Numerical Investigation On Centrifugal Compressor Based On CFX

In the modern society, the internal combustion engine has already been one of the most useful power generators from its invention. It is remarkable that the power and the efficiency of the engine have been greatly enhanced, as well as the exhaust emission of the engine has been reduced, which is due to the invention of turbocharger. As we know that the centrifugal compressor has wide application in the existing diesel engine turbocharger. Therefore it is of great significance to understand well the interior flow situation of the centrifugal compressor to design the high-performance air compressor and high-performance turbocharger.The numerical simulation of the flow field for the centrifugal compressor, which is used in turbocharger of certain marine diesel engine, has been carried out in this paper.The internal flow channel models for the compressor assembly are established by using Pro/E software according to the request of the drawing, then the structured grids are obtained by using ICEM-CFD software. And the three dimensional numerical simulation to the air compressor are carried out by using Computational Fluid Dynamics (CFD) software CFX, then the performance map for the centrifugal compressor and the rule of pressure and velocity for each component are obtained. Compared with the experimental data, the results of CFX method satisfies the basic requirement. Finally, the analysis of the flow situation for the gas in the flow passage of the Impeller, the Diffuser and the Volute at different working conditions are made, also the reasons for each kind of loss are analyzed.Because the flow in the passage of the diffuser is very poor, two optimizing strategies are given in this paper. Firstly, the entrance angle of the diffuser is changed, and the numerical computations for the flow field of the diffuser are performed without changing the blade. When we increase 5°than the original one, we will get better flow distribution. Secondly, for the serious separation in the diffuser, a new blade is designed. And we confirm that the gas separation has been reduced, and the isentropic efficiency has been raised by 3.88% and the pressure rate has been raised by 2.46%. The simulation above provide theory instruction for further optimization of this series turbocharger.