A generalized flat plate cascade model is used in this study to predict the unsteady aerodynamics of a vibrating blade row with nonuniform blade spacing in subsonic compressible flow. The blade row is assumed to vibrate in an isolated family of blade-dominated modes. The effect of nonuniform blade spacing on compressor rotor flutter stability is demonstrated by case studies based on the geometric and flow conditions of a high-speed three-stage axial research compressor. The results show that nonuniform blade spacing can greatly alter the blades’ aerodynamic damping. At certain vibrational nodal diameters, some blades are destabilized so much that their aerodamping becomes negative. However, negative aerodamping of some blades do not necessarily lead to the instability of the whole blade row. A general multibladed system aeroelastic model is derived to study the effects of the nonuniform blade spacing on rotor stability through an eigenvalue approach. The aerodynamic influence coefficients matrix can be calculated using the generalized flat plate cascade model for a blade row with any user-specified blade spacing patterns. The case studies investigated in this paper show that alternating blade spacing and shifting only one blade position can slightly increase the stability of the least-stable eigenmode, whereas sinusoidal blade spacing has a slightly destabilizing effect. On the other hand, the eigenvectors of the least-stable mode for the nonuniformly spaced blade rows can be significantly different from the uniform blade spacing case.

本研究使用广义平板叶栅模型来预测亚音速可压缩流中叶片间距不均匀的振动叶片列的非定常空气动力学。假定叶片列以叶片主导模式的孤立族振动。基于高速三级轴向研究压气机的几何和流动条件的案例研究证明了不均匀叶片间距对压气机转子颤振稳定性的影响。结果表明，不均匀的叶片间距可以极大地改变叶片的气动阻尼。在某些振动节点直径下，一些叶片的不稳定程度如此之大，以至于它们的空气阻尼变为负值。然而，一些叶片的负空气阻尼并不一定会导致整个叶片列的不稳定。推导出通用的多叶片系统气动弹性模型，通过特征值方法研究非均匀叶片间距对转子稳定性的影响。可以使用具有任何用户指定的叶片间距模式的叶片列的广义平板叶栅模型计算空气动力学影响系数矩阵。本文研究的案例研究表明，交替叶片间距和仅移动一个叶片位置可以略微增加最不稳定本征模式的稳定性，而正弦叶片间距具有轻微的不稳定效应。另一方面，非均匀间隔叶片列的最不稳定模式的特征向量可能与均匀叶片间隔情况显着不同。