压气机叶栅角区分离中速度PDF双峰现象产生机理实验研究

Understanding the mechanism of corner separation in compressor cascades is the key to control more effectively the corner separation and thus improve the performance of compressor. Recently one of the researches that have improved the understanding of the mechanism of corner stall is the discovery of the velocity probability density distribution (PDF) bimodal phenomenon of corner separation in linear compressor cascade. The preliminary study of this phenomenon shows that two aperiodic modes exit in corner separation, but the generation mechanism of this phenomenon is not clear. In order to investigate the generation mechanism of this phenomenon, this project is based on the detailed experiments on instantaneous flow fields of corner separation in linear compressor cascade on different conditions. (1) To investigate the occurrence regularity of bimodal phenomenon; (2) to investigate the configuration and its evolution according to each mode, and to analyze and model the influences of flow factors on the configuration of each mode; (3) to investigate the interactions of unsteady flow fields that induce bimodal phenomenon. After completing this project, the understanding of the mechanism of corner separation will be improved further, and thus the guidance for the design of high efficiency, high loaded, high stability margin compressors will be provided, at the same time the experimental database that can be used to calibrate subgrid-scale models and numerical methods of LES will be established.

压气机叶栅角区分离机理研究是实现对角区分离更有效控制，进而提高压气机性能的关键。最近提高了对角区分离机理认识的一个研究成果是发现了角区分离中速度概率密度分布（PDF）双峰现象，对此双峰现象的初步研究表明角区分离中存在着两个非周期性的模态，但是此双峰现象的产生机理目前还不清楚。本项目拟基于对多工况下压气机叶栅角区分离中瞬态流场的详细测量，对角区分离中双峰现象的产生机理进行深入研究。（1）探索双峰现象出现的规律性；（2）探索双峰现象中各个模态所对应的瞬态流场结构形态及其演化规律，分析流场因素对各模态流场结构形态的影响并进行建模；（3）探索双峰现象是由流场中哪些非定常流动的相互作用引起的。本项目的实现，将进一步提高对角区分离机理的认识，为更有效地控制角区分离奠定基础，进而为设计高效率、高负荷、高稳定性裕度压气机提供指导，并将创建目前急缺的可用于校准大涡模拟（LES）模型和数值方法的实验数据库。

压气机叶栅角区分离机理研究是实现对角区分离更有效控制，进而提高压气机性能的关键。最近提高了对角区分离机理认识的一个研究成果是发现了角区分离中速度概率密度分布(PDF)双峰现象，对此双峰现象的初步研究表明角区分离中存在着两个非周期性的模态，但是此双峰现象的产生机理目前还不清楚。为了对角区分离中双峰现象的产生机理进行深入研究，本项目详细测量了角区分离内部流场。结合数值计算，本项目成功探索了角区分离中双峰现象出现的规律性、双峰现象中各个模态所对应的瞬态流场结构形态及其演化规律、以及引起双峰现象的相互作用。为了提高项目中使用的麦克风阵列反卷积计算效率，项目成功提出使用压缩网格的思路，将DAMAS算法的计算效率提升了近100倍。本项目的开展，为更有效地控制角区分离奠定基础，进而为设计高效率、高负荷、高稳定性裕度压气机提供指导，并且本项目创建实验数据库可用于校准数值方法。