Effect of vanned diffuser on a modified turbocharger centrifugal compressor performance

Abstract

A numerical study that was made in a three-dimensional flow, carried out in a modified centrifugal compressor, having vanned diffuser stage, used as an automotive turbo charger. In order to study the influence of vanned diffuser meridional outlet section with a different width ratio of the modified centrifugal compressor. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between the compressor impeller along the vanned diffuser. The aerodynamic characteristics were compared under different meridional width ratio. In addition, the velocity vectors in diffuser flow passages, and the secondary flow in cross-section near the outlet of diffuser were analyzed in detail under different meridional width ratio. Another aim of this research was to study and simulate the effect of vanned diffuser on the performance of a centrifugal compressor. The simulation was undertaken using commercial software so-called ANSYS CFX, to predict numerically the performance characteristics. The results were generated from CFD and were analyzed for better understanding of the fluid flow through centrifugal compressor stage and as a result of the minimum width ratio the flow in diffuser passage tends to be uniformity. Moreover, the backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Conclusively, it was observed that the efficiency was increased and both the total pressure ratio and static pressure for minimum width ratio are increased.