高负荷压气机失稳机制及关键设计参数对失速裕度的影响研究

In this proposal, in order to explore the propagation route of compressor instability spatiotemporally, key links still unclear for now in both views of time and space will be mainly focused on. In view of time, the propagation period in time domain, from unstable turbulence phenomena to stall precursor then to compressor instability, will be studied. In view of space, the effects of spatial distribution of pressure gradient on compressor instability will be first presented. After that, the weight analysis of the influence of compressor physical boundaries (such as pre-swirl, inlet distortion, solidity and so on) on the compressor stall margin will be investigated. To capture the stall evolutions, most work in this proposal will be carried out experimentally including transonic compressor and subsonic compressor stall experiments. The results will be analyzed in both time and frequency domains by the FFT, wavelet and framelet data processing methods. At the same moment, numerical simulations by URANS, LES and DES will be conducted to obtain more detailed flow field data. After that, high-fidelity nonlinear artificial intelligence model and data assimilation method will be used to build the theoretical model relating compressor physical boundaries and compressor instability. The reasonable achievements in this proposal are: 1) the deep insight into the propagation procedure from local turbulence phenomena to compressor instability, further into unified mechanism about the switch of different types of stall inceptions; 2) the weight analysis report of the influence of compressor design parameters on the compressor stall margin. All achievements will provide supports to finally establish the general mechanism of compressor instability in high loaded compressors and to improve the compressor design system with unsteady factors.

本项目拟针对压气机失稳机制在时间和空间两维度尚未清晰的环节开展研究，力图形成相对完整的时空发展图谱和统一的机理认识。项目重点探索局部湍流不稳定流动结构与失稳先兆的物理关联、逆压梯度空间分布对压气机稳定性的决定性作用、探索压气机不同物理边界对失速裕度的影响权重。项目以实验研究为主，重点以跨声速风扇、低速压气机为实验对象，以小波分析、框架分析技术针对复杂频域的失速过程进行数据分析，以全周URANS、角区LES/DES等数值模拟为辅助的数据生成手段，采用高精度非线性人工智能替代模型和数据同化方法建立压气机物理边界影响失速裕度的理论模型。项目将完善从局部湍流不稳定流动结构直至压气机失稳的完整物理链条，形成诱发三类失速先兆机制的统一认识；并通过获得压气机关键设计参数对失速裕度的影响权重，将近失速的非定常因素纳入设计体系。研究成果将对该学科领域最终建立高负荷压气机失稳统一机制起到科学支撑作用。

压气机失稳机制在时间和空间两维度尚未清晰，缺乏相对完整的时空发展图谱和统一的机理认识，严重制约航空发动机的性能的进一步提升。因此本项目通过在时间维度上探究压气机内部湍流流动结构如何诱导失速先兆，以及在空间维度上探究不同局部不稳定流动结构的触发条件，形成了相对完整的压气机流动失稳时空发展图谱和统一机理认识。取得的主要成果如下：（1）针对新型叶根失稳先兆局部喘振，通过实验和数值研究，构建了“局部高负荷—局部不稳定流动结构—失稳先兆—压气机失稳”的完整物理链条，建立了局部湍流不稳定流动结构与压气机失稳的物理关联；（2）针对不同类型失稳先兆，通过对逆压梯度径向、周向以及轴向分布的调节，获得了逆压梯度变化情况下压气机不同失稳先兆间的转化规律，进一步揭示了逆压梯度空间分布对压缩系统稳定性的决定性作用；（3）通过发展基于分布式力源体积力模型的快速计算方法，突破了压气机物理边界与失速裕度关联的敏感性分析技术，获得了部分关键设计参数对压气机稳定性的影响权重，相关理论成果已应用于工业部门在研型号的失速边界预测和失速流动控制方案设计。