Prediction of acoustic resonance in a multistage high-speed axial compressor

喷气发动机和发电厂对高运行灵活性的经济和监管要求导致涡轮机械部件更频繁的非设计运行。关于运行稳定性，压缩机构成了这些涡轮机器中最关键和最具挑战性的部件。除了众所周知的喘振、旋转失速和旋转不稳定等气动不稳定性外，高压波动已被确定为高速和高压轴流压气机在特定非设计工作点的声共振。最近的研究表明，声共振可以激发机械振动，这可能导致严重的叶片损伤或立即致命的结构破坏。此外，研究表明，声波共振可以通过触发旋转失速和喘振，将稳定性极限转移到更高的质量流量。由于涡轮机械的几个工业生产商都经历过声学共振，因此在未来的设计过程中，对这种现象的物理机制的理解和表征是相当需要的。申请人和他的同事首先提出了两个模型来预测和表征声学共振，但这些现象的数据很少在公开文献中报道。因此，有必要对这些模型进行验证。为此，提高对驻波形成机制和激发机制的物理认识是必不可少的。本研究的目的是进一步了解多级轴流压气机的激励机制和共振条件。本文首次对高速多级轴流压气机的叶尖泄漏流和谐振声场进行了广泛的同时测量，得到了近似于实际机况的结果。基于高精度的测量和数值模拟，将对预测模型进行验证和校准，从而形成一种预测声共振发生的方法。

Economic and regulatory requirements for high operational flexibility of jet engines and power plants lead to more frequent off-design operation of turbomachinery components. Regarding operating stability, the compressor constitutes the most critical and challenging component in these turbomachines. Besides the well-known and intensely investigated aerodynamic instabilities of surge, rotating stall, and rotating instability, high pressure fluctuations have been identified as acoustic resonance in high-speed and high-pressure axial compressors at specific off-design operating points. Recent research shows that acoustic resonance can excite mechanical vibrations, which might result in severe blade damage or immediately fatal structural failure. In addition, research shows that acoustic resonances can shift the stability limit to higher mass flow rates by triggering rotating stall and surge. As several industrial producers of turbomachinery have experienced acoustic resonances there is considerable need for the understanding and characterization on the physical mechanism of this phenomenon for future design processes. First approaches by the applicant and his coworkers have led to two models to predict and characterize acoustic resonance, but data of these phenomena have rarely been reported in open literature. Therefore, validation of these models is necessary. To this end, improved physical understanding of the formation mechanism of the standing waves and of the excitation mechanisms is essential. The objective of the proposed project is to give further insights into the excitation mechanism and the resonance conditions in multi-stage axial compressors. Extensive simultaneous measurements of the tip leakage flow and the resonant acoustic field are carried out for the first time in a high-speed multistage axial compressor, which approximates realistic machine conditions. Based on the highly accurate measurements and numerical simulations, validation and calibration of the prediction models will be performed, which will lead to an approach to predict the occurrence of acoustic resonance.