Circumferential Propagation of Tip Leakage Flow Unsteadiness for a Low-Speed Axial Compressor

• Published in: Journal of thermal science Vol. 18; no. 3; pp. 202 - 206
• Main Authors: Geng, Shaojuan, Lin, Feng, Chen, Jingyi, Zhang, Hongwu, He, Lei
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.09.2009
• Subjects: Classical and Continuum Physics; Engineering Fluid Dynamics; Engineering Thermodynamics; Heat and Mass Transfer; Physics; Physics and Astronomy; 不稳定; 失稳转速; 泄漏流动; 转子转速; 轴流压缩机; 非定常数值模拟; phase shift; circumferential wave; axial compressor; unsteady tip leakage flow
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-009-0202-6

Full-annulus three-dimensional unsteady numerical simulations were conducted for a low-speed isolated axial compressor rotor, intending to identify the behavior of self-induced unsteady tip leakage flow within multi-blade passages. There is a critical mass flow rate near stall point, below it, the self-induced unsteadiness of tip leakage flow can propagate circumferentially and thus initiates two circumferential waves. Otherwise, the self-induced unsteady tip leakage flow oscillates synchronously in each single blade passage. The major findings are： 1） while the self-induced unsteadiness of tip leakage flow is a single-passage phenomenon, there exist phase shifts among blade passages in multi-passage environments then evolving into the first short length wave propagating at about two times of rotor rotation speed after the transient period ends; and 2） the time traces of the pseudo sensors located on the rotor blade tips reveal another much longer length-scale wave modulated with the first wave due to phase shift propagating at about half of rotor rotation speed. Features of the short and long length-scale circumferential waves are similar to those of rotating instability and modal wave, respectively.