Full-Annulus Simulation of the Surge Inception in a Transonic Centrifugal Compressor

• Published in: Journal of thermal science 2015, Vol.24 (5), p.442-451
• Main Authors: Trébinjac, I., Benichou, E., Buffaz, N.
• Format: Article
• Language: English
• Subjects: Classical and Continuum Physics; Engineering Fluid Dynamics; Engineering Sciences; Engineering Thermodynamics; Fluids mechanics; Heat and Mass Transfer; Mechanics; Physics; Physics and Astronomy; 仿真; 实验数据; 数值模拟; 时间滞后; 流量模式; 离心式压缩机; 跨声速; 边界层分离
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-015-0807-x

Full annulus simulations of the flow which develops in a transonic centrifugal compressor are performed at two stable operating points （peak efficiency and near surge） and during the path to surge. At stable conditions, the flow field properties are analyzed by comparisons with experimental data and numerical simulations using a phase lagged approach previously carried out. Regarding the stage overall performance, an excellent agreement is obtained between the numerical results （both with time lagged approach and full-annulus calculation） and the ex- periments. From the full-annnlus simulations, the change in flow pattern from peak efficiency to surge is found to be perfectly similar to that obtained from the simulations using the time lagged approach. In particular, pro- vided that the operating point is stable, the flow proves to be chorochronic. The full-annulus simulations were continued after a unique small change in the throttle law applied at the exit of the numerical domain. The mass flow, pressure ratio and efficiency then significantly drop all the more the time progresses. The simulation becomes unstable and the surge inception well underway. The path to surge is found to be due to the enlargement of the boundary layer separation on the suction side of the diffuser vanes in accordance with the conclusions drawn from the chorochronic simulations and experiments. But as the time progresses, the flow loses its chorochronic character. Stall cells rotating at around 7% of the rotor speed develop and lead to surge in around 5 revolutions.