Multidisciplinary Analysis Transient Flow Effects on the Impeller in a Semi-open Centrifugal Impeller Stage

摘要

Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady aerodynamic load on blades surface may be related to the blade fracture. This issue involves aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open impeller stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and aerodynamic load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high aerodynamic load on the impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open impeller stage of a centrifugal compressor.