Abstract
This study investigates the effect of radial clearance between the impeller and diffuser on the aerodynamic performance and internal flow in a centrifugal compressor with a large flow coefficient. Three different types of radial clearances were examined: D_3= 1.05 D_2, 1.10 D_2, and 1.15 D_2. Qualitative and quantitative analysis of the effect of radial clearance on the internal flow field of the centrifugal compressor impeller and vaned diffuser, utilizing a combination of time-averaged flow field and modal decomposition method. The results indicate that compared to a smaller impeller-diffuser radial clearance, a larger radial clearance reduces the operating range of the centrifugal compressor under low flow conditions. As a result, the stall (or surge) margin is reduced by at least 6.68%. The appropriate radial clearance in the centrifugal compressor stage can improve its flow adaptability at low mass flow rate conditions. The Proper Orthogonal Decomposition method and the flow field reconstruction technique are used to identify the spatial and temporal distribution of large-scale coherent flow structures in the impeller and diffuser near the shroud side, as well as the key factors contributing to unstable flow. The findings of this research enhance the understanding of flow loss and the mechanisms behind the unstable flow associated with radial clearance in centrifugal compressors.
NETL
NSTL
Springer Nature