轴流压气机机匣处理扩稳能力相似方法及扩稳机理研究

The new generation aircraft engine demands for safer and wider operational envelope, which will be a big challenge due to the inherent characteristic of the low stability at part speed in high-speed compressors. To avoid the potential catastrophic consequences of compressor stall, casing treatment becomes a particularly prominent issue to the turbomachinery industry. However, due to the compact geometry of the high-speed compressor, it is difficult to measure the flow structures inside of the casing treatment in detail. The numerical simulations cannot be fully validated. Although there have been various studies on the interaction between the rotor tip flows and the flow in casing treatment, the flow mechanism for the stability improvement is still unclear. This project will carry out the following studies: 1) proposing criteria for similarity of casing treatments based on the cumulative axial momentum curve for the tip region, which was proposed by the applicant; 2) measuring the flow fields of the inner groove/slot casing treatments and the rotor tip region in details and then with the validated CFD results, investigating the stability enhancement mechanism due to casing treatment with; 3) optimizing the casing treatment configuration in the low-speed compressor and then testing the high-speed counterpart in the targeted high speed compressor. The main innovations is that with the help of similarity, the casing treatments can be studied and optimized in large low-speed compressors, which significantly reduces the risk of development if that was to be done on the high-speed compressor directly. This study might provide a new route to safer and better compressors.

高负荷压气机部分转速的稳定裕度问题在宽工作范围压气机设计概念下将尤为突出，机匣处理设计面临严峻挑战。受限于高速原型机的尺寸，动叶端区和机匣处理之间的相互作用难于得到详尽可靠的测量，扩稳机制诠释上的分歧难以得到验证分析。本申请拟以新思路，将高速原型机部分转速(无激波)机匣处理模化到具有相似扩稳特征的低速大尺寸压气机机匣处理上开展研究，包括：1）基于申请人前期形成的衡量机匣处理扩稳能力的动叶端区动量积分曲线，首先探索高/低速压气机间机匣处理扩稳能力的动力及几何相似准则，从而保证扩稳后内部流场的特性相似；2）对模化的机匣处理内部及端区流场进行详细测量，校核非定常计算结果并据此分析机匣处理对端区流动结构的改变，以推进扩稳机理的认识；3）优化方案并按相似准则返回原型机开展实验验证。主要创新点体现在探索近失速点扩稳相似准则，藉此深入流动机制并优化机匣处理，为实用的高速压气机稳定性优化设计提供有益思路。

高负荷压气机中低转速的稳定裕度问题对机匣处理设计面临严峻挑战。本项目借鉴了压气机模化设计的思路，将空间小、难测量的高速压气机部分转速(无激波)机匣处理按照相似方法转换至放大空间、低转速的大尺寸压气机上进行研究，旨在依靠详尽可靠的测量诠释扩稳机理认识上的分歧，更经济、高效的对机匣处理进行改进设计。通过数值模拟和实验研究，本项目：1）建立了保证低速与高速压气机近失速点内部流场相似的模化准则，对高速压气机转子完成了低速模化设计；2）提炼了高/低速压气机间机匣处理扩稳能力的动力学准则，即动叶端区轴向动量累加曲线——钟形曲线的顶点轴向位置规律一致；3）通过对机匣处理内部流场的实验测量验证了机匣处理与叶顶流动相互作用与扩稳效果的关联。建立了流动损失量化模型并提炼了机匣处理几何相似准则；4）优化设计了兼顾效率和失速裕度的机匣处理优化方案，通过相似变换应用回高速压气机并完成了验证。本项目摸索了一个机匣处理的模化反演初步方法，在深入到处理机匣内部流场测量的基础上加深了对扩稳机理的认识，完成了低速模型压气机设计-机匣处理流动机理研究-机匣处理方案改进-低速实验验证-机匣处理相似变换-高速原型机效果验证的整个流程。此方法为高速压气机的高性能机匣处理设计开辟了一条新思路，具有一定的借鉴意义与工程应用前景。