Spatiotemporal characteristics of rotating stall in a centrifugal compressor with a volute at low-flow rate conditions

Abstract

In this paper, the characteristic of the internal flow structure and the spatiotemporal evolution of the rotating stall cell for a centrifugal compressor are investigated through the computational fluid dynamics approach at low-flow rate conditions. The qualitative study like generation mechanisms of the instable internal flow, the movement trend of the stall, and the spatiotemporal characteristics of fluctuation in the impeller are mainly focused in the present work. The stall cells in the impeller move along the impeller rotating direction, and significantly influenced by the volute tongue. The traveling mechanism of rotating stall is closely related to the volute tongue, which easily deteriorates the obvious distortion of the flow structure. Furthermore, the transition law of the rotating stall is quantificationally described through the density and velocity fluctuations. The stall evolution on the circumferential monitoring points is demonstrated by the pressure fluctuation both time and frequency scale, which verifies the influence of the volute tongue on the fluid structure in different operating conditions. In addition, the damage of the volute tongue that performed on the impeller passage and blade is analyzed specifically. The mean value of the fluctuation in the passage and the load on the blade decreases about 2.5% and 3.3%, respectively, after the blade passes through the volute tongue. The spatiotemporal evolution provides a profound understanding of the flow characteristics of stall evolution within the centrifugal compressors.