Unsteady flow around suction elbow and inlet guide vanes in a centrifugal compressor

Abstract

Suction elbow and inlet guide vanes (IGVs) are typical upstream components in front of the first-stage impeller in a centrifugal compressor. As the flow field in the front of the impeller is subsonic, the flow motion induced by the rotating impeller interacts with the elbow and IGVs. These interactions induce turbulent unsteady flows inside compressors. The resulting unsteadiness affects efficiency, vibration, and noise generation of the compressor. To understand the mechanism controlling the interactions between upstream components and to optimize the compressor design for better efficiency and reliability, the turbulent unsteady flow inside the first stage of the compressor was simulated. The model included the suction elbow, IGV housing, and firststage impeller. HFC 134a was used as the working fluid. The thermodynamic and transport properties of the refrigerant gas were modelled by the Martin-Hou equation of state and power laws, respectively. The three-dimensional unsteady flow field was numerically simulated. The overall performance parameters were obtained by integrating the field quantities. The force, torque, and the arm of moments acting on the IGVs were then calculated. The results can be used to design IGVs and their motion control system to achieve higher efficiency and improve reliability.