Numerical Simulation of Rotating Stall and Surge for the Determination of Dynamic Loads and Blade Response in Aero-engine Core Compressors

航空发动机压缩机在高压下输送大量空气。从效率的观点来看，希望在尽可能高的压力比下操作它们，但是这样的操作点固有地不稳定，因为它们非常接近不希望的失速和喘振的空气动力学现象。旋转失速是一种局部不稳定性，其中降低的流量引起流动分离并导致失速单元的形成。这些单元开始围绕环旋转并撞击叶片，从而引起高振动载荷。喘振是一种全局不稳定性，在这种不稳定性中，整个机器中发生流动逆转，导致叶片中的高瞬态应力。在理解确切机制方面的缺陷和建模方法的缺乏阻碍了动态载荷和随后叶片响应的确定。因此，当前的设计是基于叶片排间距不是最佳的安全裕度。使用先进的计算方法，它是建议建立一个大规模的模型，一个典型的工业核心压缩机，这一直是以前的研究的主题，由提案人和实验数据。该项目的目的不仅是了解旋转失速和喘振机制以及它们之间的联系，而且要证明大规模建模方法作为设计工具的可行性。另一个目的是研究旋转失速和喘振的改出机理。

Aero-engine compressors deliver a large quantity of air at high pressure. From an efficiency viewpoint, it is desirable to operate them at the highest possible pressure ratios but such operating points are inherently unstable because of their close proximity to undesirable aerodynamic phenomena of stall and surge. Rotating stall is a local instability where reduced flow rate gives rise to flow separation and results in the formation of stall cells. These cells begin to rotate around the annulus and hit the blades, thus causing high vibratory loads. Surge is a global instability in which flow reversal occurs throughout the machine, causing high transient stresses in the blading. Deficiencies in understanding the exact mechanisms and a lack of modelling methodology prevent the determination of the dynamic loads and the ensuing blade response. Therefore, current designs are based on safe margins where the bladerow spacing is not optimum. Using an advanced computational method, it is proposed to build a large-scale model of a typical industrial core-compressor which has been the subject of previous studies by the proposers and for which experimental data are available. The aim of the project is not only to understand the rotating stall and surge mechanisms and the links between them, but also to prove the feasibility of the large-scale modelling approach as a design tool. A further objective is the investigation of recovery mechanisms from rotating stall and surge..