which is believed to be promising because the flow separation in the first compressor stage occurs far early before the occurrence of spikes or modes in the compressor stages with high loadings and high hub-to-tip ratios.