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。从效率的角度来看，在尽可能高的压力比下运行是可取的，但这样的工作点本质上是不稳定的，因为它们非常接近失速和喘振等不良的空气动力学现象。旋转失速是一种局部不稳定现象，在这种情况下，流速降低会引起流动分离，从而导致失速气泡的形成。这些电池开始绕环旋转并撞击叶片，从而产生高振动负荷。喘振是一种全局不稳定现象，在整个机器中都会发生反流，从而在叶片中产生高的瞬时应力。缺乏对确切机制的了解和建模方法的缺乏，阻碍了动态载荷的确定和随之而来的叶片响应。因此，目前的设计是基于安全裕度，其中叶片间距不是最佳的。利用一种先进的计算方法，建议建立一个典型的工业核心压气机的大比例模型，这是作者以前研究的主题，并且有实验数据可用。该项目的目的不仅是为了了解旋转失速和喘振机制及其之间的联系，而且还为了证明大规模建模方法作为设计工具的可行性。另一个目标是研究旋转失速和喘振的恢复机制。

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..