Combined Numerical and Experimental Investigation of a Centrifugal Compressor with Surge Supression Holes at the Impeller Hub

Abstract

Centrifugal compressor surge is a very dangerous phenomenon to the working environment of a compression system. Unfortunately, the most efficient working range is close to the boundary of stable operation and surge situation. One of the main aims of this research project is to find a solution which can help to operate centrifugal compressor close to the instabilities with a much higher level of safety. A numerical investigation was made to examine the flow field and the centrifugal compressor behaviour at the onset of surge conditions both when compressor discharge bleed air was set and when the bleed air valve was closed. With the help of the numerical investigation, the calculation of the flow field was calculated in every compressor impeller blade passage. In this way the development and the behavior of the injected bleed air to the main flow field in the impeller blade passages could be analyzed. The results of the numerical investigation was validated later with a test bench with the exact geometry of the numerical investigation.